Papers by Muhammad Aldhshan
Journal of the American Association for Laboratory Animal Science, 2018
Mice are the most commonly used laboratory animal species in research. 3,23 In their natural habi... more Mice are the most commonly used laboratory animal species in research. 3,23 In their natural habitat, a social patriarchal hierarchy is established in which the dominant male mouse defends its territory by scent marking, while other males become subordinates or escapees. 15,14,30 The ability of mice to escape or become submissive in aggressive interactions makes incidences of severe injury and deaths rare. 14 However, in laboratory settings, intermale aggression is an important animal welfare and experimental concern. When mice are unable to escape within their home cage, increased amounts of aggression can occur, some of which may result in severe wounds and even mortality. Aggression is a behavior commonly observed among grouphoused male laboratory mice and is defined as a violent or defensive behavior directed toward another conspecific. These agonistic behaviors consist of biting, chasing, pinning, threatening postures, and fighting and may lead to fight wounds that require medical treatment, separation leading to single housing, and even euthanasia in severe cases. 14,32 In general, aggression is demonstrated predominantly among males, although breeding females display postpartum maternal aggression when protecting their litters from intruders. In addition, the effects of aggression can lead to altered experimental data, such as increased corticosterone levels, decreased immune responses, and premature experimental endpoints. 7,22 In turn, the principle of animal reduction is compromised by the need to test additional subjects due to unanticipated losses. 13,14,18 Furthermore, some strains, such as SJL and FVB mice, are characterized by particularly high levels of aggression; due to these undesirable traits, investigators may be inclined to select female mice or other, more compatible strains for research experimentation to avoid issues associated with aggression. 1,14 Efforts to reduce aggression in group-housed male mice include transferring cotton squares during routine cage changes, decreasing housing density to 3 mice per cage, 30 and cohousing littermates or familiar conspecifics. 6,14,17,28 Similarly, various types of environmental enrichment items have been evaluated to mitigate agonistic interactions, including shelters, wheels, and toys. 12,26,27 Even though cotton squares have positive effects on decreasing intermale aggression, their efficacy may diminish as a long-lasting form of enrichment. 13 In addition, providing environment enhancements, such as shelters, may lower the incidence of aggression, 25 but they have also been shown to augment these behaviors. 10 Overall, the cited studies present conflicting evidence of whether particular practices or forms of environmental enrichment are effective in reducing aggression. Common husbandry and experimental practices, such as cage changing and extracting animals from the home cage for procedures, affect physiologic responses. 15,22 Although cage changes are an essential component of maintaining animal wellbeing,
International Journal of Molecular Sciences
Feeding-regulating neurotrophic factors are expressed in both neurons and glial cells. However, n... more Feeding-regulating neurotrophic factors are expressed in both neurons and glial cells. However, nutritional regulation of anorexigenic glial cell line-derived neurotrophic factor (GDNF) and orexigenic mesencephalic astrocyte-derived neurotrophic factor (MANF) expression in specific cell types remains poorly understood. Hypothalamic glucose sensing plays a critical role in the regulation of food intake. It has been theorized that local glucose concentration modulates microglial activity partially via glucose transporter 5 (GLUT5). We hypothesized that an increased local glucose concentration stimulates GDNF expression while inhibiting MANF expression in the hypothalamus and microglia via GLUT5. The present study investigated the effect of glucose on Gdnf and Manf mRNA expression in the mouse hypothalamus and murine microglial cell line SIM-A9. Intracerebroventricular glucose treatment significantly increased Gdnf mRNA levels in the hypothalamus without altering Manf mRNA levels. Expo...
Journal of the Endocrine Society, 2021
The hypothalamus controls food intake and metabolism by integrating nutrient and hormonal signals... more The hypothalamus controls food intake and metabolism by integrating nutrient and hormonal signals from peripheral tissues. Both central and peripheral administration of glucose leads to a reduction in food intake in rodents. Similarly, administration of the adipocyte hormone leptin or the gastrointestinal hormone xenin reduces food intake. In contrast, impairments in hypothalamic signaling of these factors cause hyperphagia and obesity in rodents and humans. Environmental factors affect behavior including feeding behavior and energy metabolism in rodents and humans. Studies have found that environmental enrichment (EE), in which mice interact with complex sensory and motor stimulation, led to a significant reduction in adiposity and resistance to diet-induced obesity in mice. This effect is independent of energy expenditure and is associated with enhanced hypothalamic signaling, but the exact mechanism is unknown. We hypothesized that EE potentiates the feeding suppressing effects o...
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Papers by Muhammad Aldhshan