Possible involvement of opioid receptors in moclobemide-induced hypothermia in mice.

Effect of moclobemide, a selective monoamine oxidase-type A enzyme inhibitor, was investigated on the body temperature of male mice. Moclobemide (15-30 mg kg(-1), i.p.) produced significant reductions of body temperature in both normal and yeast-induced hyperthermic male mice. The hypothermic effect of moclobemide was moderate and short-lasting. Moclobemide-induced hypothermia was not antagonized by previous administration of prazosin (10 and 20 mg kg(-1), s.c.), propranolol (5, 10, and 20 mg kg(-1), s.c.), haloperidol (2 and 10 mg kg(-1), s.c.), atropine (10 and 20 mg kg(-1), s.c.), mepyramine (25 and 50 mg kg(-1), s.c.), or methysergide (0.5, 1, and 2 mg kg(-1), s.c.). Pretreatment with the opioid antagonist naloxone (10 mg kg(-1), s.c.), however, was able to reverse the hypothermic effect of moclobemide (30 mg kg(-1), i.p.) in both normal and yeast-induced hyperthermic mice. The present results indicate a possible role for central opioid receptors in the hypothermic effect of moclobemide. Also, a peripheral component for this effect of moclobemide at the mitochondria of peripheral tissues is suspected. The peripheral tissue mitochondria could be considered a common target for moclobemide and opioids actions on body temperature.