Woulfe J M, Hrycyshyn A W, Flumerfelt B A
Department of Anatomy, University of Western Ontario, London, Canada.
Exp Neurol. 1988 Oct;102(1):121-4. doi: 10.1016/0014-4886(88)90084-2.
The A1 noradrenergic cell group in the caudal ventrolateral medullary reticular formation of the rat sends efferent projections to a number of regions in the basal forebrain and hypothalamus, but the extent to which these projections represent collateral branches of individual axons is not known. Immunohistochemical labeling of medullary neurons containing the catecholamine biosynthetic enzymes tyrosine hydroxylase, dopamine beta-hydroxylase, and phenylethanolamine N-methyltransferase was used to reveal the anatomical location of A1 noradrenergic neurons within the ventrolateral medulla. Subsequently, the retrograde fluorescence double-labeling technique was employed to investigate the collateralization of ascending A1 efferent axons. The subcommissural bed nucleus of the stria terminalis (BST) was injected with rhodamine-fluorescent latex microspheres and the ipsilateral left paraventricular nucleus of the hypothalamus (PVN) was injected with Fast blue. Within the ventrolateral medulla, single- and double-labeled neurons were identified in a distribution corresponding to that demonstrated for A1 noradrenergic perikarya. The results indicate that some ascending axons from cells within the A1 region collateralize to effect a simultaneous innervation of the BST and PVN. The innervation of multiple efferent targets by single neurons within the A1 region may have important implications with respect to A1's postulated role in central cardiovascular regulation.
大鼠延髓尾端腹外侧网状结构中的A1去甲肾上腺素能细胞群向基底前脑和下丘脑的多个区域发出传出投射，但这些投射在多大程度上代表单个轴突的侧支尚不清楚。利用免疫组织化学方法标记含有儿茶酚胺生物合成酶酪氨酸羟化酶、多巴胺β-羟化酶和苯乙醇胺N-甲基转移酶的延髓神经元，以揭示A1去甲肾上腺素能神经元在腹外侧延髓内的解剖位置。随后，采用逆行荧光双标记技术研究A1传出轴突的侧支化情况。向终纹床核（BST）注射罗丹明荧光乳胶微球，并向下丘脑同侧室旁核（PVN）注射快蓝。在腹外侧延髓内，鉴定出单标记和双标记神经元，其分布与A1去甲肾上腺素能神经元胞体的分布一致。结果表明，来自A1区域内细胞的一些上行轴突发生侧支化，以同时支配BST和PVN。A1区域内单个神经元对多个传出靶点的支配可能对A1在中枢心血管调节中的假定作用具有重要意义。
