On the presence of autoreceptors on dopamine neurons in different brain regions.
The alpha-methyltyrosine-induced disappearance of dopamine was inhibited by the selective dopamine autoreceptor agonist B-HT 920 in the corpus striatum, the nucleus accumbens, the olfactory tubercle, the limbic cortex, and the rostral part of the cerebral cortex of the rat. These inhibitory actions of B-HT 920 were almost completely reversed by the dopamine receptor antagonist haloperidol, indicating that they were caused by a stimulation of dopamine autoreceptors. In the caudal cortex and the cerebellum, the effects of B-HT 920 and haloperidol were less clear, perhaps due to a low concentration of dopamine and to the occurrence of this dopamine in both dopamine and noradrenaline neurons. In the hypothalamus, B-HT 920 and haloperidol did not change the alpha-methyltyrosine-induced disappearance of dopamine in agreement with previous findings that the tubero-infundibular dopamine neurons are not regulated via dopamine receptors.
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects / Q000378:metabolism*
D000316:Adrenergic alpha-Agonists; D001381:Azepines; D008781:Methyltyrosines; D011954:Receptors, Dopamine; C022260:alpha-methyltyrosine methyl ester; C024763:talipexole; D004298:Dopamine; D009638:Norepinephrine