Developing a Model of Vitamin A Deficiency in a Hibernating Mammal, the 13-Lined Ground Squirrel (Ictidomys tridecemlineatus)

Abstract

Retinoic acid, a bioactive metabolite of vitamin A, plays key roles in immune function and vision and adipose tissue development. Our goal was to study the effect of vitamin A deficiency in physiologic changes seen in hibernating 13-lined ground squirrels (Ictidomys tridecemlineatus). In this study, we first developed a model of vitamin A deficiency that was based on published mouse models; we then examined the role of RA in the circannual cycle of and adipose accumulation in this hibernating species. Gravid female ground squirrels began consuming a deficient diet during the last 2 wk of their 4-wk gestation; pups received the diet until they were 8 wk old, when severe symptoms of hypovitaminosis were observed, requiring the animals' removal from the protocol. Body size and adipose mass were significantly lower in vitamin-deficient pups than controls. To avoid these complications, we developed a second model, in which pups started on the deficient diet after weaning. The revised model produced few symptoms of deficiency, and squirrels were able to remain on the diet through spring emergence. Liver retinol analysis showed that deficient squirrels essentially had no vitamin A stores. Our data suggest that 13-lined ground squirrels maintain higher concentrations of stored retinol than other rodent species, such that their dietary needs may differ from those of traditional laboratory rodent models. Our results indicate that ground squirrels are especially susceptible to vitamin A deficiency, and ground squirrels should not be fed a deficient diet until after weaning, to avoid severe symptoms. Interestingly, vitamin A deficiency does not seem to affect this species' ability to hibernate successfully.

Comparative transcriptomics of the Djungarian hamster hypothalamus during short photoperiod acclimation and spontaneous torpor

“…This enzyme is important for vision. It does not only play a role in the retina, but also play a role in other tissues to metabolize vitamin A [60,61]. In the photoperiodic context, retinoic acid-signaling genes were reported to be differentially regulated within the hypothalamus and may play a role in body mass regulation and energy metabolism [62,63].…”

Remodeling of skeletal muscle myosin metabolic states in hibernating mammals

“…For instance, small (<8 kg) fat-storing hibernating mammals such as 13-lined ground squirrels ( Ictidomys tridecemlineatus ) or garden dormice ( Eliomys quercinus ) experience extended bouts of a hypo-metabolic state (torpor), punctuated by spontaneous periods of interbout euthermic arousals (IBA), during which metabolic activity transiently increases back to basal levels. During torpor, metabolic rate decreases below 5% of euthermic values and core body temperatures decrease from 35°C–38°C to 4°C–8°C ( Sprenger et al, 2018 ; Haugg et al, 2024 ). In contrast, either medium (10–20 kg, e.g.…”

Vitamins a and E Content in the Tissues of the Bank Vole (Myodes (Clethrionomys) Glareolus) and Common Shrew (Sorex Araneus) Inhabiting in Karelia

“…Витамины A и E играют важную роль в метаболизме, характеризуются разносторонними физиологическими эффектами и биохимическим действием и являются низкомолекулярными антиоксидантами. Витамин A имеет особое значение в процессе восприятия света, необходим для нормального развития плода, а также влияет на процесс увеличения белой и бурой жировых тканей, имеющих важное значение для благополучной зимовки млекопитающих [10,11]. Витамин E в организме выполняет роль основного биологического антиоксиданта, является регулятором энергетического метаболизма [12].…”