Lesion effects on cholinergically elicited drinking in the rat

Small unilateral lesions were made at positive cholinergic drinking loci in the lateral hypothalamus, anterior thalamus or septal region of the rat. Lesions of the thalamus or septum had no affect on cholinergic drinking elicited at other limbic system sites. Hypothalamic lesions, however, did suppress drinking-to-carbachol elicited at other limbic system or hypothalamic sites as early as 30 min and as late as 12 days following lesioning. The hypothalamic lesion did not have to be centered at a positive cholinergic drinking site to be effective; nor did it have to produce an inhibition of food and water ingestion (the lateral hypothalamic syndrome). Atropine injection into the lesioned sites was still effective in blocking carbachol drinking, even though lesioning was not. These data suggest that atropine does not act as a functional lesion of an excitatory cholinergic drinking system.