Silveyra Patricia, Cataldi Natalia I, Lux-Lantos Victoria, Libertun Carlos
Instituto de Biología y Medicina Experimental-CONICET, Argentina.
Regul Pept. 2009 Nov 27;158(1-3):121-6. doi: 10.1016/j.regpep.2009.08.002. Epub 2009 Aug 21.
Orexins A and B (hypocretins A and B) are regulatory peptides that control a variety of neuroendocrine and autonomic functions including feeding and sleep-wakefulness. Previously, we described a clear relationship between the hormonal milieu of the estrous cycle and the mRNA expression of the components of the orexinergic system, in the hypothalamus, pituitary and ovary. Here, we investigate whether steroid hormones are involved in the modulation of the hypocretin/orexin type-1 receptor expression at the protein level, and its time of the day dependence, in hypothalamus and pituitary of castrated male and female rats and castrated receiving hormone replacement. Orchidectomy decreased the hypocretin/orexin type-1 receptor expression in anterior hypothalamus, but not in mediobasal hypothalamus or cortex; in pituitary this treatment resulted in an increase. Testosterone and dihydrotestosterone were able to restore receptor expression and gonadotropins. In females, pituitary and ovarian hormones increased during proestrous afternoon. Hypocretin/orexin type-1 receptor expression was higher at 19:00 of proestrus in hypothalamus and pituitary. Ovariectomized treated with estradiol or oil and sacrificed at 11:00 h showed the receptor expression similar to 11:00 h of proestrus in hypothalamus and pituitary. At 19:00 h, low expression persisted in these areas in oil-treated ovariectomized rats; in contrast, estradiol replacement increased the expression to high levels of normal cycling rats at 19:00 h. Sexual steroids modulate the orexinergic system and the anatomical regions, hormones and times of the day all have to be considered when the roles of orexins, and probably other peptides, are under consideration.
食欲素A和B（下丘脑泌素A和B）是调节肽，可控制多种神经内分泌和自主功能，包括进食和睡眠-觉醒。此前，我们描述了发情周期的激素环境与下丘脑、垂体和卵巢中食欲素能系统各成分的mRNA表达之间的明确关系。在此，我们研究类固醇激素是否参与去势雄性和雌性大鼠以及接受激素替代的去势大鼠下丘脑和垂体中食欲素/下丘脑泌素1型受体蛋白水平的调节及其昼夜依赖性。睾丸切除术降低了下丘脑前部食欲素/下丘脑泌素1型受体的表达，但在中基底部下丘脑或皮质中未降低；在垂体中，这种处理导致该受体表达增加。睾酮和双氢睾酮能够恢复受体表达和促性腺激素。在雌性中，垂体和卵巢激素在发情前期下午升高。发情前期19:00时，下丘脑和垂体中食欲素/下丘脑泌素1型受体的表达较高。用雌二醇或油处理并在11:00处死的去卵巢大鼠，其下丘脑和垂体中的受体表达与发情前期11:00时相似。在19:00时，油处理的去卵巢大鼠这些区域的表达持续较低；相反，雌二醇替代使表达增加到正常周期大鼠19:00时的高水平。性类固醇调节食欲素能系统，在考虑食欲素以及可能其他肽的作用时，必须考虑解剖区域、激素和昼夜时间。
