The effects of choline on body temperature in conscious rats


Unal C., Demiral Y., Ulus I.

EUROPEAN JOURNAL OF PHARMACOLOGY, vol.363, pp.121-126, 1998 (SCI-Expanded) identifier identifier identifier

Abstract

Choline (75-300 mu g) produced dose-dependent hypothermia when injected intracerebroventricularly (i.c.v.). Pre-treatment with the muscarinic receptor antagonist, atropine (10 mu g, i.c.v.), blocked the hypothermic effect of choline (150 mu g), but the response was only partially attenuated by pre-treatment with the nicotinic receptor antagonist, mecamylamine (20 mu g, i.c.v.). Pirenzepine (25 mu g), a muscarinic M-1 receptor antagonist, or hexahydro-siladifenidol (HHSD) (100 mu g), a muscarinic M-3 receptor antagonist, also blocked choline-induced hypothermia when injected centrally. Unlike the other muscarinic receptor antagonists, M-2-selective 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepin-6-one (AF-DX116) (10 mu g), did not affect choline-induced hypothermia. We also found that choline-induced hypothermia was very sensitive to the ambient temperature. Similar to its effect at room temperature, choline produced dose-dependent hypothermia at 4 degrees C, but this effect was abolished at 32 degrees C. These data suggest that choline produces hypothermia and this effect is mediated by muscarinic receptors. (C) 1998 Elsevier Science B.V. AU rights reserved.