ABSTRACT
<p><b>AIM</b>To investigate the toxic response in auditory cortex of guinea pigs caused by cis-platinum (DDP), and the protective role of melatonin in this effect.</p><p><b>METHODS</b>Cis-platinum and melatonin were injected peritoneally. LDH, MDA, NO in the auditory cortex were detected by spectrophotometeR.</p><p><b>RESULTS</b>The body weight of the guinea pigs was diminished by peritoneal injection of Cis-platinum for 7 days (P < 0.01). Peritoneal injection of Cis-platinum induced the increased leakage of LDH (P < 0.05 vs injection of normal saline). This effect was reduced by injection of MT (P < 0.05). The content of MDA in the auditory cortex was also increased because of injection of Cis-platinumv for 7 days (P < 0.01) and MT reduced this effect (P < 0.05). The change of NO in the auditory cortex was not statistically significant after injection of Cis-platinum or Cis-platinum with MT.</p><p><b>CONCLUSION</b>Peritoneal injection of Cis-platinum could destroy neurons in the auditory cortex. This effect could be reduced by melatonin by an anti-free radials mechanism.</p>