Chronic Toxic Effects of Tramadol on the Brains of Adult Albino-Rats and possible Ameliorative Effects of Melatonin

Background: Tramadol chronic use as an analgesic represents a noteworthy public health concern due to its neurotoxicity. Melatonin has potent antioxidant and anti-apoptotic properties, therefore mitigating oxidative damage to the brain. Aim of work: this experimental research purposed to assess the chronic toxic impacts of tramadol on the brains of adult albino rats of both sexes (males & females) using physical, behavioral, biochemical, histopathological, and immuno-histochemical parameters, and to investigate the possible ameliorative effects of melatonin. Material & methods: This work was performed on 56 adult albino rats (28 males & 28 females) weighing between 180-200 gm. Rats were randomly separated into seven groups of eight rats each: three control groups [negative, solvent & melatonin-treated (10mg/kg/day) group]. The four treated groups were tramadol treated male group, tramadol treated female group (50mg/kg body weight), tramadol-melatonin treated male group, and tramadol-melatonin treated female group. The rats were treated once daily for six months. Results: Tramadol administration significantly affected the rats’ brains evidenced by reduction in body weight and relative brain weight (RBW%), behavioral alterations, increased levels of ubiquitin-c-terminal hydrolase-1 (UCH-L1), serotonin & noradrenaline and increased the oxidative stress indices, plus the alteration in the brain histology and increased casepase3 immunohistochemical expression that could be ameliorated by melatonin administration. All resulted showed insignificant differences between the corresponding male and female studied groups. Conclusion: Daily exposure of adult albino rats of different sexes to (50 mg/kg) tramadol for 6 months resulted in toxic brain effects that could be improved by(10mg/kg/day) melatonin administration.