Dopamine regulation of gonadotropin-releasing hormone (GnRH) gene expression in the female rat brain.
The effects of the dopaminergic antagonist haloperidol (HAL) as well as the D2 dopamine receptor agonist bromocriptine (BRO) on gonadotropin-releasing hormone (GnRH) mRNA levels in intact and hypophysectomized rats were investigated by quantitative in situ hybridization. In situ hybridization was performed using a 35S-labelled 48-base oligodeoxynucleotide complementary to the GnRH coding region of the GnRH DNA. In intact animals, a 14-day treatment with BRO increased by 70% the number of silver grains per neuron while HAL decreased by 20% the value of this parameter. Hypophysectomy which induced a 32% decrease in the hybridization signal could not prevent the effects of BRO or HAL. The present data clearly demonstrate that GnRH mRNA levels are positively regulated by dopamine and that the effects of BRO and HAL on GnRH mRNA are not mediated by variations in pituitary hormone secretion.
Li
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S
MRC Group in Molecular Endocrinology, CHUL Research Center, St-Foy, Que., Canada.
Pelletier
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G
D000818:Animals; D001921:Brain / Q000033:anatomy & histology; D001923:Brain Chemistry / Q000502:physiology*; D001971:Bromocriptine / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology*; D004971:Estrus / Q000502:physiology; D005260:Female; D015870:Gene Expression / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics*; D006220:Haloperidol / Q000494:pharmacology; D007016:Hypophysectomy; D017403:In Situ Hybridization; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats
D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D001971:Bromocriptine; D006220:Haloperidol; D004298:Dopamine