In the transverse medullary slice prepared from neonatal rats the hypoglossal nerve rootlets exhibit a bursting 'respiratory' rhythm as do neurones in the pre-B

This study was to observe the changes of the neuronal and inducible nitric oxidesynthase(nNOS ＆ iNOS) as well as their mRNAs in the rostral ventrolateral mudulla(RVLM) of stress-induced hypertensive rats before and after acupuncture, and thereby to infer the curative mechanism of acupuncture on hypertension. The result indicated that the systolic blood pressure(SBP) of stress group rats was increased significantly(P＜0.01), it was accompanied that the expression of nNOS in the RVLM, including the immunoreactive neuron number(P＜0.05), the optical density(OD)(P＜0.01), and the mRNA(P＜0.01) were obviously elevated, while those of iNOS(P＜0.05, P＜0.01 and P＜0.01) were evidently lowered in the stress-induced hypertensive rats. Electroacupuncture(EA) points at "Zusanli" (St.36) and "Lanwei"(Extra 37) on the same hindlimb were stimulated by an EA apparatus(Type G6805-2) with dense sparse wave(4-20Hz) and 4mA intensity. EA application could return the SBP(P＜0.05), and the changes on the expression of both nNOS and iNOS(P＜0.05, P＜0.01 and P＜0.01). These results suggest that the curative mechanism of acupuncture on stress-induced hypertension is related to the changes of nNOS and iNOS in the RVLM of rats

采用多管微电泳结合细胞外记录的方法研究了肾上腺髓质素(adrenomedullin, ADM)对大鼠延髓头端腹外侧区(rostral ventrolateral medulla, rVLM)压力反射敏感性神经元电活动的作用及其可能机制。结果显示：在29 个rVLM压力反射敏感神经元中，20个神经元在30、60 和90 nA 的电流微电泳大鼠ADM (rADM)过程中，放电频率由(10.8±2.7) spikes/s分别增加到(14.6±3.6)、(19.8±4.7)和(31.9±6.4) spikes/s(P<0.05，n=20)。微电泳rADM特异性受体阻断剂人ADM (human ADM, hADM) (22-52)可明显减小神经元放电频率的增加幅度，比正常放电频率仅增15.4％ [(11.4±2.5) sipkes/s, P<0.05, n=10]，而降钙素基因相关肽1 (CGRP1)受体阻断剂hCGRP (8-37)对rADM兴奋性神经元电活动影响较小。在另外23个神经元中，10个神经元的放电频率在10、20 和40 nA 电流微电泳神经型NOS(nNOS)抑制剂7-NiNa 过程中放电减少，由正常的(10.1±3.5)spikes/s分别减少为 (7.5±2.5)、(5.3±2.1)和(3.1±1.4) spikes/s (P<0.05, n=10)。在微电泳7-NiNa 过程中同时微电泳rADM，则rADM增加神经元放电频率的效应减弱，增加幅度为基础水平的17％ [(6.2±1.9) spikes/s]。8个神经元在10、20 和40 nA电流微电泳诱导型NOS 抑制剂(iNOS) aminoguanidine (AG)过程中放电频率由(11.5±5.1) spikes/s 增加到(17.8±5.6)、(22.5±6.3)和(29.1±6.4) spikes/s (P<0.05, n=8)，rADM 与AG 同时微电泳时，AG对rADM本身增加神经元放电的效应无明显影响。上述结果提示，rADM在rVLM可通过其特异性受体或来源于nNOS 的NO作用于压力反射敏感神经元，使其活动增强而发挥调节心血管活动的作用。

Expiratory neurones, with a decrementing firing pattern during the first phase of expiration (EDEC) and located in the rostral ventrolateral medulla, are thought to be involved in the network generating respiratory rhythm, which also includes expiratory neurones with augmenting firing patterns (E-AUG). We used crosscorrelation to detect their synaptic interconnections and connections to phrenic motoneurones in 32 vagotomised, decerebrate, paralysed and ventilated male rats. Pairs of neurones were recorded extracellularly with glass-insulated tungsten microelectrodes and the whole phrenic nerve with bipolar silver wire electrodes. Of the 79 crosscorrelograms computed between pairs of E-DEC neurones, 8 (-10%) showed evidence for inhibitory connections. Of the 67 cross-correlograms computed between EDEC and E-AUG neurones, 5 (7.5%) showed evidence for a monosynaptic inhibition of the E-AUG neurone by the E-DEC neurone, while 3 (4.5%) showed evidence for a monosynaptic inhibition of the E-DEC neurone by the EAUG neurone. An inhibitory connection from E-DEC neurones to phrenic motoneurones was detected in 5 (-2%) of the cross-correlograms, and from E-AUG neurones to phrenic motoneurones in 4 (-3.7%). These results are the first demonstration that network models of rhythm generation in the rat involving reciprocal inhibition between E-DEC and E-AUG neurones could have a neurophysiological basis, and the first to demonstrate that phrenic motoneurones are inhibited during the early phase of expiration by E-DEC neurones.