Age‐dependent differences in pain‐related depression of nesting in mice

Abstract

Pain‐related inference with behavior is a key clinical diagnostic indicator and target in the treatment of pain. Increasingly, preclinical studies on the expression, mechanisms, and treatment of pain have been aimed at improving understanding of pain‐related interference with behavior. Although there are well‐known changes to sensory, motor, and cognitive functions across the lifespan, no studies have examined the expression, mechanisms, and treatment of pain‐related depression of behavior from an aging perspective. The present studies compare the effects of a noxious pain stimulus and a clinically relevant analgesic on nesting behavior in 12‐, 18‐, and 48‐ week old mice. Nesting was operationally defined as the clearance of pieces of cotton nesting material from six zones within the home cage. This is the first step of consolidating the nesting material into a single zone for nest construction. Nesting was observed over the course of a 60‐minute session. First, the rate of nesting was compared across the age groups. Early in the nesting session, 12‐week old mice cleared more zones of nesting material than 18‐ and 48‐week old mice, but there were no differences in the number of zones cleared after 60 minutes. Next, the potency of intraperitoneal injection of lactic acid to depress nesting was determined in each age group. Lactic acid was more potent in the 48‐week old mice than the 18‐week old mice, but no other age related differences were observed. Finally, the effects of the nonsteroidal anti‐inflammatory drug (NSAID), ketoprofen, on lactic acid‐induced depression of nesting were determined. There were no age‐related differences in the potency or efficacy of ketoprofen. Together, these findings support the validity of assays of pain‐related depression of behavior to examine age‐related changes in the expression and treatment of functional impairment caused by pain. Moreover, these findings suggest that aging may result in increased susceptibility to pain‐related functional impairment, and that aging does not affect the ability of NSAIDs to treat pain‐related functional impairment.Support or Funding InformationSupport was provided by the Augusta University Center for Undergraduate Research and ScholarshipThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.