The Influences of Dopamine on Glutamate Receptor NMDA NR_1 and NMDA NR_(2A) in the Cochlea of Guinea Pigs / 听力学及言语疾病杂志

ABSTRACT

Objective To study the correlation between dopamine and glutamate receptor NMDA NR_1 and NMDA NR_(2A),and to share the understanding of the mechanism of dopamine in the synaptic complex of inner hair cells.Methods Forty guinea pigs were divided randomly into four groups and the whole intacochlear perfusions were performed.The perfused cochleas were taken out as preparations 2 hours after perfusing,the contralateral cochleas were also taken out as the normal control group in the group perfused with artifical perilymph solutions.All the preparations were divided into 5 groups①normal control cochleas;②perfused with artificial perilymph solutions;③perfused with artifical perilymph solutions containing 10 mmol/L dopamine；④perfused with artificial perilymph so lutions containing 30 mmol/L dopamine；⑤perfused with artifical perilymph solutions containing 50 mmol/L dopa mine.The semi-quantitive RT-PCR was used to observe the difference in the amount of glutamate receptor NMDA NR_1、NMDA NR_(2A).Results Dopamine inhibited the compound action potential(CAP),the increase of CAP threshold was observed and correlated with the contentration of dopamine in the perfusion solution.Regarding the amount of glutamate receptor NMDA NR_1 mRNA,there was no significant difference between group ① and group ② (P＞0.05).But a significant difference was observed the other 3 groups when compared to group ①(P＜0.05).No significant difference was detected among the 5 groups in the amount of glutamate receptor NMDA NR_(2A) (P＞0.05).Conclusion Dopamine may inhibit the cochlear auditory afferent nerve.The significant correlation between dopamine and glutamate receptor NMDA NR_1 was observed,the amount of glutamate receptor NMDA NR_1 decreased along with the increasing of the contentration of dopamine in the perfusion solution.And there was no significant correlation between dopamine and glutamate receptor NMDA NR_(2A).