title: Neuropeptide Arginine Vasotocin Positively Affects Neurosteroidogenesis in the Early Brain of Grouper, Epinephelus coioides.
abstract: The neuropeptide arginine vasotocin (AVT) has versatile physiological functions in non-mammalian vertebrates. However, the functional association between AVT and neurosteroidogenesis in the early brain of teleosts remains elusive. We thus studied the developmental expression patterns of the avt gene and their V1 type receptor (avt-rv1 ) at various stages of development [90-150 days after hatching (dah)] in relation to neurosteroidogenesis and oestrogen signalling in the early brain of the orange-spotted grouper (Epinephelus coioides). avt and avt-rv1 mRNAs displayed a significantly increase in expression at 110 dah in the telencephalon and diencephalon. Further, avt mRNAs were localised in three magnocellular neuronal populations of the preoptic area, such as parvocellular, magnocellular and gigantocellular preoptic neurones. Intriguingly, the avt transcripts in those neurones were more abundant in 110 dah compared to other ages. Subsequently, dual fluorescence in situ hybridisation analysis showed that the avt and avt-rv1 genes were highly coexpressed with cyp11a1, hsd3b1, cyp17a1, erα, erβ and gpr30, which indicates their potential for functional association. Cyp19a1b-immunoreactive positive fibres were found in close proximity to avt-expressing neurones. Moreover, our results showed that exogenous Avt caused a significant increase in the cellular and gene levels of steroidogenic enzymes and oestrogen receptors (ers), whereas the administration of an Avt-rv1 antagonist caused a decrease in the expression of both steroidogenic enzymes and ers genes in the brain. Furthermore, exogenous oestradiol (E2 ) strongly up-regulated avt mRNAs in the grouper brain. Taken together, the present studies suggest that avt and steroidogenesis may positively work together to increase both E2 biosynthesis and early brain development.
authors.affiliation: Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan.
authors.forename: G
authors.initials: G
authors.lastname: Nagarajan
authors.affiliation: Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.
authors.forename: A
authors.initials: A
authors.lastname: Aruna
authors.affiliation: Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan.|Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.
authors.forename: C-F
authors.initials: CF
authors.lastname: Chang
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism*; D029941:Fish Proteins; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D006066:Gonads / Q000378:metabolism*; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012333:RNA, Messenger; D011960:Receptors, Estrogen / Q000378:metabolism*; D017483:Receptors, Vasopressin / Q000235:genetics / Q000378:metabolism*; D012733:Sex Differentiation; D014668:Vasotocin / Q000235:genetics / Q000378:metabolism*
chemical_list: D029941:Fish Proteins; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D017483:Receptors, Vasopressin; D004958:Estradiol; D014668:Vasotocin
keywords: avt; brain development; fish; gonadal differentiation; oestrogen receptors; steroidogenic enzymes