Abstract: Objective To build the over active bladder (OAB) related to chronic cystitis model which is similar to clinical process including pathogenesis and urodynamic performance. Methods Forty female SD rats were randomly divided into model group and saline control group. Model group: the bladders were instilled with Escherichia coli ATCC35218 (1×10⁸~1.2×10⁸CFU/mL) 100 μL, and a urine test were done after 3 days to confirm cystitis. The rats were given by gavage with Gentamicin (0.5 mL, 2 million units) 4 times a day × 7 days and urine were retested 10 days a cycle. The rats were done urodynamics and HE staining for bladder tissue after 4 cycles. Saline control group: were given by gavage with the same amount of saline solution instead of Escherichia coli, the remaining process was the same as the model group. The animals were raised under the same conditions. Results A small amount of epithelial was found degeneration, apoptosis, loss, and scattered lymphocytes in the lamina propria in model group. Thirteen rats were successfully modeled. Conclusion The OAB animal model can be established after cystitis by repeated E.coli infusion into bladder of female SD rats’. It offers ideas for pathogenesis, treatment and research about OAB associated with chronic cystitis.

Key words: Chronic cystitis, Overactive bladder (OAB), Escherichia coli, Rat model