GABA and GAD immunoreactiviy of photoreceptor terminals in primate retina
GABA and GAD immunoreactiviy of photoreceptor terminals in primate retina
复制标题
灵长类视网膜光感受器末梢的 GABA 和 GAD 免疫反应性
作者：
Y. Nishimura;M. Schwartz;P. Rakic
在脊椎动物的视网膜中，有两种感光细胞--视杆细胞和视锥细胞--负责视觉信号的传递，并通过与双极细胞和水平细胞的突触传递信息。虽然在这些一阶突触的神经递质尚未确定，电生理研究1，2，3表明，它可能是兴奋性的。然而，在本研究中，我们发现恒河猴视网膜中的感光末梢与γ-氨基丁酸（GABA）或L-谷氨酸脱羧酶（GAD，一种参与GABA合成的酶）的抗体呈免疫反应性。在视网膜的中央凹周围区域中，具有视杆或视锥末梢的超微结构特征的突触前轮廓的大约25%与一种或另一种抗体免疫反应。这一证据表明感光末梢中存在一种抑制性神经递质，这对目前对视网膜突触功能的理解提出了挑战。
Within the vertebrate retina, two types of photoreceptor cells—the rods and cones—transduce visual signals and convey this information through synapses with bipolar and horizontal cells. Although the neurotransmitter at these first-order synapses has not been identified, electrophysiological studies1,2,3 suggest that it might be excitatory. In the present study, however, we have found photoreceptor terminals in the rhesus monkey retina which are immunoreactive with antibodies to either γ-aminobutyric acid (GABA) or L-glutamic acid decarboxylase (GAD, an enzyme involved in the synthesis of GABA). In the perifoveal region of the retina, approximately 25% of presynaptic profiles having ultrastructural characteristics of either rod or cone terminals are immunoreactive with one or the other antibody. This evidence for a putatively inhibitory neurotransmitter in photoreceptor terminals challenges present understanding of retinal synaptic function.