Distribution Of Gama-aminobutyric Acid (GABA) Ergic Neurons In Auditory Center Different Parts Of Unilateral Cochlea Ablation Rats

Object: To explore the basic properties of distortion product otoacoustic emission (DPOAE) in normal rats and to observe the distribution of gama-aminobutyric acid (GABA) ergic neurons in rat auditory center in pre and post-operation.Methods: DP-gram, I/O function curves and threshold of forty rats were measured by CELESTA-503 Cochlear Emission Analyzer. The technique of direct anti-GABA imrnunocytochemistry (SP) was used in this study.Results: 1) The incidence of DPOAE in all frequencies were 100%.The amplitude of DPOAE in 1kHz was 17.60?.96dBSPL. The amplitudes of DPOAE above 2kHz were larger than 25dBSPL. I/O function curves demonstrated that there was a significant relation betweem the amplitudes of DPOAE and the levels of primary stimuli in the statistics, that is, the higher levels of primary stimuli was, the larger amplitudes of DPOAE was. There was not a significant difference between left ears and right ears in all indeies. We could not obtain the amplitudes of DPOAE in lesion side of unilateral cochlea ablation rats. 2) The GABAergic neurons existed extensively in auditory center:auditory cortex(AC), inferior colliculus(IC) and cochlear nuclei(CN). But the number ,shape and staining of GABAergic neurons were different in every nucleus. AC had the largest number of GABAergic neuron, CN was second, IC had less GABAergic cells.The volume of GABAergic cells in IC was larger than those in AC and CN, and stained heavy. The GABA cells in CN was more heavily staining than those in IC and AC.In CN, the number of GABAergic cells in lesion side was less than those in intact side after unilateral cochlea ablation one to two weeks, then the number of GABAergic cells increased after three weeks and almost reached normal number in a month of post-operation,the difference has no statistically significance(P>0.05). In IC,the number of GABAergic cells in intact side was less than those in lesion side after unilateral cochlea ablation one to three weeks, then the number of GABAergic cells increased but stiil less than that of normal number in a month of post-operation,which showed significant difference between intact and lesion sides(P<0.05). In AC, the number of GABAergic cells in intact side was less than those in lesion side after unilateral cochlea ablation one to two weeks,then the number of GABAergic cells increased after three weeks and almost reached normal number in a month of post-operation(P>0.05).Conclusion: 1) In rats, the incidence of DPOAE was high, the amplitudes ofDPOAE was larger and all indeies were stabilization.The rat of unilateral cochlea ablation could serve for father study.2) The changes of GABAergic neurons reflect the balance between excitatory and inhibitory of neurons, it suggest that changes in the extent of GABAergic inhibition have been shown to contribute to the reorganization of auditory central system after unilateral cochlea ablation in rats.