Effects of neuroglobin gene transfer in vivo on hearing response properties of neurons in the inferior colliculus in mice after administration of sodium salicylate.

The effects of neuroglobin (NGB) gene transfer in vivo mediated by GeneJamer on the hearing response properties of the inferior colliculus (IC) neurons in mice after administration of sodium salicylate were studied. Forty-eight Kunming mice were divided into 4 groups (n=12 in each group): Group A1 (negative control);Group A2 (positive control);Group B, sodium salicylate (450 mg/kg every day) + pEGFP-C1;Group C, sodium salicylate (450 mg/kg every day) + pEGFP-NGB. The GeneJamer and pEGFP-NGB were mixed and injected into IC neurons in mice. The expression of NGB mRNA and protein of IC neurons in mice was detected by using RT-PCR and Western blot methods. The intensity-rate functions, intensity-latency functions and frequency-turning curves in IC neurons were recorded by extracellular electrophysiological recording techniques and the effects of pEGFP-NGB transfer following injection of sodium salicylate on them were studied. It was found that: (1) The GeneJamer-mediated pEGFP-NGB could be effectively transferred into the IC brain tissues in mice and NGB could be expressed intensively. (2) The intensity-rate functions of IC neurons were raised after administration of sodium salicylate. The non-monotonic styles of intensity-rate functions in groups A1, A2 and C were accounted for 74.6%, 72.2 %, 59.3 %, respectively, and the function in group B for 47%. There were significant differences between group B and groups A1, A2 or C (P<0.01, P<0.01, P<0.05). (3) The intensity-latency functions in IC neurons were reduced after administration of sodium salicylate. The non-monotonic styles of intensity-latency functions in groups A1, A2 and C were accounted for 3.2 %, 5.1 %and 21 %, respectively, and that in group B for 45.5 %. There were significant differences between group B and groups A1, A2 or C (P<0.01, P<0.01, P<0.05, respectively). (4) The frequency-turning curves in groups A1 and A2 were sharpened. In 72 acoustic neurons recorded in the group B, the frequency-turning curves from 53 neurons were broadened while those of the rest were sharpened. In group C the frequency-turning curves recorded from 12 of 67 acoustic neurons were broadened while those of the remaining were sharpened. These results suggest that in vivo transfer of NGB gene is highly expressed in IC neurons in mice. In vivo transfer of NGB gene reverses the change of intensity-rate functions, intensity-latency functions and the code styles after administration of sodium salicylate in IC neurons in mice.