Electrophysiological and theoretical investigation of melatonin effect on experimental sciatic nerve injury

Electrophysiological, histological, biochemical studies have been performed for getting information about peripheral nerve injuries and nerve regeneration. The aim of this study was to evaluate the electrophysiological and theoretical effect of melatonin in peripheral nerve injury.In this study, adult male Wistar rats (n=32) were randomly allocated into four groups. Sciatic crush was constituted on left sciatic nerves. Treatment groups received intraperitonal melatonin at doses of 5 mg/kg and 20 mg/kg for 21 days. A vehicle of ethanol was injected to control group and sham group received %0.9 NaCl. Functional nerve recovery was evaluated using sciatic functional index (SFI) every week during the experiment. EMG measurements were done before crush, one week after crush and at the end of experiments. In vivo and in vitro electrophysiological measurements were performed at the end of the treatment. The electrophysiological data were also analyzed by using wavelet analysis.Melatonin treatments increased the SFI values in the injured sciatic nerves. In EMG measurements, reduction was determined on latencies while increments were observed on attenuated amplitude and peak to peak amplitude in left sciatic nerves. In vivo electrophysiological measurements showed that melatonin increased the conduction velocities. In vitro electrophysiological measurements demonstrated that melatonin applications caused enhancement in the amplitude and peak to peak amplitude of compound action potential (CAP). The wavelet analysis showed that melatonin treatment reduced the densities of high frequency components of CAP.These results suggest that melatonin application is a promising strategy for the treatment of peripheral nerve crush injuries.