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At least 181 records · Page 10Linked to original sources
PubMed1989

[The effect of electro-acupuncture of "neiguan" acupoint on cortical potential evoked by stimulating C-fibers of splanchnic nerve].

In this paper the averaged cortical evoked potential (C-CEP) induced by stimulating the C-fibers of the splanchnic nerve was used as an index of visceral pain to further study the effects of acupuncture and morphine on it. Experiments were carried out on 35 cats anesthetized with chloralose and immobilized with flaxedil. The splanchnic nerve was stimulated with electric pulses of varied strength and blocked by a galvanic current so as to cause A- or C-fibers input selectively. The cortical evoked potential was recorded on the contralateral post-sigmoid gyrus and averaged by TQ-19 Medical Data Processor. The compound action potential of splanchnic nerve was monitored. "Neiguan" acupoint was stimulated with electric pulses (0.1ms, 4v and 5Hz). The results were as follows: 1) when "Neiguan" acupoint, was excited with the electric pulses, C-CEP and the late component of A-CEP which was evoked by stimulating A-fibers of splanchnic nerve were obviously reduced in amplitudes. It was suggested that electro-acupuncture (EA) of "Neiguan" acupoint could inhibit visceral pain (the slow and fast pain). 2. After intravenous injection of morphine, the amplitudes of C-CEP and the late component of A-CEP were depressed significantly, indicating that C-CEP might reflect the visceral slow pain and the late component of A-CEP reflect the fast pain. 3. Naloxone could block partially the inhibitory effect of EA of "Neiguan" acupoint on C-CEP, suggesting that the inhibition of EA might be associated with the release of endogenous opiate like substances.

Acupuncture Points↗
PubMed1989

[The effect of electrical stimulation of the head of caudate nociceptive neuronal activities in the mesencephalon reticular formation and its relation to the acupuncture effect].

38 rabbits were anesthetized with chloralose and urethane. As soon as the animal recovered its consciousness it was immobilized with flaxedil and artificial respiration. The electrical activities of the nociceptive neurons were recorded by glass microelectrodes (tip 1-3 microns) in the ranges P7-11 R2-3 HO+1-6, with the aid of a stereotaxic apparatus. 116 of the nociceptive units responded to noxious stimuli which applied to the peroneal nerve with a short train of pulses. Among them, 64 units (55%) responded by an increase in frequency of the discharge to noxious stimuli (pain-excitation neuron, PEN). In contrast, there were 52 units (45%), which responded to noxious stimuli quite differently, by having a decrease in the frequency of the discharge (pain-inhibition neuron, PIN). Similar results were obtained by the stimulation of the head of caudate nucleus with the same train of pulses: an excitatory effect was observed in PEN, and an inhibitory effect in PIN. However, after electroacupuncture by penetrating acupoint "Hegu" or dolantin given intravenously, under the same conditions used above. We again stimulated both the head of caudate nucleus, eliciting an inhibitory effect on PEN. And a reduction of inhibition or release from it on PIN. From the results presented, it indicated that head of caudate nucleus was connected with the modulation of the nociceptive neuronal activity in M.R.F. and was related to the effect of acupuncture. The effect of atropine on the head of caudate nucleus stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Mechanisms of effects of electrical stimulation of "Renzhong" (Du 26) on phrenic discharge in rabbits].

Experiments were performed on urethane anesthetized, bivagotomized, flaxedil paralyzed and artificially ventilated rabbits. The effects of stimulation of "Renzhong" (Du 26) on phrenic discharge were not caused secondarily by blood pressure alteration. The effects were abolished by bilateral section of infraorbital nerves, were similar to those of stimulation of the central end of the infraorbital nerve, and were not qualitatively changed by mid-colliculi decerebration. The responses of the bulbar respiratory related neurons were coordinated with those of the phrenic nerve to stimulation of "Renzhong", i.e., the responses of almost all of the inspiratory neurons were consistent with phrenic responses and those of the most of the expiratory neurons were contrary to them. It can be concluded that the effects of electrical stimulation of "Renzhong" on phrenic discharge result from the nervous reflex. Its afferent is infraorbital nerve and the higher centers are not essential for it. The bulbar respiratory related neurons might play an important part in it.

Acupuncture Points↗
PubMed1989

[Role of rostral ventrolateral medulla in the pressor response to intracerebroventricular injection of neostigmine].

Experiments were carried out on 47 urethane-chloralose anesthetized and flaxedil immobilized rabbits under artificial respiration. Intracerebroventricular injection (ICV) of neostigmine (100 micrograms/200 microliters) caused a marked increase in blood pressure (BP), left ventricular pressure (LVP) and renal sympathetic nerve discharge (RND), while femoral blood flow (FBF) and conductance (COND), were decreased and the heart rate (HR) was initially reduced and then slightly increased. Microinjection of atropine (0.25 micrograms/site) into the rostral ventrolateral medulla (rVLM) caused a decrease in BP, HR, RND and LVP and a increase in FBF and COND. Pretreatment of atropine injection into rVLM before ICV of neostigmine blocked the pressor response of neostigmine. These results indicate that rVLM is important for the pressor response to ICV neostigmine, which may be mediated via cholinergic muscarinic receptors in rVLM.

Animals↗
PubMed1988

Study of descending inhibitory and facilitory effect of the orbital cortex on the electrical discharges of medial geniculate body (MGB) neurons in rabbits.

Experiments were performed on 16 rabbits immobilized with flaxedil. The recording of spontaneous discharges and the discharges of single MGB neurons caused by clicks showed that when the cerebral-orbital cortex was stimulated, of 92 MGB neurons responding to clicks, 25 units (27.2%) were inhibited, 14 units (15.2%) were facilitated, and 15 units with spontaneous discharges were completely inhibited. The topographical distribution of stimulated points with such inhibitory and facilitory effect is quite concentrated on the orbital cortex. Stimulation of two adjacent points of the orbital cortex could respectively result in different kinds of inhibitory and facilitory effect on discharges of a same MGB neuron. Due to the existence of this descending effect with a short latent period (2-3 ms), the authors have reason to believe that there might be an "orbital cortex-MGB" direct pathway. Moreover, application of 2% procaine to block the auditory cortex behind the rhinal sulcus (ACBRS) could abolish the facilitory effect, with a long latency, of the orbital cortex. Therefore, the influence of the orbital cortex on MGB might be also transmitted via the "orbital-ACBRS-MGB" circuit.

Animals↗
PubMedDate not supplied

[Effect of tranquilizers on cerebral cortex excitability in cats].

Chronic tests on cats showed that diazepam and nitrazepam lower the amplitude of primary responses (PR) of the second somatosensory zone of the brain cortex both to a single and paired stimulation of the thalamo-cortical radiation of fibers. Meprotan, while potentiating the PR to a single stimulation, does not influence the course of the PR restitution cycles. Benacryzine, while enhancing the PR to a single stimulation, produces the appearance of a lengthy phase of depression throughout the PR restitution cycle. In acute tests with unanesthetized, flaxedil immobilized cats, with an isolated cortical band underneath a stimulating electrode, analogous changes in PR both to a single and paired stimulation of the thalamo-cortical radiation of fibers were noted.

Animals↗
PubMed1979

[Habituation in the cortical division of the visceral analyzer].

Reactions of neurons without background activity ("silent" neurons) on long-lasting stimulation of mesenteric nerves were studied in cats anesthetized with chloralose 65-70 mg/kg) and paralyzed with flaxedile. It is shown that the "silent" neurons of the parietal and first projections areas are characterized by habituation during long-lasting stimulation of visceral nerves. Habituation developed faster in the parietal cortex and in the focus of maximal activity of the first somatosensory areas as compared to the second somatosensory area. The particularities of neuronal habituation in the cortex on visceral stimulation are discussed.

Animals↗
PubMedDate not supplied

Dynamics of habituation in different cortical regions of the cat brain.

The dynamics of habituation in the rostral part of the parietal association region and also in the first and second somatosensory areas was studied by the evoked potentials (EP) method in cats anesthetized with chloralose (80-90 mg/kg) and immobilized with flaxedil. During repeated stimulation of the splanchnic nerve brief habituation of EP developed in the cortex. It corresponded in its basic features to habituation observed in other sensory systems. On comparison of the rates of development of habituation in the primary and secondary projection zones of the splanchnic nerve in the cortex differences were found: habituation developed more rapidly in the secondary projection zones. The functional importance of this phenomenon is discussed.

Animals↗
PubMed1981

Influence of monoaminergic nuclei in lower medulla and their neurotransmitters on the activity of nociceptive units in spinal cord.

In this article, seventy nociceptive units of dorsal horn and five preganglionic sympathetic units of spinal cord in forty-four anesthetized cats immobilized with Flaxedil were studied. The results observed were: 1. Electrophoretic administration of noradrenaline (NA) induced a remarkable depression of both evoked and spontaneous discharges of nociceptive units. Similar effects could be produced by electric stimulation of noradrenergic Al nuclei or injection of amphetamine or hand pressing of "Zusanli" (one form of acupuncture) respectively. 2. The effect of 5-hydroxytryptamine (5-HT on evoked nociceptive discharge was similar to NA, but on spontaneous discharge of nociceptive units was excitement. 3. Effects of the above-mentioned factors on the nociceptive discharges of preganglionic sympathetic neurons were similar to the nociceptive units too. 4. On the contrary, the activity of inhibited neuron by noxious stimulation was augmented by administration of NA, amphetamine, the stimulation of Al nuclei and the deep muscle. It is suggested that the noradrenergic nuclei in lower brain stem may play an important role in descending inhibitory circuits of nociceptive spinal reflex.

Acetylcholine↗
PubMed1984

[Pharmacological actions on the activity of muscle spindles induced by electrostimulation of the pericruciate cortex in the cat].

In anesthetized cats, effects of a number of neuroactive substances on results of local electrical stimulation of the motor (field 4) and supplementory motor (field 6) cortex were studied in intra - and extrafusal elements of the foot flexors. Flaxedil in subparalytic doses blocked selectively the contractions of extrafusal fibers whereas facilitating effects on activity of muscle afferents from the fields 4 and 6 were preserved which attests a possibility of cortical regulation of the gamma-system irrespective of alpha-motoneurons. Nembutal (5 mg/kg) rapidly suppressed the cortico-fugal excitatory effects which was easily opposed by bemegride. Aminasine (3-5 micrograms/kg) completely and for a long time blocked the cortical-motoneuronal influences. The cortico-reticular projections, anatomically well developed in cats, are supposed to be an essential component of the systems originating in the field 4 and particularly field 6.

Animals↗
PubMed1978

[Responses of neurons in the Clare-Bishop cortical association area of the cat cerebral cortex to photic stimulation].

In acute experiments on cats with protrigeminal section immobilized by flaxedil the electrical activity of single neurons in associative visual cortex of Clare-Bishop was investigated by the extracellular registration of their spike activity. 95.5% of investigated neurons responding to natural stimulation (light spots) were sensitive to the movement of stimulus through the receptive field. Nearly 55% of neurons exhibited selective responses to the direction of stimulus movement. Some neurones responded only when the stimulus was crossing the border points of receptive field. Nearly 85.3% of neurons responded to the flashing spot with "on", "on-off" and "off" reactions, and also to the stimulation by diffuse flashes. Receptive fields of neurons in the Clare-Bishop area were of strip-like form with longitudinal axis in horizontal orientation. Presented observations allow concluding that the Clare-Bishop cortical association area plays an essential role in the central processing of visual information.

Animals↗
PubMed1983

Study of inhibitory effect of amygdaloid stimulation on auditory response of medial geniculate body (MGB) and analysis of transmissive pathway of the said effect.

Experiments performed on 103 rabbits immobilized with Flaxedil, and the recording of the electrical discharges of single MGB neuron caused by clicks, burst or sustained tone showed marked inhibition of the reaction of 47 out of 75 (62.7%) MGB units responding to sound stimuli, when the amygdaloid complex was stimulated. The latent period of such an inhibitory effect was 5-12 msec and its duration about 2-13 msec. Evoked responses with the latency of 1-2 msec for the stimulation of medial, central and lateral nuclei of amygdala could be recorded from the temporal and parietal cortex. The largest response was recorded from Woolsey's AI area of the temporal cortex. Stimulation of the Woolsey's AI auditory area could also result in a distinct inhibition of the spontaneous as well as the evoked discharges of MGB neurons in response to sound stimulation. Moreover, application of 1% procaine to the surface of auditory cortex could block the inhibitory effect of the amygdala on the MGB neurons. Based on the facts mentioned above, the authors have reason to believe that the inhibitory effect of the amygdaloid complex on the activity of MGB units might be transmitted via the amygdala-auditory cortex-MGB circuit. The biological significance of such an suppressive effect has been discussed.

Acoustic Stimulation↗
PubMed1981

Effects of gallamine triethiodide on membrane currents in amphibian and mammalian peripheral nerve.

Gallamine triethiodide ("Flaxedil") is in common clinical and experimental use specifically to block neuromuscular transmission. Voltage-clamp studies show that gallamine also has direct effects on amphibian and mammalian nerve fibers, whether applied externally or internally. With external application, gallamine (0.1-10.0 mM) is about 5 times more potent than tetraethylammonium chloride in blocking the delayed potassium conductance (gk), where this is present. The sodium conductance is completely unaffected by external gallamine in both species. Internal application of gallamine to myelinated nerve fibers slows sodium inactivation. In addition, at positive potentials, gallamine can enter Na+ channels and occlude them, thereby almost eliminating outward sodium currents. In rat fibers, a significant fraction of the sodium channels fail to inactivate and thus large inward sodium tail currents occur upon repolarization. The general consequences of these findings with regard to possible "side-effects: in gallamine-paralyzed preparations is discussed.

Action Potentials↗
PubMedDate not supplied

Participation of the reticular formation of the mesencephalon in the development of habituation to visceral influences.

In experiments on cats anesthetized with chloralose and immobilized with flaxedil, the influence of the reticular formation (RF) of the mesencephalon on the development of habituation of evoked potentials (EP) in the cerebral cortex (CC) to repeated stimulation of the splanchnic nerve was studied. It was established that high frequency stimulation of the RF (100 counts/sec) for 15 sec before testing for habituation to visceral stimulation inhibited the amplitude of the EP and shortened the time of development of habituation to repeated stimulation of the splanchnic nerve. Low-frequency stimulation of the RF (1 pulse/sec), applied during the development of habituation, restored the amplitude of the EP to the initial level. The turnoff of the activity of the RF by intravenously injected chlorpromazine (3-6 mg/kg) was accompanied by an acceleration of the development of habituation of evoked potentials in the associative region of the cortex. The participation of the RF in processes of habituation and dehabituation is discussed.

Animals↗
PubMed1977

Substantia nigra and somatosensory evoked responses in the caudate nucleus.

The nigro-caudate relationships were studied in fifteen adult anesthetized cats, paralyzed with Flaxedil. Single shocks applied to substantia nigra (SN) evoked biphasic field potentials in the ipsilateral caudate nucleus. Similar positive-negative waves were recorded in the caudate nucleus by sciatic stimulation, although with longer latencies. A triphasic field potential was also observed after cerebral peduncle stimulation. Conditioning stimuli applied to the SN at varying time intervals prior to sciatic stimulation did not modify the test response. In contrast, conditioning stimulation of the cerebral peduncle produced a marked inhibition between 25 and 100 msec. Recovery was complete after 200 msec. The present observations indicate that nigral stimulation does not influence the pool of neurons responding to sciatic nerve in the caudate nucleus. On the other hand, the cerebral peduncles exert an inhibitory action on such activity.

Animals↗
PubMed1978

[Effect of acetylcholine on the pituitrin induced osmotic flow of water through the wall of the frog urinary bladder].

The role of intercellular pathways in the ADH-dependent water transport was studied on the frog urinary bladder by means of acetylcholine (AC) and other cholinergic compounds. AC (10(-3) M) was found to cause a strong suppression of the pituitrin-stimulated water flow. Analogous effect was produced by AC on the osmotic flow stimulated by cyclic adenosine monophosphate (cAMP) and theolin. The antipituitrin effect was not reproduced either by nicotine, nor by potent M-cholinomimetic agents (methylfurmetide and F-2268), and was not prevented by M- and N-cholynolytic drugs (atropine, metacin, flaxedil, hexamethonium). However, the antipituitrin effect of AC was completely removed by the anticholinesterase drugs with different mode of action (eserine, proserine, armin, acridine iodmethylate, GD-42) in concentrations of 10(-6)--10(-3) M. It was concluded that the smooth muscles contraction with the subsequent closure of the intercellular spaces was not responsible for the antipituitrinic action of AC. This effect appears to be connected with cholinesterase activation. A possible role of the phosphoinositides in the water permeability regulation of the urinary bladder wall is discussed.

Acetylcholine↗
PubMedDate not supplied

[Activity of lateral reticular nucleus neurons during scratching].

The activity of neurones of the lateral reticular nucleus (LRN) was recorded in thalamic cats immobilized with Flaxedil during "fictitious scratching", that is during rhythmical activity of motoneurones typical of normal scratching. The LRN neurones exhibited a distinct modulation of their discharge related to the rhythmical activity of motoneurones in spite of the absence of the rhythmical afferent inflow. The pattern of modulation was identical both in normal and in "fictitious" scratching. Therefore, the spino-reticulo-cerebellar path transmits information about the activity of the spinal motor centres.

Animals↗
PubMed1993

[A study on the effect of stimulation of amygdaloid complex on the electrical response of auditory cortex in rabbits].

Experiments were performed on 40 adult rabbits immobilized with Flaxedil. The effect of stimulation of amygdaloid complex on the click evoked potential of Woolsey's AI, AII and the auditory cortex behind the rhinal sulcus (ACBRS) was examined by single unit analysis. The results showed that stimulation of lateral nucleus and basal nucleus of amygdala could induce either a facilitory or an inhibitory effect on the evoked potential and the unit discharges. The latency of the inhibitory effect was about 10-25ms, and lasted for 20-115ms. A facilitory effect with a latency as short as 2ms was also observed in one animal. The experimental results indicate that the effect of amygdaloid complex stimulation as transmitted through polysynaptic circuit while the facilitatory effect was monosynaptic. The functional significance of the amygdaloid effect was discussed.

Acoustic Stimulation↗