Based on the previously suggested hypothesis that MCP-1 plays a critical role in the induction of histamine release from MCs in bladder tissues of patients diagnosed with IC/BPS, the current study was designed to quantify the expression of MCP-1 in bladder tissues and the levels of both MCP-1 and histamine present in urine using rat models of IC/BPS. This evidence concerns the gene CCL2 and Bartsocas-Papas syndrome 1.