Introduction

Studies on structure and function of reproductive system of experimental animal by developing cold stress model have been getting attractions from researchers. The study on changes of reproductive system of offspring from experimental animal which had cold stress has been done in recent times.

Goal

Cold stress modeling in female experiment rats and, identifying the changes of stages of estrous cycle and reproductive hormone.

Materials and Methods

In order to identify stages of changes of reproductive hormone of experiment female rat which is model of cold stress, 90 Wistar breeding rats weight of 170-178 g were divided into following 6 groups: Non-gravid control group–15, gravid control group–15, non-gravid group for cold stress–15:15:15, gravid group for cold stress–15. Pathologic cold stress was modeled in 15:15:15 rats of non-gravid group for cold stress by putting in fridge everyday between 8 to 11 o’clock for 7:14:21 days and in 15 rats of gravid group for cold stress by putting in fridge (-150) every day between 8 to 11 o’clock for 28 to 30 days (Avcina AP(1989), Melovanov АP(1991)). Time to vaginal opening was determined to use method of Volkova OB in offspring of gravid experiment rats and control group after 2 months. After that selected 15 female offspring were put to sleep with ether and taken blood of 4-5 ml from their hearts and compared the amount of estradiol and progesterone in that blood using rat kits of Ausmausco Pharma with control group.

Result

Determining hormone level in blood of control group, estradiol is 4.73±0.45ng/l, progesterone is 2, 45±0,50ng/l. After a week pathologic cold stress was modeled in rats, estradiol is determined 3.93±0.70ng/l, progesterone is determined and after 2 weeks, estradiol is 4.0±0.53ng/l, progesterone is 1.97ng/l and after 3 weeks, estradiol is 3,8±0,63ng/l, progesterone is 1,94±0,09ng/l Birth weight of offspring from gravid rats with cold stress, was 1,6g (р=0,001) less than control group. Time to vaginal opening of offspring was 14 days later than control group. 

Determining hormone of control group offspring, estradiol is 4.53±0.51ng/l, progesterone is 2,39±0,40ng/l. Estradiol is 3.73±0,59.ng/l, progesterone is determined 1.97±0.07ng/l in offspring of gravid experiment rats.

Conclusion: 1. When develop cold stress model, gravid rats had miscarriage and preterm delivery and born low birth-weight offspring in 16-22 days of experiment and this reveals that pathologic changes occurred in sexual hormonal regulation of 3 groups of non-gravid rats of experiment because of cold stress. 3. In offspring from gravid rats which had cold stress time of vaginal opening was lengthened and estradiol and progesterone level was decreased in offspring from gravid rats and 

Key words: cold stress, rat, estradiol, progesterone

Pp. 28-30, Table 1, References 5

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