PHOTOPERIOD-INDUCED CHANGE IN RESPONSIVENESS OF THE HYPOTHALAMIC-PITUITARY AXIS TO EXOGENOUS 5-ALPHA-DIHYDROTESTOSTERONE AND 17-BETA-ESTRADIOL IN CASTRATED MALE HAMSTERS
PHOTOPERIOD-INDUCED CHANGE IN RESPONSIVENESS OF THE HYPOTHALAMIC-PITUITARY AXIS TO EXOGENOUS 5-ALPHA-DIHYDROTESTOSTERONE AND 17-BETA-ESTRADIOL IN CASTRATED MALE HAMSTERS
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DOI：
10.1159/000123075
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发表时间：
1980-01-01
影响因子：
4.1
通讯作者：
TUREK, FW
中科院分区：
文献类型：
--
作者：
ELLIS, GB;TUREK, FW
暴露在短日照下9周，阉割仓鼠的下丘脑-垂体轴对外源性睾酮的负反馈效应非常敏感。全身性和/或局部睾酮向5 - α的转化。-二氢睾酮（5. - dht）或17. --雌二醇（E2）被认为是作用于靶组织的重要步骤。结果表明，光周期可诱导下丘脑-垂体轴对5. α抑制作用的敏感性发生变化。-DHT或E2。5.α。- 2、4或8毫米长的填充dht的硅胶胶囊大大降低了暴露于非刺激性LD[光照和黑暗]8:16光周期的阉割动物血清LH [lutropin]和FSH[卵泡素]水平，但暴露于刺激性LD 14:10光周期的动物则没有。E2胶囊长度为1、2、4或8 mm，大大降低了暴露于ld8∶16的去势动物的血清LH和FSH水平，但在暴露于ld14∶10的动物中没有。血清促性腺激素水平在所有接受较大5. α的动物中都有所降低。-DHT（20或50毫米长）或E2（20毫米长）胶囊，不考虑光周期。因此，光周期可以改变促性腺激素控制中心对这两个负反馈效应的敏感性。-减少的睾酮衍生物，5。-DHT，以及睾酮的芳香化代谢物E2。除睾丸激素外，睾丸分泌物和/或睾丸激素向其代谢物的转化可能参与了仓鼠生殖系统的光周期抑制。
Exposure to short day lengths for 9 wk renders the hypothalamic-pituitary axis of the castrate hamster extremely responsive to the negative feedback effect of exogenous testosterone. The systemic and/or local conversion of testosterone to 5.alpha.-dihydrotestosterone (5.alpha.-DHT) or 17.beta.-estradiol (E2) is considered to be an important step in its action on target tissues. It was determined that the photoperiod can induce changes in the sensitivity of the hypothalamic-pituitary axis to the inhibitory effects of 5.alpha.-DHT or E2. 5.alpha.-DHT-filled Silastic capsules that were 2, 4 or 8 mm long greatly reduced serum LH [lutropin] and FSH [follitropin] levels in castrates that were exposed to a nonstimulatory LD [h of light and dark] 8:16 light cycle, but not in animals exposed to a stimulatory LD 14:10 light cycle. E2 capsules that were 1, 2, 4 or 8 mm long greatly reduced serum LH and FSH levels in castrates exposed to LD 8:16, but not in animals exposed to LD 14:10. Serum gonadotropin levels were reduced in all of the animals receiving the larger 5.alpha.-DHT (20 or 50 mm long) or E2 (20 mm long) capsules, irrespective of photoperiod. Thus, the photoperiod can alter the sensitivity of the gonadotropin control center to the negative feedback effect of both the 5.alpha.-reduced derivative of testosterone, 5.alpha.-DHT, and the aromatized metabolite of testosterone, E2. Testicular secretions besides testosterone and/or extratesticular conversion of testosterone to its metabolites may be involved in the photoperiodic inhibition of the hamster reproductive system.