大鼠听皮层发育关键期胶质纤维酸性蛋白表达及听功能变化

摘要

目的：观察大鼠听觉发育关键期听功能的变化及听皮层星形胶质细胞标记物胶质纤维酸性蛋白（glial fibrillary acidic protein ，GFAP）的表达。方法清洁级 SD 大鼠幼鼠50只随机分成出生后第14、21、28、35和42天组，每组10只，分别检测各组大鼠 ABR 反应阈后，采用免疫组化染色方法及 Western blot 检测各组大鼠听皮层 GFAP 的表达。结果大鼠出生后第14、21、28、35、42天组 ABR 平均反应阈分别为84．5±4．97、70．5±3．69、58．5±5．80、37．0±4．83和35．5±3．69 dB SPL，除第35天组与第42天组之外，其余各组两两之间比较差异均有统计学意义（P＜0．05或 P＜0．01）；第14、21、28、35、42天组大鼠听皮层 GFAP 平均累积光密度值（IOD）分别为474．36±234．56、1465．93±474．96、2163．06±353．36、6572．01±808．88和7244．37±932．90，各组间两两相比差异均有显著统计学意义（P＜0．05或 P＜0．01）。第14、21、28、35和42天组大鼠听皮层 GFAP 蛋白表达水平分别为1．00±0．06、3．07±0．07、4．92±0．05、6．88±0．03和8．92±0．04，各组间两两相比差异有统计学意义（P＜0．05）。结论大鼠出生后第14～42天其 ABR 反应阈逐渐下降，GFAP 表达逐渐增强，提示星形胶质细胞可能有促进听皮层及听觉中枢的发育与成熟的作用。%Objective To study changes of auditory brainstem evoked potentials (ABR)and the expression of glial fibrillary acidic protein (GFAP)during the critical period of the development of the auditory cortex in rats. Methods Fifty Sprague - Dawley (SD)rat pups were divided into five groups(n=10 per group):postnatal 14 days group,postnatal 21 days group,postnatal 28 days group,postnatal 35 days group and postnatal 42 days group.The rats were decapitated after the evaluation of ABR.The auditory cortex was taken and immunohisto-chemical staining was used to detect the expression of GFAP in rat auditory cortex in each group.The protein ex-pressions of GFAP in rat auditory cortex in each group were tested by western blot methods respectively.ResuIts The ABR thresholds gradually decreased along with the increasing days after the birth.The average ABR thresholds in postnatal 14 days group,postnatal 21 days group,postnatal 28 days group,postnatal 35 days group and postnatal 42 days group were (84.5 ± 4.97)dB SPL ,(70.5±3.69)dB SPL ,(58.5±5.80)dB SPL,(37.0±4.83)dB SPL and(35.5±3.69)dB SPL,respectively.There were no significant differences in ABR thresholds between the postnatal 35 days group and the postnatal 42 days group (P>0.05),whereas,significant differences were found among the other groups(P<0.05 or P<0.01.GFAP expression in auditory cortex gradually increased in all five groups.The average integrated optical density (IOD)of postnatal 14 days group,postnatal 21 days group,postnatal 28 days group,postnatal 35 days group and postnatal 42 days group were 474.36±234.56,1465.93 ±474.96,2163.06 ± 353.36,6572.01±808.88 and 7244.37±932.90,respectively.The differences among all five groups were statisti-cally significant (P<0.05 orP<0.01 ).The protein levels of GFAP in the auditory cortex of postnatal 14 days group,postnatal 21 days group,postnatal 28 days group,postnatal 35 days group and postnatal 42 days group were 1.00±0.06,3.07±0.07,4.92±0.05,6.88±0.03 and 8.92±0.04.The differences among all five groups were sta-tistically significant (P<0.05).ConcIusion The ABR threshold gradually decreased and GFAP expression in audi-tory cortex gradually increased from postnatal 14 days to postnatal 42 days ,suggesting that astrocytes may promote the development and maturation of the auditory cortex and the auditory central system in rats.