Purpose: Diabetes is a grave and progressive condition characterized by debilitating complications. Diabetic bladder dysfunction (DBD) is a very common complication with no specific treatments currently available. Unlike other tissues affected by this disease, the bladder is subjected to two independent insults; 1) polyuria, created by the osmotic effects of glucose in the urine, and 2) hyperglycemia itself. Based on our understanding of inflammation as a major contributor to the underlying organ damage in several other diabetic complications, its presence in the bladder during DBD and the contribution of polyuria and hyperglycemia to its development were assessed.
Methods: Awake, restrained cystometry was performed on wild type C57BL/6 mice and diabetic (Akita) mice on a C57BL/6 background at 15 weeks of age. A subgroup of the Akita mice were treated with phlorizin, an inhibitor of sodium-glucose linked transporter types 1 and 2 that prevents glucose reabsorption in the kidney. All groups were assessed for serum glucose, 4-hour voiding totals, and inflammation in the bladder (Evans blue assay).
Results: Akita mice develop cystometrically-defined DBD by 15 weeks of age, as evidenced by an increase in urinary frequency, a decrease in voiding volume, and an increase in post-voiding residual volume. Phlorizin effectively normalized serum glucose in these animals while increasing the urine output. Inflammation in the bladder was present in the diabetic animals at this time point, but not detectable in animals receiving phlorizin.
Conclusion: Inflammation in the bladder of diabetic mice correlates with the development of DBD and is triggered by hyperglycemia, not polyuria.
Keywords: cystitis; diabetes; immunity; inflammation; innate; urinary bladder; urodynamics.