Grooming behavior in mice induced by stimuli of corn oil in oral cavity

Mice show a strong preference for corn oil, which was thought to be elicite d by stimulation in the oral cavity. Grooming behavior is known to be induc ed by dopamine D-1 stimulation in rodents. Therefore, we evaluated stimulat ion by corn oil in the oral cavity and the contribution of D-1 receptors to corn-oil-induced grooming in mice. Intraoral injection (0.1 mi) of corn oi l induced grooming behavior similarly to SKF 38393 (10 mg/kg i.p.), a D-1 a gonist, and both were antagonized by pretreatment with SCH 23390, a D-1 ant agonist. However, a higher dose was needed for antagonism of the corn-oil-i nduced grooming compared with that induced by SKF 38393. Long-chain fatty a cids, their methyl esters and alcohol, their triglycerides, mineral oil and silicone oil but not glycerin, a short-chain triglyceride, xanthan gum sol ution, or sucrose solution also induced grooming in mice. Xanthan gum solut ion, which was suggested to mask oil-like texture, attenuated the silicone- oil- but not corn-oil-induced grooming when injected intraorally as a mixtu re with an equal volume of the oil (50% suspension). The silicone-oil-induc ed grooming was reduced by SCH 23390 similarly to that induced by corn oil. These results suggested that stimulation by the oil-like texture in the or al cavity in mice induced grooming behavior and that it might be mediated a t least partially via D-1 receptors. Moreover. stimuli other than texture m ight also contribute to the corn-oil-induced grooming. (C) 2000 Elsevier Sc ience Inc. All rights reserved.