Foot shock stress generates persistent widespread hypersensitivity and anhedonic behavior in an anxiety-prone strain of mice

Abstract

A significant subset of patients with urologic chronic pelvic pain syndrome (UCPPS) suffer from widespread, as well as pelvic, pain and experience mood-related disorders, including anxiety, depression, and panic disorder. Stress is a commonly-reported trigger for symptom onset and exacerbation within these patients. The link between stress and pain is thought to arise, in part, from the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the response to stress and can influence the perception of pain. Previous studies have shown that stress exposure in anxiety-prone rats can induce both pelvic and widespread hypersensitivity. Here, we exposed female A/J mice, an anxiety-prone inbred murine strain, to 10 days of foot shock stress to determine stress-induced effects on sensitivity, anhedonia, and HPA axis regulation and output in. At 1- and 28-days post-foot shock, A/J mice displayed significantly increased bladder sensitivity and hind paw mechanical allodynia. They also displayed anhedonic behavior, measured as reduced nest building scores and a decrease in sucrose preference during the 10-day foot shock exposure. Serum corticosterone was significantly increased at 1-day post-foot shock and bladder mast cell degranulation rates were similarly high in both sham- and shock-exposed mice. Bladder cytokine and growth factor mRNA levels indicated a persistent shift toward a pro-inflammatory environment following foot shock exposure. Together, these data suggest that chronic stress exposure in an anxiety-prone mouse strain may provide a useful translational model for understanding mechanisms that contribute to widespreadness of pain and increased comorbidity in a subset of UCPPS patients.