Involvement of catecholaminergic and cholinergic mechanisms in the pulsatile release of LH in the long-term ovariectomized rat.
In the long-term ovariectomized rat the secretion of LH has a pulsatile character. In such rats no difference was observed between morning and afternoon LH secretion. The administration of phenoxybenzamine, an chi-adrenergic blocker, resulted in depressed plasma LH levels. chi-Methyl-tyrosine (chi-MT), an inhibitor of tyrosine hydroxylase had no effect on plasma LH levels, whereas bis(4methyl-1-homopiperazinil-thiocarbonil) disulphide (FLA 63), an inhibitor of dopaminic-beta-hydroxylase, induced decreased plasma LH levels and disappearance of the pulsations. The same effect was observed after the administration of apomorphine, a dopaminic receptor stimulating drug, whereas the administration of 1-hydroxy-3-amino-pyrrolidone-2 (HA-966), which blocks dopamine release, significantly raised plasma LH levels. Scopolamine, a cholinergic muscarinic receptor blocking drug, had no effect on plasma LH levels, whereas mecamylamine, a cholinergic nicotine receptor blocking agent, decreased them. These results are consistent with the hypothesis that the pulsatile release of LH in the long-term ovariectomized rat is caused by the stimulating activity of adrenergic and cholinergic, probably nicotinic, systems and the inhibitory activity of a dopaminergic system.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D005406:Bis(4-Methyl-1-Homopiperazinylthiocarbonyl)disulfide / Q000494:pharmacology; D002395:Catecholamines / Q000494:pharmacology*; D002940:Circadian Rhythm / Q000187:drug effects; D005260:Female; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism; D008464:Mecamylamine / Q000494:pharmacology; D008781:Methyltyrosines / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D010053:Ovary / Q000502:physiology; D010643:Phenoxybenzamine / Q000494:pharmacology; D010902:Pituitary Gland / Q000187:drug effects*; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D012601:Scopolamine / Q000494:pharmacology
D002395:Catecholamines; D008781:Methyltyrosines; D018377:Neurotransmitter Agents; D011760:Pyrrolidinones; D010643:Phenoxybenzamine; D005406:Bis(4-Methyl-1-Homopiperazinylthiocarbonyl)disulfide; D008464:Mecamylamine; D007986:Luteinizing Hormone; D012601:Scopolamine; C001369:1-hydroxy-3-amino-2-pyrrolidone; D001058:Apomorphine