Descending vasomotor pathways from the dorsomedial hypothalamic nucleus: role of medullary raphe and RVLM
Descending vasomotor pathways from the dorsomedial hypothalamic nucleus: role of medullary raphe and RVLM
复制标题
DOI：
10.1152/ajpregu.00221.2004
复制
发表时间：
2004-10-01
影响因子：
2.8
通讯作者：
Dampney, RAL
中科院分区：
文献类型：
--
作者：
Horiuchi, J;McAllen, RM;Dampney, RAL
下丘脑背内侧核(DMH)被认为在介导急性应激引起的血管运动和心脏反应中发挥关键作用。抑制延髓头端腹外侧区(RVLM)神经元可显著降低由DMH激活引起的肾交感神经活动(RSNA)的增加，表明RVLM神经元至少部分地介导DMH诱发的反应中的血管运动成分。在这项研究中，第一个目的是确定延髓中缝苍白带(RP)区的神经元是否也参与DMH诱发的血管舒缩反应，因为已经证明DMH诱发的心动过速是由RP区介导的。第二个目的是直接评估DMH激活对RVLM交感运动前神经元放电频率的影响。在乌拉坦麻醉的大鼠，在RP区注射GABA(A)受体激动剂蝇草酚(但不是溶剂)引起的RSNA增加幅度不大(与25%相似)，但显著降低DMH去抑制(通过微量注射荷包牡丹碱)引起的RSNA增加。在其他实验中，去抑制DMH导致RVLM中6个投射压力敏感神经元中的5个产生强烈的兴奋(放电率类似于400%)。结果表明，在DMH引起的肾交感兴奋反应中，RVLM区神经元的贡献较小，而RVLm内的交感前运动神经元接受DMH神经元的强烈兴奋性输入，这与RVLM在介导DMH引起的交感血管舒缩反应中起关键作用的观点一致。
The dorsomedial hypothalamic nucleus (DMH) is believed to play a key role in mediating vasomotor and cardiac responses evoked by an acute stress. Inhibition of neurons in the rostral ventrolateral medulla (RVLM) greatly reduces the increase in renal sympathetic nerve activity (RSNA) evoked by activation of the DMH, indicating that RVLM neurons mediate, at least in part, the vasomotor component of the DMH-evoked response. In this study, the first aim was to determine whether neurons in the medullary raphe pallidus ( RP) region also contribute to the DMH-evoked vasomotor response, because it has been shown that the DMH-evoked tachycardia is mediated by the RP region. The second aim was to directly assess the effect of DMH activation on the firing rate of RVLM sympathetic premotor neurons. In urethane-anesthetized rats, injection of the GABA(A) receptor agonist muscimol (but not vehicle solution) in the RP region caused a modest (similar to25%) but significant reduction in the increase in RSNA evoked by DMH disinhibition (by microinjection of bicuculline). In other experiments, disinhibition of the DMH resulted in a powerful excitation ( increase in firing rate of similar to400%) of 5 out of 6 spinally projecting barosensitive neurons in the RVLM. The results indicate that neurons in the RP region make a modest contribution to the renal sympathoexcitatory response evoked from the DMH and also that sympathetic premotor neurons in the RVLM receive strong excitatory inputs from DMH neurons, consistent with the view that the RVLM plays a key role in mediating sympathetic vasomotor responses arising from the DMH.