Identification of growth factors for neutronal and non-neutronal cells in the rat inner ear

1998 Fiscal Year Final Research Report Summary

• Project/Area Number: 09671744
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Otorhinolaryngology
• Research Institution: Osaka University
• Principal Investigator: DOI Katsumi Osaka University Medical School, Assistant Professor, 医学部, 講師 (40243224)
• Co-Investigator(Kenkyū-buntansha): TAMURA Manabu Osaka University Medical School, Assistant Professor, 医学部, 講師 (50273644)
• Project Period (FY): 1997 – 1998
• Keywords: cochlea / spiral ganglion cell / hair cell / HGF / c-met / RT-PCR / immunohistochemistry / sequence

Research Abstract

RT-PCR and DNA sequencing with rat cochlear cDNAs revealed expressions of mRNAs of hepatocyte growth factor (HGF) and its high-affinity receptor c-met in the rat cochlea. Immunohistochemistry with specific polyclonal antibodies raised against HGF and c-met demonstrated that HGF and c-met proteins were located within the organ of Corti (hair cells and neighboring supporting cells). HGF and c-met proteins were never detected in the Spiral ganglion cells of the normal rats.
Kanamycin-deaf rats were developed by daily kanamycin intra-peritoneal injections after birth. Effects of systemic application of HGF on the survival rates of neuronal and non-neuronal cells were examined. After eight weeks, all hair cells were disappeared in the cochleae of both the HGF-treated and no-HGF deal rats. The number of surviving spiral ganglion cells of the HGF-treated rats was slightly larger than that of the no-HGF deaf rats, although there was no statistical significance between them. In the HGF-treated deaf rats, c-met proteins were detected in the spiral ganglion cells.
These results suggest that HGF and its high affinity receptor c-met are active in the rat cochlea and that they could exert some protective effects on neuronal and non-neuronal cells there.