The central effect of estrogen on the regulation of food intake and osmoregulation.

1.雌激素替代对去卵巢大鼠摄食行为的影响。7周龄大鼠切除卵巢，分为雌二醇（E2-T）组和安慰剂（Pla-T）组。E2-T组日摄食量和体重增加量均显著低于Pla-T组。Pla-T组在光照期和黑暗期的摄食量均大于E2-T组，且在光照期两组之间的差异更为显著。在暗相开始时，Pla-T组视交叉上核（SCN） c-Fos - ir细胞数量与E2-T组无显著差异，但在亮相开始时低于E2-T组。E2-T大鼠的弓形核（ARC）表达c-Fos的细胞数量在明暗期均低于Pla-T大鼠。两组动物的摄食反应和ARC时c-Fos的表达无显著差异。这些结果表明：1)雌激素具有强直性抑制ARC新神经元的活性和摄食作用；2)雌激素可能在光期SCN神经元昼夜活动节律的产生和摄食的衰减中起作用；3)雌激素调节自发摄食，但不影响禁食诱导的摄食反应。雌激素替代对去卵巢大鼠渗透调节的影响。为了阐明雌激素对渗透诱导水摄入的影响及其中枢机制，我们研究了水摄入和下丘脑神经元激活（c-Fos表达）对血浆高渗和中枢血管紧张素II （ANGII）的反应。将去卵巢大鼠分为E2-T组和Pla-T组。切除卵巢2周后，大鼠ig高渗生理盐水（1.5 M;0.33 ml/100g/BW；静脉注射）。输注后30分钟给予饮水，并测量30分钟的饮水量。几天后，我们也用免疫组织化学方法检测了c-Fos的表达。在其他大鼠中采用相同的方案来检查中枢注射ANGII （5ng; c.c.v）的反应。E2-T大鼠在高渗刺激和中央ANGII给药时的饮水量明显少于Pla-T大鼠。在E2-组和Pla-T组之间，对渗透或ANGII刺激反应的OVLT中c-Fos细胞的数量没有差异。与Pla-T组相比，E2-T组在渗透攻击后PVN外侧的c-Fos - ir细胞数量较少。与Pla治疗相比，E2治疗降低了SFO和SON中血管内皮细胞诱导的c-Fos表达。由此可见，雌激素对渗透调节性水摄入的抑制作用可能位于与体液调节相关的渗透受体和下丘脑核之间的通路上。中枢性ANGII可能参与雌激素对渗透调节性饮酒的影响。少

1.Effect of estrogen replacement on food intake behavior in ovariectomized rats.Seven-week-old rats were ovariectomized and were assigned into estradiol- (E2-T) and placebo-treated (Pla-T) groups. The daily food intake and increase in body weight in the E2-T group were significantly lower than the Pla-T group. Food intake during both light and dark phases in the Pla-T group was larger than the E2-T group, and the difference between the two groups was more prominent during light phase. The number of c-Fos ir cells in suprachiasmatic nucleus (SCN) in the Pla-T group was not different from the E2-T group at the beginning of dark phase, but was lower than the E2-T group at the beginning of light phase. The c-Fos expressing cell number at the arcuate nucleus (ARC) in E2-T rats was lower than Pla-T rats in both light and dark phases. The responses of feeding and c-Fos expression at ARC were not different between the two groups. These results suggest that 1)estrogen tonically inhibits ARC neu … More ronal activity and feeding, 2)estrogen might play a role in the production of circadian SCN neuronal activity rhythm and attenuation of feeding during light phase, and 3)estrogen modulates spontaneous feeding but does not influence fasting-induced feeding response.2.Effect of estrogen replacement on osmoregulation in ovariectomized rats.To clarify the effect of estrogen on osmotically-induced water intake and its central mechanism, we examined the responses of water intake and hypothalamic neuronal activation (c-Fos expression) to plasma hyperosmolality and central angiotensin II (ANGII) administration. Ovariectomized rats were assigned into E2-T and Pla-T groups. Two weeks after the ovariectomy, rats were infused with hypertonic saline (1.5 M;0.33 ml/100g/BW ; i.v.). Access to water was provided 30-min after the infusion, and water intake was measured for 30 min. A few days later, we also examined c-Fos expression immunohistochemically. The same protocols were employed in other rats to examine the responses to central ANGII injection (5ng ; i.c.v.). E2-T rats drank significantly less amount of water than Pla-T rats in response to both hyperosmotic challenge and to central ANGII administration. The number of c-Fos ir cells in the OVLT in response to either osmotic or ANGII stimulations was not different between the E2- and Pla-T groups. The E2-T group showed lower number of c-Fos ir cells in the lateral part of the PVN after osmotic challenge compared to the Pla-T group. E2 treatment decreased AngII-induced c-Fos expression in the SFO and the SON as compared to Pla treatment. Thus, estrogen attenuates osmoregulatory water intake, and the site of this inhibitory action might be located on the pathway between the osmoreceptors and hypothalamic nuclei related to body fluid regulation. Central ANGII might be involved in the estrogen effect on osmoregulatory drinking. Less