Wilkes M M, Lu K H, Fulton S L, Yen S S
Adv Exp Med Biol. 1978;113:127-47. doi: 10.1007/978-1-4684-8893-7_8.
The neuroendocrine status of Long-Evans female rats was evaluated at several key stages of reproductive senescence. Young (4-8 mo), middle-aged (10-14 mo) and old (24-30 mo) animals were studied according to reproductive state. The reproductive states studied were (1) regularly cycling, (2) constant estrus and (3) pseudopregnant, as determined by vaginal smear cytology. Neuroendocrine parameters at the levels of the hypothalamus, pituitary and steroid-producing organs were compared between each group. DA3, E and NE concentrations in the median eminence of the hypothalamus were determined by a highly sensitive radioenzymatic assay. LRF content in the median eminence was measured by radioimmunoassay. Circulating levels of LH, FSH, PRL and six steroids were determined. Changes in hormone and neurotransmitter concentrations were deomonstrated in association with the various stages of reproductive senescence and with age advancement. These changes involved the hypothalamic, pitiutary and steroid systems. NE content in the median eminence, FSH in serum and circulating androstenedione were all significantly increased in middle-aged, cyclic rats prior to the onset of senescent anovulation. DA concentration in 24 mo. old constant estrous rats (30.7 +/- 7.7 pg/microgram, N = 6) and in 30 mo. old pseudopregnant rats (27.5 +/- 7.1 pg/microgram, N = 6) was significantly reduced compared to young (6 mo. old), cyclic controls on proestrous (55.0 +/- 4.7 pg/microgram, N = 12). This DA reduction was associated with a 3-fold increase in circulating prolactin. The results are discussed in terms of a regulatory cascade model of female reproductive senescence (Finch, 1976).
在生殖衰老的几个关键阶段对Long-Evans雌性大鼠的神经内分泌状态进行了评估。根据生殖状态对年轻（4-8个月）、中年（10-14个月）和老年（24-30个月）的动物进行研究。所研究的生殖状态包括：（1）规律发情周期；（2）持续发情；（3）假孕，通过阴道涂片细胞学检查确定。比较了每组下丘脑、垂体和类固醇生成器官水平的神经内分泌参数。采用高灵敏度放射酶法测定下丘脑正中隆起处的多巴胺（DA3）、雌二醇（E）和去甲肾上腺素（NE）浓度。通过放射免疫法测定正中隆起处的促性腺激素释放激素（LRF）含量。测定促黄体生成素（LH）、促卵泡生成素（FSH）、催乳素（PRL）和六种类固醇的循环水平。激素和神经递质浓度的变化与生殖衰老的各个阶段以及年龄增长相关。这些变化涉及下丘脑、垂体和类固醇系统。在中年、规律发情且尚未出现衰老性无排卵的大鼠中，正中隆起处的NE含量、血清中的FSH以及循环中的雄烯二酮均显著增加。与年轻（6个月）、处于发情前期的规律发情对照大鼠（55.0±4.7 pg/μg，N = 12）相比，24个月龄持续发情大鼠（30.7±7.7 pg/μg，N = 6）和30个月龄假孕大鼠（27.5±7.1 pg/μg，N = 6）的DA浓度显著降低。这种DA的降低与循环催乳素增加3倍有关。根据女性生殖衰老的调节级联模型（芬奇，1976年）对结果进行了讨论。
