[Effects of cold exposure on estrous cycle of female C57BL/6 mice]

To study the effects of cold exposure on estrous cycle of female C57BL/6 mice.

Twelve healthy female C57BL/6 mice were randomly divided into two groups: control group and cold exposure group, 6 in each group. Cold exposure group was exposed to 4℃, 4 h per day, while control group stayed in normal conditions. Vaginal smears were used to observe the estrous cycle. After 2 weeks, blood and uteri were collected from each mouse after anesthetized and weighted. Serum levels of estradiol(E2), follicle-stimulating hormone(FSH), luteinizing hormone(LH), prolactin(Prl) and progesterone(P) were determined by using mouse ELISA kits. The uterus and ovary pathological slices were prepared to observe the structural changes.

Compared with the control group, body weight gain showed no significant differences (P＞0.05). The cold group had significant lower coefficients of uterus and the diestrus phase was significantly increased after cold exposure (P＜0.01). Serum level of FSH in cold group was higher and Prl was lower significantly (P＜0.01). Pathological examination of uterus and ovary showed that uterine glands of cold group were expanded and the amount of follicles was decreased significantly.

Cold exposure might increase mouse estrous cycle and affect their reproductive function.