Tan Peter S P, Potas Jason R, Killinger Suzanne, Horiuchi Jouji, Goodchild Ann K, Pilowsky Paul M, Dampney Roger A L
Department of Physiology and Institute for Biomedical Research, The University of Sydney, Sydney, NSW 2006, Australia.
Brain Res. 2005 Mar 2;1036(1-2):70-6. doi: 10.1016/j.brainres.2004.12.018.
Microinjections of low doses (in the femtomolar or low picomolar range) of angiotensin II (Ang II) into the nucleus tractus solitarii (NTS) evoke depressor responses. In this study we have mapped in the rat the precise location of the subregion within the NTS at which Ang II evokes significant sympathoinhibitory and depressor responses. Microinjections of 1 pmol of Ang II evoked large decreases (>or=20% of baseline) in renal sympathetic nerve activity (RSNA), from a highly restricted region in the medial NTS, at or very close to the level 0.2 mm caudal to the obex. Microinjections of the same dose of Ang II into the commissural or lateral NTS at the same rostrocaudal level, or into the medial and lateral NTS at the level of the obex evoked significantly smaller sympathoinhibitory responses, while microinjections into more rostral or caudal levels of the NTS evoked significant sympathoinhibitory responses even less frequently. In most cases (71%), the sympathoinhibitory responses were accompanied by depressor responses, the magnitudes of which were also greater within the medial NTS at the level 0.2 mm caudal to obex, as compared to the surrounding subregions. The results demonstrate that the cardiovascular effects of Ang II in the NTS are highly site-specific. Taken together with previous studies, the results also indicate that the neurons in the NTS that mediate the Ang II-evoked sympathoinhibition are a discrete subgroup of the population of sympathoinhibitory neurons within the nucleus.
向孤束核（NTS）微量注射低剂量（飞摩尔或低皮摩尔范围）的血管紧张素II（Ang II）可引起降压反应。在本研究中，我们已在大鼠中确定了NTS内Ang II引起显著交感神经抑制和降压反应的精确亚区域位置。向内侧NTS中高度局限的区域（在闩尾侧0.2毫米处或非常接近该水平）微量注射1皮摩尔的Ang II可引起肾交感神经活动（RSNA）大幅下降（≥基线的20%）。在相同的头尾水平，向连合部或外侧NTS微量注射相同剂量的Ang II，或在闩水平向内侧和外侧NTS微量注射，引起的交感神经抑制反应明显较小，而向NTS更高或更低水平微量注射引起显著交感神经抑制反应的频率更低。在大多数情况下（71%），交感神经抑制反应伴有降压反应，与周围亚区域相比，在闩尾侧0.2毫米水平的内侧NTS内降压反应的幅度也更大。结果表明，Ang II在NTS中的心血管作用具有高度的位点特异性。结合先前的研究，结果还表明，介导Ang II引起的交感神经抑制的NTS神经元是该核内交感神经抑制神经元群体中的一个离散亚组。
