哇巴因刺激肺慢适应感受器

钠钾泵抑制剂——哇巴因能引起气道内慢适应感受器异相发放,表现为冲动在正常时的吸气相发放,呼气相终止转变为在呼气相发放,吸气相终止。我们推测异相发放由过度兴奋所致,如果假设正确,那么降低气道压力从而减少对感受器刺激,将能防止异相发放。本工作在麻醉、开胸、机械通气（在呼气末附加3cm水柱的正压）的家兔中记录颈迷走神经中慢适应感受器的单位放电,向感受野注射微量哇巴因（1μmol／L,20μ1）,可观察到感受器活动发生变化。感受器放电经历紧张性发放、异相发放、以及不规则发放三个时期,随后放电终止,进入静息状态。在紧张期,感受器呈持续发放,冲动频率随肺部通气变化的波动幅度明显减小。在异相发放期,感受器活动出现突然发放（呼气相）与终止（吸气相）,其冲动快速转换于高频发放和静止之间。此时,若撤除呼气末正压而减少气道内压力,感受器活动恢复正常,即冲动频率于气管压峰值时为最高,在呼气相减少或终止。在不规则期,感受器通常处于静止状态,时而出现突发高频冲动,且与呼吸周期无关。可以设想：在吸气相,感受器受到牵拉,引起钠、钙等阳离子内流,产生感受器电位。正常时,由于激活钠泵,将钠离子泵出细胞,使感受器电位回复。当钠泵受到抑制后,钠外流受阻,感受器电位加大。在异相发放期,肺充气时牵拉感受器,进一步增加感受器电位,当它超越了产生动作电位的活动范围后,则感受器因过度去极化而失去兴奋性。     

失血引起兔肾神经和肾上腺交感神经活动的变化

本文观察了急性失血引起的戊巴比妥钠麻醉兔的肾交感神经活动(RSNA)和肾上腺交感神经活动(AdSNA)的变化。股动脉放血,在10min内使平均动脉压(MAP)下降至5.3kPa。失血过程中RSNA先兴奋后抑制,AdSNA则一直呈兴奋反应,这反应可由动脉压力感受器去神经而消失。失血前和失血后切断迷走神经均可翻转失血引起的RSNA抑制,但不能阻断AdSNA的兴奋反应。静脉注射纳洛酮和延髓腹外侧头端(RVLM)微量注射纳洛酮可翻转失血引起的RSNA抑制,但对AdSNA兴奋反应无显著影响。失血引起心率(HR)和RSNA一样,但不能为纳洛酮所反转。上述结果表明:失血引起的RSNA抑制是由迷走神经传入纤维和阿片肽(尤其是RVLM中的阿片肽)参与所致,而AdSNA的兴奋则与动脉压力感受器传入纤维有关。     

Characterization of cholecystokinin receptors in bullfrog (Rana catesbeiana) brain and pancreas

The binding of biologically active 125I-Bolton-Hunter-CCK-33 to bullfrog brain and pancreatic membrane particles was characterized. Both tissues exhibited time-dependent, saturable, reversible, and high affinity binding without evidence for cooperative interaction. Both bullfrog CCK receptors resembled their mammalian counterparts in having acidic pH optima for tracer binding and a Kd of about 0.5 nM. However, the receptors differed from their mammalian counterparts in that (1) the bullfrog brain membranes bound more tracer per mg protein than did the pancreatic membranes, (2) both bullfrog CCK receptors were relatively insensitive to dibutyryl cGMP, and (3) both bullfrog brain and pancreatic CCK receptors exhibited the same general specificity toward a variety of CCK and gastrin peptides. For both tissues, the relative order of receptor binding potency was CCK-8 greater than caerulein = CCK-33 greater than gastrin-17-II greater than CCK-8-ns = gastrin-17-I greater than caerulein-ns greater than gastrin-4 with the sulfated CCK peptides being 1000-fold more potent than their nonsulfated analogs. Sulfated gastrin was also relatively potent, being only 10-fold weaker than CCK-8. Gastrin-4 was 20 000-fold weaker than CCK-8 in interacting with the brain CCK receptor. The latter finding is in sharp contrast to the mammalian brain CCK receptor. We conclude that the bullfrog brain and pancreas contain similar CCK receptors of probable physiological significance and may represent an ancestral condition from which the two distinct CCK receptors present in mammalian brain and pancreas have evolved.     

Effect of truncal vagotomy on intestinal phase of pancreatic polypeptide release in dogs

In order to elucidate the role of the vagus nerve in the intestinal phase of pancreatic polypeptide (PP) release, mongrel dogs were given a 4-min intraduodenal infusion of saline, 20% glucose, or 10% soybean oil solution (50 ml each), before and one month after truncal vagotomy including pyloroplasty (TV). The saline infusion did not change the basal PP level, while the glucose infusion elicited a monophasic transient PP release, and the soybean oil infusion elicited a monophasic prolonged PP release in the intact dogs. The PP response following glucose infusion was almost abolished after TV, while the PP response to fat was attenuated, but a significant increase was nevertheless observed after TV. These results suggest that the vagus nerve has an important role in the intestinal phase of PP release and that other factors, e.g. hormonal, might also be involved in the regulatory mechanism, especially after fat loading.     

大鼠灰翼区微量注射6-羟多巴胺对迷走-迷走抑胃反射的影响

本文用乌拉坦麻醉的大鼠,观察了灰翼区微量注射6-羟多巴胺(6-OHDA)对迷走-迷走抑胃反射的影响。实验动物分三组:空白对照组、溶媒组和6-OHDA 组。实验结果表明,在溶媒组刺激迷走神经中枢端使胃电慢波的振幅和胃内压分别下降到刺激前对照值的36.87±22.07%和32.52±25.41%,与空白对照组相比无显著的差异(P>0.05)。但是,在6-OHDA组,刺激迷走神经中枢端对胃电和胃运动的抑制效应明显减弱,慢波的振幅与胃内压分别下降到刺激前对照值的67.48±13.21%和50.88±21.40%,同溶媒组相比有非常显著的差异(P<0.01)。结果提示,延髓灰翼区的儿茶酚胺能神经参与迷走-迷走抑胃反射的中枢机制。     

The enteric nervous system relays psychological stress to intestinal inflammation

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刺激兔下丘脑诱发的防御反应和室性期前收缩

电刺激兔下丘脑近中线区可以引起血压升高、肢体血流量增多、内脏血流量减少、瞳孔扩大和呼吸急促、鼻翼扇动、四肢爬动等一系列类似于猫发生防御反应时的植物、躯体性反应,但其中肢体血流增多反应不能为阿托品所阻断。在出现上述反应的同时可出现心交感活动亢进、产生室性期前收缩等心律失常。摘除双侧星状神经节后,刺激下丘脑诱发的室性期前收缩(HVE)几乎消失,升压反应也减弱。在颈部切断双侧迷走神经可使 HVE 增多、升压反应增强,静脉注射阿托品(0.2mg/kg)不产生 HVE 增多和升压反应增强的效应。根据上述结果,可以认为兔下丘脑也存在着“防御反应区”,HVE 主要是兴奋了防御反应区造成心交感活动亢进所致。迷走神经对 HVE 有抑制作用,其效应可能与传入纤维的活动有关。     

Chronic exposure to a 60-Hz electric field: effects on synaptic transmission and peripheral nerve function in the rat

Several reports have suggested that the nervous system can be affected by exposure to electric fields and that these effects may have detrimental health consequences for the exposed organism. The purpose of this study was to investigate the effects of chronic (30-day) exposure of rats to a 60Hz, 100-kV/m electric field on synaptic transmission and peripheral-nerve function. One hundred forty-four rats, housed in individual polycarbonate cages were exposed to uniform, vertical, 60-Hz electric fields in a system free of corona discharge and ozone formation and in which the animals did not receive spark discharges or other shocks during exposure. Following 30 days of exposure to the electric field, superior cervical sympathetic ganglia, vagus and sciatic nerves were removed from rats anesthetized with urethan, placed in a temperature-controlled chamber, and superfused with a modified mammalian Ringer's solution equilibrated with 95% O2 and 5% CO2. Several measures and tests were used to characterize synaptic transmission and peripheral-nerve function. These included amplitude, area, and configuration of the postsynaptic or whole-nerve compound-action potential; conduction velocity; accommodation; refractory period; strength-duration curves; conditioning-test (C-T) response, frequency response; post-tetanic response; and high-frequency-induced fatigue. The results of a series of neurophysiologic tests and measurements indicate that only synaptic transmission is significantly and consistently affected by chronic (30-day) exposure to a 60-Hz, 100-kV/m electric field. Specifically, and increase in synaptic excitability was detected in replicated measurements of the C-T response ratio. In addition, there are trends in other data that can be interpreted to suggest a generalized increase in neuronal excitability in exposed animals.     

家兔减压神经颈部变异的几种新类型

用解剖学方法结合电生理学方法鉴别减压神经形态上的变异。在35只纯种青紫蓝家兔中,减压神经颈部有形态变异者达23只(占65.71％)20种,观察到减压神经变异的三种新类型:减压神经三分支型、“无”减压神经型和减压迷走交感干型;至于减压神经的起点,以起于喉前神经者居多。     

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。     

Vagus nerve bundle stimulation using 1505-nm laser irradiation in an in-vivo rat model

Laser nerve stimulation using near-infrared laser irradiation has recently been studied in the peripheral nervous system as an alternative method to conventional electrical nerve stimulation. Bringing this method to the vagus nerve model could leverage this emerging stimulation approach to be tested in broader preclinical applications. Here, we report the capability of the laser nerve stimulation method on the rat vagus nerve bundle with a 1505-nm diode laser operated in continuous-wave mode. Studies of the stimulation threshold and laser-induced acute thermal injury to the nerve bundle were also performed to determine a temperature window for safe, reliable and reproducible laser stimulation of the rat vagus nerve bundle. The results show that laser stimulation of the vagus nerve bundle provides reliable and reproducible nerve stimulation in a rat model. These results also confirm a threshold temperature of >42°C with acute nerve damage observed above 46°C. A strong correlation was obtained between the laser time required to raise the nerve temperature above the stimulation threshold and the mean arterial pressure response. Advantages of the method such as non-contact delivery of external stimulus signals at mm scaled distance in air, enhanced spatial selectivity and electrical artefact-free measurements may indicate its potential to counteract the side effects of conventional electrical vagus nerve stimulation.     

Activation of latent efferent sympathetic fibers in a viscero-visceral reflex circle under conditions of visceral pain in rats

Activation of “silent” efferent fibers due to stimulation of the mesenteric nerve within a definite frequency range is described; the effect is supposed to result from sensitization in reflex circles related to visceral pain. Neirofiziologiya/Neurophysiology, Vol. 38, No. 4, pp. 368–369, July–August, 2006.     

Electron microscopic autoradiography for demonstration of pineal serotonin in rat

Summary The fine localization of rat pineal serotonin has been studied by means of electron microscopic autoradiography. Two hours after the intravenous injection of tritium labelled 5-hydroxytryptophan, the location of large number of silver tangled threads is seen in the sympathetic nerve terminals. There is also a less specific accumulation of the silver grains in the pinealocytes, some appearing in the cytoplasmic organelles and some in the nucleus.In quantitative terms, 43% of the total count of silver grains were in the nerve endings whereas pinealocytes, which comprise a much larger volume of the section, contain a proportionally much smaller number of silver particles (53%). Furthermore the perivascular spaces, which comprise a larger percentage in volume of the section than the nerve endings has nevertheless only about 4% of the grains counted.Although the precise localization of the silver grains is obscure, the reaction of the granulated vesicles in the nerve terminals to the double fixation used, is similar to that shown by the extremely dense material in vesicles of platelets, which was demonstrated to contain serotonin. The results therefore suggest that the silver grains appearing in the nerve terminals two hours after the administration of 5-hydroxytryptophan are in the serotonin binding site in the axon terminals, containing the granulated vesicles.     

Further studies on absorption changes arising in dye-stained nerves during excitation

Summary Changes in light absorption during nerve excitation (absorption responses) were detected from the crab leg nerve, the rabbit vagus, and the rat superior cervical ganglion (SCG) stained with a merocyanine-rhodanine. Dependences of the responses on the wavelength and polarization of the incident light (absorption spectra) showed characteristic features with the respective nerves. In the crab nerve, the pattern of response spectra was precisely analyzed based on the previously proposed scheme, which included the shift of absorption bands and the statistical reorientation of absorption oscillators of the dye molecules in the membrane matrix during nerve excitation. Different patterns of the response spectra between the crab nerve and the rabbit vagus suggested that distinct physicochemical environments of the dye occurred in these two classes of membranes. On the other hand, the characteristic pattern that arose in the rat SCG was explained by its morphological form, that is, unlike those in a bundle of axons, the membrane elements in the ganglion were randomly oriented with respect to the direction of the light polarization.     

Neural uptake of catecholamines and their molecular structures: A histopharmacologic study

Using ultrastructural and histofluorescence methods, we investigated the uptake mechanism of catecholamines by the nerve terminals in the cutaneous smooth muscles of stump-tailed macaques (Macaca arctoides). This in vivo approach ultilized the observed cytotoxic effects of 6-hydroxydopamine on these catecholamine-containing terminals and the protective effects of simultaneous treatment with catecholamines (dopamine, norepinephrine, and epinephrine), their 3–0-methylated derivatives (metanephrine and normetanephrine), and catechol acids (3,4-dihydroxymandelic acid and 2, 4, 5-trihy-droxymandelic acid). Both catecholamines and 3–0-methylated derivatives protected these nerve terminals from destruction by 6-hydroxydopamine, but catechol acids did not. However, the 3–0-methylated derivatives were less effective than the catecholamines. The degree of protection afforded by these amines depended largely on their concentration. Only catecholamines intensified the electron density of the intravesicular mass or the fluorescence in the nerve terminals; therefore, 3–0-methylated derivatives may inhibit 6-hydroxydopamine uptake at axoplasmic membrane sites, but not inside the axon. These observations led to the discovery that there are two sites for the catecholamine uptake process. One site is the axoplasmic membrane. The terminals are protected by catecholamines and their 3–0-methylated derivatives from 6-hydroxydopamine uptake and thus destruction. The other site is the intra-axonal compartments. Here competitive binding between the vesicular protein and both 6-hydroxydopamine and the catecholamines plays a main role.     

Ectopic discharges trigger sympathetic sprouting in rat dorsal root ganglia following peripheral nerve injury

Experimental backgrounds of ectopic discharges were made by i.p. administrating of 4-aninopyriding (4-AP), a K+ channel blocker, or anisodamine, a muscarinic receptor blocker, in CCI rats, and the sympathetic sprouting in the dorsal root ganglia (DRG) as well as the heat-hyperalgesia was observed. It was demonstrated that the increased ectopic discharges induced by 4-AP promote sympathetic sprouting in the DRG and a greater number of sympathetic basket cells were developed, causing exacerbation of heat-hyperalgesia in CCI rats. On the contrary, the sympathetic sprouting in the DRG and heat-hyperalgesia are evidently diminished after anisodamine injection. Our results suggest that ectopic discharges may be an immediate factor in triggering sympathetic sprouting in DRG following peripheral nerve injury.     

Regeneration of an adult peripheral nerve preparation in culture

The methods used to maintain the vagus nerve from the adult rat in culture and how regeneration is studied in this preparation are described. A hypothesis is presented on the triggering of the cell body reaction. It is suggested that this reaction is initiated by proteins synthesized in nonneuronal cells at the site of a nerve lesion. These proteins, referred to as regenerins, reach the nerve cell body by retrograde axonal transport, where they initiate the regeneration process.     

迷走神经背核对胃机能调控的研究进展

神经解剖学和生理学的研究证明,迷走神经背核（dorsal motor nucleus of the vagus,DMV）是调控胃机能的重要副交感初级中枢。支配胃的迷走神经纤维主要发自于延髓的DMV。就DMV的细胞构筑和突触联系、DMV对胃的神经支配、电刺激DMV对胃机能的影响以及DMV内的神经递质和受体对胃机能的调控进行综述。