青蛙视网膜电图反应的嘌呤能调节:嗜离子受体P2X7的作用。

IF 1.1 4区 医学 Q4 NEUROSCIENCES
Petia Kupenova, Elka Popova, Liliya Vitanova
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引用次数: 7

摘要

通过测试P2X7R选择性拮抗剂A438079和P2X7R选择性激动剂Bz-ATP在不同刺激条件下对灌注蛙(Rana ridibunda)眼杯制剂视网膜电图的影响,研究嘌呤能受体P2X7 (P2X7Rs)对视网膜电图(ERG)反应的贡献。200µM A438079阻断P2X7R降低了光感受器成分的振幅:a波和药理学分离的质量受体电位。在纯杆驱动和纯锥驱动的反应中,感受器后ON (b波)和OFF (d波)分量的振幅也减小。OFF反应比ON反应受到更大程度的影响。在介观强度范围内,棒状和锥状混合驱动响应中,b波振幅增大,d波振幅减小。振荡电位的幅度减小。与适应光的眼睛相比,适应暗的眼睛中P2X7R阻断产生的相对振幅变化更大。应用100µM Bz-ATP产生与拮抗剂相反的小作用,而长时间(>20 min)使用1mm Bz-ATP可导致b波和d波的幅度明显降低甚至消除。我们的研究结果表明,内源性ATP通过其P2X7Rs对ERG光感受器和受体后反应具有显著的增强作用。对ERG后受体反应的影响具有明显的开/关不对称,有利于OFF反应:它们总是被强烈增强,而ON反应要么被减弱(在杆驱动和大多数锥体驱动的反应中),要么甚至被抑制(在杆和锥体混合驱动的反应中)。P2X7Rs的过度刺激可产生急性病理改变,即ERG反应的减少或消除。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Purinergic modulation of frog electroretinographic responses: The role of the ionotropic receptor P2X7.

The contribution of the purinergic receptors P2X7 (P2X7Rs) to the electroretinographic (ERG) responses was studied by testing the effects of the selective P2X7R antagonist A438079 and the selective P2X7R agonist Bz-ATP on the electroretinograms obtained in perfused frog (Rana ridibunda) eyecup preparations under a variety of stimulation conditions. The P2X7R blockade by 200 µM A438079 diminished the amplitude of the photoreceptor components: the a-wave and the pharmacologically isolated mass receptor potential. In the pure rod-driven and pure cone-driven responses, the amplitude of the postreceptoral ON (b-wave) and OFF (d-wave) components was also diminished. The OFF responses were affected to a greater extent compared to the ON responses. In the mixed rod- and cone-driven responses, obtained in the mesopic intensity range, the b-wave amplitude was increased, while the d-wave amplitude was decreased. The amplitude of the oscillatory potentials was diminished. The relative amplitude changes produced by the P2X7R blockade were greater in the dark-adapted compared to the light-adapted eyes. The application of 100 µM Bz-ATP produced small effects opposite to those of the antagonist, while a prolonged (>20 min) treatment with 1 mM Bz-ATP resulted in a significant amplitude reduction or even abolishment of b- and d-waves. Our results show that endogenous ATP through its P2X7Rs exerts significant, mostly potentiating effects on the ERG photoreceptor and postreceptoral responses. There is a clear ON/OFF asymmetry of the effects on the ERG postreceptoral responses favoring OFF responses: they are always strongly potentiated, while the ON responses are either less potentiated (in the rod-driven and most of the cone-driven responses) or even inhibited (in the mixed rod- and cone-driven responses). The overstimulation of P2X7Rs can produce acute pathological changes, that is, a decrease or abolishment of the ERG responses.

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来源期刊
Visual Neuroscience
Visual Neuroscience 医学-神经科学
CiteScore
2.20
自引率
5.30%
发文量
8
审稿时长
>12 weeks
期刊介绍: Visual Neuroscience is an international journal devoted to the publication of experimental and theoretical research on biological mechanisms of vision. A major goal of publication is to bring together in one journal a broad range of studies that reflect the diversity and originality of all aspects of neuroscience research relating to the visual system. Contributions may address molecular, cellular or systems-level processes in either vertebrate or invertebrate species. The journal publishes work based on a wide range of technical approaches, including molecular genetics, anatomy, physiology, psychophysics and imaging, and utilizing comparative, developmental, theoretical or computational approaches to understand the biology of vision and visuo-motor control. The journal also publishes research seeking to understand disorders of the visual system and strategies for restoring vision. Studies based exclusively on clinical, psychophysiological or behavioral data are welcomed, provided that they address questions concerning neural mechanisms of vision or provide insight into visual dysfunction.
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