Interstitial cystitis: increased sympathetic innervation and related neuropeptide synthesis

To investigate the possibility of a neural deterioration of the bladder wall in interstitial cystitis, bladder tissue from 10 patients with interstitial cystitis was compared with that from 10 control subjects by means of immunohistochemistry. An enhanced innervation of the bladder in the submucosa and detrusor muscle was found to represent an increase of sympathetic but not cholinergic neurons. In interstitial cystitis the number of neurons positive for vasoactive intestinal polypeptide and neuropeptide Y was higher and carried a larger number of axonal varicosities, whereas the number of neurons positive for substance P and calcitonin-gene-related peptide was not significantly different in both groups. We conclude that interstitial cystitis is associated with increased sympathetic outflow into the bladder and altered metabolism of vasoactive intestinal polypeptide and neuropeptide Y. Since similar changes have been observed in other inflammatory diseases of a presumably autoimmune nature, such as rheumatoid arthritis, Crohn's disease and colitis ulcerosa, the pathophysiology of interstitial cystitis may share common pathways with the latter. Experience in these diseases may facilitate a better understanding of the pathophysiology of interstitial cystitis and suggest new therapeutic concepts.