Examining The Effects Of Early Life Stress From Maternal Separation On Measures Of Pain And Anxiety

Abstract

Animal models of stress-induced conditions have provided important insight into the physiological mechanisms of many chronic disorders. Models of early life stress involve procedures designed to induce prenatal or postnatal stress upon pups, which produces adult rats with enhanced stress responses and behavioral similarities to animal models of schizophrenia, anxiety, and depression. Since little research has focused on the effect of maternal separation on adult pain processing, the purpose of the current study is to examine both sensory and affective pain measures in adult rats following repeated maternal separation in infancy, a common model of early life stress. Eighty-six male pups were utilized following either early maternal separation (EMS) or early handling (EH). Although sensory thresholds remained unaltered for adult EMS rats, their emotional response to nociceptive stimuli intensified under certain conditions. In addition, EMS rats demonstrated more hyperactivity and anxiety-like behavior in the elevated plus maze. This indicates that early life stress leads to exaggerated emotional responses to novel or nociceptive stimuli in adulthood. Further research could determine whether or not this pattern holds true for different pain models, or if post-weaning enrichment could reverse the effects of maternal separation on pain processing.