Rawat Arpana, Chaube Radha, Joy Keerrikkattil P
Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
Department of Biotechnology, Cochin University of Science and Technology, Kochi, 682022, India.
Fish Physiol Biochem. 2019 Jun;45(3):885-905. doi: 10.1007/s10695-018-0590-1. Epub 2018 Dec 3.
In the catfish Heteropneustes fossilis, three vasotocin (VT) receptor subtype genes, v1a1, v1a2, and v2a, were cloned and characterized previously. In the present study, using RNA probes, we localized the distribution of the gene transcripts in the brain-pituitary-gonadal (BPG) axis. The V1a-type receptor, v1a1 and v1a2, genes showed similar and overlapping distribution in the brain. The gene paralogs are distributed in the radial glial cells (RGCs) of the telencephalic ventricle and around the third ventricle in the hypothalamus and thalamus, olfactory tract, nucleus preopticus, nucleus lateralis tuberis, nucleus recessus lateralis and posterioris, nucleus saccus vasculosi, thalamic nuclei, habenular nucleus, habenular commissure, basal part of pineal stalk, accessory pretectal nucleus, optic tectum, corpus and valvula of the cerebellum, and facial and vagal lobes. The V2a receptor gene (v2a) has restricted distribution and is largely confined to the anterior subependymal region of the telencephalon. The localization pattern shows that the V1a-type receptors are distributed in major sensorimotor processing centers and the neuroendocrine/reproductive centers of the brain. In the pituitary, the receptor genes were localized differentially in the three divisions with the V1a-type receptor genes strongly expressed in the rostral pars distalis compared to the v2a paralog. In the ovary, the V1a-type receptor genes were localized in the follicular layer while v2a was localized in the oocyte membrane. In the testis, v1a2 and v2a are densely distributed in the interstitial tissue and seminiferous epithelium but the v1a1 is lowly expressed. The results suggest that the VT receptor genes have an extensive but differential distribution in the BPG axis. Future experimental studies are required to correlate the cellular localizations with specific functions of VT in the BPG axis.
在鲶鱼（Heteropneustes fossilis）中，先前已克隆并鉴定出三种血管紧张素（VT）受体亚型基因，即v1a1、v1a2和v2a。在本研究中，我们使用RNA探针定位了基因转录本在脑-垂体-性腺（BPG）轴中的分布。V1a型受体基因v1a1和v1a2在脑中显示出相似且重叠的分布。这些基因旁系同源物分布于端脑脑室的放射状胶质细胞（RGCs）以及下丘脑、丘脑的第三脑室周围、嗅束、视前核、外侧结节核、外侧和后侧隐窝核、血管囊核、丘脑核、缰核、缰连合、松果体柄基部、副视前核、视顶盖、小脑体和小脑瓣以及面神经叶和迷走神经叶。V2a受体基因（v2a）分布受限，主要局限于端脑的前室管膜下区域。定位模式表明，V1a型受体分布于大脑的主要感觉运动处理中心和神经内分泌/生殖中心。在垂体中，受体基因在三个部分有不同的定位，与v2a旁系同源物相比，V1a型受体基因在远侧部前部强烈表达。在卵巢中，V1a型受体基因定位于卵泡层，而v2a定位于卵母细胞膜。在睾丸中，v1a2和v2a密集分布于间质组织和生精上皮，但v1a1表达较低。结果表明，VT受体基因在BPG轴中具有广泛但不同的分布。未来需要进行实验研究，以将细胞定位与VT在BPG轴中的特定功能相关联。
