Saha S, Batten T F, Henderson Z
Institute for Cardiovascular Research, School of Medicine, Worsley Building, University of Leeds, LS2 9JT, Leeds, UK.
Neuroscience. 2000;99(4):613-26. doi: 10.1016/s0306-4522(00)00240-2.
The central nucleus of the amygdala is involved in the modulation of autonomic, somatic and endocrine functions, as well as behavioural responses to stressful stimuli. Anatomical and physiological studies have suggested that this nucleus sends projections to the nucleus of the solitary tract, the primary site of termination of vagal and glossopharyngeal afferent fibres in the brain stem. To determine the neurochemical nature of the amygdaloid input to the nucleus of the solitary tract, anterograde tracing with biotinylated dextran amine was combined with post-embedding immunogold labelling for GABA and glutamate immunoreactivities and with pre-embedding labelling for the vesicular GABA transporter. Following injection of biotin dextran amine into the central nucleus of the amygdala, anterogradely labelled axons and varicosities were found throughout the rostrocaudal extent of the nucleus of the solitary tract, particularly in the medial, ventral and ventrolateral subnuclei. The anterogradely labelled terminals were found to make predominantly symmetrical synaptic contacts with dendrites, and occasionally onto cell bodies and dendritic spines, and to contain immunoreactivity for GABA and for the vesicular GABA transporter. Immunolabelling of serial sections with antibodies to glutamate showed that none of these axon terminals contained high enough densities of gold particle labelling to suggest that they contained other than low metabolic levels of glutamate immunoreactivity. These results provide conclusive evidence for a GABAergic pathway from the central nucleus of the amygdala to the nucleus of the solitary tract. This GABAergic projection may provide a substrate for inhibition of lower brain stem visceral reflexes, including baroreflex inhibition, through which the central nucleus of the amygdala could participate in cardiovascular regulation related to emotional behaviour and the defence reaction.
杏仁核中央核参与自主神经、躯体和内分泌功能的调节，以及对应激刺激的行为反应。解剖学和生理学研究表明，该核向孤束核发出投射，孤束核是迷走神经和舌咽神经传入纤维在脑干的主要终止部位。为了确定杏仁核向孤束核输入的神经化学性质，将生物素化葡聚糖胺的顺行追踪与针对γ-氨基丁酸（GABA）和谷氨酸免疫反应性的包埋后免疫金标记以及针对囊泡GABA转运体的包埋前标记相结合。将生物素葡聚糖胺注入杏仁核中央核后，在孤束核的整个 rostrocaudal 范围内发现了顺行标记的轴突和曲张体，特别是在内侧、腹侧和腹外侧亚核中。发现顺行标记的终末主要与树突形成对称突触联系，偶尔与细胞体和树突棘形成联系，并含有GABA和囊泡GABA转运体的免疫反应性。用抗谷氨酸抗体对连续切片进行免疫标记表明，这些轴突终末中没有一个含有足够高的金颗粒标记密度，表明它们除了含有低代谢水平的谷氨酸免疫反应性外不含有其他物质。这些结果为从杏仁核中央核到孤束核的GABA能通路提供了确凿证据。这种GABA能投射可能为抑制脑干下部内脏反射提供底物，包括压力反射抑制，通过这种方式，杏仁核中央核可以参与与情绪行为和防御反应相关的心血管调节。
