A presumptive role for GABA in the stimulatory effects of Des-Gly10, [D-Ala6]-LHRH-ethylamide and pimozide on the gonadotropin release in carp.
To investigate the effect of endogenous gamma-aminobutyric acid (GABA) on the blood maturating gonadotropin (GtH) levels, or to study its interaction with pimozide (dopamine antagonist) and a luteinizing hormone-releasing hormone analog (LHRH-a), sexually mature male and female carps were treated with drugs that may either inhibit GABA biosynthesis or GABA degradation. In females the irreversible inhibitor of GABA-transaminase, gamma-vinyl GABA (GVG), which was to increase the endogenous GABA-ergic tone, had no influence on GtH release. On the other hand, the increased GtH response to the combination of pimozide (PIM) and LHRH-a was clearly enhanced by the administration of 3-mercaptopropionic acid (MPA), an inhibitor of the rate limiting enzyme of GABA-biosynthesis. In males the GABA-ergic compound, valproic acid (DPA) decreased LHRH-a stimulated GtH levels. In male carps that received PIM to diminish the dopaminergic inhibition of GtH release, the spermiating response to LHRH-a was increased by administration of MPA. These data suggest that GABA interacts with the action of dopamine and the gonadotropin releasing hormone (GnRH) on the release of GtH.
Roelants
I
I
Dept. of Ichthyobiology and Fisheries, Agricultural Academy, Cracow, Poland.
Epler
P
P
Mikolajczyk
T
T
Breton
B
B
Bieniarz
K
K
Ollevier
F
F
D015097:3-Mercaptopropionic Acid / Q000494:pharmacology; D000818:Animals; D002347:Carps / Q000502:physiology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000494:pharmacology; D006062:Gonadotropins / Q000378:metabolism*; D008297:Male; D010868:Pimozide / Q000494:pharmacology*; D013076:Sperm Count / Q000187:drug effects; D014635:Valproic Acid / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D006062:Gonadotropins; D010868:Pimozide; D007987:Gonadotropin-Releasing Hormone; C010661:surfagon; D005680:gamma-Aminobutyric Acid; D014635:Valproic Acid; D015097:3-Mercaptopropionic Acid