Bina K G, Rusak B, Semba K
Department of Psychology, Dalhousie University, Halifax, Nova Scotia, Canada.
J Comp Neurol. 1993 Sep 8;335(2):295-307. doi: 10.1002/cne.903350212.
In mammals, the suprachiasmatic nucleus is responsible for the generation of most circadian rhythms and their entrainment to environmental cues. Cholinergic agents can alter circadian rhythm phase, and fibres immunoreactive for choline acetyltransferase, the biosynthetic enzyme for acetylcholine, are present in the suprachiasmatic nucleus. Since there are no cholinergic somata in the suprachiasmatic nucleus, these fibres must represent the terminals of cholinergic neurons whose cell bodies are located elsewhere in the brain. This study was aimed at locating the cholinergic neurons that project to the suprachiasmatic nucleus by retrograde and anterograde tract-tracing and immunohistochemistry for choline acetyltransferase in the rat. After injection of fluorogold, a retrograde tracer, into the suprachiasmatic nucleus, retrogradely labelled neurons that were immunopositive for choline acetyltransferase were located throughout the rostrocaudal extent of the cholinergic basal nuclear complex, with highest densities in the substantia innominata and the nucleus basalis magnocellularis. A few cells were also located in the medial septum and in the vertical and horizontal limbs of the diagonal band of Broca. In the brainstem, double-labelled neurons were located in the laterodorsal tegmental nucleus, pedunculopontine tegmental nucleus and the parabigeminal nucleus. Injections of the anterograde tracer biocytin in these three brainstem nuclei resulted in fibre labelling in the suprachiasmatic nucleus, consistent with the retrograde findings. No clearly double-labelled cells were located in the retina. These results suggest that the suprachiasmatic nucleus receives cholinergic afferents from both the basal forebrain and mesopontine tegmentum which may mediate cholinergic effects on circadian rhythms.
在哺乳动物中，视交叉上核负责大多数昼夜节律的产生及其与环境线索的同步。胆碱能药物可改变昼夜节律相位，并且视交叉上核中存在对胆碱乙酰转移酶（乙酰胆碱的生物合成酶）呈免疫反应的纤维。由于视交叉上核中不存在胆碱能神经元胞体，这些纤维必定代表其细胞体位于脑内其他部位的胆碱能神经元的终末。本研究旨在通过逆行和顺行束路追踪以及对大鼠胆碱乙酰转移酶进行免疫组织化学来定位投射至视交叉上核的胆碱能神经元。将逆行示踪剂荧光金注射到视交叉上核后，对胆碱乙酰转移酶呈免疫阳性的逆行标记神经元遍布胆碱能基底核复合体的前后范围，在无名质和大细胞基底核中密度最高。也有一些细胞位于内侧隔以及布洛卡斜带的垂直和水平支中。在脑干中，双标记神经元位于外侧背侧被盖核、脚桥被盖核和副视束核中。将顺行示踪剂生物胞素注射到这三个脑干核中导致视交叉上核出现纤维标记，与逆行研究结果一致。视网膜中未发现明显的双标记细胞。这些结果表明，视交叉上核接受来自基底前脑和中脑桥被盖的胆碱能传入纤维，这可能介导胆碱能对昼夜节律的影响
