Abstract
Background and Objectives: Radiotherapy uses ionizing radiation for cancer treatment. One of the side effects of radiotherapy is peripheral neuropathy. After irradiation, the first stage of neuropathy involves electrophysiological, biochemical and histopathological variations, while the fibrosis of soft tissues surrounding the exposed nerve occurs in the second stage. The present study aimed to examine the radioprotective effects of melatonin against ionizing radiation-induced sciatic nerve damage. Materials and Methods: Sixty male Wistar rats were assigned to four groups: C (Control + Vehicle), M (Melatonin), R (Radiation + Vehicle), MR (Radiation + Melatonin). Their right legs were irradiated with a 30 Gy single dose of gamma rays. Then, 100 mg/kg melatonin was administered to the animals 30 min before irradiation once daily (5 mg/kg) until the day of rats’ sacrifice. Their exposed nerve tissues were assessed using the sciatic functional index (SFI) and histological evaluation. Results: Four, 12 and 20 weeks post irradiation, the SFI results showed that irradiation led to partial loss of motor nerve function after 12 and 20 weeks. Histological evaluation showed the various stages of axonal degeneration and demyelination compared to the C and M groups. Scar-like tissues were detected around the irradiated nerves in the R group at 20 weeks, but were absent in the MR group. The SFI and histological results of the R group showed partial nerve lesion. However, in all cases, treatment with melatonin prevented these effects. Conclusions: Results showed that melatonin has the potential to improve functional and morphological features of exposed sciatic nerves. This could possibly improve the therapeutic window of radiotherapy.
Highlights
Radiotherapy is a treatment modality for cancer using ionizing radiation
In addition to its anti-inflammatory property, it protects tissues against radiation-induced injuries by scavenging free radicals [16,17]. In view of these properties, the present study aimed to examine the radioprotective effects of melatonin against ionizing radiation-induced sciatic nerve damage
Results from this study have shown that melatonin has the potential to improve functional and morphological features of irradiated sciatic nerves
Summary
Radiotherapy is a treatment modality for cancer using ionizing radiation. It is administered to about 60% of cancer patients during the course of their treatment [1]. The first stage involves electrophysiological, biochemical and histopathological variations, while the fibrosis of soft tissues surrounding the exposed nerve occurs in the second stage [7]. These stages have key roles in the onset of peripheral neuropathy [3,8]. The first stage of neuropathy involves electrophysiological, biochemical and histopathological variations, while the fibrosis of soft tissues surrounding the exposed nerve occurs in the second stage. 100 mg/kg melatonin was administered to the animals 30 min before irradiation once daily (5 mg/kg) until the day of rats’ sacrifice Their exposed nerve tissues were assessed using the sciatic functional index (SFI) and histological evaluation. Scar-like tissues were detected around the irradiated nerves in the R group at 20 weeks, but were absent in the MR group
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