Studies on the mode of action of neuropeptide Y (NPY) on maturational gonadotropin (GtH) secretion from perifused rainbow trout pituitary glands |
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| Authors: | B Breton T Mikolajczyk C Weill J M Danger H Vaudry |
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| Institution: | (1) I.N.R.A., Laboratoire de Physiologie des Poissons, Campus de Beaulieu, 35042 Rennes Cedex, France;(2) Groupe de Recherche en Endocrinologie Moleculaire, C.N.R.S. URA650, Université de Rouen, 76134 Mont St. Aignan, France;(3) Department of Ichthyobiology, Academy of Agriculture, Krakow Midlniki, Poland;(4) Present address: Department of Ichthyobiology and Fisheries, Academy of Agriculture, Krakow, Poland |
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| Abstract: | The action of neuropeptide Y (NPY) and gonadotropin releasing hormone (s-GnRH) have been compared on the release of gonadotropin
(GtH) by perifused rainbow trout pituitary glands sampled from freshly ovulated female rainbow trout. We have already demonstrated
that NPY stimulated the secretion of GtH in vitro.
The pituitary responses to s-GnRH and NPY were similar either after repeated 10 min infusions or a one hour prolonged application.
In both cases, after the first application, the pituitary did not responded to subsequent secretagogues stimulations, and
appeared to be desensitized. The stimulatory action of s-GnRH was partly inhibited (60%) by LH-RH antagonist (DpGlu1, DPhe2, DTrp3–6) LH-RH, which completely inhibited the response to NPY in perifused pituitary glands sampled from freshly ovulated females,
but did not modify the response of pituitaries taken from vitellogenic animals in which NPY induced a transient inhibition
of the GtH secretion. These results may indicate that the mode of action of NPY would differ between vitellogenic and matured
animals. NPY also stimulated the GtH secretion from perifused pituitary dispersed cells prepared from pituitaries taken from
freshly ovulated rainbow trout, indicating that NPY may act directly on the pituitary gonadotropic cells to stimulate GtH
secretion. |
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| Keywords: | neuropeptide Y GnRH gonadotropin |
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