A Study On The Changes Of Reproductive Gland And Reproductive Endocrinology During The Wintering Period In Rana Dybowskii

Northeast brown frog(R dybowskii Guenther), formerly known as the northeast cluster of Chinese brown frog, Amphibia, Anura, Ranidae, frog, legally accepted as China’s second class of national animal protection, mainly distributed in Liaoning Province, Jilin Province and Heilongjiang province. Dry oviduct of Northeast brown frog commonly known as Oviductus Ranae, is a kind of rare medicinal material, with a variety of medicinal efficacy. Because of over harvesting and the seriously damaging of their living environments, wild resources of northeast brown frog are reducing increasingly. In order to meet the increasing demand of Oviductus Ranae and the protection of endangered species of wild resources, people began to try artificial breeding technology. For the development of artificial breeding of brown frog, in-depth knowledge of physical laws of brown frog must be available. The purpose of this paper is to study the physiology of gonad and subsidiary organs as well as reproductive hormone changes of the northeast forest frog throughout the wintering period, to understand the law of reproduction of Rana dybowskii in wintering period, for providing the scientific basis for further understanding and artificial breeding of Rana dybowskii.Experiment 1: from mid October to mid March of the next year, each of 6 acquisitions of 10 2 or 3-year old adult female and male northeast brown frogs were collected with interval of about 30 d, for weight determination of the gonads and accessory organs. The results showed that: no significant change(p>0.05) of testicular weight was found in the male northeast brown frogs during wintering period, the fat body in the late winter was significantly reduced(p<0.01). There were significant correlations between the testes and live body weight of male frogs(p<0.01), as well as fat body weight. Significantly negative correlation was found between fat body weight and wintering time(p<0.01) in male northeast brown frogs. Female northeast brown frogs fallopian tube in the wintering period did not change significantly(p>0.05), while, ovary weight significantly increased in late winter(p<0.01). Both the oviduct and ovarian weight were significantly and positively correlated(p<0.01) with the live body weight of female frogs. Significantly positive correlation was found between the weight of ovary and wintering time(p<0.01) in female northeast brown frogs.Experiment two: from November to March the next year, the interval of about 30 d, each of 5 acquisition of 10 female northeast brown frogs were applied for anatomy, moisture, crude fat, crude protein of the gonads and accessory organs was determined. The results showed that there were not significant difference(p<0.01) in moisture of ovarian and oviduct over wintering in female northeast brown frogs. The level of crude fat of fallopian tubes decreased significantly in the January sampling(p<0.01); the level of crude fat in ovary increased significantly in the late winter(p<0.05). Crude protein level of fallopian tubes was significantly lower in March(p<0.05), while, the level of crude protein in the ovary was decreased significantly in March(p<0.01).Experiment three: serum of both female, male frogs were collected with the acquisition of Experiment 2 for the determination of reproductive hormones by Elisa kits. Results showed that: the serum GnRH of northeast brown frogs decreased during the wintering period, and, GnRH in the serum of male frogs had bigger amplitude of change than females over the wintering period. Serum FSH showed a rising trend in the winter period. The highest serum FSH concentration of male frog occurred in February when sampling, the highest serum FSH concentration of female frogs was observed in March when sampling. LH increased at first and then decreased in male frogs in the wintering period, and serum LH of female frogs began to increase from the February sampling. The estrogen level of female northeast brown frogs was higher than serum progesterone level and their changing trends were in the opposite way. To the late winter, the estrogen level in serum of female northeast brown frogs reduced while the level of progesterone was elevated and exceeding the estrogen level. Serum androgen levels in male frogs increased first and then decreased, and to the end of winter, androgen level was recovered again.