ABSTRACT
Objective To investigate the different expression levels of Na+ - K+ - 2Cl- co- transporter NKCC1 mRNA in the cochlea of rats after sodium salicylate injection and to explore the mechanism underlying the change of outer hair cells, induced by different salicylate administration. Methods Twenty-four normal adult rats were randomly divided into four groups with six rats in each group. Rats in control group,did not recieve sodium sa-licylate injection. The other three groups were acute group,chronic group,and recovered group according to the dif-ferent doses of sodium salicylate. The fluorescence quantitative PCR method was used to detect the expression levels of NKCC1 mRNA in the rat cochleas of the four groups. Results NKCC1 mRNA was expressed in all of the four groups. After sodium salicylate injection, the expressions of NKCC1 mRNA in chronic and recovered group were higher than that in control group(P<0.05). While the expression of NKCC1 mRNA in acute group was lower than that in control group(P(0. 05). Conclusion The expression of NKCC1 mRNA in the normal cochlea indicates that NKCC1 may play an important role in the maintenance of Cl- in the endolymph of the cochlea. The alteration of NKCC1 mRNA expression caused by sodium salicylate injection may lead to the change of the outer hair cell electro-motility.
ABSTRACT
Objective The prestin,a motor protein responsible for outer hair cell(OHC)electromotility,is expressed on the OHC surface.Previous experiments revealed that OHC electromotility and its associated nonlinear capacitance was mainly located at the OHC lateral wall and was absent at the apical cuticular plate and the basal nucleus pole.Immunofluorescent staining for prestin failed to demonstrate the prestin expression at the OHC basal ends in whole-mount preparation of the organ of Corti.The aim of this study is to investigate the distribution of prestin at OHC.Methods In this experiment,the localization of prestin protein in single dissociated OHCs from cochlea of normal mouse,rat and guinea pig,were examined by immunofluorescent staining and confocal microscopy.Results We found that prestin was uniformly expressed on the OHC basolateral surface,including its basal pole.No staining was observed on the cuticular plate and stereocilia.The OHC lateral wall had a trilaminate organization and was composed of the plasma membrane,cortical lattice,and subsurface cisternae.By with co-staining with a membrane marker di-8-ANEPPS,prestin-labeling was found locating at the outer layer of the OHC lateral wall.Further separating the plasma membrane from the underlying subsurface cisternae,using a hypotonic extracellular solution,prestin-labeling was shown locating at the plasma membrane instead of the subsurface cisternae.Conclusion The data revealed that prestin is expressed in the plasma membrane on the whole OHC basolateral surface.
ABSTRACT
Objective To investigate the different expression levels of Na+-K+-2Cl-co-transporter NKCC1 mRNA in the cochlea of rats after sodium salicylate injection and to explore the mechanism underlying the change of outer hair cells,induced by different salicylate administration.Methods Twenty-four normal adult rats were randomly divided into four groups with six rats in each group. Rats in control group,did not recieve sodium salicylate injection. The other three groups were acute group,chronic group,and recovered group according to the different doses of sodium salicylate.The fluorescence quantitative PCR method was used to detect the expression levels of NKCC1 mRNA in the rat cochleas of the four groups.Results NKCC1 mRNA was expressed in all of the four groups.After sodium salicylate injection,the expressions of NKCC1 mRNA in chronic and recovered group were higher than that in control group(P