Abstract
BackgroundMelatonin, the chief secretary product of pineal gland, is a strong free radical scavenger and antioxidant molecule. The radioprotective efficacy and underlying mechanisms refer to its antioxidant role in somatic cells. The purpose of this study, therefore, was to investigate the prophylactic implications of melatonin against γ-ray-induced injury in germinal cells (testes). C57BL/6 male mice were administered melatonin (100 mg/kg) intra-peritoneally 30 min prior to a single dose of whole-body γ-irradiation (5 Gy, 1 Gy/minute) using 60Co teletherapy unit. Animals were sacrificed at 2h, 4h and 8h post-irradiation and their testes along with its spermatozoa taken out and used for total antioxidant capacity (TAC), lipid peroxidation, comet assay, western blotting and sperm motility and viability. In another set of experiment, animals were similarly treated were sacrificed on 1st, 3rd, 7th, 15th and 30th day post-irradiation and evaluated for sperm abnormalities and histopathological analysis.ResultsWhole-body γ-radiation exposure (5 Gy) drastically depleted the populations of spermatogenic cells in seminiferous tubules on day three, which were significantly protected by melatonin. In addition, radiation-induced sperm abnormalities, motility and viability in cauda-epididymes were significantly reduced by melatonin. Melatonin pre-treatment significantly inhibited radiation-induced DNA strands breaks and lipid peroxidation. At this time, radiation-induces activation of ATM-dependent p53 apoptotic proteins-ATM, p53, p21, Bax, cytochrome C, active caspase-3 and caspases-9 expression, which were significantly reversed in melatonin pre-treated mice. This reduced apoptotic proteins by melatonin pre-treatment was associated with the increase of anti-apoptotic-Bcl-x and DNA repair-PCNA proteins in irradiated mice. Further, radiation-induced decline in the TAC was significantly reversed in melatonin pre-treated mice.ConclusionsThe present results indicated that melatonin as prophylactic agent protected male reproductive system against radiation-induced injury in mice. The detailed study will benefit in understanding the role of melatonin in modulation of radiation-induced ATM-dependent p53-mediated pro-vs.-anti apoptotic proteins in testicular injury. These results can be further exploited for use of melatonin for protection of male reproductive system in radiotherapy applications involving hemibody abdominal exposures.Electronic supplementary materialThe online version of this article (doi:10.1186/s12929-015-0156-9) contains supplementary material, which is available to authorized users.
Highlights
Melatonin, the chief secretary product of pineal gland, is a strong free radical scavenger and antioxidant molecule
We have investigated the radioprotective potential of melatonin, for its ability to rescue germinal cells injuries induced by γ-irradiation at sub-lethal dose of 5 Gy in C57BL/6 male mice
The results showed that more number of spermatogonia per sertoli cell was present in melatonin pre-treated mice (p < 0.001) on 7th day following irradiation (Fig. 2d)
Summary
The chief secretary product of pineal gland, is a strong free radical scavenger and antioxidant molecule. Animals were sacrificed at 2h, 4h and 8h post-irradiation and their testes along with its spermatozoa taken out and used for total antioxidant capacity (TAC), lipid peroxidation, comet assay, western blotting and sperm motility and viability. In another set of experiment, animals were treated were sacrificed on 1st, 3rd, 7th, 15th and 30th day post-irradiation and evaluated for sperm abnormalities and histopathological analysis. Testes possesses germ cells at different stages of development, a process known as spermatogenesis, and developing sperms are very sensitive to ionizing radiation, known to affect morphology, function and the spermatogenesis [4, 5]. It is desired that the promising radioprotector to have efficacy for protection of reproductive systems
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