Sukhotinsky I, Reiner K, Govrin-Lippmann R, Belenky M, Lu J, Hopkins D A, Saper C B, Devor M
Department of Cell and Animal Biology, Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
J Chem Neuroanat. 2006 Dec;32(2-4):159-78. doi: 10.1016/j.jchemneu.2006.08.003. Epub 2006 Oct 16.
Pentobarbital microinjected into a restricted locus in the upper brainstem induces a general anesthesia-like state characterized by atonia, loss of consciousness, and pain suppression as assessed by loss of nocifensive response to noxious stimuli. This locus is the mesopontine tegmental anesthesia area (MPTA). Although anesthetic agents directly influence spinal cord nociceptive processing, antinociception during intracerebral microinjection indicates that they can also act supraspinally. Using neuroanatomical tracing methods we show that the MPTA has multiple descending projections to brainstem and spinal areas associated with pain modulation. Most prominent is a massive projection to the rostromedial medulla, a nodal region for descending pain modulation. Together with the periaqueductal gray (PAG), the MPTA is the major mesopontine input to this region. Less dense projections target the PAG, the locus coeruleus and pericoerulear areas, and dorsal and ventral reticular nuclei of the caudal medulla. The MPTA also has modest direct projections to the trigeminal nuclear complex and to superficial layers of the dorsal horn. Double anterograde and retrograde labeling at the light and electron microscopic levels shows that MPTA neurons with descending projections synapse directly on spinally projecting cells of rostromedial medulla. The prominence of the MPTA's projection to the rostromedial medulla suggests that, like the PAG, it may exert antinociceptive actions via this bulbospinal relay.
将戊巴比妥微量注射到上脑干的一个特定部位会诱导出一种全身麻醉样状态，其特征为张力缺失、意识丧失以及通过对有害刺激的伤害性反应丧失来评估的疼痛抑制。这个部位就是中脑桥被盖麻醉区（MPTA）。尽管麻醉剂直接影响脊髓的伤害性处理，但脑内微量注射时的抗伤害感受表明它们也可在脊髓以上水平发挥作用。使用神经解剖示踪方法，我们发现MPTA有多个下行投射至与疼痛调制相关的脑干和脊髓区域。最显著的是向延髓嘴内侧的大量投射，延髓嘴内侧是下行疼痛调制的一个枢纽区域。与导水管周围灰质（PAG）一起，MPTA是该区域主要的中脑桥输入。密度较低的投射靶向PAG、蓝斑和蓝斑周区域，以及延髓尾侧的背侧和腹侧网状核。MPTA也有适度的直接投射至三叉神经核复合体和背角浅层。光镜和电镜水平的双重顺行和逆行标记显示，具有下行投射的MPTA神经元直接与延髓嘴内侧的脊髓投射细胞形成突触。MPTA向延髓嘴内侧的投射突出表明，与PAG一样，它可能通过这种延髓脊髓中继发挥抗伤害感受作用。
