Localization of the site of the haloperidol-induced, prolactin-mediated increase of dopamine turnover in the median eminence: studies in rats with complete hypothalamic deafferentations.
Complete hypothalamic deafferentations were made in male rats with a modified Halász knife to isolate tuberoinfundibular dopaminergic neurons from the rest of the brain. A radioenzymatic procedure was employed to quantify dopamine and norepinephrine concentrations in various regions of the hypothalamus. Dopamine concentrations were unaltered while norepinephrine concentrations were reduced 50% in the median eminence and hypothalamic island 16-33 days after surgery. Basal serum prolactin concentrations were unaltered in these rats but were elevated 16 hours after the injection of haloperidol and 1 hour after alpha-methyltyrosine. The isolation of tuberoinfundibular neurons from the rest of the brain did not alter the ability of haloperidol to increase the rate of alpha-methyltyrosine-induced decline of dopamine in the median eminence. These results indicate that the haloperidol-induced, prolactin-mediated increase of dopamine turnover in the median eminence results from a direct action of this hormone on neurons within the medial basal hypothalamus.
D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D006220:Haloperidol / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D008473:Median Eminence / Q000378:metabolism*; D008781:Methyltyrosines / Q000494:pharmacology; D009434:Neural Pathways / Q000502:physiology; D009638:Norepinephrine / Q000378:metabolism; D011388:Prolactin / Q000097:blood*; D051381:Rats
D008781:Methyltyrosines; D011388:Prolactin; D006220:Haloperidol; D004298:Dopamine; D009638:Norepinephrine