title: Blockade of the LH surge and ovulation by GABA-T inhibitory drugs that increase brain GABA levels in rats.
abstract: The present experiments were designed to evaluate the effects of GABA increase in the brain on the LH surge and ovulation in female rats. GABA-transaminase (GABA-T) inhibitory drugs were administered intraperitoneally in the early afternoon hours on the day before the expected ovulation. Gamma-acetylenic GABA (GAG) prevented the proestrus LH surge and ovulation in freely moving adult female rats. In a similar manner, GAG blunted the enhanced LH release found at 1800 h on the preovulatory day and the subsequent ovulation in PMSG-treated 32-day-old rats. LH secretion and ovulation in these animals was restored by administration of the selective GABA antagonist, bicuculline. The other GABA-T inhibitors, amino-oxyacetic acid and gamma-vinyl GABA, produced similar effects to GAG in the PMSG-treated rats. These results indicate that the increase of brain GABA levels during the preovulatory day alters LH release and prevents ovulation in rats.
mesh_terms: D000612:4-Aminobutyrate Transaminase / Q000037:antagonists & inhibitors*; D000480:Alkynes; D000614:Aminocaproates / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001923:Brain Chemistry / Q000187:drug effects*; D004971:Estrus; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000097:blood*; D010060:Ovulation / Q000187:drug effects*; D051381:Rats; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D000480:Alkynes; D000614:Aminocaproates; D006064:Gonadotropins, Equine; D005680:gamma-Aminobutyric Acid; C013785:4-amino-5-hexynoic acid; D007986:Luteinizing Hormone; D000612:4-Aminobutyrate Transaminase; D001640:Bicuculline