Cataldi Natalia I, Lux-Lantos Victoria A R, Libertun Carlos
Instituto de Biología y Medicina Experimental-CONICET, Vuelta de Obligado 2490, C1428ADN, Argentina.
Regul Pept. 2012 Oct 10;178(1-3):56-63. doi: 10.1016/j.regpep.2012.06.008. Epub 2012 Jun 29.
Orexin-A and orexin-B are neuropeptides controlling sleep-wakefulness, feeding and neuroendocrine functions via their G protein-coupled receptors, orexin-1R and orexin-2R. They are synthesized in the lateral hypothalamus and project throughout the brain. Orexins and orexin receptors have also been described outside the brain. Previously we demonstrated the presence of both receptors in the ovary, their increased expression during proestrous afternoon and the dependence on the gonadotropins. Here we studied the effects of orexins on the mRNA expression of both receptors, by quantitative real-time PCR, on luteal cells from superovulated rat ovaries and granulosa cells from diethylstilbestrol-treated rat ovaries. Effects on progesterone secretion were also measured. In luteal cells, 1 nM of either orexin-A or orexin-B decreased progesterone secretion. Orexin-A treatment increased expression of both orexin-1R and orexin-2R mRNA. The effect on orexin-1R mRNA expression was abolished by an orexin-1R selective receptor antagonist SB-334867 and the effect on orexin-2R mRNA expression was abolished by a selective orexin-2R antagonist JNJ-10397049. Orexin-B did not modify orexin-1R mRNA expression, but increased orexin-2R mRNA expression. The effect of orexin-B on orexin-2R was abolished by a selective orexin-2R antagonist. Neither the expression of orexin receptors nor progesterone secretions by granulosa cells were affected by orexins. FSH, as positive control, increased both steroid hormones secretion, but did not induce the expression of OX receptors in granulosa cells isolated from late preantral/early antral follicles. Finally in ovaries obtained immediately after sacrifice, the expression of orexin-1R and orexin-2R was higher in superovulated rat ovaries compared to control or diethylstilbestrol treated rat ovaries. A selective presence and function of both orexinergic receptors in luteal and granulosa cells is described, suggesting that the orexinergic system may have a functional role in the ovary.
食欲素-A和食欲素-B是神经肽，它们通过其G蛋白偶联受体——食欲素-1R和食欲素-2R来控制睡眠-觉醒、进食及神经内分泌功能。它们在下丘脑外侧合成，并投射至整个大脑。在脑外也发现了食欲素和食欲素受体。此前我们证实卵巢中存在这两种受体，在动情前期下午其表达增加，且依赖于促性腺激素。在此，我们通过定量实时PCR研究了食欲素对来自超排卵大鼠卵巢的黄体细胞以及己烯雌酚处理的大鼠卵巢颗粒细胞中两种受体mRNA表达的影响。同时也检测了对孕酮分泌的影响。在黄体细胞中，1 nM的食欲素-A或食欲素-B均可降低孕酮分泌。食欲素-A处理可增加食欲素-1R和食欲素-2R mRNA的表达。食欲素-1R选择性受体拮抗剂SB-334867可消除对食欲素-1R mRNA表达的影响，而选择性食欲素-2R拮抗剂JNJ-10397049可消除对食欲素-2R mRNA表达的影响。食欲素-B未改变食欲素-1R mRNA表达，但增加了食欲素-2R mRNA表达。食欲素-B对食欲素-2R的作用可被选择性食欲素-2R拮抗剂消除。食欲素对颗粒细胞中食欲素受体的表达及孕酮分泌均无影响。作为阳性对照，促卵泡激素（FSH）可增加两种甾体激素的分泌，但未诱导从晚窦前/早窦卵泡分离出的颗粒细胞中OX受体的表达。最后，在处死后立即获取的卵巢中，与对照或己烯雌酚处理的大鼠卵巢相比，超排卵大鼠卵巢中食欲素-1R和食欲素-2R的表达更高。本文描述了食欲素能受体在黄体细胞和颗粒细胞中的选择性存在及功能，提示食欲素能系统可能在卵巢中发挥功能性作用。
