Interaction of three dimensional network of the feeding regulation neurons and steroid hormones

据报道，有两种来源于pre-pro-orexin的orexin肽，分别称为orexin A和orexin B。orexin A是一种具有33个残基的肽，在n端区域有两个分子内二硫键，而orexin B是一种线性的28个残基肽。这些肽由单个mRNA转录物编码，具有46%的氨基酸序列同源性（Sakurai T et al. 1998）。它们的作用由受体介导，即食欲素1和食欲素2受体。orexin- a对这两种受体具有相似的亲和力，而orexin- b对orexin 2受体亚型具有更高的亲和力。也有报道称，orexin-A和-B mRNA及其细胞体主要在下丘脑区域检测到，特别是在下丘脑外侧区和皮层周围核。近年来有研究报道，免疫反应纤维与黄体生成素释放激素（LHRH）神经元系统在中隔视区和中位隆起区重叠分布，提示食欲素与性激素分泌有关。然而，食欲素a和食欲素b表达的性别差异尚未被阐明。在本项目中，我们研究了雄性、雌性和去卵巢大鼠（OVX）摄食相关神经元，特别是食欲素神经元分布模式的性别差异以及雌激素对食欲素肽表达的影响。食欲素神经元分布于下丘脑皮层周围区和外侧区，这一区域通常与摄食行为的控制有关，并将其轴突投射到下丘脑和整个中枢神经系统，参与摄食行为的控制。在本项目中，我们利用特异性的orexin- a和orexin- b抗体研究了orexin神经元的性别差异。雄性大鼠食欲素a和食欲素b免疫阳性神经元的密度均优先高于雌性大鼠。另一方面，雌性大鼠卵巢切除引起雄性模式的改变。没有观察到食欲素和雌激素受体的共定位。这些结果表明，雌激素通过其他依赖雌激素的神经元间接调节食欲素神经元。少

It has been reported that there are two orexin (from the Greek word for appetite, orexis) peptides derived from pre-pro-orexin, designated as orexin A and B. Orexin A is a 33-residue peptite with two intramolecular disulfide bonds in the N-terminal region, and orexin B is a linear 28-residue peptide. These peptides, encoded by a single mRNA transcript, has a 46% amino acid sequence identity (Sakurai T et al. 1998). Their effects are mediated by receptors, orexin 1 and 2 receptor. Orexin-A has ha similar affinity for both receptors, whereas orexin-B has a higher affinity for the orexin 2 receptor subtype.It has been also reported that orexin-A and -B mRNA and their cell bodies were mainly detedted in the hypothalamic area, particularly in the lateral hypothalamic area and the perifornical nucleus. Recently, it has been reported that the distribution of immunoreactive fibers overlaps with the luteinizing hormone-releasing hormone(LHRH) neuronal system in the septopreoptic area and the ar … More cuate nucleus median eminence region, suggesting that orexins are involved with the sex hormone secretion. However, the sex difference of the expression of orexin-A and -B has not been elucidated. In the project, we investigated the sex difference of the distribution pattern of the feeding related neurons, particularly orexin neuorns and the effect of estrogen for the expression of orexin peptides in the male, female and ovariectomized (OVX) rats.Orexin neurons are distributed in the perifornical and lateral hypothalamic area, a region classically implicated in the control of feeding behavior, and project their axons within the hypothalamus and throughout the central nervous system to be involved in the control of feeding. In the project, we investigated the sexual difference of orexin neurons using specific orexin-A and orexin-B antibodies. The density of both orexin-A and orexin-B immunopositive neurons in male was preferentially higher than those in female rats. On the other hand, ovariectomy in female rats induced the change to the male pattern. Colocalization of orexin and estrogen receptor was not observed. These results suggested that orexin neurons were indirectly regulated by estrogen through the other estrogen dependent neurons. Less