The effects of choline on body temperature in conscious rats.
Choline (75-300 microg) produced dose-dependent hypothermia when injected intracerebroventricularly (i.c.v.). Pre-treatment with the muscarinic receptor antagonist, atropine (10 microg, i.c.v.), blocked the hypothermic effect of choline (150 microg), but the response was only partially attenuated by pre-treatment with the nicotinic receptor antagonist, mecamylamine (20 microg, i.c.v.). Pirenzepine (25 microg), a muscarinic M1 receptor antagonist, or hexahydro-siladifenidol (HHSD) (100 microg), a muscarinic M3 receptor antagonist, also blocked choline-induced hypothermia when injected centrally. Unlike the other muscarinic receptor antagonists, M2-selective 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5,11-dihydro-6H-pyri do[2,3-b][1,4]benzodiazepin-6-one (AF-DX116) (10 microg), 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.
Unal
C B
CB
Department of Pharmacology, Medical Faculty, Uludag University, Bursa, Turkey.
Demiral
Y
Y
Ulus
I H
IH
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D002794:Choline / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006426:Hemicholinium 3 / Q000494:pharmacology; D007276:Injections, Intraventricular; D018727:Muscarinic Antagonists / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000378:metabolism; D013696:Temperature
D018727:Muscarinic Antagonists; D011950:Receptors, Cholinergic; D006426:Hemicholinium 3; D002794:Choline; D000109:Acetylcholine