Mosko S, Moore R Y
Brain Res. 1979 Mar 23;164:1-15. doi: 10.1016/0006-8993(79)90002-7.
The suprachiasmatic nucleus (SCN), the terminal nucleus of the retinohypothalamic (RH) tract, was ablated electrolytically in 2-day-old rats. Since previous studies have demonstrated that the earliest retinal fibers arrive on postnatal day 3 to 4 (refs. 4, 17), the lesions were inflicted prior to the formation of retinal connections. At day 25, [3H]proline was injected into the eye and autoradiography performed to determine if developing RH fibers would exhibit plasticity and innervate any hypothalamic nucleus other than the SCN. No evidence was found for the formation of anomalous retinal connections after complete, bilateral SCN lesions. Incomplete lesions, however, result in some alteration in the distribution of retinal fibers to the SCN. If a part of the caudal three-quarters of the SCN remains, RH projections form in a pattern dependent upon the size and location of the intact SCN fragment. These results indicate a high degree of specificity in developing RH fibers for their normal target tissue and a minimal capacity for plasticity in contrast with the various forms of neuronal reorganization observed after early destruction of other components of the visual system.
视交叉上核（SCN）是视网膜下丘脑（RH）束的终末核，在2日龄大鼠中通过电解法将其损毁。由于先前的研究表明最早的视网膜纤维在出生后第3至4天到达（参考文献4、17），因此在视网膜连接形成之前造成损伤。在第25天，将[3H]脯氨酸注入眼睛并进行放射自显影，以确定发育中的RH纤维是否会表现出可塑性并支配除SCN之外的任何下丘脑核。在完全双侧SCN损伤后，未发现异常视网膜连接形成的证据。然而，不完全损伤会导致视网膜纤维向SCN分布的一些改变。如果SCN尾侧四分之三的一部分保留下来，RH投射会以一种取决于完整SCN片段大小和位置的模式形成。这些结果表明，发育中的RH纤维对其正常靶组织具有高度特异性，与早期破坏视觉系统其他成分后观察到的各种神经元重组形式相比，可塑性极小。
