Effects of apomorphine on thermoregulatory responses of rats to different ambient temperatures.
Either systemic or central administration of apomorphine produced dose-related decreases in rectal temperature at ambient temperatures (Ta) of 8 and 22 degrees C in rats. At Ta = 8 degrees C, the hypothermia was brought about by a decrease in metabolic rate (M). At Ta = 22 degrees C, the hypothermia was due to an increase in mean skin temperature, an increase in respiratory evaporative heat loss (Eres) and a decrease in M. This increased mean skin temperature was due to increased tail and foot skin temperatures. However, at Ta = 29 degrees C, apomorphine produced increased rectal temperatures due to increased M and decreased Eres. Moreover, the apomorphine-induced hypothermia or hyperthermia was antagonized by either haloperidol or 6-hydroxydopamine, but not by 5,6-dihydroxytryptamine. The data indicate that apomorphine acts on dopamine neurons within brain, with both pre- and post-synaptic sites of action, to influence body temperature.
D015115:5,6-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects; D001833:Body Temperature Regulation / Q000187:drug effects*; D001923:Brain Chemistry / Q000187:drug effects; D002395:Catecholamines / Q000032:analysis; D006220:Haloperidol / Q000494:pharmacology; D006892:Hydroxydopamines / Q000494:pharmacology; D008297:Male; D051381:Rats; D013696:Temperature
D002395:Catecholamines; D006892:Hydroxydopamines; D006220:Haloperidol; D001058:Apomorphine; D015115:5,6-Dihydroxytryptamine