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EVIDENCE FOR AN ENDOGENOUS DOPAMINE‐MEDIATED HYPOTHERMIA IN THE RAT
Author(s) -
COX B.,
LEE T.F.
Publication year - 1979
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1979.tb08707.x
Subject(s) - methysergide , pimozide , phentolamine , amphetamine , tranylcypromine , dopamine , hypothermia , chemistry , dopaminergic , endocrinology , apomorphine , medicine , phenoxybenzamine , anesthesia , pharmacology , haloperidol , serotonin , propranolol , monoamine oxidase , biochemistry , enzyme , receptor
1 Unilateral intrahypothalamic injection of either dopamine (10 μg) or amphetamine (10 μg) caused a fall in core temperature in the rat. Pimozide (0.5 mg/kg, i.p.) significantly reduced the hypothermic response, whereas pretreatment with phentolamine (1 mg/kg, i.p.) or methysergide (5 mg/kg, i.p.) was ineffective. 2 Systemic pretreatment with cocaine (20 mg/kg) abolished the hypothermic effect of amphetamine, but slightly enhanced the hypothermic response to dopamine. 3 Systemic pretreatment with tranylcypromine (10 mg/kg) had no significant effect on the fall in core temperature induced by either amphetamine or dopamine. 4 Intraperitoneal injection of cocaine and tranylcypromine, on their own, caused a fall in core temperature in the rat, which was significantly antagonized by either systemic or central pretreatment with pimozide. Phentolamine and methysergide failed to block the hypothermia. 5 Unilateral intrahypothalamic injection of cocaine (20 μg) or tranylcypromine (10 μg) also caused a significant fall in core temperature, which was reduced by intrahypothalamic pretreatment with pimozide (0.5 μg), but not significantly changed by pretreatment with phentolamine (25 μg) or methysergide (5 μg). 6 These results provide evidence for the presence of a dopaminergic system within the preoptic region, which mediates a lowering of core temperature in the rat.