Department of Structures, Functions and Biological Technologies, University of Naples Federico II, Via Veterinaria 1, I-80137 Naples, Italy.
Gen Comp Endocrinol. 2012 Oct 1;179(1):137-42. doi: 10.1016/j.ygcen.2012.07.020. Epub 2012 Aug 13.
The orexins A (oxA) and B are peptides discovered in the rat hypothalamus and successively found in some peripheral organs of the mammalian body. They binds two protein G-coupled receptors defined receptor 1 (ox1r) and 2 for orexins, the first of which is highly specific for oxA while the second binds both the peptides with equal affinity. This work aimed to detect the presence of oxA and ox1r in the testis of the South American camelid alpaca (Vicugna pacos) and investigate the role played by them on Leydig cell steroidogenesis. The species alpaca acquired, in the last years, increasing zootechnical interest for the quality of the wool produced and its breeding spread from the country of origin to USA, Australia and Europe. Immunohistochemistry allowed us to detect oxA in Leydig and Sertoli cells, spermatogonia, resting spermatocytes, round and oval spermatids. Ox1r-immunoreactivity was found in Leydig cells and round, oval and elongated spermatids. The expression of the two peptides in tissue extracts was established by using Western blotting technique. Such results demonstrated that in the alpaca testis exists in a cellular complex able to produce and/or internalize oxA. Finally, the effect of oxA on steroidogenesis was investigated by means of in vitro cultured thin testis slices which were added with oxA or/and Müllerian Inhibiting Substance (MIS), a steroidolitic agent basally produced by the Sertoli cell. OxA evoked increase of testosterone production while MIS a decrease. The consecutive addition of oxA and MIS, or vice versa, highlighted an antagonistic interplay between the two substances which has been thought to be the main molecular event at the basis of the oxA-stimulated steroidogenesis mechanism.
食欲素 A（oxA）和 B 是在大鼠下丘脑发现的肽，随后在哺乳动物身体的一些外周器官中相继发现。它们结合两种蛋白 G 偶联受体定义的食欲素受体 1（ox1r）和 2，其中第一种受体对 oxA 具有高度特异性，而第二种受体对两种肽具有相同的亲和力。这项工作旨在检测南美洲驼羊（Vicugna pacos）睾丸中 oxA 和 ox1r 的存在，并研究它们在睾丸间质细胞类固醇生成中的作用。近年来，驼羊因其所产羊毛的质量和其繁殖分布从原产国到美国、澳大利亚和欧洲而获得了越来越多的动物养殖关注。免疫组织化学使我们能够在 Leydig 和 Sertoli 细胞、精原细胞、静止精母细胞、圆形和椭圆形精细胞中检测到 oxA。Ox1r-免疫反应性存在于 Leydig 细胞和圆形、椭圆形和伸长的精细胞中。使用 Western blotting 技术确定了两种肽在组织提取物中的表达。这些结果表明，在驼羊睾丸中存在一个能够产生和/或内化 oxA 的细胞复合物。最后，通过添加 oxA 或/和 Müllerian 抑制物质（MIS）的体外培养薄睾丸切片研究了 oxA 对类固醇生成的影响，MIS 是一种基础上由 Sertoli 细胞产生的类固醇溶解剂。oxA 引起睾酮产生增加，而 MIS 引起减少。oxA 和 MIS 的连续添加或反之亦然，突出了两种物质之间的拮抗相互作用，这被认为是 oxA 刺激类固醇生成机制的主要分子事件。
