PT  - JOURNAL ARTICLE
AU  - S. M. Rawls
AU  - A. Cowan
AU  - R. J. Tallarida
AU  - Ellen B. Geller
AU  - Martin W. Adler
TI  - <em>N</em>-Methyl-<span class="sc">d</span>-aspartate Antagonists and WIN 55212-2 [4,5-Dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-naphthalenyl-carbonyl)-6<em>H</em>-pyrrolo[3,2,1-<em>i</em>,<em>j</em>]quinolin-6-one], a Cannabinoid Agonist, Interact to Produce Synergistic Hypothermia
AID  - 10.1124/jpet.102.037473
DP  - 2002 Oct 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 395--402
VI  - 303
IP  - 1
4099  - http://jpet.aspetjournals.org/content/303/1/395.short
4100  - http://jpet.aspetjournals.org/content/303/1/395.full
SO  - J Pharmacol Exp Ther2002 Oct 01; 303
AB  - CB1 cannabinoid receptors mediate profound hypothermia when cannabinoid agonists are administered to rats. Glutamate, the principal excitatory neurotransmitter in the central nervous system (CNS), is thought to tonically increase body temperature by activatingN-methyl-d-aspartate (NMDA) receptors. Because NMDA antagonists block cannabinoid-induced antinociception and catalepsy, intimate glutamatergic-cannabinoid interactions may exist in the CNS. The present study investigated the effect of two NMDA antagonists on the hypothermic response to WIN 55212-2 [4,5-dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1-i,j]quinolin-6-one], a selective cannabinoid agonist, in rats. WIN 55212-2 (1–10 mg/kg i.m.) produced dose-dependent hypothermia that peaked 60 to 180 min postinjection. Dextromethorphan (5–75 mg/kg i.m.), a noncompetitive NMDA antagonist, or LY 235959 [(−)-6-[phosphonomethyl-1,2,3,4,4a,5,6,7,8,8a-decahydro-isoquinoline-2-carboxylate]](1–4 mg/kg i.m.), a competitive and highly selective NMDA antagonist, evoked hypothermia in a dose-sensitive manner, suggesting that endogenous glutamate exerts a hyperthermic tone on body temperature. A dose of dextromethorphan (10 mg/kg) that did not affect body temperature by itself potentiated the hypothermic response to WIN 55212-2 (1, 2.5, or 5 mg/kg). The enhancement was strongly synergistic, indicated by a 2.7-fold increase in the relative potency of WIN 55212-2. Similarly, a dose of LY 235959 (1 mg/kg) that did not affect body temperature augmented the hypothermia associated with a single dose of WIN 55212-2 (2.5 mg/kg), thus confirming that NMDA receptors mediated the synergy. We have demonstrated previously that CB1 receptors mediate WIN 55212-2-evoked hypothermia in rats. The present data are the first evidence that NMDA antagonists exert a potentiating effect on cannabinoid-induced hypothermia. Taken together, these data suggest that interactions between NMDA and CB1 receptors produce synergistic hypothermia. The American Society for Pharmacology and Experimental Therapeutics