单耳堵塞沙土鼠下丘听反应域面积与谷氨酸、γ-氨基酸受体的关系

Relationship of glutamic acid and gamma-aminobutyric acid receptor to the auditory spatial response areas of the inferior collicular neurons in monaural plugged gerbil

目的考察γ-氨基酸(GABA)、荷包牡丹碱(bicuculline)、N-甲基-天冬氨酸(NMDA)和PL-2-氨基-5-磷酸戊酸(APV)对单耳堵塞沙土鼠堵耳对侧下丘中央核(ICc)的听反应域面积的影响。方法分别在出生后3周龄(21d)、6周龄(42d)和成年(70d)对沙土鼠单耳堵塞(各10只),4周后在ICc微电泳上述4种药物,记录听反应域面积的变化。结果各组听反应域面积在GABA、APV作用下减小,Bicuculline、NMDA作用下扩大。除APV对3周龄组作用(t=5.8408,P=0.1538)外,用药前后均差异有显著意义(P<0.05);比较各组间的药物所致听反应域变化率可见,GABA作用下的3周龄组与成年龄组间、bicuculline和APV分别作用下的6周龄组与成年龄组间差异都有显著意义(t=2.4065,P=0.0208;t=2.0665,P=0.0448;t=3.1751,P=0.0037),而其余实验组间均差异无显著性意义。结论沙土鼠听觉发育中GABA能抑制机制建立的“关键期”要延续到出生后6周,NMDA兴奋机制的建立却可能在6周前,GMWW者间有一磨合匹配的过程。

Aim To study the effects of gamma aminobutyric acid(GABA), bicuculline, NMDA and DL 2 amino 5 phosphonovaleric acid(APV) on the auditory spatial response areas of the contralateral inferior collicular (IC) neurons in monaural plugged gerbils ( Meriones unguicul ). Methods 4 weeks after plugging one side ear at the different postnatal ages (21 dpn, 42 dpn and 70 dpn), gerbils were treated with GABA, bicuculline, NMDA and APV respectively by iontrphoretic technique and the changes of auditory spatial response areas of the contralateral IC were recorded by electrophysiological method.Results The auditory spatial response areas of 3 week, 6 week, adult plugging groups were 0.270± 0.579, 0.145± 0.096 and 0.067± 0.049(m2) respectively and there was no significantly difference between the former two groups (t=0.756 9,P=0.450 8).After treatment the areas were reduced by GABA, APV and enlarged by bicuculline, NMDA. Except the APV effect on 3 week plugging group ( P=0.153 8,t=5.840 8), there were significantly different among the other groups before and after treatment.Comparing the variety rate of auditory spatial response areas by drug in three groups, there was a significant difference between the 3 week plugging and adult plugging groups by GABA, and between the 6 week plugging and adult plugging groups by bicuculline or APV(P=0.020 8,t=2.406 5;P=0.044 8, t=2.066 5; P=0.003 7, t=3.175 1).But there was no significant difference among the other groups.Conclusion During the auditory development course of gerbil, the critical period of GABA inhibitive mechanism foundation is continued to the sixth week postnatal,the NMDA excitative mechanism foundation is at the sixth week prenatal and there is a phase to adjust and match with each other.