激活蓝斑在孤束核水平对迷走神经传入的抑制

在戊巴比妥钠麻醉兔,电刺激颈迷走神经中枢端,在同侧孤束核（NTS）区可记录到一个由三个子波组成的复合电位。它们的潜伏期分别为6．8±0．6ms（P1）,25．8±4．2ms（P2）和89．1±2．7ms（P3）。这可能代表着不同性质的迷走传入纤维的突触后电位。同侧蓝斑（LC）内微量注射谷氨酸钠使P2,P3波的幅值明显降低。电刺激LC在同侧NTS区诱发出111个有反应单位,其潜伏期平均为6．3±1．4ms。在169个对迷走传入刺激有反应的NTS单位中,有90个对LC刺激也有反应。39个（占43．3％）会聚性单位对上述两种刺激的反应相似,而其余的呈不同的反应。对LC和迷走刺激分别均呈兴奋反应的25个NTS单位中,如预先刺激LC,则有14个单位对迷走刺激的兴奋反应受到明显抑制,另11个单位的兴奋反应完全被抑制。上述结果提示：激活蓝斑核具有抑制NTS对迷走传入刺激反应的作用。     

猫颈动脉区压力和化学感受性刺激对孤束核自发放电的影响

对27只氯醛糖和氨基甲酸乙酯麻醉的猫观察了选择性激活颈动脉压力和化学感受器对孤束核(NTS)及其附近区域单位放电的影响。共记录到103个对颈动脉压力感受器激活(新福林1—2μg/kg,iv)和/或颈动脉化学感受器激活(尼古丁,5—20μg,注入甲状腺动脉)起反应的单位,其中81个位于NTS,在这些单位中,14个仅对化学感受器激活起反应(10个兴奋和4个抑制),44个以各种组合形式对化学和压力感受性刺激都起反应,23个仅对压力感受器刺激起反应(18个兴奋和5个抑制)。在定位分布上,对两种刺激都起反应的单位主要位于NTS尾部,仅对化学感受性刺激起反应的单位多位于NTS的腹外侧,其它有反应的单位分别位于舌下神经旁区,旁正中网状核和延髓腹侧尾端。这些结果表明,颈动脉区压力和化学感受器活动传入到NTS,并在其中的一些神经元上发生会聚。 在全部有反应的NTS单位中,68个对压力感受性刺激起反应,其中46个兴奋,21个抑制(P<0.005);58个对化学感受性刺激起反应,其中36个兴奋,22个抑制(P>0.05)。这些结果提示,化学感受性刺激对NTS神经元引起兴奋和抑制两种反应,而压力感受性刺激则诱发兴奋为主的反应。     

刺激大鼠下丘脑室旁核激活的中脑中央灰质神经元对躯体传入的反应

电刺激大鼠下丘脑室旁核(PVH),在同侧中脑中央灰质(CG)内寻找逆行及顺行反应单位,然后观察它们对躯体感觉刺激的反应。实验结果表明:CG 及邻近网状结构内有10%(32/318)的单位呈逆行反应。逆行传导速度平均为0.37±0.24m/s(均数±标准差);推测这种CG→PVH 投射纤维属于细有髓或无髓神经纤维。这些单位分布于 CG 的腹外侧及背外侧亚核。50%(14/28)的逆行单位对坐骨(胫)神经的强电刺激和夹尾等损伤性刺激起反应,但对触毛或低强度的神经干刺激无明显反应。以上结果表明:外周躯体感觉,特别是损伤性信息传入 PVH 时,CG 是其中枢驿站之一。电刺激 PVH 还能顺行激活7.55(24/318)、抑制0.7%(2/318)的 CG 单位。有69%(18/26)的顺行反应单位对外周躯体神经强电刺激及夹尾起反应。提示 PVH 可能通过影响 CG神经元的活动而参与中枢痛觉的整合。     

肌神经刺激和穴位电针诱发的延脑网状巨细胞核的单位放电

电刺激麻痹家兔的腓深神经,在延脑内侧网状结构记录诱发电位和单位反应。此外,还观察电针足三里-三阴交穴对后者的影响。结果如下:1.根据动作电位各成分的大小,测得:腓深神经Ⅰ、Ⅱ、Ⅲ类纤维的兴奋阈分别是1、2和5—10T,而最大反应阈则分别是2、4—10和15—25T。当电刺激强度达到5T 时,通常能在双侧网状巨细胞核区记录到诱发反应,并随强度增大而增大。中缝大核区的反应相似。2.分析了共81个单位对不同刺激强度的放电反应,大体划为三类:Ⅰ类有5个,Ⅱ类24个,Ⅲ类52个。在Ⅱ类单位中,有14个仅对Ⅱ类传入发生反应,另10个则对Ⅱ和Ⅲ类传入均产生反应,称作“会聚型”单位。此外,还观察到半数单位能被皮神经δ类传入所兴奋。3.5个巨细胞核单位和2个中缝大核单位对电针穴位的反应表现为:电针频率为2周/秒时,细胞放电率虽增不多,但在20分钟的电针期间能维持同样的兴奋水平;频率为80周/秒时,初期放电率明显增加,但5分钟后迅速下降至低于2周/秒时水平。这似可提示临床远节段穴位电针以低频刺激为宜。     

猫颈动脉区压力和化学感受性刺激对巨细胞旁外侧核单位放电的影响

在31只氯醛糖和氨基甲酸乙酯麻醉的猫,观察了选择性激活颈动脉压力和化学感受器对巨细胞旁外侧核(PGL)单位放电的影响。136个PGL自发放电单位中,有84个在激活颈动脉压力感受器(BA)(新福林,1—2μg/kg,iv)和/或激活颈动脉化学感受器(CA)(nicotine 5—20μg,溶于0.25—0.5ml生理盐水中,注入甲状腺动脉)时,放电频率有变化。在这些有反应的单位中,16个仅对CA起反应(11个兴奋、5个抑制);54个以各种组合方式对CA和BA都起反应,其中以CA引起兴奋反应而BA引起抑制反应的占比例最大;14个仅对BA起反应(7个兴奋,7个抑制)。在定位分布上,那些只对CA起反应的单位多位于PGL的腹侧部份;仅对BA起反应的单位则位于对CA起反应单位的较背侧;对BA和CA均起反应的单位介于上述两者之间或在较深区域。这些结果表明,颈动脉区压力和化学感受器活动传入到PGL,并会聚在其中一些神经元上。 在PGL内全部有反应的单位中,68个对激活颈动脉压力感受器起反应,其中兴奋的29个,抑制的39个(P>0.05);70个对激活颈动脉化学感受器起反应,其中48个兴奋,22个抑制(P<0.005)。这些结果提示,BA对PGL神经元引起兴奋和抑制两种效应,而CA则诱发兴奋为主的反应。     

羟戊甲吗啡和纳洛酮微电泳给药对丘脑外侧前核区诱发单位放电的影响

本文用五管微电极离子微电泳方法,记录家兔丘脑外侧前核区诱发单位放电,并观察药物徼电泳的影响,以探讨该区内啡肽及阿片受体在感觉传递过程中的作用。根据对电刺激腓肠神经的反应型式,将所记录的90个单位归纳为兴奋型与抑制型二类。兴奋型单位共63个,包括会聚性、非会聚性长潜伏期及非会聚性短潜伏期三种类型的单位。羟戊甲吗啡能选择性地抑制会聚性单位的第二串放电,而对第一串反应无明显影响,此种抑制效应可被纳洛酮所阻断。对于非会聚性单位羟戊甲吗啡能选择性地抑制长潜伏期诱发放电反应,而对短潜伏期的则无明显影响。抑制型单位共27个,包括在强电震刺激后出现的初期短串放电、后期放电抑制的单位以及具有长潜伏期放电抑制的单位。羧戊甲吗啡对5个单位中4个单位的诱发反应无明显影响,而纳洛酮则对12个单位中的11个单位解除了抑制反应。 在羧戊甲吗啡与纳洛酮作用下兴奋型会聚性单位与抑制型单位的诱发反应型式可以相互转化。 实验结果提示,来自细纤维的传入冲动在丘脑外侧前核区的传递受内啡肽和阿片受体活动的控制。     

大鼠下丘脑室旁核神经元对电刺激蓝斑和中缝背核的反应

用玻璃微电极细胞外记录大鼠室旁核(PVH)神经元的单位放电,观察它对电刺激蓝斑(LC)和中缝背核(DR)的反应。 在435个被试验单位中,5个单位对LC电刺激呈现逆行反应,75个单位呈现顺行反应。在这75个顺行反应单位中,27个对单刺激发生反应,48个对串刺激发生反应。对电刺激DR发生反应的有74个单位,其中15个对单刺激发生反应,59个对串刺激发生反应而对单刺激不反应。值得注意的是有23个PVH神经元既对LG刺激又对DR刺激发生顺行反应。实验结果提示,PVH与LC、DR之间存在神经联系。     

伤害性刺激诱发体感皮层单位放电的互协方差函数分析

用伤害性刺激猫的腓浅神经（ＰＮ）诱发体感皮层Ⅰ区（ＳⅠ）单位放电（ＥＤ）,以放电阵列图和标准化互协方差函数进行定量分析。结果显示,用２５Ｖ刺激时引起Ａ类和Ｃ类纤维传入,在ＳⅠ记录到潜伏期为１４．８±５．０ｍｓ的早期ＥＤ（Ｅ）,与用３Ｖ弱刺激ＰＮ时只引起单纯Ａ类纤维传入引起的放电反应比较,潜伏期无显著区别。用极化电流阻断Ａ类纤维传入后,单纯Ｃ类传入只引起潜伏期为２２２．６±２８．７ｍｓ的晚期ＥＤ（Ｌ）或１２９．２４±２３ｍｓ的中期ＥＤ（Ｍ）,Ｍ、Ｌ可相互抑制,也可被Ａ类纤维传入所抑制。静脉注射镇痛剂吗啡后,Ｍ和Ｌ显著减少,Ｅ变化不显著。提示Ｃ类纤维传入可能分两类分别到达ＳⅠ区引起两种不同潜伏期的诱发放电,均与疼痛关系密切,都可作为慢痛反应的指标。     

猫体感皮层神经元对同时刺激隐神经的A类和C类纤维的反应型式

记录了麻痹猫的体感皮层(SI)神经元的自发和隐神经的A类和C类纤维传入诱发放电(A-ED和C-ED)。用NCCVF分析神经元放电。结果表明,SI区神经元对同时刺激隐神经的A类和C类纤维的反应呈多种型式:(1)A-ED和C-ED共存,包括Ⅰ.A-ED和C-ED始终相互伴随出现;Ⅱ.在刺激之初,只出现A-ED,但是,当阻断A类纤维传入并由C类纤维传入诱发神经元放电后,再同时刺激A类和C类纤维时,A-ED和C-ED便同时出现。(2)A-ED制约C-ED,特点是,只要A-ED存在,C/ED就不出现。只有阻断A类纤维传入后,C-ED才产生。(3)单一A-ED,不管在什么刺激条件下,这类神经元都只有A-ED,而不产生C-ED 结论:根据反应型式的不同,可将SI区的神经元分为Ⅰ.A类和C类纤维传入同时驱动的神经元;Ⅱ.A-ED制约C-ED的神经元;Ⅲ.只由A类纤维传入驱动的神经元。     

猫体感皮层神经元对同时刺激隐神经的A类和C类纤维的反应型式

记录了麻痹猫的体感皮层(SI)神经元的自发和隐神经的A类和C类纤维传入诱发放电(A-ED和C-ED)。用NCCVF分析神经元放电。结果表明,SI区神经元对同时刺激隐神经的A类和C类纤维的反应呈多种型式:(1)A-ED和C-ED共存,包括Ⅰ.A-ED和C-ED始终相互伴随出现;Ⅱ.在刺激之初,只出现A-ED,但是,当阻断A类纤维传入并由C类纤维传入诱发神经元放电后,再同时刺激A类和C类纤维时,A-ED和C-ED便同时出现。(2)A-ED制约C-ED,特点是,只要A-ED存在,C/ED就不出现。只有阻断A类纤维传入后,C-ED才产生。(3)单一A-ED,不管在什么刺激条件下,这类神经元都只有A-ED,而不产生C-ED 结论:根据反应型式的不同,可将SI区的神经元分为Ⅰ.A类和C类纤维传入同时驱动的神经元;Ⅱ.A-ED制约C-ED的神经元;Ⅲ.只由A类纤维传入驱动的神经元。     

Role of the medullary lateral tegmental field in reflex-mediated sympathoexcitation in cats

We tested the hypothesis that blockade of N-methyl-D-aspartate (NMDA) and non-NMDA receptors on medullary lateral tegmental field (LTF) neurons would reduce the sympathoexcitatory responses elicited by electrical stimulation of vagal, trigeminal, and sciatic afferents, posterior hypothalamus, and midbrain periaqueductal gray as well as by activation of arterial chemoreceptors with intravenous NaCN. Bilateral microinjection of a non-NMDA receptor antagonist into LTF of urethane-anesthetized cats significantly decreased vagal afferent-evoked excitatory responses in inferior cardiac and vertebral nerves to 29 +/- 8 and 24 +/- 6% of control (n = 7), respectively. Likewise, blockade of non-NMDA receptors significantly reduced chemoreceptor reflex-induced increases in inferior cardiac (from 210 +/- 22 to 129 +/- 13% of control; n = 4) and vertebral nerves (from 253 +/- 41 to 154 +/- 20% of control; n = 7) and mean arterial pressure (from 39 +/- 7 to 21 +/- 5 mmHg; n = 8). Microinjection of muscimol, but not an NMDA receptor antagonist, caused similar attenuation of these excitatory responses. Sympathoexcitatory responses to the other stimuli were not attenuated by microinjection of a non-NMDA receptor antagonist or muscimol into LTF. In fact, excitatory responses elicited by stimulation of trigeminal, and in some cases sciatic, afferents were enhanced. These data reveal two new roles for the LTF in control of sympathetic nerve activity in cats. One, LTF neurons are involved in mediating sympathoexcitation elicited by activation of vagal afferents and arterial chemoreceptors, primarily via activation of non-NMDA receptors. Two, non-NMDA receptor-mediated activation of other LTF neurons tonically suppresses transmission in trigeminal-sympathetic and sciatic-sympathetic reflex pathways.     

15th Annual spring brain conference,march 10–13, 2004,summary report

The present study was designed (1) to characterize the subliminal responses of dorsal horn neurons to stimulation of the sural nerve, and (2) to correlate the type of response to this stimulus with the responses to natural mechanical stimulation of the skin. To accomplish this, intracellular and extracellular recordings were carried out in L⁶ and L⁷ dorsal horn neurons in the cat. The excitatory responses of each cell to electrical stimulation of the sural nerve and to mechanical stimulation of the skin were noted.

Of 35 dorsal horn cells recorded intracellularly, 11 responded with impulses to sural nerve stimulation, 9 responded with excitatory postsynaptic potentials (EPSPs) but not impulses, and 15 had no excitatory responses to this stimulus. The type of response to sural nerve stimulation was strongly correlated with receptive field modality. Most cells receiving an input from high-threshold cutaneous mechanoreceptors responded with impulses or gave no excitatory response to sural nerve stimulation, whereas most cells that had only low-threshold mechanoreceptor input responded with EPSPs only or gave no response. In cells with only low-threshold (LT) mechanoreceptive input, response to sural nerve stimulation was highly correlated with receptive field locus. Those LT cells with no excitatory responses to sural nerve stimulation had receptive fields confined to the foot and/or toes, whereas those that gave EPSPs had more proximal receptive fields. The possible significance of these data with reference to changes observed after lesions, such as increased response to sural nerve stimulation, increased receptive field size, and somatotopic reorganization, is discussed.     

调制多觉型伤害性感受器持续放电的体液因素

利用复合致痛剂引起大鼠皮肤多觉型伤害性感受器(PMN)持续放电的模型,发现刺激坐骨神经中枢端对 PMN 持续放电有显著的抑制或先易化后抑制效应。通过交叉灌流,刺激供血动物的坐骨神经也可对受血动物的 PMN 持续放电产生类似的效应。注射刺激坐骨神经动物的血清,可显著影响 PMN 的活动。大部分单位的抑制效应不被纳洛酮翻转。对吗啡耐受的动物,刺激坐骨神经仍可引起抑制效应。预先利血平化,则使刺激的易化效应基本取消。结果证实,躯体神经传入冲动诱发体液因素调制 PMN 的持续性活动。其中参与抑制效应的因子可能有阿片类与非阿片类,参与易化效应的因子可能是儿茶酚胺。     

情前期与间情期大鼠内侧视前区-下丘脑前区神经元的电活动

在氯化筒箭毒制动的情前期及间情期大鼠上进行实验。用玻璃微电极记录内侧视前区-下丘脑前区(mPOA-AHA)的单位放电。mPOA-AHA 的大多数单位表现连续性或周期性自发放电。情前期大鼠周期性放电单位所占的百分比显著地多于间情期大鼠(P<0.01)。刺激子宫颈部可以使单位放电发生两种反应。一种单位对宫颈刺激发生放电频率增加的反应(宫颈兴奋神经元,CE 神经元),另一种单位则发生放电频率降低的反应(宫颈抑制神经元,CI神经元)。情前期大鼠 CE 与 CI 神经元所占的百分比与间情期大鼠没有明显的差异(P>0.05)。但情前期大鼠的 CE和 CI 神经元多呈现周期性放电,而间情期大鼠的 CE 和 CI 神经元则多呈现连续性放电。这说明 mPOA-AHA 神经元的电活动随生殖周期发生明显的变化。脑室注射去甲肾上腺素(NE)能使 mPOA-AHA 内大多数 CE 神经元对宫颈刺激的兴奋反应暂时受到抑制,而注射 NE 却使大多数 CI 神经元发生抑制解除。这些结果提示 NE 可能有抑制 CE 神经元和刺激 CI 神经元的作用。     

兔腹部迷走神经、内脏大神经活动在孤束核中的相互作用

本实验在67只家兔身上分别观察了电解损毁孤束核(NTS)前后刺激腹迷走神经和内脏大神经中枢端对血压的影响,以及刺激这两种神经中枢端对 NTS 神经元放电活动的影响。结果表明:来自腹迷走神经和内脏大神经的感觉冲动不仅都可以投射至 NTS,而且这两种传入冲动在 NTS 还存在着会聚现象。一种传入神经的阈下刺激(背景刺激)可以削弱另一传入神经的血压效应,一种传入神经的(背景刺激)可以抑制另一种神经元引起的 NTS 神经元电活动。本文对这两种传入冲动之间存在的相互作用关系的可能机制及意义进行了讨论。     

Unit responses in the anterior and posterior hypothalamus to stimulation of the splanchnic and sciatic nerves and to photic stimulation

By extracellular recording of spike discharges the sensory properties of neurons of the anterior and posterior regions of the cat hypothalamus were studied during stimulation of the splanchnic and sciatic nerves and during photic stimulation. Hypothalamic neurons were shown to be characterized by wide convergence of heterosensory excitation: 68% of spontaneously active hypothalamic neurons responded to somatovisceral and photic stimulation. Some posterior hypothalamic neurons responded to somatovisceral stimulation but not to photic stimulation. Neurons responding only to photic stimulation were found in the anterior hypothalamus; no neurons responding only to visceral stimulation were found in the hypothalamus. Total convergence of somatic and visceral afferentation of neurons of the posterior and anterior hypothalamus was observed. Mostly responses of phasic type were obtained to stimulation of all modalities. The study of the quantitative ratio between responses of excitatory and inhibitory types showed that the former predominate. The principles governing the functional organization of hypothalamic afferent systems are discussed.Academician L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 8, No. 3, pp. 276–282, May–June, 1976.     

Possible mechanisms of the anterior limbic cortex influence on the neuron activity of the vago-solitary complex

In ananesthetized cats, neurons of the nucleus of the tractus solitarius (NTS) and the dorsal motor nucleus of the vagus nerve (DMNV) revealed phasic excitatory responses to separate single vagal and cortical stimuli. Stimulation of the anterior limbic cortex combined with vagal stimulation resulted in inhibitory or excitatory modification of the vagal induced responses of the NTS and DMNV neurons. The data obtained suggest that complete inhibitory effects are related to general cortical mechanisms of control of the functional state of the brain stem visceral neurons. Selective inhibition of the vagal induced responses by limbic cortex stimulation is due to particular cortical mechanisms of the visceral sensory transmission control via the NTS neurons.     

D-glucose modulates synaptic transmission from the central terminals of vagal afferent fibers

Experimental evidence suggests that glucose modulates gastric functions via vagally mediated effects. It is unclear whether glucose affects only peripheral vagal nerve activity or whether glucose also modulates vagal circuitry at the level of the brain stem. This study used whole cell patch-clamp recordings from neurons of the nucleus of the tractus solitarius (NTS) to assess whether acute variations in glucose modulates vagal brain stem neurocircuitry. Increasing D-glucose concentration induced a postsynaptic response in 40% of neurons; neither the response type (inward vs. outward current) nor response magnitude was altered in the presence of tetrodotoxin suggesting direct effects on the NTS neuronal membrane. In contrast, reducing d-glucose concentration induced a postsynaptic response (inward or outward current) in 54% of NTS neurons; tetrodotoxin abolished these responses, suggesting indirect sites of action. The frequency, but not amplitude, of spontaneous and miniature excitatory postsynaptic currents (EPSCs) was correlated with d-glucose concentration in 79% of neurons tested (n = 48). Prior surgical afferent rhizotomy abolished the ability of D-glucose to modulate spontaneous EPSC frequency, suggesting presynaptic actions at vagal afferent nerve terminals to modulate glutamatergic synaptic transmission. In experiments in which EPSCs were evoked via electrical stimulation of the tractus solitarius, EPSC amplitude correlated with D-glucose concentration. These effects were not mimicked by L-glucose, suggesting the involvement of glucose metabolism, not uptake, in the nerve terminal. These data suggest that the synaptic connections between vagal afferent nerve terminals and NTS neurons are a strong candidate for consideration as one of the sites where glucose-evoked changes in vagovagal reflexes occurs.     

膈下迷走神经切断降低LPS所致大鼠发热及室旁核神经元放电频率

目的：探讨迷走神经是否可以作为LPS信息由外周组织传入中枢神经系统的桥梁。方法：将Wistar大鼠随机分组,实验组为膈下迷走神经切断并给予LPS组,三个对照组为假手术生理盐水组,假手术LPS组,膈下迷走神经切断生理盐水组。用数字体温检测仪测定大鼠体温,用玻璃微电极记录正常大鼠和膈下迷走神经切断大鼠给予LPS前后下丘脑室旁核的单位放电。结果：体温变化：实验组大鼠体温变化值与假手术LPS组相比明显降低（P＜0．05）。单位放电变化：正常大鼠给予LPS后室旁核单位放电放电频率明显增加,膈下迷走神经切断大鼠给予LPS后室旁核单位放电频率无明显变化,结论：外周LPS信息可能通过迷走神经传递到脑组织。