Effects of dopamine D_(1) receptor blockade on the ERG b- and d-waves during blockade of ionotropic GABA receptors

作     者：Elka Popova Momchil Kostov Petia Kupenova 

作者机构：Department of PhysiologyMedical University of SofiaSofiaBulgaria 

出 版 物：《Eye and Vision》 (眼视光学杂志（英文）)

年 卷 期：2016年第3卷第1期

页      面：245-252页

核心收录：

学科分类：0710[理学-生物学] 1002[医学-临床医学] 07[理学] 071006[理学-神经生物学] 

主　　题：Dopamine D_(1)receptors GABA Electroretinogram b-wave d-wave 

摘      要：Background:Some data indicate that the dopaminergic and GABAergic systems interact in the vertebrate retina,but the type of interactions is not well understood.Methods:In this study we investigated the effect of dopamine D_(1) receptor blockade by 75μM SCH 23390 on the electroretinographic ON(b-wave)and OFF(d-wave)responses in intact frog eyecup preparations and in eyecups where the ionotropic GABA receptors were blocked by 50μM picrotoxin.Student’s t-test,One-way repeated measures ANOVA with Bonferroni post-hoc test and Two-way ANOVA were used for statistical evaluation of the data.Results:We found that SCH 23390 alone significantly enhanced the amplitude of the b-and d-waves without altering their latency.The effect developed rapidly and was fully expressed within 8-11 min after the blocker application.Picrotoxin alone also markedly enhanced the amplitude of the ERG ON and OFF responses and increased their latency significantly.The effect was fully expressed within 25-27 min after picrotoxin application and remained very stable in the next 20 min.The effects of SCH 23390 and picrotoxin are similar to that reported in our previous studies.When SCH 23390 was applied on the background of the fully developed picrotoxin effect,it diminished the amplitude of the b-and d-waves in comparison to the corresponding values obtained during application of picrotoxin alone.Conclusion:Our results demonstrate that the enhancing effect of D_(1) receptor blockade on the amplitude of the ERG b-and d-waves is not evident during the ionotropic GABA receptor blockade,indicating an interaction between these neurotransmitter systems in the frog retina.We propose that the inhibitory effect of endogenous dopamine mediated by D_(1) receptors on the ERG ON and OFF responses in the frog retina may be due to the dopamine-evoked GABA release.