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

据报道，有两种来源于前食欲素原的食欲素肽（来自希腊词食欲，orexis），命名为食欲素A和B。食欲素A是一个33个残基的肽，在N-末端区域具有两个分子内二硫键，食欲素B是一个线性的28个残基的肽。这些肽由单个mRNA转录物编码，具有46%的氨基酸序列同一性（Sakurai T et al. 1998）。它们的作用是通过受体，食欲素1和2受体介导的。Orexin-A和Orexin-B对Orexin 2受体的亲和力相近，而Orexin-A和Orexin-B对Orexin 2受体的亲和力更高，Orexin-A和B的mRNA及其胞体主要分布于下丘脑外侧区和穹窿周围核。最近有报道，在视隔区和视前区，免疫反应纤维的分布与促黄体生成素释放激素（LHRH）神经元系统重叠 ...更多信息 结果表明，食欲素参与了性激素的分泌。然而，食欲素-A和-B的表达的性别差异尚未阐明。本课题研究了摄食相关神经元，特别是食欲素神经元在雄性、雌性和去卵巢大鼠中的分布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穹窿周围区和外侧区，并将它们的轴突投射到下丘脑和整个中枢神经系统中，以参与控制进食。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，雌性大鼠卵巢切除导致向雄性模式的改变。未观察到食欲素和雌激素受体的共定位。这些结果表明，雌激素通过其它雌激素依赖性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