Effect of post-weaning diet on hibernation occurrence in Syrian hamsters.

Mammalian hibernation is an adaptive strategy for surviving harsh cold seasons and food scarcity by suppressing the metabolic rate and thermogenesis. The Syrian hamster (Mesocricetus auratus) (hereafter termed as hamsters), a small mammalian hibernator, hibernates upon exposure to winter-like, short-photoperiod and cold (SP-Cold) conditions throughout a year in a laboratory, and therefore is a useful animal model obtained from a commercial breeder to study mechanisms of hibernation. However, the rates of hibernation occurrence often vary among experiments and facilities, the reason for which is largely unclear. Here we examined the effects of diet given to hamsters during post-weaning stages on hibernation occurrence. Hamsters fed either a high-nutrient (H) diet suitable for reproduction or a standard (STD) diet during the post-weaning period (from 3 or 4 weeks of age to sexual maturation) were exposed to winter-like conditions, and the occurrence of hibernation was assessed. Females showed a higher hibernation induction rate (over 80%) regardless of the post-weaning diet type than males. Approximately half (52%) of the males fed the STD diet from 3 weeks hibernated, whereas males fed the STD diet from 4 weeks or the H diet showed markedly lower hibernation induction rates (≤33%). These results suggest that female Syrian hamsters are more prone to hibernation than males and that the hibernation induction rate in male hamsters is influenced by diet during a critical developmental window between 3 and 4 weeks of age.