Matt D W, Tedeschi M L, Sayles T E
Department of Obstetrics and Gynecology, Medical College of Virginia, Richmond 23298-0034, USA.
Neuroendocrinology. 1992 Dec;56(6):780-7. doi: 10.1159/000126308.
During aging female rats enter an anovulatory condition with chronically elevated circulating levels of estrogen described as persistent estrus (PE). Since this endocrine state is dramatically different from the fluctuating steroid milieu of young regularly cycling females, interpretations of altered neuroendocrine responses in aged rats have been difficult to attribute to aging per se. In the present study, young cyclic and middle-aged PE rats were treated with an LHRH agonist, [DTrp6,Pro9-NHEt]-LHRH, continuously (2.5 micrograms/h) for 12 days to suppress gonadotropin and ovarian steroid secretion. On the evening of the first day of LHRH agonist (LHRH-AG) treatment both young cyclic and middle-aged PE rats showed marked (p < 0.01) increases in plasma LH and FSH followed by progressive decreases in gonadotropin secretion which reached significantly (p < 0.05) lower levels than pretreatment values by day 7. LHRH-AG treatment significantly (p < 0.01) reduced circulating 17 beta-estradiol (E2) levels in both young and PE rats while progesterone concentrations did not change. Following LHRH-AG treatment, ovariectomy (OVX) resulted in increases of plasma LH and FSH that were delayed and attenuated in PE rats as compared to those of young females. When compared to nontreated rats, 12 days of LHRH-AG treatment in both young and PE females had a minimal and transient effect on the post-OVX gonadotropin responses, suggesting that the endocrine status immediately prior to OVX does not profoundly influence the post-OVX responses in young cyclic and middle-aged PE rats. Furthermore, LHRH-AG treatment does not appear to have permanent inhibitory effects on the hypothalamic-pituitary axis.(ABSTRACT TRUNCATED AT 250 WORDS)
在衰老过程中，雌性大鼠会进入一种无排卵状态，其循环雌激素水平持续升高，被称为持续性发情（PE）。由于这种内分泌状态与年轻的规律发情雌性大鼠波动的类固醇环境截然不同，因此很难将老年大鼠神经内分泌反应的改变单纯归因于衰老本身。在本研究中，对年轻的发情期和中年的PE大鼠连续12天（2.5微克/小时）给予促性腺激素释放激素（LHRH）激动剂[DTrp6,Pro9-NHEt]-LHRH，以抑制促性腺激素和卵巢类固醇分泌。在LHRH激动剂（LHRH-AG）治疗的第一天晚上，年轻的发情期和中年的PE大鼠血浆促黄体生成素（LH）和促卵泡生成素（FSH）均显著（p < 0.01）升高，随后促性腺激素分泌逐渐下降，到第7天时显著（p < 0.05）低于预处理值。LHRH-AG治疗显著（p < 0.01）降低了年轻和PE大鼠的循环17β-雌二醇（E2）水平，而孕酮浓度未发生变化。LHRH-AG治疗后，卵巢切除术（OVX）导致血浆LH和FSH升高，与年轻雌性大鼠相比，PE大鼠的升高出现延迟且减弱。与未治疗的大鼠相比，年轻和PE雌性大鼠接受12天的LHRH-AG治疗对OVX后的促性腺激素反应影响最小且短暂，这表明OVX前的内分泌状态对年轻的发情期和中年的PE大鼠的OVX后反应没有深远影响。此外，LHRH-AG治疗似乎对下丘脑-垂体轴没有永久性抑制作用。（摘要截短于250字）
