Melatonin protects against ionizing radiation‐induced oxidative damage in corpus cavernosum and urinary bladder in rats

Abstract

The objective of this study was to examine the potential radioprotective properties of pharmacological doses of melatonin on corpus cavernosum and bladder tissues of whole-body irradiated (IR) rats. A total of 32 male Sprague-Dawley rats were exposed to irradiation performed with a LINAC which produced 6 MV photons at a focus 100 cm distant from the skin. Under ketamine anesthesia, each rat received a single whole-body dose of 800 cGy. Immediately before and after IR, rats were treated with either saline or melatonin (20 and 10 mg/kg, i.p.) and decapitated at 12 hr after exposure to irradiation. Another group of rats was followed for 72 hr after IR, where melatonin injections were repeated once daily. Tissue levels of malondialdehyde (MDA), an index of lipid peroxidation, and glutathione (GSH), a key antioxidant, were estimated in corpus cavernosum and urinary bladder. Tissues were also examined microscopically. The results demonstrate that both 12 and 72 hr following IR, tissue levels of MDA were elevated (P < 0.001), while GSH levels were reduced (P < 0.01) in both tissues. On the other hand, melatonin reversed these changes significantly (P < 0.05-0.01), concomitant with the improvement in histological appearances. Our results show that whole-body irradiation causes oxidative damage in the tissues of the genitourinary system. As melatonin administration reversed oxidative organ injury, as assessed by biochemical and histopathological findings, it is suggested that supplementing cancer patients with adjuvant therapy of melatonin may have some benefit for successful radiotherapy.

The melatonin immunomodulatory actions in radiotherapy

“…The administration of melatonin can prevent or ameliorate chronic inflammation and oxidative damage, fibrosis, necrosis, thrombus, vascular damage, and increased numbers of immune cells in various tissues, such as heart, lung, parotid and submandibular glands, kidneys, spinal cord, the lens, genitourinary system, and others (Karslioğlu et al 2005;Canyilmaz et al 2016;Cakmak Karaer et al 2016;Gürses et al 2014;Haddadi et al 2013;Serin et al 2007;Şener et al 2004;Tahamtan et al 2015). Prevention of pathological damage induced by ionizing radiation using melatonin at different times before and after exposure is a promising outcome.…”

On the Role of Melatonin in Skin Physiology and Pathology

“…Other studies have also shown that melatonin administration can reverse oxidative injury in other tissues and organs, as assessed with biochemical and histopathologic techniques. Thus, melatonin could be useful as a damage-limiting supplement in patients undergoing radiotherapy ( 77,78 ). The mechanisms of action could include inhibition of lipid peroxidation, shown in human fibroblasts ( 79 ), direct radical-scavenging properties, and stimulation of antioxidative enzymes in human skin fibroblasts ( 80 ) and other organ systems ( 16,17 ).…”

Effectiveness of Melatonin, as a Radiation Damage-Mitigating Drug in Modulating Liver Biochemical disorders in γ-Irradiated Rats

“…Increased CAT activity is probably related to the inability of the cell to cope with overproduction of H 2 O 2 or *OH (Weiss et al, 2003). Oxidative injury of the colon is accompanied with neutrophil infiltration in both early and later phases after irradiation, whereas contribution of neutrophils to the irradiation injury of the liver occurs at the later phase (Sener et al, 2004). Melatonin-treatment modulated hepatic GST and maintained CAT and MPO activities within the control levels.…”

“…Consequently the cellular antioxidant capacity is decreased and the organs become more susceptible to the deleterious effects of ROS (Karbownik and Reiter, 2000). Similarly, total body irradiation in rats has been reported to cause oxidative tissue damage (Sener et al, 2004). The aim of the present study is to investigate the radiation damage mitigating-role of melatonin (delivered after irradiation) against oxidative stress induced liver injury in rats.…”