Rubin B S, Elkind-Hirsch K, Bridges R S
Neurobiol Aging. 1985 Winter;6(4):309-15. doi: 10.1016/0197-4580(85)90009-0.
Hypothalamic LHRH was measured by RIA in young and middle-aged (MA) female rats in several endocrine conditions. Temporal alterations in LHRH content associated with the steroid induced gonadotropin surge were compared in medial basal hypothalamic and anterior hypothalamic-preoptic area fragments of ovariectomized young and MA subjects. LHRH content was also compared in ovariectomized, untreated subjects from the two age groups. Finally, LHRH content in MA constant estrous females was compared with content in young females on the morning of proestrus. In all conditions, LHRH levels in both brain regions of MA females were similar to, or significantly elevated above levels measured in young females, yet both the steroid induced surge and the castration induced hypersecretion of gonadotropins were markedly attenuated in aging females. Because studies have verified the responsiveness of the pituitary of MA rats to LHRH, the data suggest that adequate amounts of hypothalamic LHRH do not reach the pituitary. Rather, high levels of hypothalamic LHRH measured in MA subjects may represent accumulation of the peptide in LHRH neurons due to an age-related impairment in release.
采用放射免疫分析法（RIA）测定了处于几种内分泌状态下的年轻和中年雌性大鼠下丘脑促性腺激素释放激素（LHRH）水平。比较了去卵巢年轻和中年大鼠内侧基底部下丘脑及下丘脑前部-视前区片段中，与类固醇诱导的促性腺激素峰相关的LHRH含量的时间变化。还比较了两个年龄组去卵巢未处理大鼠的LHRH含量。最后，比较了中年持续发情雌性大鼠与年轻雌性大鼠在动情前期早晨的LHRH含量。在所有情况下，中年雌性大鼠两个脑区的LHRH水平与年轻雌性大鼠测得的水平相似，或显著高于年轻雌性大鼠的水平，然而，在衰老雌性大鼠中，类固醇诱导的峰和去势诱导的促性腺激素高分泌均明显减弱。由于研究已证实中年大鼠垂体对LHRH有反应性，因此数据表明，足够量的下丘脑LHRH未到达垂体。相反，在中年大鼠中测得的下丘脑LHRH高水平可能代表由于与年龄相关的释放受损，该肽在LHRH神经元中的积累。
