Park Sung-Jin, Lee Dong Seong, Lim Eun-Jin, Choi Su-hwan, Kang Wha-Sun, Kim In-Beom, Chun Myung-Hoon
Department of Anatomy, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Republic of Korea.
Neurosci Lett. 2008 Jul 11;439(2):165-9. doi: 10.1016/j.neulet.2008.05.013. Epub 2008 May 10.
The high rate of exocytosis at the ribbon synapses is balanced by following compensatory endocytosis. Unlike conventional synaptic terminals where clathrin-mediated endocytosis (CME) is a predominant mechanism for membrane retrieval, CME is thought to be only a minor mechanism of endocytosis at the retinal ribbon synapses, but CME is present there and it works. We examined the clathrin expression in the FVB/N rd1 mouse, which is an animal model of retinitis pigmentosa. The broadly distributed pattern of clathrin immunoreactivity in the inner plexiform layer was similar in both the control and FVB/N mouse retinas, but the immunoreactive punta within the rod bipolar axon terminals located in the proximal IPL were decreased in number and reduced in size at postnatal days 14 and they came to disappear at postnatal days 21. This preferential decrease of the clathrin expression at ribbon synapses in the rod bipolar cell axon terminals of the FVB/N mouse retina demonstrates another plastic change after photoreceptor degeneration and this suggests that clathrin may be important for normal synaptic function at the rod bipolar ribbon synapses in the mammalian retina.
带状突触处的高胞吐率通过随后的代偿性内吞作用得以平衡。与传统突触终末不同，在传统突触终末网格蛋白介导的内吞作用（CME）是膜回收的主要机制，而在视网膜带状突触处，CME被认为只是内吞作用的次要机制，但CME在那里存在且发挥作用。我们检测了FVB/N rd1小鼠（一种视网膜色素变性动物模型）中的网格蛋白表达。在内网状层中，网格蛋白免疫反应性的广泛分布模式在对照小鼠和FVB/N小鼠视网膜中相似，但位于内网状层近端的视杆双极轴突终末内的免疫反应性亮点在出生后第14天数量减少且尺寸减小，并在出生后第21天消失。FVB/N小鼠视网膜视杆双极细胞轴突终末的带状突触处网格蛋白表达的这种优先减少表明了光感受器退化后的另一种可塑性变化，这表明网格蛋白对于哺乳动物视网膜视杆双极带状突触的正常突触功能可能很重要。
