Succinate decreases bladder function in a rat model associated with metabolic syndrome

Abstract

Succinate and its receptor, GPR91, have been implicated in different aspects of metabolic syndrome. As GPR91 is expressed in the urinary bladder, the aim of this study is to show the effect of chronically increased succinate levels on bladder function. Healthy Sprague-Dawley (SD) rats and hypertensive Dahl rats received an intraperitoneal injection of either saline or succinate (50 mg/kg) daily for a period of 4 weeks. Conscious cystometry was performed at the end of this period. Bladders were collected and used for contractility studies and morphological assessment. Two-way ANOVA was performed to compare between the two strains and student t-tests to compare treatment groups within each strain. Compared to SD rats, Dahl rats showed signs of bladder dysfunction. Succinate treatment led to higher urinary succinate levels and lower bladder capacities compared to saline-treated animals. In SD rats, this was associated with higher collagen content, lower GPR91 expression and an altered bladder nerve profile in the bladder. In succinate-treated Dahl rats, detrusor contractility was reduced and associated with decreased cholinergic innervation and increased collagen content. It is suggested that succinate negatively affects bladder function via effects through its receptor, GPR91, and that its effects are enhanced in the presence of metabolic disturbance. These findings contribute to our understanding of the pathophysiology of bladder dysfunction, specifically in a metabolic syndrome setting.