Journal of Jilin University(Medicine Edition) ›› 2022, Vol. 48 ›› Issue (4): 875-882.doi: 10.13481/j.1671-587X.20220405

• Research in basic medicine • Previous Articles     Next Articles

Effects of high altitude hypoxia on auditory conduction and peripheral auditory nerve myelin regeneration in plateau migrated rats

Shuyuan YU1,Ping WANG1,Xinrui WANG2,Lanzi GONGGA3,Li YANG2()   

  1. 1.Department of Otolaryngology and Head-Neck Surgery,First Hospital,Jilin University,Changchun 130021,China
    2.Institute of Zoonoses,Ministry of Education,College of Zoology,Jilin University,Changchun 130062,China
    3.Department of Preventive Medicine,School of Medical Sciences,Tibet University,Tibet 850000,China
  • Received:2021-10-09 Online:2022-07-28 Published:2022-07-26
  • Contact: Li YANG E-mail:ccyangli@jlu.edu.cn

Abstract: Objective

To explore the effects of altitude anoxic environment on the hearing of rats that migrated from the plain to the plateau,and to elucidate the molecular mechanism of sound acclimation in the rats.

Methods

A total of 72 Wistar rats were divided into plain control group,migration plateau 2 months group,migration plateau 4 months group and migration plateau 10 months group,with 18 rats in each group. The auditory brainstem response evoked by click(ABR)thresholds and latencies of the rats were detected at 2, 4 and 10 months after migration to the plateau. The ultrastructures of neurons and myelin sheath in cochlear tissue of the rats were observed by transmission electron microscope. The expression levels of growth associated protein-43(GAP-43)and myelin basic protein (MBP) mRNA and proteins in cochlear tissue of the rats in various groups were analyzed by real-time fluorescence quantitative PCR (RT-qPCR) method,Western blotting method and immunohistochemistry method.

Results

Compared with control group, the thresholds of ABR of the rats in migration plateau groups were increased for 5-13 dB, but there were no statistical differences(P>0.05). The lantencies of ABR of rats were detected after stimulated with Crik of 80 dB SPL;compared with control group,the lantencies of wave Ⅰ and Ⅲ of the rats in migration plateau 2 months group and migration plateau 4 months group were prolonged(P<0.05).The transmission electron microscope results showed that myelin sheath structure appeared intact and lamellar arrangement was close and orderly in control group; the most serious myelin injury occurred at the time of 2 months after the migration to the plateau, appeared the lamellar arrangement separated, the myelin sheaths around neurons were broken, and the space between cells and myelin sheaths was increased; meanwhile, the abnormal mitochondrial structure was also found. At the time of 4 months after the migration to the plateau, the myelin lesion was relieved, and at the time of 10 months, the myelin structure was almost normal. The results of RT-qPCR and Western blotting methods showed that compared with control group, the expression levels of MBP mRNA and protein in cochlear tissue of the rats in migration plateau 2 months group and migration 4 months group were decreased(P<0.01);but the expression levels of MBP and GAP-43 mRNA and protein in cochlear tissue of the rats in migration plateau 10 months group had no significant differences(P>0.05).Compared with control group,the expression levels of GAP-43 mRNA and protein in cochlear tissue of the rats in migration plateau 2 months group were decreased(P<0.01). Compared with plateau migration 2 months group, the expression levels of GAP-43 mRNA and protein in cochlear tissue of the rats in migration plateau 4 months group were increased(P<0.05).

Conclusion

High altitude hypoxic environment can cause the peripheral auditory nerve myelin injury, lead to the prolonged ABR latency and affect the auditory signal transduction. Long-term hypoxic environment can induce myelin sheath regeneration and induce auditory adaptive repair.

Key words: Auditory nerve, Myelination, Hypoxia, Adaptation, Altitude environment, Signal transduction

CLC Number: 

  • R363.16