Habituation of oral responding in adult rats

The effects of repeated oral stimulation on ingestive responding were investigated in adult rats. A series of brief intraoral infusions of flavored diet was delivered to female rats once every minute through an oral cannula. When the flavor of the infused diet remained constant, significant decreases in mouthing behavior were observed by the end of testing, whereas switching the flavor of the diet during testing resulted in enhanced responding and infusions delivered through gastric cannulas produced minimal effects. Patterns of oral responding were also similar in food-restricted rats. These patterns of responding suggest that adult rats habituate to oral stimulation. Finally, oral habituation led to decreased ingestion, whereas gastric infusions had minimal effects. Thus, oral habituation may represent a mechanism influencing intake in rats at all ages.