ABSTRACT
Objective To investigate the effects of PPTA on auditory brainstem responses (ABR) and the change of co-chlear histomorphology in guinea pig cochlea with ischemia/reperfusion injury .Methods The ischemia/reperfusion model was made by blocking bilateral vertebral artery and the right common carotid artery .Thirty -two healthy guinea pigs were used in this study ,they were divided into four groups randomly ,8 animals/group ,the normal control group(group I ,no treatment group) ,blank control group (group II ,guinea pig were only dissected of the bilateral vertebral artery ,bilateral common carotid artery without occlusion of the artery ) ,and ischemia/reperfusion control group(group III ,equal dose of normal saline were given by intravenous injection to the successful ischemia/reperfusion model through femoral vein) ,ischemia/reperfusion group treated with PPTA (group IV ,PPTA ,10 mg/kg ,were given by intravenous injection to the successful ischemia/reperfusion model) . Ischemia/reperfusion treated with PPTA group injected PPTA via femoral vein after reperfusion immediately ,ischemia/reper-fusion control group inject same dose of normal saline .Thresholds of ABR were measured before and after every experiment . The cochlea were taken quickly when 24h after reperfusion ,four guinea pigs in each group were assigned to Scanning Electron Microscope(SEM) randomly ,while others were assigned to Transmission Electron Microscope (TEM) to observe the change of histomorphology of cochlear .Results Before ischemia ,the ABR threshold of the four groups had no differences .At 24h of ischemia/reperfusion ,the ABR thresholds in group III and group IV were significantly higher than those of in group I and group II(P<0 .05);the threshold of group IV was significantly lower than that of group III (P<0 .05) .Morphological results showed that the cilia of outer hair cell of ischemia reperfusion control group were lodging and scaling ,the cilia of the inner hair cell were scattered ,the nucleus of vascular endothelial cell were pycnosis and margination ,the neurons were demyelinating . Application of PPTA decreased the cochlear structure damage after ischemia/reperfusion .Conclusion Intravenous application of PPTA in the early period of cochlear with ischemia/reperfusion can protect hearing and decrease the damage of cochlea in g uinea pig s .