Effects of cold exposure and hibernation on the liver, brown fat, and testes from golden hamsters.

Abstract

AbstractAdult, male hamsters, (Mesocricetus auratus, Waterhouse), were exposed to an environment of 5 C (2 months and 3 to 4 months) to investigate the effects of cold‐exposure and 2 to 5 days of hibernation on the following parameters: (1) body weights, (2) testes weights, (3) testes and brown fat histology and histochemistry, and (4) liver and brown fat mitochondrial succinate oxidation. Controls were maintained at room temperature. Only the hibernating animals lost a significant amount of weight during exposure. Although the testes regressed in both cold‐exposed and hibernating animals, the testes of hibernators showed some signs of recrudescence relative to the cold‐exposed non‐hibernators, as indicated by increased spermatogenic activity, slightly larger seminiferous tubules, greater organ weights, and the presence of PAS positive, diastase sensitive material. Brown fat in experimental animals had smaller and more numerous fat droplets per cell than the controls and nuclei which appeared to be more centrally located. Analysis of liver mitochondrial activity revealed the rate of succinate oxidation to be reduced in hibernators and increased in cold‐exposed non‐hibernators. Brown fat succinate oxidation was unaltered in both experimental groups. These results indicate that, early in the hibernation cycle, both physiological and morphological changes occur which distinguish hibernating hamsters from cold‐exposed hamsters which failed to hibernate.