Modification of the behavioural effects of haloperidol and of dopamine receptor regulation by altered thyroid status.
Rats made hypothyroid by the chronic oral administration of 200 mg/kg propylthiouracil were less sensitive to the cataleptic effects of haloperidol (0.1 mg/kg) treatment than were euthyroid rats chronically treated with isotonic saline. However, rats made hyperthyroid by the chronic injection of 200 micrograms/kg thyroxine were not more sensitive to the cataleptic suppressant effects of haloperidol (0.1 mg/kg). Higher doses of haloperidol (1 and 5 mg/kg) produced significantly greater catalepsy in the hyperthyroid rats and significantly reduced catalepsy in the hypothyroid rats. Receptor binding studies carried out on the striata from rats sacrificed 48 h after a 6-day course of chronic haloperidol (0.1 mg/kg once daily) treatment revealed a significant upregulation (increase) of dopamine receptors in the hypothyroid rats only. These findings are consistent with the hypothesis that altered thyroid status can modify the sensitivity of dopamine receptors.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001831:Body Temperature; D002375:Catalepsy / Q000139:chemically induced; D006220:Haloperidol / Q000494:pharmacology*; D006801:Humans; D006980:Hyperthyroidism / Q000523:psychology; D007037:Hypothyroidism / Q000523:psychology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D013134:Spiperone / Q000378:metabolism; D013963:Thyroid Hormones / Q000502:physiology*
D011954:Receptors, Dopamine; D013963:Thyroid Hormones; D013134:Spiperone; D006220:Haloperidol