Ameliorative effect of Melatonin on 5-Fluorouracil-induced reproductive toxicity in male rats

5-Fluorouracil (5-FU) is an antimetabolite chemotherapeutic agent that can cause oxidative stress and complications in normal organs, including the reproductive system. This study was conducted to investigate the effect of melatonin (MEL) on 5-FU-induced reproductive toxicity in male rats. Male Wistar rats weighing 180 ± 20 g were divided into five groups: control, 5-FU (50 mg/kg), 5-FU + MEL (2.5, 5 & 10 mg/kg). The testes and prostates were removed, and histopathological aspects, biochemical markers, and gene expression were investigated. The effect of 5-FU on the normal TM4 cell line (murine testicular Sertoli line) and co-treatment of 5-FU and MEL were studied using MTT assay. Results showed that MEL prevented cell death in the TM4 cell line induced by 5-FU. MEL also reduced edema, hyperemia, and vacuolization in testis and prostate tissues induced by 5-FU. Additionally, MEL increased the activity of antioxidant enzymes and reduced the levels of MDA (p < 0.0001) and MPO (p < 0.0001). The levels of testosterone (p < 0.01) and the number of spermatocytes and spermatogonia (p < 0.0001) were increased in groups receiving 5-FU with MEL compared to 5-FU alone. The prostate-specific antigen (PSA) level in prostate samples was lower in the groups receiving 5-FU with MEL compared to the 5-FU group. Furthermore, the genes expression of COX-2 and TNF-α in testis tissues was reduced in the presence of MEL. in conclusion, the antioxidant property of MEL can protect the male reproductive system against 5-FU toxicity, as evidenced by the improved histopathological and biochemical parameters, as well as the reduced gene expression of COX-2 and TNF- α genes.