Objective       To determine the therapeutic effect of N-acetylcysteine (NAC) in the treatment of protamine sulfate (PS)-induced cystitis model in rats.       Methods       A total of 64 female SD rats were randomly divided into normal saline (NS) infusion group

PS infusion group

PS infusion+NS treatment group

PS infusion+NAC treatment group

with 16 rats in each group. NS or 300 mg/kg NAC solution of 0.5

mL was intra-peritoneally injected to the rats from the 2 treatment groups. In 2 h later

NS or 30 mg/mL NS of 0.5 mL were poured into the rat bladder from the infusion groups and then preserved in the bladder for 30 min. All rats were treated 3 times every week for a month. Rat urodynamic urodynamic test

HE staining and bladder wet weight was used to measure rat bladder inflammation index

edema and mast cell infiltration. Western blotting was used to detect the expression of rat bladder inflammatory cytokines TNF-α and IL-6.       Results       NAC treatment resulted in better urodynamic parameters (contraction intermittence 330.02±69.49 s)

bladder inflammation index (1.37±0.91)

and infiltrated mast cells (1.93±1.34) when compared with PS infusion group (161.32±58.17 s

2.75±0.46

3.40±2.19

P

0.01). Western blotting showed the expression of TNF-α and IL-6 was also reduced in the bladder of NAC treatment group (

P

0.01).       Conclusion       NAC can attenuate PS-induced cystitis in rats

which may be due to its reducing the mast cell infiltration and down-regulating TNF-α and IL-6.