[Effect of white noise on activity and gene expression of nitric oxide synthase in cochlear nuclei of guinea pigs].

NADPH-diaphorase (NADPH-d) histochemistry method and semiquantitative polymerase chain reaction (PCR) technology were adopted to study nitric oxide synthase (NOS) neurons and to investigate the content change of NOS mRNA and the relationship between it and auditory threshold and to explore the possible role of NOS neurons in cochlear nuclei of guinea pigs after exposed to white noise. The results showed that the quantity and staining intensity of positive NOS neurons in cochlear nuclei increased obviously after exposed to noise. It reached the peak 2 week later and remained 5 week than normal. The regulation of NOS mRNA was consistent with that of morphological observation. NOS mRNA content in 2 w group was the highest and was 4.02 times higher than normal. After exposed to noise, ABR threshold shift was in positive correlation with NOS mRNA content in cochlear nuclei (r = 0.9655, P < 0.01). It is suggested that positive NOS neurons in cochlear nuclei might be involved in controlling injury and repair of cochlear nerves. The high expression of NOS gene might be an important factor in pathogenic mechanism of noise deafness.