Opposing viscerovisceral effects of surgically induced endometriosis and a control abdominal surgery on the rat bladder

Abstract

To determine, in rats, how surgically induced endometriosis and a control surgery (partial hysterectomy; sutures in abdomen) affects micturition thresholds and bladder vascular permeability. Two animal studies, each performed in three groups of urethane-anesthetized rats in proestrus. Academic facility. Seventy-three female, regularly cycling Sprague-Dawley rats studied in proestrus. Surgical induction of endometriosis (ENDO), surgical control (shamENDO), intact control (NoSURG), and bladder inflammation via intravesicular turpentine in all three groups. [1] Micturition thresholds (MTs; volume voiding thresholds), as measured by repetitive transurethral cystometry before and after bladder inflammation and [2] bladder inflammation, as assessed by extravasation of Evans Blue dye. In the uninflamed bladder, MTs were significantly lower and dye extravasation significantly higher in ENDO rats than in shamENDO and NoSURG rats. Bladder inflammation increased dye extravasation in all groups and reduced MTs in the NoSURG and ENDO rats, but not in the shamENDO rats. Endometriosis reduces MTs and produces signs of inflammation in the healthy bladder. Surprisingly, the control surgical procedure (partial hysterectomy; sutures on mesenteric blood vessels) protects bladder reflexes from the influence of bladder inflammation, a condition that is named silent bladder inflammation. Such cross-system inducing and masking effects have important clinical relevance.