Activation of NADPH-diaphorase-positive projections to the rostral ventrolateral medulla following cardiac mechanoreceptor stimulation in the conscious rat
Activation of NADPH-diaphorase-positive projections to the rostral ventrolateral medulla following cardiac mechanoreceptor stimulation in the conscious rat
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DOI：
10.1152/ajpregu.00532.2005
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发表时间：
2006-06-01
影响因子：
2.8
通讯作者：
Badoer, E
中科院分区：
文献类型：
--
作者：
Kantzides, A;Badoer, E
在容量扩张期间刺激心脏机械感受器诱发交感神经活动（SNA）的代偿性变化。下丘脑室旁核（PVN）和孤束核（NTS）是已知参与这种反射的自主神经区域。这两个核团都投射到延髓头端腹外侧（RVLM），这在SNA的紧张性生成中至关重要。我们实验室最近的报告显示，这些途径1）在心脏机械感受器刺激后被激活，2）产生一氧化氮，已知会影响SNA。本研究的目的是确定1）PVN和NTS内激活的神经元是否为氮能神经元，2）这些神经元是否投射到RVLM。在全身麻醉下，通过将逆行转运的示踪剂微量注射到RVLM的加压区并在右静脉心房交界处放置球囊来准备动物。在清醒的大鼠中，球囊膨胀以刺激心脏机械感受器或保持未膨胀。球囊膨胀引起Fos阳性神经元在小细胞PVN（7倍）和NTS（5倍）显着增加。在PVN中，51%的氮能神经元和61%的RVLM投射的氮能神经元被激活。在NTS中，这些比例分别为8%和18%。这些数据表明，在PVN内的氮能神经元，并在较小程度上，在NTS，其中一些项目的RVLM，可能有助于影响SNA引起的心脏机械感受器刺激的中枢通路。
Stimulation of cardiac mechanoreceptors during volume expansion elicits reflex compensatory changes in sympathetic nerve activity (SNA). The hypothalamic paraventricular nucleus (PVN) and nucleus of the tractus solitarius (NTS) are autonomic regions known to contribute to this reflex. Both of these nuclei project to the rostral ventrolateral medulla (RVLM), critical in the tonic generation of SNA. Recent reports from our laboratory show that these pathways 1) are activated following cardiac mechanoreceptor stimulation, and 2) produce nitric oxide, known to influence SNA. The aims of the present study were to determine whether 1) the activated neurons within the PVN and NTS were nitrergic and 2) these neurons projected to the RVLM. Animals were prepared, under general anesthesia, by microinjection of a retrogradely transported tracer into the pressor region of the RVLM and the placement of a balloon at the right venoatrial junction. In conscious rats, the balloon was inflated to stimulate the cardiac mechanoreceptors or was left uninflated. Balloon inflation elicited a significant increase in Fos-positive neurons in the parvocellular PVN (sevenfold) and NTS (fivefold). In the PVN, 51% of nitrergic neurons and 61% of RVLM-projecting nitrergic neurons were activated. In the NTS, these proportions were 8 and 18%, respectively. The data suggest that nitrergic neurons within the PVN and, to a lesser extent, in the NTS, some of which project to the RVLM, may contribute to the central pathways influencing SNA elicited by cardiac mechanoreceptor stimulation.