| The cochlea, a part of the inner ear, is an important component of the peripheral auditory system, which can conduct and feel sound waves. Its core component is Corti’s organ. Corti’s organ can convert sound signal from the middle ear to the corresponding neural electric signals, passed through the auditory nerve to auditory center, and finally generate the hearing. The process of compiling and amplify the voice signal of Corti’s organ contains a high energy-consuming. Sugar and fat are the main material of energy supply,but less glucose and more lipids in the internal and external lymph. The role of lipid droplets in the voice signal conversion process is not clear. This research analyzed cochlea tissue staining, quantitative 3D reconstruction,noise exposure of the guinea pig to illuminate lipid droplets distribution features and pathophysiological significance of the guinea pig cochlea.PartⅠ Validation of lipid droplets in guinea pig cochleaObjective: To evaluate the lipid droplets in guinea pig cochlea and it’s existence in the living cells. Method: Hartley guinea pig’s Cochlear tissue is stained by 1% osmic acid, Sudan Ⅲ, Sudan Ⅳ, oil red O and Bodipy493/503 respectively. Observe lipid droplets distribution and morphology in guinea pig cochlea by microscope. Observe the living cells of cochlea through Bodipy 493/503 dye. Result: Black particles were visible in guinea pig cochlea Corti organ edge after osmic acid fixed; Orange spherical particles were visible in guinea pig cochlea Coti Hensen cells after sudan Ⅲ dyeing;Red spherical particles were visible in guinea pig cochlea Corti Hensen cellsafter sudan Ⅳ dyeing; Red spherical particle distribution were visible in guinea pig cochlea Coti Hensen cells after Oil red O staining;Green particles scattered distribution in the cytoplasm were visible in Hensen cells after Bodipy 493/503 dyeing under the fluorescence microscope. Conclusion: The above five kinds of methods all can proved that a large number of lipid droplets existed in guinea pig cochlea. The high transparent material in live Hensen cells were lipid droplets.PartⅡ The distribution of lpid droplets in guinea pig cochleaObjective: To quantify the distribution of lipid droplets in all kinds of tissues and cells in the guinea pig inner ear, and to provide the basis of fatty acid metabolism in guinea pig inner ear. Method: Hartley guinea pig’s Cochlear tissue is stained by 1% osmic acid and Bodipy 493/503, observed and taken photos by stereomicroscope and laser confocal microscope.Fluorescence image analysis, processing and calculating the volume of lipid droplets by Imaris 7.0 image processing software. Result: There has no lipid droplet in the 1st turn, droplet average volume in the 2nd turn lipid is8.84±5.24 um3, the 3rd turn is 23.38±8.31 μm3, and the 4th turn is64.71±10.33μm3.Conclusion: Lipid droplets of guinea pig cochlea mainly distributed in the Corti’s Hensen cells. The numbers and sizes of lipid droplets in Hensen cells were different. Through confocal laser scanning technology3 D reconstruction and Imaris7.0 image processing software analysis guinea pig cochlea, We found that the volume of a single lipid droplet is widely distributed in 0.1~1000μm3, and mainly distributed in 1~100μm3. Lipid droplets distribution in guinea pig cochlea basilar membrane from bottom to top is from scratch and the 2nd turn is a ‘turning point’.PartⅢ The function study of lipid droplets in the guinea pig’s cochlearObjective: To discuss the pathophysiological role of lipid droplets in the process of auditory transformation in guinea pig cochlear. Method: 1.To explore the effect of the noise exposure to the lipid droplets in the guinea pig cochlea. Three pairs Hartley guinea pigs were divided into two groups according to compatriots, sex, and weight. One group was given noise exposure, and another not. Measure the lipid droplets volume of two groups. 2.To explore the effect of lipid droplets to noise deafness in guinea pig. Hartley guinea pigs were divided into three groups, given intraperitoneal injection of fatty acid transporter nhibitor(insulin, A group),fatty acid transporter agonist(troglitazone, B group),and DMSO(control, C group) within 0.5 hours before noise exposed. Hartley guinea pigs exposed by 120 d B SPF white noise4h/day consecutive 4 days. Observed the threshold of auditory brainstem evoked potential(ABR) before noise exposed, immediate and 3day after noise exposed. Result: After the noise exposed, the quantity of lipid droplets reduced obviously in guinea pig’s cochlea. Hearing loss between B group and A group or B group and C group had significance, but no significance between A group and C group. Conclusion: Noise causes a decline of lipid droplets in the cochlea, the lipid droplets were involved in the material metabolism of auditory. The catabolism of lipid droplets can reduce that noise induced hearing loss. |
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