Molliver M E
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
J Clin Psychopharmacol. 1987 Dec;7(6 Suppl):3S-23S.
A review of the anatomic organization of ascending serotonin projections is followed by recent findings showing that these axonal projections are not diffuse but have an intricate and orderly pattern. The dorsal and median raphe nuclei and the B9 cell group have overlapping but differential projections to all parts of the forebrain. While most raphe projections extensively overlap, the dorsal raphe projects most heavily to frontal cortex and striatum, while the median raphe predominantly innervates hippocampus and septum. Small clusters of raphe cells project in a mosaic pattern to multiple, widely distributed islands of cortex. Yet, a coarse topographic order is preserved in the ascending dorsal raphe projections. Recent studies demonstrate two classes of serotonin axon terminals that differ in axon morphology, cells of origin, regional distribution, and response to psychotropic drugs. Dorsal raphe axons are extremely fine and highly vulnerable to certain neurotoxic amphetamines, e.g., 3,4-methylenedioxymethamphetamine; median raphe axons have large varicosities and are resistant to these mood-elevating drugs. We propose that there are two anatomically and functionally distinct serotonergic projections to cortex and that neurons in the dorsal raphe nucleus appear to play a major role in the control of affective state.
对5-羟色胺上行投射的解剖结构进行综述后，近期研究发现这些轴突投射并非弥散分布，而是具有复杂且有序的模式。中缝背核、中缝正中核和B9细胞群对前脑各部分有重叠但有差异的投射。虽然大多数中缝投射广泛重叠，但中缝背核主要投射到额叶皮质和纹状体，而中缝正中核主要支配海马体和隔膜。中缝细胞的小簇以镶嵌模式投射到多个广泛分布的皮质岛。然而，中缝背核上行投射中仍保留着粗略的拓扑顺序。近期研究表明，两类5-羟色胺轴突终末在轴突形态、起源细胞、区域分布以及对精神药物的反应方面存在差异。中缝背核轴突极其纤细，对某些神经毒性苯丙胺类药物（如3,4-亚甲基二氧甲基苯丙胺）高度敏感；中缝正中核轴突有大的膨体，对这些能提升情绪的药物有抗性。我们提出，存在两条在解剖学和功能上截然不同的向皮质的5-羟色胺能投射，并且中缝背核中的神经元似乎在情感状态的控制中起主要作用。
