Intracerebral implantation of carbachol in the rat: Its effect on water intake and body temperature

Abstract

Intracerebral carbachol produces a fall in body temperature as well as drinking in the rat when implanted in various subcortical structures, related to the emotion-motivation limbic circuit. These effects are due to a central cholinergic stimulation since they can be prevented by the systemic administration of the centrally active anticholinergic substance atropine sulphate and to a lesser degree by methylatropine nitrate. By withholding water during the first hr following carbachol implantation it could be shown that the hypothermic response is independent from water intake. When carbachol as well as atropine sulphate are implanted in two localisations, which both induce hypothermia as well as drinking following carbachol stimulation, atropine sulphate nearly always blocked drinking, but practically only when atropine sulphate was applied caudally to carbachol did it block hypothermia. The results suggest a drinking and hypothermic circuit within the limbic system, anatomically linked but functionally different and independent.