IMMUNOHISTOCHEMICAL DEMONSTRATION OF OXYTOCIN-LIKE, NEUROPEPTIDE Y-LIKE AND GONADOTROPIN-RELEASING HORMONE-LIKE SUBSTANCES IN THE HYPOTHALAMOHYPOPHYSEAL SYSTEM OF AYU, PLECOGLOSSUS-ALTIVELIS ALTIVELIS, IN OSMOTICALLY DIFFERENT ENVIRONMENTS

Citation
Y. Honma et al., IMMUNOHISTOCHEMICAL DEMONSTRATION OF OXYTOCIN-LIKE, NEUROPEPTIDE Y-LIKE AND GONADOTROPIN-RELEASING HORMONE-LIKE SUBSTANCES IN THE HYPOTHALAMOHYPOPHYSEAL SYSTEM OF AYU, PLECOGLOSSUS-ALTIVELIS ALTIVELIS, IN OSMOTICALLY DIFFERENT ENVIRONMENTS, Ichthyological research, 45(1), 1998, pp. 35-42
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Zoology
Journal title
ISSN journal
1341-8998
Volume
45
Issue
1
Year of publication
1998
Pages
35 - 42
Database
ISI
SICI code
1341-8998(1998)45:1<35:IDOONY>2.0.ZU;2-M
Abstract
To ascertain the role of neuropeptides on the hypothalamo-hypophysial system of a fish in osmotically different environments, an immunohisto chemical study of oxytocin (OXT), neuropeptide Y (NPY) and gonadotropi n-releasing hormone (GnRH) was carried out on the anadromous salmonoid fish, Plecoglossus altivelis altivelis, commonly known as Ayu. River fish caught were acclimatized in a freshwater aquarium, half of them b eing subsequently kept as a control group and the remainder being tran sferred to a sea water aquarium, through 1/3 diluted sea water, as an experimental group. OXT-like immunoreactivity as demonstrated in the n eurosecretory pathway, having the same pattern was that shown by aldeh yde fuchsin staining. Noticeably, a mass of nucleus preopticus (NPO) a nd a marginal portion of the pars nervosa in the control group became strongly immunoreactive, whereas a very weak reaction was obtained in the sea water-retained fish, suggesting the release of the labelled su bstance. In the latter, NPY-like substance was widely distributed in t he brain without NPO, with the positive substance being dense in the t erminal rami of the pars nervosa bordering the pars distalis. However, no remarkable difference in GnRH-like and NPY-like immunoreactivities in the hypothalamo-hypophysial system was apparent between the two gr oups. These results suggested that OXT (probably isotocin)-like substa nce may play a role in osmoregulation.