Experimental model of Hemorrhagic Cystitis induced by intravesical injection of Acrolein – Uroprotective effects of thiol compounds (Mesna, Glutathione and Amifostine)

Acrolein (ACR) is a highly reactive and toxic aldehyde produced as a metabolic urinary product of the anticancer drugs Cyclophosphamide (CYP) and Ifosfamide (IFO) that was related as the causative agent of Hemorrhagic Cystitis (HC) induced by these compounds. Systemic administration of CYP or IFO would induce HC through the release of ACR. However, a possible direct effect of ACR to the urothelium is yet to be demonstrated. In this study we aimed to evaluate the effects of the local intravesical (i.ve.) injection of ACR to mice, as well as the cytoprotective action of the thIol compounds: Mesna, the classical ACR chemical antagonist; the reduced form of the endogenous thiol Glutathione (GSH), and Amifostine (AMF), an agent that selectively protects normal tissues against a wide variety of toxic effects induced by anticancer chemotherapy. Male Swiss mice received ACR (25, 75, or 225 mg) i.ve. - 3, -6, -12 or -24 h before sacrifice. the increase in vascular permeability (VP) in the bladders was evaluated by the measure of the concentration of Evans blue dye extravasation, injected 30 min before ACR (25mg/kg e.v.) and by comparison of the Bladder Wet Weight between the groups. The macroscopical and histopathologycal changes were evaluated using the Gray’s criteria. Groups received local (i.ve.) Mesna (2mg), GSH (2mg) or AMF(1,5mg) or systemic (i.p.) Mesna (80 mg/kg), GSH (125,250,500 mg/Kg), and AMF(25,50,100 mg/Kg) 30 min before ACR. Local ACR induced a dose and time-dependent increase in bladder edema as well as in the macroscopical and histopathological lesions, that was significantly different from controls, being maximal 12 h after ACR injection (p<0.05). Pretreatment with either Mesna, GSH, or AMF inhibited both the edema, macroscopical and the histopathological changes, regardless of local or systemic adminstration. This protective effect of the thiol compounds was also demonstrated in HC induced by IFO (400 mg/Kg ip). In conclusion, our results confirmed the role of ACR in the genesis of HC induced by oxazaphosphorines and indicated the thiol compounds as an important celular defense line in this pathological condition.A Acroleína (ACR) é um aldeído altamente reativo e tóxico produzido como metabólito urinário das drogas antineoplásicas Ciclofosfamida (CFM) e Ifosfamida (IFO); tem sido apontada como o agente causal da Cistite Hemorrágica (CH) induzida por estes compostos. Os dados anteriores da literatura sobre CH induzida por oxazafosforinas foram obtidos após sua administração intraperitoneal (ip), a partir da qual a ACR seria supostamente produzida ou liberada, mas não pela demonstração de sua ação direta na bexiga. Assim, o presente estudo objetivou avaliar os efeitos da injeção intravesical (ive) de ACR em camundongos, assim como a ação citoprotetora de alguns compostos tióis como o Mesna, clássico antagonista químico da ACR, a Glutationa reduzida (GSH), importante tiol endógeno e a Amifostina (AMF), agente que protege seletivamente os tecidos normais contra uma grande variedade de efeitos tóxicos induzidos pela quimioterapia anti-câncer. Para tanto, a CH foi induzida em camundongos Swiss machos (25-35 g; n=6 por grupo) através de injeção ive de ACR nas doses de 25, 75, 225 g, os quais foram sacrificados após 3, 6, 12 ou 24 horas e tiveram suas bexigas analisadas quanto as alterações do peso úmido (PUV), permeabilidade vascular (PV) pela técnica do extravasamento do Azul de Evans (25 mg/Kg, ev, 30 minutos antes do sacrifício) e análises macroscópica e histopatológica, ambas realizadas segundo os critérios de Gray. Observamos que a ACR induziu de forma dose e tempo dependente significativo (p