Asian J. Adv. Basic Sci.: 2019, 7(1), 01-12
ISSN (Print): 2454 – 7492
ISSN (Online): 2347 – 4114
www.ajabs.org
Morphological and Skeletal Malformations Induced by Gabapentin in Rat
Fetuses and their Amelioration by Ginger
Gamal M. Badawy1, Marwa N. Atallah2*and Saber A. Sakr3
1
Associate Professor of Experimental Embryology, Zoology Department, Faculty of Science,
Menoufia University, EGYPT
2
Lecturer of Vertebrates, Comparative Anatomy and Embryology, Zoology Department,
Faculty of Science, Menoufia University, EGYPT
3
Late Professor of Histology, Zoology Department, Faculty of Science, Menoufia University, EGYPT
*
Correspondence: E-mail:
[email protected]
(Received 02 Jan, 2019; Accepted 10 Feb, 2019; Published 18 Feb, 2019)
ABSTRACT: The present study aimed to investigate the possible morphological and skeletal fetotoxicity of the new
antiepileptic drug, gabapentin (GBP) during the organogenesis phase of the rat embryonic development and to examine the possible ameliorative role of ginger (Zingiber officinale). Morphologically, there was evident growth retardation and a high frequency of malformations in the skin, head, trunk, limbs and tail of fetuses maternally injected with GBP. Skeletal investigation revealed that rat fetuses of the GBP group exhibited delayed ossification
and various skeletal malformation. Limb deformities was the most prominent feature observed followed by coastal
malformations, vertebral deformities, skull anomalies and sternal defects, respectively. The most evident skull malformation was maxillary and mandibular hypoplasia. Ginger extract caused an evident decrease in GBP-induced
fetotoxicity at the investigated parameters. In conclusion, treatment with GBP should be approached with highly
caution during pregnancy and ginger is recommended to be taken in parallel for its ameliorative role in this regard.
Keywords: Gabapentin; organogenesis; malformation; morphology; skeletal and ginger.
INTRODUCTION: Epilepsy is a commonly encountered serious chronic neurological problem which
affects millions of people worldwide. Due to relapsing
and severity of epilepsy, many women cannot stop
using medications even during pregnancy [1]. It is a
well-documented fact that teratogens affect the development of embryo, mostly during the process of organogenesis, which starts on GD 6 in rats and continues
to GD 15 [2]. Currently, management of epilepsy
mainly depends on antiepileptic drugs (AEDs), which
are notoriously known for their adverse side effects
and this explains the reason for their several generations. Infants of mothers treated with AEDs during
pregnancy were found to have a greater incidence of
congenital malformations than those of either normal
control or non-treated epileptic women [3]. Therefore,
it is strongly believed that AED therapy rather than
the maternal disease or convulsions are the cause of
malformations identified at birth [3]. It has been reported that AEDs should be chosen to be effective,
safe and free from fetal toxicity as possible as it can
[4].
larity as an adjunctive therapy for chronic pain [5].
There is a little information on the teratogenic effects
of GBP [6]. It has been labelled category C on the
basis of the adverse effects produced in rodent fetuses
[7]. Despite expanding data on the usage of GBP,
there is little information, so far, on its teratogenic
effects [8]. It is well known that AEDs belong to the
drugs which have traditionally been considered as
bone damaging [9]. Administration of AEDs may lead
to the development of osteomalacia or osteoporosis
[10]. Studies on rodents have shown that oral consumption of GBP caused delayed ossification of several bones in the skull, vertebral column, upper, and
lower limbs during the organogenesis period [8].
Traditionally, ginger has been applied for treating
colic, indigestion, stomach ulcers, rheumatism and
joint problems. Furthermore, ginger has anti-cancer,
anti-inflammatory properties as well as antinausea/vomiting properties [11]. Moreover, no toxic
effects on the morphology or endoskeleton of rat embryos maternally administered ginger were observed
[12]. Weidner and Sigwart [13] examined the effect of
oral administration of three different doses of ginger
extract to pregnant female rats from GD 6 to 15 and
Gabapentin (GBP) was originally introduced for the
treatment of epilepsy but has achieved greater popu-
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[(Asian J. Adv. Basic Sci.: 7(1), 2019, 01-12) Morphological and Skeletal Malformations Induced by Gabapentin in Rat…]
Embryotoxicity estimation: On GD 20, the pregnant
females were anaesthetized using ether and then sacrificed. A ventral incision in the abdomen was made,
and then the whole uterus was removed, weighed and
photographed. Fetuses were removed individually
from each horn and living fetuses were anaesthetized
by ether and examined grossly for investigating the
morphological abnormalities under a dissecting microscope. A total of 187 fetuses were included in the
present study. Embryotoxicity were initially assessed
morphologically by counting the number of implants,
live, resorbed and dead fetuses. Morphometric parameters were recorded. 59 of the fetuses were eviscerated and kept in 10 % formalin for detection of endoskeletal malformations.
found no signs of embryotoxicity. The present study
was designed to investigate the ameliorative role of
ginger against morphological and skeletal malformations induced by GBP in rat fetuses.
MATERIALS AND METHODS:
Animals and grouping: Principles of animal care and
use were carefully followed during the conducting of
all experiments. Healthy mature virgin females and
fertile males of Wistar albino rats (Rattus norvegicus),
weighing 135 ± 15g and aged 17 ± 1 weeks, were
obtained from Hellwan Animal Breeding Farm, Ministry of Health, Cairo, Egypt. Animals were kept in the
laboratory for at least one week before initiation of the
experiments for acclimatization. They were housed in
specially designed plastic rodent cages at Faculty of
Science, Menoufia University. They were maintained at
25 ± 2ºC in 12h light: 12h dark cycle. Free access of
water and standard diet composed of 50% ground
barely, 20% ground yellow maize, 20% milk and 10%
vegetables were supplied.
Investigated parameters:
Morphological parameters:
Mating was achieved by housing virgin females with
fertile males at a ratio of one male with two females
overnight. Females were checked daily in the morning
for the presence of a copulatory plug and the presence
of sperms in unstained native vaginal smears. Therefore, vaginal smears were carried out to give a precise
determination of the onset of gestation. The day at
which vaginal smear was positive has been considered
as day zero of pregnancy. Day 20 was determined as
the end point for experimentation. A total of 36 rats
were used for the present study. The pregnant rats
were divided into four groups, six rats each, as follows:
Control group, administrated distilled water.
Ginger group given oral injection of ginger (200
mg/kg).
Experimental GBP group given intraperitoneal
injection of GBP (162 mg/kg).
Crown-rump length: The crown rump length
(cm) of the fetuses of different groups was recorded.
Body weight: The weight (g) of the fetuses of
different groups was recorded.
Skeletal investigation: For endo-skeletal preparations, double staining technique was applied as described in a recent study emerged from our laboratory
[15].
Data evaluation and statistical analysis: All data
sets were expressed as mean ± standard error of the
mean (SEM). The data were analyzed statistically for
normal distribution (student’s T test) and homogeneity
of variances (Levene test) using statistical package of
social sciences (IBM SPSS) statistics software for
Windows, Version 22 (IBM Corp., Armonk, NY,
USA). Differences were considered insignificant
whenever P>0.05. The significances of the obtained
data were classified into three categories, i.e.
P<0.0001, P<0.001 and P<0.05 according to P values.
RESULTS AND DISCUSSION:
Morphological investigation:
Combined GBP and ginger injected group, received intraperitoneal injection of GBP first followed by oral injection of ginger one hour later.
Body weight gain of mothers: The differences in
mothers’ weight gain of control and experimental
groups are summarized in Figure (1). The dams that
were administered ginger exhibited a gradually progressive increase in body weight gain similar or even
more than that of the control group starting with 5.38
gm in GD 8 and ending with 64.70 gm in GD 20.
Contrarily, there was reduction in body weight gain of
GBP injected mothers just before the end of injection
at the GD 15 then the weight gain increased slowly
until GD 18 after which the body weight gradually
increased in lower values until GD 20 (-3.52, -1.93, -
GBP administration: GBP, with the trade name Gaptin, (Delta Pharma Company, Egypt) was employed
for the study. The applied dose was 162 mg/kg per day
during the organogenesis phase of gestation, i.e. starting on GD 6 and ending on GD 15 [7].
Water extraction of ginger: Fresh rhizomes of ginger
(Zingiber officinale) were purchased from a local
market at Shebeen El-Koom, Menoufia, Egypt and
processed as described in our previous study [14].
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It has been accepted that when embryos or fetuses
become maternally subjected to a potentially teratogenic agent, developmental alteration occurs due to
their interaction. The final result of this interaction can
lead to a number of abnormalities including morphological, skeletal, anatomical, delay in intrauterine
growth and development or even fetal death [15, 16].
Susceptibility of teratogenicity in an organism towards any teratogen depends on many factors such as
critical developmental stage at which the organisms
are exposed, the teratogen nature, the dose and route
of teratogen and also on the types of initiating mechanism of teratogenesis [17]. It has been known that
administration of higher dosages of old AEDs is associated with higher risks for anatomical teratogenesis
in the embryo [18]. However, there is no sufficient
knowledge concerning teratogenic effect of newer
AEDs and few studies have assisted their teratogenic
risks [18].
0.48, 5.23, 8.30, 13.83, 27.23 gm). The mothers of
GBP plus ginger group exhibited a gradual increase in
the body weights but in low values when compared
with the control group (3.72, 8.25, 11.07, 17.27,
25.98, 36.28, 47.50 gm).
M ot her weig ht ga in
Cont rol
70
Ginger
60
GBP
Weight (gm)
50
GBP+Gin
ger
40
30
20
10
0
-10
8
10
12
14
16
18
Padmanabhan et al. [19] observed much less weight
gain in mice mothers treated with vigabatrin. A study
of Etemad et al. [3] showed that pregabalin administration in mice decreased mother weight gain accompanied by reduced uterus weight. Morse et al. [20]
also showed that oral injection of pregabalin resulted
in reduced maternal body weight gain. The present
study revealed that pregnant mothers injected with
GBP during organogenesis exhibited a reduction in
the uterine weights, though the number of implantation sites and resorption of most fetuses from the different groups were similar to that of the control group.
Thus, changes in maternal weight gain in treated dams
could be due to an effect on the uterine compartment
rather than on the maternal weight.
20
Gestation Day
Figure 1: Graph showing changes in the body
weight gain of mothers in different groups.
Average weight of uteri: No significant difference
was recorded in fetal resorptions among different
groups. Table (1) shows the difference of uterus
weight in different groups. The average weight of the
uteri of pregnant rats injected with ginger only
showed insignificant difference (51.33±0.30) compared with control (52.03±0.28). On contrast, the average weight of uteri of pregnant rats injected with
GBP exhibited a highly significant decrease
(35.37±0.31) compared with that of the control group
(52.03±0.28). The average weight of uteri of pregnant
rats injected with both GBP and ginger exhibited a
low significant reduction (46.52±0.32) compared with
the control group and a highly significant increase
when compared with the GBP group (35.37±0.31).
Morphometric analysis: The reproductive toxicity
data from the control, ginger, GBP and GBP plus ginger injected groups are presented in Table (2). The
fetal growth parameters evaluated in this study were
fetal crown-rump length and body weight. The results
revealed that GBP led to proportionate intrauterine
growth retardation relative to the control group as it
affected the growth parameters of the fetuses with no
mortality. On the other hand, a marked improvement
in fetal growth parameters was recorded in fetuses
maternally injected with GBP and followed by ginger
compared with the GBP group.
Table 1: Weight of uteri of pregnant rats at the end
of experimentation, i.e. GD 20.
Groups
Average weight
of uteri
C%
Control
Ginger
GBP
52.03±0.28
51.33±0.30
35.37±0.31***
0%
-0.7 (-1.35%)
-16.66 (-32.02%)
GBP + ginger
46.52±0.32*c
-5.51 (-10.60%)
Fetal crown-rump length: As Table (2) shows, the
crown-rump length of fetuses exhibited insignificant
increase in ginger group compared with that of the
control group. The length of fetuses maternally injected with GBP displayed a significant shortening
compared with control group. On the other hand, the
fetuses maternally injected with GBP followed by
ginger displayed a significant increase in the length
C% = percentage of change compared with control; Asterisks (*-***) refer to the P values compared with the control group; c= highly significant (P<0.0001) compared with
GBP group; * P<0.05; *** P<0.0001
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There was a high frequency of malformations in the
skin, head, trunk, limbs and tail of fetuses of this
group (Table 3). Co-administration of GBP and ginger
resulted in an evident reduction in the incidence of the
malformations observed in GBP injected group (Table
3).
compared with GBP alone. This in return, led to a low
significant difference between GBP plus ginger group
when compared with the control group.
Fetal body weight: Table (2) illustrates the changes in
body weight of fetuses in both control and experimental groups. The fetuses of the control and maternally
ginger injected group had somewhat similar values
(5.47 ± 0.17; 5.32 ± 0.07 for the two, respectively).
There was a highly significant decrease in the body
weight of fetuses of the maternally GBP injected
group (3.53 ± 0.18). Administration of ginger after
GBP injection led to a marked amelioration of body
weight compared with fetuses of GBP group. This
significant amelioration of body weight led to a low
significant difference towards the control group.
Thin skin had the most prominent malformation in
fetuses of the GBP group and GBP plus ginger group
(36.1%; 14.8%, respectively) (Fig. 2C). Ear malformations came second in the incidence of teratogenic
abnormalities which was in the form of small (microtia) or absent (anotia) ear pinna (Fig. 2C, D & F)
(29.5%; 9.3% for the two groups, respectively). Subcutaneous hemorrhage was detected in the head and
hind limb regions (Fig. 2E & F) and came in the third
place (23%; 7.4% for fetuses maternally injected with
GBP individually or in combination with ginger, respectively). The investigation showed that about
21.3% of fetuses maternally injected with GBP and
5.6% of fetuses of combined GBP and ginger group
had malformed limbs. These deformities included
malrotation and delayed development in fore and hind
limbs which appeared as syndactyly, micromelia and
angulated (Fig. 2D-H). In some fetuses, the tail was
evidently malformed (19.7%; 7.4 for GBP and GBP
plus ginger injected groups, respectively). These deformities can be described as angulated and short tails
(Fig. 2I & J). Another common malformation observed was the evident backward deviation in normal
curvatures or kyphosis (Fig. 2C) occurred with incidence of 19.7% in fetuses of maternally injected GBP
group and 7.4% in fetuses of GBP and ginger coadministered mothers. Head malformations including
exencephaly (Fig. 2H) and unequal jaws or brachygnathia (Fig. 2D), where the snout was narrow and
pointed due to the small mandible, were clearly evident. About 18% and 4.9% of fetuses of mothers injected with GBP suffered from brachygnathia and
exencephaly, respectively, whereas only 3.7 % of
fetuses of combined GBP and ginger co-administered
mothers had brachygnathia and none of them had
exencephaly. Exomphalos was observed in fetuses of
GBP and combined GBP and ginger injected mothers
with incidence of 9.8% and 5.6%, respectively (Fig.
2K). Ginger extract caused an evident decrease in
GBP-induced embryotoxicity when given after GBP
injection. The fetuses of this group exhibited marked
improvement in terms of shape, size and length (Fig.
2L).
Marchi et al. [21] reported reduction in body weight
when lamotrigine was administered in rats at four
times the median effective dose during the organogenesis period. Offspring of lamotrigine treated rat demonstrated relatively lower length and body weight
[22]. Significant reduction in fetal body weight and an
increase in the frequency of intrauterine growth retardation (IUGR) were evident in mice fetuses prenatally
exposed to vigabatrin [23]. Fetal weight was significantly reduced when pregnant rats was administered
topiramate orally [24, 25]. Of the old generation,
AEDs, valproic acid was the most known drug to induce fetal growth retardation [26-28]. Decrease in
fetal body weight may be due to its lower mitotic
growth rate because of chemical administration to
embryos [29].
Table 2: Crown-rump length and body weight of
fetuses aged 20 days in different groups.
Groups
Control
Ginger
GBP
GBP + Ginger
Fetal Growth Parameters
Length
Weight
5.02 ± 0.06
5.47 ± 0.17
4.72 ± 0.05
5.32 ± 0.07
3.58 ± 0.05**
3.53 ± 0.18***
4.12 ± 0.05* b
4.93 ± 0.10* c
Data are represented as mean ± SEM; Asterisks (* - ** ***) refer to the P value compared with the control group;
c= highly significant (P<0.0001) compared with GBP
group; b= significant (P<0.001) compared with GBP
group; a= low significant (P<0.05) compared with GBP
group; * P< 0.05, ** P<0.001, *** P< 0.0001
Morphological abnormalities: Fetuses of control and
ginger injected mothers taken on the day of scarifying,
i.e. GD 20 displayed normal size, length and morphological appearance (Fig. 2A&B). However, there was
a low incidence of subcutaneous hemorrhage and thin
skin (2.6 %; 3% for the two groups, respectively)
(Table 3). On the other hand, various malformations
were detected in fetuses maternally injected with GBP.
These results were consistent with the work of Prakash et al. [7] in mice. Afshar et al. [8] found that
maternal injection of GBP during different stages of
pregnancy in mice caused brachygnathia, vertebral
column deformity, limb anomalies, exencephaly and
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[(Asian J. Adv. Basic Sci.: 7(1), 2019, 01-12) Morphological and Skeletal Malformations Induced by Gabapentin in Rat…]
Caudal abnormalities of the present study included
short or angulated tails. Treatment with valproic during pregnancy induced similar malformation in the
offspring who had reduced curled or kinked tails [34,
35]. The authors suggested that these tail abnormalities could be attributed to abnormal intrauterine position of the fetus. Deformities in vertebrae were another anomaly that appeared as abnormal curvatures
along the vertebral column like scoliosis. GBP is
known by its effect on the vertebral column curvature
and it was proved to induce such alterations in many
studies after its intraperitoneal injection in pregnant
mice with different doses during the organogenesis
period [6-8].
severe trunk malformations. Vigabatrin, which is also
a new AED similar to GBP, induced similar alterations
in mice fetuses [30].
The lack of skin wrinkled appearance which led to its
thinning was the most common morphological anomaly in the fetuses of the GBP group. This was also
observed in the study of Fadel et al. [31] who found
that maternal injection of diazepam during the organogenesis period induced loss of wrinkled appearance
of the skin in the growth-retarded rat fetuses. Akhtar
et al. [32] stated that valproic acid also is known to
have teratogenic effects on the development of skin.
Ear malformation was the second most observed malformation in the fetuses of the present study with
29.5% of the fetuses suffering from either anotia or
microtia. In a case study, Montouris et al. [33] found
that pregnant women who received GBP and lamotrigine during pregnancy had an incidence of having
infants with congenital malformation in the left external ear canal.
Brachygnathia was the most prevalent anomaly in
mice fetuses maternally injected with GBP [8]. However, in the present study only 18% of the fetuses suffered from this alteration. Exomphalos or umbilical
hernia was among the least GBP induced anomalies in
the fetuses. This was consistent with the study of Abdulrazzaq et al. [30] who found a significant incidence
of exomphalos in vigabatrin treated mice and attributed this to developmental defects in the abdominal
wall. Afshar et al. [8] recorded the presence of exencephaly in mice fetuses maternally subjected to GBP
during the first 15th days of gestation. Lamotrigine,
when orally administered to pregnant rats, was also
found to induce exencephaly in the offspring [22].
Subcutaneous hemorrhage came third in the overall
GBP induced gross malformations in the fetuses. Mohanty et al. [22] reported widespread of hemorrhages
in offspring maternally treated with lamotrigine. Limb
deformities were common in the fetuses maternally
injected with GBP which included malrotation, syndactyly, micromelia and angulated fore and hind
limbs. Prakash et al. [7] admitted that administration
of GBP to pregnant female mice during the midgestation period resulted in malrotated and rudimentary limbs of the fetuses. Similar results were observed
in mice fetuses maternally injected with GBP during
the first 10 or 15 days of pregnancy [6, 8]. In the
offspring of dams treated with topiramate or pregabalin during the period of organogenesis, the frequency
of limb malformations was increased [3, 25].
Endo- skeletal investigation: In developmental studies, the fetal skeleton is an important indicator of
embryonic development health and changes in skeletal
development commonly reflect changes in the maternal-fetal environment [36]. Fetuses maternally injected with GBP had various skeletal malformations
including mandibular hypoplasia, malformation in the
ribs and delayed ossification of the vertebrae, skull
and limbs. Table (4) summarizes the different skeletal
malformations in the fetuses of different groups.
Table 3: Percentage of fetuses with morphological abnormalities (%) recorded at the end of experimentation, i.e. GD 20 in different groups.
Groups
Malformation
Control
n=39
Ginger
n=33
GBP
n=61
GBP + Ginger
n=54
Thin skin
Ear malformations
Subcutaneous hemorrhage
Limb deformities
Tail abnormalities
Kyphosis
Brachygnathia
Exomphalos
Exencephaly
(1) 2.6%
0%
(1) 2.6 %
0%
0%
0%
0%
0%
0%
(1) 3%
0%
(1) 3 %
0%
0%
0%
0%
0%
0%
(22) 36.1%
(18) 29.5 %
(14) 23 %
(13) 21.3%
(12) 19.7%
(12) 19.7%
(11) 18 %
(6) 9.8%
(3) 4.9 %
(8) 14.8 %
(5) 9.3 %
(4) 7.4 %
(3) 5.6 %
(4) 7.4 %
(4) 7.4%
(2) 3.7 %
(3) 5.6%
0%
The percentage of every abnormality was calculated according to each group.
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la articulated at their proximal ends but were separated along two-thirds of their length by a wide cleft
and joined together distally. Femur, tibia, and fibula
were only partially ossified (diaphysis), while the
tarsal bones were in the shape of a cartilage draft and
stained blue. Ossification was determined to begin in
the diaphyses of the metatarsal bones. The proximal
and medial phalanges were yet completely cartilaginous in nature. The endo-skeletal elements were well
formed with no deformity and the ossification went on
a proximo-distal direction (Fig.3 A).
Ginger group: Comparing the skeleton of the fetuses
of the ginger group with that of the control group revealed no significant difference. The skull, vertebral
column, sternum, ribs and limbs showed normal skeletal structure and had the same degree of ossification
like that of the control group (Fig. 4 B).
GBP group: Fetuses maternally injected with GBP
showed various skeletal abnormalities (Table 4; Fig.
3C-K). Malformation of calvaria bones constituted
40.9% of the endo-skeletal malformations. The most
evident skull malformation was mandibular and maxillary hypoplasia (88.9% and 77.8%, respectively)
(Fig. 3C, G & H) followed by delayed ossification of
calvaria bones (Fig. 3C-F).
Figure 2: Photographs of representative fetuses
sacrificed on GD 20 showing (A) control, (B) ginger, (C-K) GBP and (L) GBP + ginger groups.
Control group: Examining the double stained endoskeletal system of the 20-day-old control fetuses revealed that most of the calvaria bones are well ossified. In particular, at the level of the sternum, just six
ossified parts (sternabrae) were visible. At the level of
the ribs, only the portions articulating with the vertebrae were ossified, while those connected to the sternum were cartilaginous. The vertebral column was
composed of number of vertebral segments, subdivided depending on their location and morphological
characteristics into 7 cervical (Cv), 13 thoracic (Tv), 6
lumbar (Lv), 5 sacral (Sv) and caudal (Cav) vertebrae
with variable number. Each vertebra was formed by a
ventral corpus, two lateral arches and by the dorsal
neural spine. Intervertebral discs and caudal vertebrae
were mostly cartilaginous in nature and therefore
stained blue. In some cases, however, the first twothree caudal vertebrae were partially ossified.
Vertebral column anomalies came in the third place
among the induced skeletal malformations. About
63.6% of fetuses showed vertebral defects. These
defects included kyphosis (50%, Fig. 3 G), abnormalities in the cervical arches, either non-fusion, absent
parts or delayed ossification of the arches (42.9%, Fig.
3 D, E, F, H & I), delayed or absent sacral vertebral
ossification (21.4%, Fig. 3 E, F & I). Malformations
of the ribs were the second most common skeletal
anomaly observed with incidence of 72.7% (Table 4).
The most prominent costal malformation was costal
separation (62.5%, Fig. 3 D, E, I & K). Other costal
defects included wavy ribs (18.8%, Fig. 4 H) as well
as costal curvature (18.8%, Fig. 3J). Delayed ossification of sternabrae was the only anomaly found in the
sternum with incidence of 36.4% (Fig. 3 C & K).
The anterior girdle was formed by the scapula and the
clavicle. The scapula possessed a red-stained main
body and a cartilaginous dorsal margin. Humerus,
radius and ulna were partially ossified. Commencement of the ossification of metacarpal bones was noticed in a proximo-distal direction. The rest of the
hand endoskeleton was still cartilage in nature.
Limb malformations were the most common skeletal
anomaly observed with incidence of 77.3% in fetuses
of GBP group (Table 4). The majority of limb malformation was higher in hind limb than the forelimb
(100% and 23.5%, respectively). There were no evident malformations in the stylopodial or zeugopodial
bones in the four groups, however, some fetuses had
defects in humerus bone (Fig. 3K). Some fetuses
showed decrease in the intensity of pelvic girdle as
well as femur, tibia and fibula ossification pattern
(Fig. 3 C&I). On the other hand, an evident delayed
ossification was observed in autopod and appeared
The pelvic girdle was composed of a dorsal ilium,
anterior pubis and posterior ischium. The ilium
formed the typical iliac crest and articulated with the
sacral vertebrae, fused together forming the sacral
bone. The femur was articulated proximally with the
pelvic girdle at the level of the acetabulum and distally with the tibia, fibula and the patella. Tibia and fibu-
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predominantly in the metacarpal and metatarsal bones.
Primary ossification centers in these bones and phalanges did not appear (Fig. 3 E & I).
days of pregnancy in mice resulted in mandibular
hypoplasia, malformations of calvaria and vertebral
column as well as delayed ossification, especially in
the metacarpal and metatarsal bones. In their study on
the effects of GBP on the endo-skeletal system of rat
fetuses, Singh et al. [37] reported that in utero exposure of GBP induced similar skeletal anomalies in
limbs and vertebrae of developing rat fetuses.
GBP + Ginger Group: Administration of GBP followed by ginger caused an evident decrease in the
skeletal malformations compared with the GBP group
(Fig. 3L). Skull anomalies were reduced to 23.1%
compared with the GBP group (Table 4).
Exposure to higher doses of pregabalin in animals
caused a reduction in ossification rate, but not dose
dependent [3, 20]. Mice and rats exposed to valproic
acid exhibited abnormal limbs including long bone
reductions and abnormal or missing digits [25, 27, 28,
38]. Similarly, rat fetuses maternally subjected to
intraperitoneal injection of phenytoin suffered from
deteriorated ossification of skull bones and costal
separation anomaly [2, 39].
Vertebral column deformities constituted 23.1% and
varied between kyphosis (66.7%), cervical arches
anomalies (33.3%) and thoracic and lumbar vertebral
defects (33.3%). Malformations of the ribs were decreased to 23.1% and were in the form of separated
ribs only (Fig. 3L). Only 15.4% of fetuses of this
group had delayed ossification of sternabrae (Table 4).
About 38.5% of fetuses of this group had limb malformations in the form of delayed ossification pattern,
especially in the hind limb with higher incidence in
the metatarsal and the phalangeal bones.
Probably, significant effects observed when administering GBP on GD 6 to GD 15 can be related to the
fact that, during days 9 and 10 of the rat embryogenesis, the mesoderm changes drastically. The formation
of the intraembryonic mesoderm and its differentiation in regions is fundamental for the formation of
cartilaginous and membranous structures that will be
the foundations for the skeletal system [40].
The present results are in agreement with the study of
Afshar and Golalipour [6] who found that intraperitoneal injection of GBP from GD 1 to GD 10 caused
delayed ossification in some bones of the skull, vertebral column, upper and lower limbs. Similar results
were reported by Afshar et al. [8] where maternal
intraperitoneal injection of GBP, during the first 15th
Table 4: Effect of GBP on the endoskeleton of the 20-day-old fetuses in different groups (Percentage %).
Groups
Endo-skeletal abnormality
Skull
Mandibular hypoplasia
Maxillary hypoplasia
Delayed ossification
Vertebral column
Kyphosis
Cervical vertebrae
Thoracic and lumbar vertebrae
Sacral vertebrae
Control
n= 13
0%
0%
Ginger
n= 11
GBP
n=22
GBP + Ginger
n= 13
0%
(9) 40.9%
(8) 88.9%
(7) 77.8%
(5) 55.6%
(3) 23.1%
(1) 33.3%
(1) 33.3%
(3) 100%
0%
(14) 63.6%
(7) 50%
(6) 42.9%
(3) 21.4%
(3) 21.4%
(3) 23.1%
(2) 66.7%
(1) 33.3%
(1) 33.3%
0%
(3) 23.1%
(3) 100%
0%
0%
Ribs
Separated
curved
Wavy
0%
0%
(16) 72.7%
(10) 62.5%
(3) 18.8%
(3) 18.8%
Sternum
0%
0%
(8) 36.4%
(2) 15.4%
Limb malformations
Fore limb
Hind limb
0%
0%
(17) 77.3%
(4) 23.5%
(17) 100%
(5) 38.5%
(1) 20%
(5) 100%
7
[(Asian J. Adv. Basic Sci.: 7(1), 2019, 01-12) Morphological and Skeletal Malformations Induced by Gabapentin in Rat…]
Similar results were obtained when measuring the
lengths of ossification centers in the long bones of
hind limbs (femur, fibula and tibia). The control and
ginger groups showed the highest lengths with insignificant difference between the two groups, femur
(0.28±0.013 cm and 0.26±0.014 cm), fibula
(0.32±0.015 cm and 0.31±0.010 cm) and tibia
(0.37±0.011 cm and 0.35±0.016 cm) for the control
and ginger groups, respectively. The lengths showed
statistically high significant decrease in the GBP
group when compared with the control group
(0.19±0.004 cm, 0.15±0.009 cm and 0.20±0.004 cm
for femur, fibula and tibia, respectively). The lengths
of the ossification centers increased in the combined
group and showed low significant difference compared with control and low (femur) and high (fibula
and tibia) significant difference when compared with
GBP group (0.23±0.013 cm, 0.28±0.006 cm and
0.29±0.005 cm for the three bones).
Administration of vigabatrin and valproic acid to 4week old rat pups led to decrease in the mass, length
and diameter of the isolated bones in comparison with
the control rats [10]. Injection with phenobarbital also
led to reduction in the length of the ulna, radius, tibia
and phalanges as shown in the study of Yan et al. [41].
Numerous studies suggest that patients treated with
AEDs may be at an increased risk for bone disease
including changes in bone turnover, osteoporosis,
alterations in bone quality, and fracture [42].
Figure 3: Photographs of the endo-skeletal system
of double stained 20-day-old fetuses of control (A)
ginger (B), GBP (C-K) and GBP + ginger (L)
groups. All lateral view except K. Scale bar = 1 cm.
Along with different skeletal defects, the present study
showed reduced length of the ossified parts of long
bones of fore and hind limbs in the fetuses injected
with GBP during the organogenesis period. The
lengths of ossification parts of the long bones (humerus, radius, ulna, femur, tibia and fibula) in the four
groups were demonstrated in Figure (4). The mean
length of the ossified part of the fore limb bones was
quite similar in both the control and ginger groups and
showed the highest values with no significant difference in-between, humerus (0.37±0.011 cm and
0.36±0.007 cm), radius (0.27±0.013 cm and
0.27±0.010 cm), ulna (0.38±0.012 cm, 0.38±0.011
cm) for the control and ginger groups, respectively.
Conversely, GBP group showed the lowest values for
the lengths of ossification centers in the fore limb long
bones with a highly significant difference compared
with that of the control (0.29±0.005 cm, 0.18±0.005
cm and 0.21±0.005 cm, for humerus, radius and ulna,
respectively). Co-administration of ginger after GBP
injection resulted in no significant difference (in case
of humerus) or low significant difference (in case of
radius and ulna) between the control group, while it
showed low (humerus) and high (radius and ulna)
significant difference when compared with GBP group
with overall moderate amelioration in the lengths of
ossification centers in fore limb long bones
(0.33±0.010 cm, 0.22±0.004 cm and 0.31±0.009 cm
for the three bones).
Yan et al. [41] assumed two possibilities to give rise to
the shortened length of long bones. First is the small
cartilage template induced by treatment as it has been
proven that the formation of a proper cartilage model
is a prerequisite for normal endochondral ossification
[43]. The other possible explanation for the shorter
long bones is that the process of mineralization was
defective due to AED treatment which causes the
blockage of calcium channels, and eventually leads to
a loss in bone mineral density [44].
It has been emphasized that one of the main mechanisms of teratogenic action which affects ossification is
oxidative stress [27]. Prenatal bone development is
known to be sensitive to many environmental conditions, which may negatively impact fetal skeletal development [45]. Adverse events during the rapid development of the appendicular skeletal during midgestation can result in reduced neonatal size, weight
and growth rates [46]. Changes in prenatal bone
health and fetal osteogenesis have been positively
correlated with excessively elevated reactive oxygen
species (ROS) that may lead to improper skeletal formation [47, 48]. The embryonic and fetal development
periods are believed to be extremely sensitive to high
levels of ROS in part because effective free radical
8
[(Asian J. Adv. Basic Sci.: 7(1), 2019, 01-12) Morphological and Skeletal Malformations Induced by Gabapentin in Rat…]
the occurrence of malformations as a consequence of
xenobiotics exposure during development [51]. In line
with the use of antioxidant and folic acid therapy for
reduction of the frequency and severity of AEDinduced teratogenic effects, it was found that concomitant vitamin E administration significantly attenuated valproic acid and phenytoin induced decrease
in crown-rump length, fetal weight and malformations
[26, 28, 39]. The study of Abd El-Aziz et al. [36]
showed that the co-administration of vitamin E with
MeHg was also associated with an improvement in the
fetal crown-rump length, body weight, head length,
and biparietal diameter of the rat fetuses. The study of
Abou-El-Naga [52] on pregnant mice injected with
polycyclic hydrocarbons and curcumin from the GD 6
till the parturition showed improved neonatal growth
retardation and reduced malformation rate.
scavenging systems are not yet fully developed [27].
Tung and Winn [49] experimentally found valproic
acid exposure resulted in increased ROS levels and
attributed developmental defects in head and neck
region to these increased ROS levels.
Combined treatment of ginger and GBP in the present
study resulted in increased mother weight gain and
greatly diminished the deleterious effects of GBP.
This finding agrees with many studies which prove
the ability of ginger in regaining body weight loss.
Gastric intubation of different doses of ginger from
GD 6 to GD 15 didn’t affect the maternal body weight
gain in rats [13]. Several reports indicated the effectiveness of ginger in the protection against characteristic diabetic weight loss in rats as there was highly
significant increase in their body weight when compared with that of the diabetic non-treated groups [50]
and they attributed this effect to the hypoglycemic
potential of ginger.
0.45
All of the above mentioned ameliorative and protective effects of ginger could be attributed to its antioxidant properties. Several studies reported that ginger
was demonstrated to be a strong antioxidant [53]. Its
antioxidant activity has been attributed to its major
active phenolic ingredients, especially, 6-gingerol, 8gingerol, 10-gingerol, and 6-shogaol [54]. In addition,
the administration of ginger has been shown to improve oxidative stress by decreasing lipid peroxidation
and protein oxidation as free radical generating
sources and elevating the levels of enzymes implicated in the antioxidant defense [55]. The increase in
body weight gain following ginger treatment may be
explained by the fact that ginger contains vitamin A
which contributes to regulation of body growth and fat
reserves. It also contains vitamin B6 which can result
in body weight gain by intensification of the protein
synthesis [56].
Fetal length of long bones ossification
centers
0.4
Length (cm)
0.35
0.3
a
***
*c
*c
*c
***
0.25
0.2
*a
***
***
*c
***
***
0.15
0.1
0.05
0
Cont rol
Ginger
GBP
GBP+Ginger
In the current study, administration of ginger after
GBP during the organogenesis phase of the rat embryonic development was associated with decrease
and improvement of skeletal malformation and increase in ossification at various level in the whole
endoskeleton together with improvements in the
lengths of long bones of both fore- and hind-limbs in
the fetuses towards the control figures. In support of
the present results, some in vivo and in vitro studies
showed the ability of ginger to increase bone ossification and reduce bone turnover. Ginger administration
was found to cause improvements in bone microarchitectures and structure and decrease the osteoporotic
changes in femur diaphysis and metaphysis caused by
cadmium chloride and bilateral ovariectomy in the
study of Mustafa et al. [57]. The authors explained
this ameliorating effect of ginger and improvement in
bone structure to be related to the antioxidant characters of ginger, as well as its bone protection against
Figure 4: Graph showing the effects of maternal
GBP administration on the lengths of ossification
centers of the long bones in 20-day-old fetuses.
Administration of ginger also ameliorated the fetal
toxic effect of GBP during pregnancy evidenced by
reduced the morphological abnormalities and growth
retardation of the fetuses. These data are in accordance with many other investigations on the effect of
ginger during pregnancy. Weidner and Sigwart [13]
reported that no significant differences were seen in
fetal body weight, the external, the skeletal or visceral
examination of the fetuses maternally treated with
ginger in doses up to 1000 mg/kg body weight during
mid gestation.
Related studies have indicated that antioxidant treatments can prevent or reduce growth retardation and/or
9
[(Asian J. Adv. Basic Sci.: 7(1), 2019, 01-12) Morphological and Skeletal Malformations Induced by Gabapentin in Rat…]
7. Prakash, Prabhu, L., Rai, R., Pai, M., Yadav, S.,
Madhyastha, S., Goel, R., Singh, G. & Nasar, M.
(2008) Teratogenic effects of the anticonvulsant
gabapentin in mice, Singapore Med J., 49, 47-53.
8. Afshar, M., Hassanzadeh-Taheri, M., Moallem,
S. A., Tamizi, A., & Golalipour, M. (2009) Teratogenic effects of gabapentin on the skeletal system of Balb/C mice fetuses, Neurosciences, 14,
239-244.
9. Mazziotti, G., Canalis, E. & Giustina, A. (2010)
Drug-induced osteoporosis: mechanisms and
clinical implications, Am J Med, 123, 877-884.
10. Nowińska, B., Folwarczna, J., Dusiło, A., Pytlik,
M., Śliwiński, L., Cegieła, U., KaczmarczykSedlak, I., Pietryka, W., Hanke, T. & Trzeciak, H.
(2012) Effects of vigabatrin on the skeletal system of young rats, Acta Poloniae PharmaceuticaDrug Research, 69, 327-334.
11. Young, H., Luo, Y., Cheng, H. & Hsieh, W.
(2005) Analgesic and anti-inflammatory activities
of [6]- gingerol, J Ethnopharmacol, 96, 207-210.
12. Wilkinson, J. (2000) Effect of ginger tea on the
fetal development of Sprague-Dawley rats, Reprod Toxicol, 14, 507-512.
13. Weidner, M. & Sigwart, K. (2001) Investigation
of the teratogenic potential of a Zingiber
officinale extract in the rat, Reproductive Toxicology, 15, 75-80.
14. Badawy, G., Atallah, M. & Sakr, S. (2019) The
ameliorative role of ginger administration against
gabapentin-induced hepatotoxicity in rat fetuses,
ejpmr, 6 (1), 622-631.
15. Badawy, G., Sakr, S., & El-Borm, H. (2018) The
ameliorative role of curcumin on the morphological and skeletal malformations induced by betamethasone in rat fetuses, Egypt J Exp Biol (Zoo),
14 (1): 53 – 68.
16. García-Peláez, I., Aguirre-Luna, O., SaavedraOntiveros, D. & Arteaga-Martínez, M. (2010) Teratogenic effect of ethylene glycol-methyl cellosolve mixture in rats. II. Craniofacial and limb
abnormalities, Int J Morphol, 28, 1173-1180.
17. Bhaskar, N., Shahani, L. & Bhatnagar, P. (2014)
Morphological and skeletal abnormalities induced by commercially available insecticides colonel-s-« and decis-« in the developing embryo
of Gallus domesticus, Int J Pharm Sci Rev Res,
26, 140-148.
18. Meador, K., Penovich, P., Baker, G., Pennel, P.,
Bromfield, E., Pack, A., Liporace, J., Sam, M.,
Kalayjian, L., Thurman, D., Moore, E. & Loring
D. (2009) Antiepileptic drug use in women of
childbearing age, Epilepsy Behav., 15, 339-343.
19. Padmanabhan, R., Abdulrazzaq, Y., Bastaki, S. &
Nurulain, M. (2010) Vigabatrin (VGB) adminis-
oxidative damage induced by cadmium. The ameliorative effect of ginger observed in the present study
pointed to its high antioxidant ability.
CONCLUSION: In the light of morphological and
endo-skeletal outcome it can be concluded that administration of gabapentin during rat organogenesis was
found to have adverse side effects on the gross morphology, morphometric parameters and endoskeleton.
On the other hand, co-administration of ginger improved these adverse effects. Therefore, treatment
with gabapentin should be restricted to the necessity
and in such cases, ginger should be taken in parallel.
The evident effect of ginger demonstrated in this
study is possibly related to its antioxidant and free
radical-scavenging properties. The outcome of the
present study called for more investigation regarding
the mechanism of action of ginger.
Abbreviations: AED, anti-epileptic drugs; At, atlas;
Ax, axis; C, carpus; Cav, caudal vertebrae; Cl, clavicle; Cv, cervical vertebrae; Cor, cornified cells; Eo,
exoccipital; Ep, epithelial cells; F, frontal; Fe, femur;
Fi, fibula; GBP, gabapentin; GD, gestation day; Hu,
humerus; Hy, hyoid; Il, Ilium; Ip, interparietal; Is,
ischium; Le, leukocytes; Lv, lumbar vertebrae; Mc,
metacarpus; Mn, mandible; Mt, metatarsus; N, nasal;
Pa, parietal; Ph, phalanges; Pre-M, premaxilla; R,
radius; Ri, ribs; S, squamosal; Sc, scapula; SEM,
standard error of the mean; So, supraoccipital; St,
sternum; Sv, sacral vertebrae; T, Tympanic; Ta, tarsus;
Ti, tibia; Tv, thoracic vertebrae; U, ulna; XP, xiphoid
process; Zy, zygomatic.
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12