ay-25-205 and 5-oxo-pro-his-trp-ser-tyr-gly-trp-leu-pro-glynh2

The effects of reserpine (catecholamine depletor) and LHRH analogues on gonadotropin secretion, spermiation and ovulation of common carp were investigated. Injections of reserpine alone at a dose of 1 or 7 mg/kg of body weight stimulated spermiation, and reserpine at a dose of 1 mg/kg of body weight in combination with (D-Arg6, Trp7, Leu8, Pro9, NEt)-LHRH (s-GnRH-A) or with (D-Ala6, Pro9)-LHRH (LHRH-A) at a dose of 50 micrograms/kg of body weight caused an increase of plasma gonadotropin levels, spermiation and ovulation in 80-90% of the females. Simultaneous injection of reserpine and LHRH analogues was as effective as injection of reserpine followed by injection of LHRH analogues 6 h later.

Topics: Animals; Carps; Cyprinidae; Female; Gonadotropin-Releasing Hormone; Gonadotropins; Kinetics; Male; Ovulation; Reference Values; Reserpine; Salmon; Spermatogenesis

The effects of LHRH-A and sGnRH-A alone and in combination with the dopamine receptor antagonists pimozide (PIM) and domperidone (DOM) on stimulation of gonadotropin (GtH) secretion and ovulation in Chinese loach (Paramisgurnus dabryanus) and common carp (Cyprinus carpio) were studied. When tested in the absence of a dopamine receptor antagonist, sGnRH-A was about 10-fold more potent than LHRH-A in stimulating GtH secretion in loach, whereas these peptides were of similar effectiveness in common carp. Both peptides were effective alone in inducing ovulation in loach, but were ineffective in common carp. PIM and DOM stimulate a small but significant increase in serum GtH, and greatly potentiate the effects of LHRH-A and sGnRH-A on GtH secretion and ovulation in both species. DOM was of equal or somewhat greater potency than PIM in potentiating the action of releasing hormone agonists in loach; however, DOM had markedly greater effectiveness in common carp. sGnRH-A in the presence of DOM was more effective than LHRH-A in stimulating GtH secretion and ovulation in common carp. The present studies suggest that there are marked differences in the relative contribution of GnRH and dopamine in the control of GtH secretion in loach and common carp, and indicate in particular that the more intense dopaminergic inhibitory control of GtH release in common carp modifies the responsiveness of the pituitary to GnRH peptides.

Topics: Animals; Carps; Cyprinidae; Cypriniformes; Domperidone; Dose-Response Relationship, Drug; Female; Gonadotropin-Releasing Hormone; Gonadotropins; Ovulation; Pimozide