Moreno A S, Franci C R
Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14049-900 Ribeirão Preto--SP, Brazil.
Life Sci. 2004 Mar 5;74(16):2049-59. doi: 10.1016/j.lfs.2003.09.049.
Several substances work as neuromediators of the estrogen direct and indirect (through glial cells or interneurons) action on luteinizing hormone- releasing hormone (LH-RH) neurons in medial basal hypothalamus and medial preoptic area (MPOA). Angiotensin II (AII) in the MPOA stimulates the LH and it inhibits PRL secretion in some situations. On the other hand, the effect of excitatory amino acids on LH and PRL surges during proestrus as well LH surge induced by steroids depend on nitric oxide (NO). In the present study we investigated the participation of MPOA endogenous NO on gonadotropin and PRL secretion mediated by estrogen and AII. Plasma LH, FSH and PRL was determinated in estrogen primed and unprimed ovariectomized Wistar rats that received microinjection of AII or saline into the MPOA, associated or not with a previous microinjection of an inhibitor for NOS. Our results show the following: 1 - there was no change in plasma FSH in estrogen- primed or unprimed ovarictomized related with microinjections of AII or NO antagonist in the MPOA; 2- the increase in LH secretion after ovariectomy depends on, at least in part, NO activity in the MPOA; 3- estrogen may have an indirect negative feedback action on LH-RH neurons in the MPOA through NO; 4- the stimulatory action of AII in the MPOA on LH secretion in ovariectomized rats treated with estrogen depends on NO; 5 - NO in the MPOA stimulates or inhibits PRL secretion depending on the absence or presence of estrogen, respectively; 6- the inhibitory action of AII into the MPOA on PRL secretion does not seem to depend on NO.
几种物质作为雌激素对内侧基底下丘脑和内侧视前区（MPOA）中促黄体生成素释放激素（LH-RH）神经元的直接和间接（通过神经胶质细胞或中间神经元）作用的神经介质。MPOA中的血管紧张素II（AII）刺激LH，并且在某些情况下抑制PRL分泌。另一方面，发情前期兴奋性氨基酸对LH和PRL激增的影响以及类固醇诱导的LH激增取决于一氧化氮（NO）。在本研究中，我们调查了MPOA内源性NO在雌激素和AII介导的促性腺激素和PRL分泌中的作用。在接受向MPOA微量注射AII或生理盐水的雌激素预处理和未预处理的去卵巢Wistar大鼠中测定血浆LH、FSH和PRL，无论是否预先微量注射一氧化氮合酶（NOS）抑制剂。我们的结果如下：1 - 在雌激素预处理或未预处理的去卵巢大鼠中，与向MPOA微量注射AII或NO拮抗剂相关的血浆FSH没有变化；2 - 去卵巢后LH分泌的增加至少部分取决于MPOA中的NO活性；3 - 雌激素可能通过NO对MPOA中的LH-RH神经元产生间接负反馈作用；4 - 在雌激素处理的去卵巢大鼠中，AII在MPOA中对LH分泌的刺激作用取决于NO；5 - MPOA中的NO分别根据雌激素的缺乏或存在刺激或抑制PRL分泌；6 - AII进入MPOA对PRL分泌的抑制作用似乎不取决于NO。
