HYPOXIA-INDUCED ABR CHANGE AND HEAT-SHOCK-PROTEIN EXPRESSION IN THE PONTINE AUDITORY PATHWAY OF YOUNG-RABBITS

The auditory brainstem response (ABR) was compared with the immunohist ochemical expression of heat shock protein (HSP-72) and microtubule-as sociated protein 2 (MAP-2) of the brainstem auditory pathway in young rabbits subjected to hypoxic stress. Severe hypoxia for 2 h produced s ignificant prolongation and decreased amplitude of the later component of ABR. HSP-72 expression was distinctly increased in the cochlear nu cleus, but there was less induction in the inferior colliculus under s evere hypoxia. MAP-2 immunostaining of neuropiles in the inferior coll icular nucleus was decreased slightly after severe-long hypoxia, but c ytoplasmic staining did not change. The present ABR change, which was produced by brainstem hypoxia-ischemia and acidosis, may be due to the neural cytoarchitectural derangement and less induction of stress pro teins in the upper brainstem.