Moreover, melatonin was shown to decrease bladder oxidative stress and lower the activities of nitric oxide synthase and peroxynitrite, while increasing the heme oxygenase-1 (HO-1) expression level, which significantly reduced the bladder symptoms and histological damage caused by cyclophosphamide-induced cystitis in rats [46, 47]. This evidence concerns the gene HMOX1 and cystitis.