CYCLOPHOSPHAMIDE-INDUCED CYSTITIS IN RATS - INVOLVEMENT OF CAPSAICIN-SENSITIVE PRIMARY AFFERENTS

The involvement of capsaicin-sensitive primary afferent neurons has be en investigated in a rat model of cyclophosphamide (CYP)-induced cysti tis. CYP (150 mg/kg i.p., 48h before) was administered in both vehicle - and capsaicin-(50 mg/kg s.c., 4 days before)-treated rats. Some expe riments were performed 96 h after bilateral removal of pelvic ganglia (bladder denervation). CYP produced a marked detrusor hyperreflexia wh ich was abolished by capsaicin pretreatment. CYP produced a marked inc rease in bladder weight and plasma protein extravasation (PPE, measure d by Evans blue leakage technique): CYP-induced PPE was reduced by bla dder denervation and was aggravated by capsaicin pretreatment. PPE agg ravation by capsaicin was abolished by ganglionectomy. The bladder con tent of calcitonin gene-related peptide, was unaffected CYP. We conclu de that CYP-induced decrease in bladder capacity is entirely mediated through stimulation of capsaicin-sensitive bladder afferents. At the t ime chosen as end point in these experiments, capsaicin-sensitive affe rents exert an antiinflammatory influence on CYP-induced cystitis.