Functional, histological structure and mastocytes alterations in rat urinary bladders following acute and chronic cyclophosphamide treatment

Neurogenic inflammation is linked to urinary bladder overactivity development. Cyclophosphamide (CYP) damages all mucosal defence lines of urinary bladder and induces cystitis with overactivity. The aim of this study was to estimate the effect of CYP on rat urinary bladder function, histological structure and mastocytes numbers following acute and chronic CYP treatment. Fourty two female rats were divided into four groups: I (control), II (acute cystitis), III (chronic cystitis), IV (sham group). Acute and chronic cystitis were induced by CYP in single dose and four doses (1 st , 3 rd , 5 th , 7 th day), respectively. In group I―III the cystometric evaluation was performed. Sections of the bladder were stained with HE and toluidine blue for the detection of mastocytes. The severity of inflammation was examined according to mucosal abrasion, haemorrhage, leukocyte infiltration and oedema. Acute and chronic CYP treatment caused inflammatory macroscopic and microscopic changes (mucosal abrasion, haemorrhage, oedema) and increased infiltration of inflammatory cells in urinary bladder. Acute treatment induced the infiltration of mastocytes within bladder wall contrary to chronic one decrement. Acute treatment caused more severe mucosal abrasion, whereas chronic one revealed more developed haemorrhage changes. Additionally, cystometric evaluation revealed urinary bladder overactivity development in both types of cystitis. Basal pressure and detrusor overactivity index after acute treatment increased considerably in comparison with the increase obtained after chronic one. Our results proved that acute model of CYP-induced cystitis in rats is more credible for further evaluation of neurogenic inflammation response in pathogenesis of overactive bladder as compared to chronic one.