[Effect of tumor necrosis factor-alpha on the permeability of strial capillary endothelial cells in guinea pig cochlea].

OBJECTIVE: To perform an initial study on possible molecular regulatory mechanisms of TNF-alpha to the permeability of strial capillary endothelial cells in guinea pig cochlea METHODS: Strial capillary endothelial cells in guinea pig cochlea was dissociated and cultured to establish a model for its permeability in vitro. The animals were divided into TNF-alpha, TNF-alpha + L-arginine (L-Arg), TNF-alpha + NG-monomethyl-L-arginine (L-NMMA) and control groups. In order to measure the alternations of permeation rate, Evans blue was used in different time by different concentrations to detect contents of F-actin in each group under immunofluorescence laser scanning confocal microscope. RESULTS: TNF-alpha increased permeability of strial capillary endothelial cells notably, and permeation rate to Evans blue heightened significantly (P < 0.01) and increased under higher concentrations of TNF-alpha as well as lengthened the durations. Being as a NO donator, L-Arg significantly enhanced the ability of TNF-alpha which increasing permeability of strial capillary endothelial cells; permeation rate to Evans blue heightened significantly (P < 0.01), which obviously rose up when the concentration of Evans blue added. L-NMMA, NO inhibitor, was able to weaken the ability of TNF-alpha which increasing permeability of strial capillary endothelial cells; permeation rate to Evans blue decreased significantly (P < 0.01), which obviously fell down when the concentration of L-NMMA added. TNF-alpha decreased F-actin in strial capillary endothelial cells (P < 0.01), more TNF-alpha, less F-actin; L-Arg could be further the inhibition to F-actin content (P < 0.05); L-NMMA held back the trend (P < 0.05). CONCLUSIONS: TNF-alpha can increase permeability of strial capillary endothelial cells of guinea pig cochlea. NO may be one of the important molecular regulators to permeability of strial capillary endothelial cells by TNF-alpha, and changes of F-actin content probably relate to the regulation in these cells.

Adenoviral-mediated up-regulation of Otos, a novel specific cochlear gene, decreases cisplatin-induced apoptosis of cultured spiral ligament fibrocytes via MAPK/mitochondrial pathway.

Previous reports have implicated Otos, a novel specific gene expressed by spiral ligament fibrocytes (SLFs) with unclear functions, as a protective gene for cochlea. However, whether Otos gene could protect SLFs against cisplatin (DDP)-induced apoptosis remains largely unknown. In the present study, we utilized Adenoviral-mediated gene transfection to up-regulate Otos expression in cultured SLFs and further assessed the cell viability and apoptosis as well as possible MAPK and mitochondrial pathways. As expected, the data showed that Otos up-regulation significantly decreased apoptosis of SLFs induced by DDP possibly through activation of ERK and partial inhibition of JNK and mitochondrial pathway but not p-38 pathway, suggesting Otos as a potential protective gene for cochlea and raising the possibility of Otos up-regulation as a promising approach to DDP-induced deafness therapy.

[Adenoviral-mediated APE/Ref-1 expression protects rat spiral ganglion cells from oxidative damage].

OBJECTIVE: To address the question if apurinic/apyrimidinic endonuclease/redox factor 1 (APE/Ref-1) involved in preventing spiral ganglion cells oxidative damage after oxidative stress. METHODS: Primary cultured rat spiral ganglion cells were infected with the adenovirus containing APE/Ref-1 for 48 h, then treated with H2O2 (0, 10, 25, 50, 100, 300 micromol/L) for 1 h, and finally changed back into normal medium. Western blot were used to detect the level of APE/Ref-1 protein in the infected cells to ensure APE/Ref-1 over expression as a result of adenovirus infection. The cell viability was determined by MTT and the apoptosis of spiral ganglion cells was determined by terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL). RESULTS: Western blot showed that infection of adenovirus resulted in APE/Ref-1 over expression in the spiral ganglion cells. Over expression of APE/Ref-1 significantly improved cell viability in cultures treated with different concentration H2O2 from 50 to 300 micromol/L However, the apoptosis of cells was significantly inhibited. CONCLUSIONS: Over expression of APE/Ref-1 could protect spiral ganglion cells from oxidative damage.

[Morphology effects of shear stress in cochlear microvascular endothelial cells in guinea pigs].

OBJECTIVE: To observe the effects of different shear stresses on the morphological changes in cochlear microvascular endothelial cells cultured in vitro so as to enrich the mechanism of the blood-labyrinth barrier. METHODS: The morphological photos of cochlear microvascular endothelial monolayer cells were obtained with the hydrodynamic system design and the morphological parameters such as Pyx and Q were detected. RESULTS: Through digestion with collagenase type I, the monolayer cells of cochlear microvascular endothelial monolayer were obtained. As to cochlear microvascular endothelial cells in guinea pigs, no morphological changes of the cells were found when shear stresses of 0. 0883 Pa acting for 24 h. When shear stress was 0.1184 Pa acting for 8 h, compliant changes from former disorderliness into orderliness happened following the direction of the flowing liquid of the cellular morphology. The changing tendency was in a time-dependent manner. CONCLUSIONS: Cochlear microvascular endothelial cells in guinea pigs after the effect of shear stress are morphologically different from statically cultured endothelial cells. Range of the shear stress that cochlear microvascular endothelial cells can tolerate is little.