ABSTRACT
OBJECTIVES: To examine the expression profile of Fas-Fas ligand (FasL) during glutamate (Glu)-induced spiral ganglion cell (SGC) apoptosis. METHODS: Cultured SGCs were treated with 10-mM, 25-mM, and 50-mM concentrations of Glu and incubated for 24 or 48 hours. The expression intensity of FasL, Fas, caspase 3, and morphology of single SGC were evaluated using immunofluorescence staining. RESULTS: In semiquantitative analysis of the Glu-treated SGC, FasL, and caspase 3 expression intensity were increased with concentration- and time-dependent manner. Fas expression intensity did not change with different concentration at 48 hours. In morphologic analysis of the Glu-treated SGC, number of apoptotic cells were increased with concentration- and time-dependent manner. CONCLUSION: FasL was expressed in apoptotic SGCs, suggesting that the Fas-FasL signaling pathway may be involved in the Glu-induced apoptosis of dissociated SGCs.
Subject(s)
Apoptosis , Caspase 3 , Fas Ligand Protein , Fluorescent Antibody Technique , Glutamic Acid , Spiral GanglionABSTRACT
BACKGROUND AND OBJECTIVES: Auditory neuropathy is a hearing disorder characterized by the absence or the marked impairment of the auditory brainstem responses with the preservation of the cochlear microphonics (CMs) and otoacoustic emissions. This suggests that outer hair cell (OHC) function is normal but proximal auditory function to OHCs is impaired. It is assumed that the lesion is localized at the level of the inner hair cells (IHCs), auditory nerve fibers, or the synapse between them. This study was aimed to observe the change of hearing threshold and pathology of spiral ganglion cell induced by ouabain application, and present basic data to explain the auditory neuropathy. MATERIALS AND METHOD: Twenty ears of twenty normal hearing cats were used in this study. Cats were treated with 100 microL ouabain (1 mM) applied on the round window. After three days, compound action potential (CAP) and CM were measured and the cochlea was obtained. Pathologic change of spiral ganglion cell was evaluated under light microscope after H&E stain. Normal saline was injected for the control group. RESULTS: In the ouabain group, CAP threshold was increased in all tested frequencies (p0.05). There was significant difference between CAP and CM threshold shift (p<0.001). In the control group, there was no significant difference in CAP and CM thresholds. Light microscopic findings show that the condensed chromatin and nuclear fragments of spiral ganglion cells of an ear was exposed to ouabain, and outer hair cell and inner hair cell were not damaged. CONCLUSION: This study shows that the CAP threshold was significantly increased but the CM threshold was not changed in the ouabain group. Ouabain induced damage of spiral ganglion cells. This study is not sufficient to explain auditory neuropathy because threshold shift of CAP is not obvious, but it would be helpful to explain that selective damage of spiral ganglion cell would be the mechanism of auditory neuropathy.
Subject(s)
Animals , Cats , Action Potentials , Chromatin , Cochlea , Cochlear Nerve , Ear , Evoked Potentials, Auditory, Brain Stem , Hair , Hearing , Hearing Disorders , Ouabain , Pathology , Spiral Ganglion , SynapsesABSTRACT
Objective To establish human brain-derived neurotrophic factor (BDNF) genetical modified marrow stromal cells and to evaluate the influence on the viability of the cultured spiral ganglion cells from Kunming mice.Methods Eukaryotic expression plasmid——pcDNA3.1(-)-BDNF was constructed according to the molecular clone approach. Marrow stromal cells(MSC) were separated and cultured. BDNF genetical modified marrow stromal cells were established and verified by biochemical analysis.The bio-effect to spiral ganglion cells, especially with the oxidative damage under the different concentration of H_2O_2 was observed.Results PcDNA3.1(-)-BDNF and BDNF genetical engineering cells were successfully established. The supernatant from BDNF-MSCs remarkably improved the survival rate of the spiral ganglion cells.Conclusion BDNF genetical modified marrow stromal cells are successfully established, and the genetical engineering cell plays an important role in the protection the spiral ganglion cells from the oxidative damage. This study provide a strong basis for genetical engineering cells transplantation into the inner ear.