Dopaminergic influence on gonadotropin secretion in white sturgeon (Acipenser transmontanus) |
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Authors: | R J Pavlick Jr G P Moberg |
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Institution: | (1) Department of Animal Science, University of California, Davis, Davis, CA 95616, USA |
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Abstract: | The effects of dopamine on the secretion of two sturgeon gonadotropins (stGTH I and stGTH II) in sexually mature male white
sturgeon (Acipenser transmontanus) were evaluated. In Experiment I, sturgeon were given intraperitoneal injections of physiological saline (PS), dopamine (100
mg kg−1), the gonadotropin releasing hormone analog D-Ala6-des-Gly10-GnRH ethylamide (GnRHA) (10 μg/kg−1), and a combination of GnRHa and dopamine. Fish receiving only GnRHa had significantly higher (p < 0.05) concentrations of
plasma stGTH I and stGTH II compared to fish receiving PS, dopamine, or a combination of GnRHa and dopamine. Two hours following
its administration, dopamine was effective in decreasing plasma concentrations of both stGTHs that were previously elevated
by GnRHa. Dopamine or PS administered by themselves did not alter plasma concentrations of either stGTH. In Experiment II,
sturgeon injected intraperitoneally with a combination of GnRHa and pimozide had significantly higher (p < 0.05) concentrations
of plasma stGTH I and stGTH II compared to males receiving GnRHa or pimozide alone. While this effect of GnRHAa + pimozide
was observed in the spring, no such potentiation was seen in these fish during the summer (Experiment III). These results
represent the first evidence of dopaminergic inhibition of GnRH-induced pituitary gonadotropin secretion in Chondrostean fish. |
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Keywords: | sturgeon dopamine pimozide gonadotropins GnRHa |
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