Increased plasma norepinephrine concentration in cats with interstitial cystitis

Purpose: Interstitial cystitis is a chronic urological syndrome affecting h umans and domestic animals, including cats (feline interstitial cystitis). The symptoms of interstitial cystitis seem to be exacerbated by stress, sug gesting involvement of the sympathetic nervous system and/or hypothalamic-p ituitary-adrenal axis. Others have described sympathetic nervous system abn ormalities in patients with interstitial cystitis but to our knowledge no d ata on plasma catecholamine concentrations or hyp othalamic-pituitary-adren al axis function in such patients have been reported. To evaluate the role of these systems in cats with feline interstitial cystitis we simultaneousl y measured baseline plasma concentrations of catecholamines and their metab olites to assess sympathetic activity, and the response of plasma adenocort icotropic hormone and cortisol concentrations to the infusion of corticotro pin-releasing factor. Materials and Methods: Eight healthy cats and 8 with feline interstitial cy stitis were anesthetized and a catheter was placed in the external jugular vein. Four hours after recovery samples were obtained for high performance liquid chromatography analysis of plasma norepinephrine, dihydroxyphenylgly col, epinephrine, dihydroxyphenylalanine, dopamine and dihydroxyphenylaceti c acid. In 4 cats per group 1 mug. ovine corticotropin-releasing factor per kg. body weight was infused and blood samples were collected at intervals for 120 minutes for determining adenocorticotropic hormone and cortisol. Results: Significant increases in plasma norepinephrine and dihydroxyphenyl glycol as well as a trend toward increased epinephrine were found, whereas no effect on dihydroxyphenylalanine, dopamine, dihydroxyphenylacetic acid, adenocorticotropic hormone or cortisol was identified in cats with feline i nterstitial cystitis. Conclusions: These results support and extend previous studies identifying an increase in sympathetic activity in cats with feline interstitial cystit is.