Effect of a novel antioxidant Silymarin on cyclophosphamide-induced cystitis in rats

Silymarin is a mixture of flavonolignans extracted from Silybum marianum and it has beneficial antioxidant and anti-inflammatory properties. Cyclophosphamide induces a haemorrhagic cystitis characterized by bladder overactivity. 92 female Wistar rats were used. The study was conducted to examine effects of silymarin, was given the oral intragastrik tube for 7 days on bladder overactivity in rats with cyclophosphamide treatment. 56 rats received a single i.p. injection of cyclophosphamide, and after 72 h, bladder function was evaluated by 1. in vitro preparations of whole bladders, 2. in vitro isolated bladder strips and 3. cystometry with continuous saline infusion under urethane anesthesia. Cyclophosphamide-treatment potentiated the basal spontaneous contractions of isolated whole bladders and isolated bladder strips compared to control rats. On the other hand cyclophosphamide-treatment did not affect the neurogenic or cholinergic contractions induced by electrical field stimulation or a muscarinic receptor agonist carbachol respectively. In anesthetized rats, during continuous infusion cystometry, intercontraction interval was significantly shorter and bladder voiding pressure was significantly greater in cyclophosphamide-injected rats than in control rats. Silymarin treatment caused a significant decrease on the amplitude, frequency (contractions/min) and area under the curve of spontaneous contractions in isolated whole bladder and isolated bladder strips. Also, silymarin treatment could increase the intercontraction intervals and decrease contraction pressure. Histopathological examination showed that silymarin had a partial improvement on rat bladders.The protective and restorative effect of Silymarin can depend on its powerful anti-inflammatory and antioxidant effects. Silymarin may be considered as an attractive strategy for the treatment of cyclophosphamide-induced bladder overactivity.