Levine J D, Weiss M L, Rosenwasser A M, Miselis R R
Department of Anatomy, University of Pennsylvania, Philadelphia 19104-6046.
J Comp Neurol. 1991 Apr 8;306(2):344-60. doi: 10.1002/cne.903060210.
There are several anatomically and functionally distinct retinofugal pathways, one of which is the retinohypothalamic tract (RHT). In this study, horseradish peroxidase conjugated to cholera toxin (CT-HRP), a sensitive neural tracer, was employed to describe the RHT in the female albino rat. Following uniocular injection of CT-HRP, both medial and lateral components of the RHT were evident. The medial component swept caudally into and through the suprachiasmatic nucleus (SCN) and dorsally to the subparaventricular zone. Terminal label was seen in the medial preoptic region, peri-SCN area, retrochiasmatic area, periventricular nucleus, anterior and central parts of the anterior hypothalamic area, and the subparaventricular zone. In contrast to the more focused and symmetrical medial component, the lateral component was diffuse with light terminal label in the lateral preoptic region, olfactory tubercle, lateral hypothalamus, supraoptic nucleus, and medial and posteroventral medial amygdaloid nuclei. The striking exception to this diffuse pattern of the lateral component was an extremely dense columnar terminal field over the dorsal border of the supraoptic nucleus. Whereas the intensity of label in terminal fields of the medial component was often similar on the sides ipsilateral and contralateral to the injection, the lateral component was consistently asymmetrical with greater labeling on the side contralateral to the injection. In addition, a light projection arrived at several thalamic nuclei by returning toward the thalamus from the tectal or pretectal areas via stria medullaris, and thus was not a part of the RHT. Implications for circadian as well as noncircadian photobiologic effects are discussed.
存在几种在解剖学和功能上截然不同的视网膜传出通路，其中之一是视网膜下丘脑束（RHT）。在本研究中，使用了与霍乱毒素结合的辣根过氧化物酶（CT-HRP），一种敏感的神经示踪剂，来描述雌性白化大鼠的RHT。在单眼注射CT-HRP后，RHT的内侧和外侧成分均清晰可见。内侧成分向尾侧延伸进入并穿过视交叉上核（SCN），并向背侧延伸至室旁核下区。终末标记见于视前内侧区、SCN周围区域、视交叉后区域、室周核、下丘脑前区的前部和中部以及室旁核下区。与更集中且对称的内侧成分不同，外侧成分较为弥散，在视前外侧区、嗅结节、外侧下丘脑、视上核以及杏仁核内侧和后腹内侧核有轻度终末标记。外侧成分这种弥散模式的显著例外是在视上核背侧边界上方有一个极其密集的柱状终末野。内侧成分终末野的标记强度在注射同侧和对侧通常相似，而外侧成分始终不对称，注射对侧的标记更强。此外，一束微弱的投射通过髓纹从顶盖或顶盖前区返回丘脑，到达几个丘脑核团，因此不属于RHT的一部分。文中讨论了其对昼夜节律以及非昼夜光生物学效应的影响。
