Gilbey M P, Spyer K M
Department of Physiology, Royal Free Hospital School of Medicine, London, UK.
Baillieres Clin Endocrinol Metab. 1993 Apr;7(2):259-78. doi: 10.1016/s0950-351x(05)80177-6.
The sympathetic nervous system consists of efferent neurones supplying the viscera. The cell bodies of preganglionic neurones are located in four areas in the thoracolumbar cord; however, the majority are found in the IML. Various tracing techniques have provided information concerning the location of the cell bodies of sympathetic preganglionic neurones projecting into various nerves and ganglia and regulating the adrenal gland, the kidney and the sympathetic supply to skeletal muscle. Numerous supraspinal neurones project to the neuropil surrounding sympathetic preganglionic neurones and may form synaptic contacts with these neurones. The areas of the brain that project to the IML appear to be part of a network of reciprocally connected supraspinal cell groups. Although much emphasis has been placed on the importance of the RVLM in the mediation of tonic and phasic inputs to sympathetic preganglionic neurones, it appears that other areas are of significant import; the RVLM should not be considered to be 'the vasomotor centre'. Spinal and cranial afferents influence the sympathetic nervous system. Baroreceptor afferents terminate in the NTS and may utilize an excitatory amino acid as their neurotransmitter. However, a number of neuropeptides are also associated with these afferents. Neurones within the NTS project to a number of brain stem areas thought to be involved in the regulation of sympathetic activity; consequently the baroreceptor reflex may be mediated over a number of parallel pathways involving both supraspinal and spinal sites of inhibition. Many neurotransmitters are thought to regulate the activity of sympathetic preganglionic neurons: monoamines, peptides and amino acids. Matching the chemical content of the cell bodies of neurones within a particular cell group with physiological characteristics is a challenging task; some barosensitive neurones of the RVLM do not appear to be adrenergic although they are in the midst of the C1 adrenergic cell group. Besides acetylcholine and noradrenaline, neurotransmission in the periphery appears to involve numerous peptides and ATP.
交感神经系统由供应内脏的传出神经元组成。节前神经元的细胞体位于胸腰段脊髓的四个区域；然而，大多数位于中间外侧柱（IML）。各种追踪技术提供了有关投射到各种神经和神经节以及调节肾上腺、肾脏和骨骼肌交感神经供应的交感节前神经元细胞体位置的信息。许多脊髓上神经元投射到交感节前神经元周围的神经毡，并可能与这些神经元形成突触联系。投射到IML的脑区似乎是相互连接的脊髓上细胞群网络的一部分。尽管人们非常强调延髓头端腹外侧部（RVLM）在介导对交感节前神经元的紧张性和相位性输入中的重要性，但似乎其他区域也具有重要意义；不应将RVLM视为“血管运动中枢”。脊髓和颅神经传入纤维影响交感神经系统。压力感受器传入纤维在孤束核（NTS）终止，并可能利用兴奋性氨基酸作为其神经递质。然而，许多神经肽也与这些传入纤维有关。NTS内的神经元投射到一些被认为参与交感神经活动调节的脑干区域；因此，压力感受器反射可能通过涉及脊髓上和脊髓抑制部位的许多平行途径介导。许多神经递质被认为调节交感节前神经元的活动：单胺、肽和氨基酸。将特定细胞群内神经元细胞体的化学内容与生理特征相匹配是一项具有挑战性的任务；RVLM的一些压力敏感神经元尽管位于C1肾上腺素能细胞群中，但似乎不是肾上腺素能的。除了乙酰胆碱和去甲肾上腺素外，外周的神经传递似乎还涉及许多肽和三磷酸腺苷（ATP）。
