Bladder dysfunction in rats with metabolic syndrome induced by long-term fructose feeding

We studied the effects of long-term fructose feeding and metabolic perturbations on bladder function in rats.

Female Wistar rats were fed a fructose enriched (60%) or control diet for 3 and 6 months. In vitro contractile responses to electrical field stimulation, KCl, carbachol and adenosine triphosphate, and in vivo cystometry were used to evaluate bladder function. Tissue staining and electron microscopy were also performed to evaluate the structural changes in rats subjected to metabolic syndrome. Biochemical and physiological data were compared between fructose fed rats and age matched controls.

All rats fed a fructose enriched diet for 3 months showed insulin resistance, hyperinsulinemia, hypertriglyceridemia and hypertension. These fructose fed rats showed a decreased contractile response to high concentrations of KCl but not to other parameters tested compared to controls. Eight of the 12 rats (66.7%) showed abnormal cystometry, mainly by increased phasic contractions. In 6-month fructose fed rats contractile responses to electrical field stimulation, KCl and carbachol were decreased significantly. However, responsiveness to high concentrations of adenosine triphosphate was significantly increased. Morphological studies in fructose fed rats showed swollen mitochondria in bladder smooth muscle, increased leukocyte infiltration between interstitial tissue and neutrophil adhesion around the endothelium of vessels.

Our data show that a significant proportion of fructose fed rats show time related alterations in bladder biochemical, morphological and functional properties. The proinflammation and myopathy of the bladder induced by metabolic perturbations have important roles in causing bladder dysfunction.