Blazynski C, Woods C, Mathews G C
Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110.
J Neurochem. 1992 Feb;58(2):761-7. doi: 10.1111/j.1471-4159.1992.tb09783.x.
Much evidence has accumulated supporting the hypothesis that the purine nucleoside adenosine may indeed function as a neuromodulator in the mammalian retina, but to date no reports have directly illustrated a physiological role for this nucleoside. In other regions of the CNS, adenosine agonists decrease transmitter release, whereas antagonists increase release. A similar role for adenosine in the retina is now apparent. The cholinergic amacrine cells of the rabbit retina were labeled with [3H]choline, and the effects of enzymatic adenosine degradation or adenosine antagonists on the light-evoked efflux of acetylcholine were evaluated. When endogenous adenosine was degraded by addition of adenosine deaminase, the light-evoked release of radioactivity derived from [3H]choline was significantly increased compared with control values. A similar response was observed when rabbit eyecups were superfused with a selective adenosine A1 receptor antagonist. The effect elicited by adenosine deaminase could be almost completely reversed by addition of cyclopentyladenosine, a highly selective A1 receptor agonist. These effects were observed in either the presence or the absence of picrotoxin. The results demonstrate a modulation of retinal physiology by adenosine.
已有大量证据支持嘌呤核苷腺苷在哺乳动物视网膜中确实可作为神经调质发挥作用这一假说，但迄今为止尚无报告直接阐明该核苷的生理作用。在中枢神经系统的其他区域，腺苷激动剂会减少神经递质释放，而拮抗剂则会增加释放。腺苷在视网膜中可能也发挥类似作用，这一点现在已很明显。用[3H]胆碱标记兔视网膜的胆碱能无长突细胞，并评估腺苷酶促降解或腺苷拮抗剂对光诱发的乙酰胆碱外流的影响。当通过添加腺苷脱氨酶降解内源性腺苷时，与对照值相比，源自[3H]胆碱的光诱发放射性释放显著增加。当兔眼杯用选择性腺苷A1受体拮抗剂灌流时，也观察到类似反应。添加高选择性A1受体激动剂环戊基腺苷几乎可以完全逆转腺苷脱氨酶引起的效应。无论有无印防己毒素，均观察到这些效应。结果表明腺苷对视网膜生理功能有调节作用。
