1. 1.|The migratroy hamster Cricetulus migratorius, a small nocturnal rodent, inhabits ecosystems characterized by dramatic seasonal fluctuations of ambient temperatures. The aim of this study was to assess seasonal acclimatization of its thermoregulatory system.
2. 2.|Heat production by means of oxygen consumption and body temperature in various ambient temperatures as well as non-shivering thermogenesis were measured in C. migratorius. The hamsters were acclimated to two different photoperiod regimes (16L:8D and 8L:16D) at a constant ambient temprature of 24°C. Overall thermal conductance was calculated for such hamsters.
3. 3.|The results of this study indicate that photoperiod manipulations adjust the thermoregulatory system of the migratory hamster mainly by affecting overall thermal conductance.
As a solitary species, rat-like hamsters (Cricetulus triton) still live in family groups before they become mature and leave their families for a solitary life. This study aimed to investigate by a laboratory experiment if housing conditions have a different effect on physiological aspects of immature and mature females. We found that paired caged adult females became significantly heavier than their original weights; whereas the singly caged did not show significant change in their body weight. Although the subadults body weights increased significantly compared to their initial weights in both paired or singly caged groups, significant changes in body weight did not occur between the two groups. Although spleen and adrenal gland sizes were not significantly different between the two adult groups, the cortisol levels were significantly elevated by paired caging. In subadults, the adrenal size of the singly caged group was larger than that in the paired caged group despite there being no significant difference in cortisol level. Flank glands became significantly larger in paired caged adults than in singly caged adults, and there were no significant differences in subadults between the two groups. Additionally, ovaries and uteri of the paired caged adult females were comparatively lighter than those of the singly caged group; in contrast, ovaries and uteri of the paired caged group were larger than those of the singly caged group in subadults, although progesterone and estradiol levels did not show significant differences between the two adult groups. These different changes in physiological traits caused by housing conditions indicated that paired caging depressed adults and facilitated subadults; isolation facilitated adults and depressed subadults. 相似文献