Eldred W D, Li H B, Carraway R E, Dowling J E
Department of Biology, Boston University, MA 02215.
Brain Res. 1987 Oct 27;424(2):361-70. doi: 10.1016/0006-8993(87)91481-8.
LANT-6 is a hexapeptide (H-Lys-Asn-Pro-Tyr-Ile-Leu-OH) isolated from chicken small intestine, which resembles the COOH-terminal half of neurotensin, except for the amino acid substitutions Lys/Arg and Asn/Arg. The present report concerns the immunocytochemical staining of vertebrate retinas using an antiserum directed against LANT-6. In the retinas from goldfish, bird and turtle, cells in both the inner nuclear and ganglion cell layers were labeled, but in the frog no cells were labeled specifically and in the rat only cells in the ganglion cell layer were labeled. Labeled cell bodies in the inner nuclear layer gave rise to processes which were seen primarily within the following laminas of the inner plexiform layer (IPL): in the goldfish, lamina 3; chicken, laminae 1, 3 and 4; and turtle, laminae 3, 4 and 5. The cell bodies of the labeled neurons in the ganglion cell layer gave rise to dendrites which entered the IPL and axons which descended to the optic fiber layer. The cells with LANT-6-like immunoreactivity were distributed in both the central and peripheral parts of the retina in all the species examined except frog. Measured by radioimmunoassays, the levels of LANT-6-like-immunoreactivity in extracts of turtle, chicken, and goldfish retinas were 5-30 times those for neurotensin-like immunoreactivity, however no LANT-6-like immunoreactivity was detected in frog. Multiple chromatographic analyses indicated that while the LANT-6-like immunoreactivity in chicken retina was indistinguishable from synthetic LANT-6, LANT-6-like immunoreactivity in turtle and goldfish retinas was primarily associated with large molecular forms. Treatment of turtle LANT-6-like immunoreactivity with pepsin, an enzyme known to mimic processing for neurotensin precursors, yielded 3 major peptides, one of which co-chromatographed with synthetic LANT-6. The present immunocytochemical localization of LLI within cells in the inner nuclear and ganglion cell layers, coupled with the biochemical characterization of LANT-6 in the vertebrate retinas and brains, suggests that neuropeptides such as LANT-6 may play a role in visual processing both within the retina and within the visual pathways to the brain.
LANT - 6是一种从鸡小肠中分离出的六肽（H - 赖氨酸 - 天冬酰胺 - 脯氨酸 - 酪氨酸 - 异亮氨酸 - 亮氨酸 - 羟基），它类似于神经降压素的羧基末端一半，只是氨基酸替换为赖氨酸/精氨酸和天冬酰胺/精氨酸。本报告涉及使用针对LANT - 6的抗血清对脊椎动物视网膜进行免疫细胞化学染色。在金鱼、鸟类和海龟的视网膜中，内核层和神经节细胞层中的细胞都被标记，但在青蛙中没有细胞被特异性标记，而在大鼠中只有神经节细胞层中的细胞被标记。内核层中被标记的细胞体产生的突起主要出现在内网状层（IPL）的以下板层中：在金鱼中是板层3；鸡中是板层1、3和4；海龟中是板层3、4和5。神经节细胞层中被标记神经元的细胞体产生进入IPL的树突和向下延伸至视神经纤维层的轴突。除青蛙外，在所有被检查的物种中，具有LANT - 6样免疫反应性的细胞分布在视网膜的中央和周边部分。通过放射免疫测定法测量，海龟、鸡和金鱼视网膜提取物中LANT - 6样免疫反应性的水平是神经降压素样免疫反应性水平的5 - 30倍，然而在青蛙中未检测到LANT - 6样免疫反应性。多次色谱分析表明，虽然鸡视网膜中的LANT - 6样免疫反应性与合成的LANT - 6无法区分，但海龟和金鱼视网膜中的LANT - 6样免疫反应性主要与大分子形式相关。用胃蛋白酶处理海龟的LANT - 6样免疫反应性，胃蛋白酶是一种已知可模拟神经降压素前体加工过程的酶，产生了3种主要肽段，其中一种与合成的LANT - 6共色谱。LLI在核内和神经节细胞层细胞中的当前免疫细胞化学定位，以及脊椎动物视网膜和大脑中LANT - 6的生化特征，表明诸如LANT - 6之类的神经肽可能在视网膜内以及通向大脑的视觉通路中的视觉处理中发挥作用。
