谷氨酸钠不同用药时程对幼年豚鼠耳蜗螺旋神经节损伤的比较

Comparison of neurotoxic effects of glutamate on spiral ganglion of juvenile guinea pigs by different administered courses

目的:比较谷氨酸钠不同用药时程对幼年豚鼠耳蜗螺旋神经节细胞及听力损伤的程度,以探索稳定而可靠的谷氨酸钠耳聋模型造模方案。方法:豚鼠单纯随机分成4组,按3g/(kg·d),腹腔注射(ip),给予谷氨酸钠(Glutamate),每组(G7,G3,G1,G0)分别给予连续7,3,1,0d,停药后饲养10d。处死前测其耳郭反射以及脑干听觉诱发电位。后取耳蜗,纵向石蜡切片,焦油紫染色,光镜观察。结果:G7组听阈为(68.4±23.9)dBSPL,耳蜗螺旋神经节平均细胞密度为(2.34±1.24)×103个/mm2;G3组听阈为(66.9±19.8)dBSPL,细胞密度为(2.52±1.19)×103个/mm2;G1组听阈为(65.8±21.5)dBSPL,细胞密度为(2.60±1.02)×103个/mm2;G0组听阈为(44.3±4.7)dBSPL,细胞密度为(4.38±2.60)×103个/mm2。经方差分析,F检验,听阈:F=21.8,细胞密度:F=18.5;G0组分别与G7,G3,G1组比较,差异显著意义,P<0.01,G7,G3,G1组之间,差异无显著性意义,P>0.05。结论:谷氨酸钠3g/(kg·d),ip.不同用药时程(1～7d)均可引起幼年豚鼠耳蜗螺旋神经节细胞明显变性甚或死亡,听力下降明显;谷氨酸钠一次性腹腔注射给药可以制作耳聋模型。

AIM:To compare the neurotoxic effects of glutamate on spiral ganglion and hearing impairment of juvenile guinea by different administered courses and to seek an ideal glutamate dependent deaf model. METHODS:Forty juvenile guineas with the weight of (255± 44) g were equally divided into four groups at random: groups treated with glutamate for 1(G1), 3 (G3) and 7 d (G7), and normal control group treated with saline (G0). The animals were intraperitoneally infused with sodium glutamate of 3g/kg once a day for 0, 1, 3 and 7 d respectively, and then fed for 10d without administration. Auricle reflection and brainstem auditory evoked potential (BAEP) were measured before the animals were killed, and then cochleae were taken out, sliced up by longitudinal paraffin section, stained by tar and observe under light microscope.RESULTS:The auditory thresholds were (44.3± 4.7),(65.8± 21.5), (66.9± 19.8) and (68.4± 23.9) dB SPL in the groups of G0, G1, G3 and G7 respectively. The mean cell densities of cochlear ganglion were , G1 group (65.8± 21.5)dB SPL, G3 group (66.9± 19.8)dB SPL, G7 group (68.4± 23.9)dB SPL. The density of ganglion cells was (4.38± 20.26) × 103 , (2.60± 1.02) × 103,(2.52± 1.20)× 103 and (2.34± 1.24)× 103/mm2 respectively in the four groups. Analysis of variance showed that there was a significant difference in the threshold and density between the G0 group and GI, G3 and G7 groups respectively(F=21.8,P< 0.01;F=18.5,P< 0.01). However, there was no significant difference among the groups of G1, G3 and G7 (P >0.05).