Role of Aging in the Expression of Pain-related Depression of Nesting in Mice

Abstract

Pain stimulates some behaviors (e.g. flinching, vocalization), and depresses others (e.g. locomotor activity, social interactions). Pain-related depression of behavior is a key diagnostic criteria and treatment target in clinical settings, but preclinical research has primarily focused on pain-related stimulation of behavior. The present study aims to improve understanding of the impact of aging on pain-related depression of behavior by examining pain-related depression of nesting behavior in male ICR mice. The mice were placed in a cage containing nesting material, and the rate of consolidation of that material was determined during one hour nesting sessions. Consistent with previous studies showing that physiologically-relevant pain stimuli depress nesting behavior, lactic acid depressed nesting in a concentration-dependent manner. Age did not mediate the effect of lactic acid on nesting. This study supports the validity of nesting as a target behavior in studies of pain related depression of behavior, and will guide future studies examining the effects of other independent variables such as analgesics, sex, and environmental variables on the expression and treatment of pain-related depression of behavior.