Neuropeptides regulating the activity of goldfish corticotropes and melanotropes |
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Authors: | James N Fryer |
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Institution: | (1) Department of Anatomy, Faculty of Health Sciences, University of Ottawa, 451 Smyth Road, Ottawa, K1H 8M5, Canada |
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Abstract: | The goldfish (Carassius auratus) has proven an advantageous model for investigations of the neuroendocrine regulation of pituitary hormone secretion in teleost
fishes. Investigations examining the secretion of adrenocorticotropin (ACTH) and melanocyte-stimulating hormone (MSH) from
pituitary cellsin vitro have been used to identify neuropeptides influencing goldfish corticotrope and melanotrope activity. Ovine CRF, urotensin
I (UI), arginine vasotocin (AVT), isotocin and angiotensins I and II stimulate the release of ACTH from corticotropesin vitro. Thyrotropin-releasing hormone (TRH), oCRF, UI and neuropeptide Y stimulate the release of MSH from melanotropesin vitro. Immunocytochemical studies have revealed the presence of separate CRF- and UI-immunoreactive perikarya in the hypothalamus
suggesting the existence of two structurally similar, yet distinct, hypothalamic CRF-UI-like peptides. Interactions of AVT
and CRF in the regulation of ACTH secretion is suggested from studies demonstrating the co-localization of AVT- and CRF-immunoreactivities
in perikarya of the preoptic-hypophyseal system. These investigations demonstrate that the secretory activity of goldfish
corticotropes and melanotropes is influenced by a diversity of neuropeptides of hypothalamic origin. |
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Keywords: | pro-opiomelanocortin corticotrope melanotrope corticotropin melanotropin pituitary neurosecretion neuropeptide goldfish |
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