INHIBITION OF ACTIVITY OF THALAMIC UNITS BY LOCAL BRAIN STIMULATION AND ELECTROACUPUNCTURE IN AWAKING RABBITS

It has been found in cats that units discharges in the spinocervical tract fibers evoked by nocuous stimulation can be inhibited by the electro-acupuncture of certain points of the body It is well known that nociceptive discharges in the spinocervical tract fibers are transmitted at least partly to the posterior nucleus group of thalamus(PO) The present study tries to analyse the correlation between the unit

The new sideway of CNTF sig-nal transduction pathway

The action of ciliary neurotrophic factor (CNTF) on intercellular free Ca2+ concentrations [Ca2+]1 induced by glutamate (Glu) in primary cultured hippocampal neurons were detected with Fura2/AM, a Ca2+-sensitive fluorophore. and the morphological influence of G-protein on it was ob-jected. Glu could induce rapid increase of [Ca2+]1 in hippo-campal neurons. CNTF had no significant action on [Ca2+]1 in resting hippocampal neurons. However, after incubation of CNTF for 5 min, the increase of [Ca2+]1 in hippocampal neurons rapidly induced by Glu was inhibited. Pretussis toxin (PTX)-sensitive G protein could block the action. These results indicate that a new non-genomic rapid sideway might exist in the upper stream of CNTF signal transduction pathway, which was related to Ca2+ signal transduction.

IPSP-EPSP interactions in lateral geniculate neurons of rat

It has been demonstrated that the lateral geniculate nucleus (LGN) of the cat possesses two types of inhibitory circuits: feedforward and recurrent inhibitory circuits. The results obtained from brain slice experiments have shown that the rat LGN also has the feedforward inhibitory circuit, which mediates an inhibitory postsynaptic potential (IPSP)

Synaptic organization of substance P, glutamate and GABA-immunoreactive boutons on functionally identified neurons in cat spinal deeper dorsal horn

In order to determine how nociceptive input conveyed by the C-fibers terminating in superficial lam-inae of the spinal cord reaches the wide dynamic range (WDR) cells in deeper dorsal horn, which functions as ascend-ing projection pathway, the morphological features of some WDR cells in the deeper dorsal horn of the cat lumbar spinal cord were studied by intracellular injection of horseradish peroxidase and physiological characterization. One of the fully stained neurons with somata in lamina V and dendrites that entered lamina Ⅱ were examined by electron mi-croscopy. Immunogold staining of ultrathin sections through the labeled proximal dendrites in lamina Ⅱ revealed that these dendrites received numerous synapses from substance P and glutamate immunoreactive (IR) axons, which were considered originating from C-fibers. In addition, many GABA-IR terminals were found presynaptic to the labeled dendrites. The results, therefore, suggest that the information carried by primary afferent can be sent from the super-ficial dorsal horn to the deeper laminae through monosynaptic contacts between C-fiber terminals and the long dorsal dendrites of some WDR cells in the deeper laminae, and that GABAergic system is involved in postsynaptic control to modulate the transmission of nociceptive sensory information.

After hyperpolarization of relay neurons in lateral geniculate nucleus of cat

The action potential （Na+ spike） of neurons is often followed by a compound after hyperpolarization （AHP） which is mediated by Ca2+-dependent K+ channels. Pyramidal cells in the cerebral cortex are known to have fast, medium and slow AHPs. It is commonly accepted that the fast AHP （fAHP） is mediated by a kind of C- or BK-K+ channels. The fAHP is characterized by a short duration of about 20 ms, its remarkable voltage dependence and sensitivity to low concentration （【1 mmol/L） of Tetraethylammonium （TEA）.The mAHP results from activation of AHP- or SK-K+ channels and has a long duration over 200 ms. It is poorly voltage-dependent and blocked by Apamin, but not by TEA.

Effects of cholecystokinin in spinal trigeminal nucleus caudalisneurons in vitro

Cholecystokinin(CCK),an intestinal hormone causing gall bladder to contract andempty,is present abundantly in the brain,which has proved to be involved in transmissionand modulation of various functional activities including the processing of pain. It has been proved that the caudal part of the spinal trigeminal nucleus caudalis(cNTST)in the medulla oblongata,known as the oral extension of substantia gelatinosa

THE EFFECT OF REPETITIVE STIMULATION OF THE SAME NERVE ON NOCICEPTIVE RESPONSES OF CAT SPINAL CORD DORSAL HORN NEURONS AND-COMPOUND ACTION POTENTIALS INDUCED BY SURAL NERVE STIMULATION

In previous studies, it has been reported that repetitive stimulation of the same nerve innervating the region where noxious stimulus was applied (the same nerve stimulation) hada powerful inhibitory actioa on the polysynaptic reflexes and the nociceptive responses of DLF fiber to the sural stimulation, and that with the inhibition of reflexes, the Aδ component of compound action potential recording from the sural nerve was depressed by the stimulation. In the present study, the changes in the compound actionpotentials of

EFFECT OF MICROINJECTION OF AOAA INTO THE NUCLEUS RAPHE DORSALIS ON PAIN THRESHOLD AND ACUPUNCTURE ANALGESIA IN RAT

The nucleus raphe dorsalis (NRD) is known to play an important role in acupuncture analgesia (AA). This nucleus contains GABAergic neurones, as shown by the work with immunocytochemistry, neurochemistry and radioautography. Recently, we have observed that the GABA content of the NRD increased significantly during AA, suggesting participation of GABA in the effect of acupuncture. In the present experiments, we injected aminoxyacetic acid (AOAA), an inhibitor of the GABA-transaminase (GABA-T), into the nucleus and observed the effect of the microinjection on the pain threshold and AA.

DIFFERENT HISTOCHEMICAL MANIFESTATION OF ACETYLCHOLINESTERASE IN SUBMANDIBULAR PREGANGLIONIC NEURONS IN CATS AND RATS

It is generally accepted that the parasympathetic preganglionic neurons are cholinergic. However, in our laboratory it has been observed that the acetylcholinesterase (ACHE) positive neurons could not be seen in the area of submandibular preganglionic neurons in the rat.Is this phenomenon universal or only special to the rat?

Physiological properties of neurons in superficial layers of superior colliculus of rabbits

Neurons in superficial layers of the superior colliculus of the rabbit are classified into three types by their electrophysiological properties. Among them, two types belong to projecting neurons which send axons to the thalamic pulvinar (N=52) and dorsal lateral geniculate nucleus (N = 54) respectively. All other neurons are pooled into the third type (N=99). Projecting neurons of both types receive monosynaptic visual inputs via optic tract fibers of similar conduction velocity, indicating that in the superior colliculus of the rabbit, there is no difference in conduction velocity between the two pathways. They also receive trisynaptic inhibitory inputs, most likely via recurrent inhibitory circuits. The third type of neurons receives disynaptic optic and trisynaptic inhibitory inputs. The function of neurons of the third type is studied.

SOME CHARACTERISTICS OF RAT NIGROSTRIATAL DOPAMINERGIC NEUROCONNECTION DURING DEVELOPMENT——A COMBINED IMMUNOCYTOCHEMICAL AND ELECTRON-MICROSCOPIC STUDY

The characteristics of the nigrostriatal dopaminergic neuroconnections in developing rats are studied by combined immunocytochemical and electron-microscopic techniques, with an antibody to tyrosine hydroxylase (TH). From the embryonic day 21 on, some of the THpositive nerve fibers are densely packed in the striatum to form a patch-like dopamine island. The percentage of the TH-positive nerve terminals among the labeled profiles is much higher inside than outside the dopamine island (P<0.01). On the other hand, the TH-positive terminals mainly form symmetrical axon-dendritic synapses, while most of the TH-negative terminals form asymmetrical axon-spinous synapses. The functional significance of the characterized dopaminergic connection is discussed.

TOOTH PULP STIMULATION AND RESPONSESIN PARAFASCICULAR NUCLEUS

Electrical stimulation of the tooth pulp in humans produces a painful sensation .It seems reasonable to assume that similar trigeminal dental pain might be elicited by tooth pulp stimulation in cats.Manyauthors have demonstratedthat trigeminal nucleus caudalis (NV Caud) neurons respond to such pulp stimulation, and it is apparent, therefore, that these NV Caud neurons are in some way involved in dental pain.We report here that the parafascicular nucleus (Pf) of the thalamus may also be involved in dental pain, as it is involved in noxious stimuli arising from sensory nerves in other body parts.

INCREASE OF ENDORPHINE IN CEREBROSPINAL FLUID OF MONKEYS DURING ELECTRO-ACUPUNCTURE

Recently we have found that the analgesic effect of electro-acupuncture could be blocked in monkeys by naloxone, a specific opiate antagonist, thus suggesting that the endogenous morphine-like substance may be involved in the process of electro-acupuncture. By determining the endorphine content in human cerebrospinal fluid (CSF), Sjlund et al. have reported an increase of endorphine content in CSF at the spinal level after electro-acupuncture. A similar effect that the endorphine content of CSF collected from cerebellomeduliary cistern was increased after acupuncture, has been observed in rabbit, provided that bacitraein, a peptidase inhibitor, was given intraven-

Enhancing Effect of Monosialoganglioside GM1 on Learning and Memory in Aged Rats

Introduction Gangliosides are found at high concentration in CNS, and are essentially combined with neuronal membrane. The chemical structures of gangliosides have been determined. They are a family of molecules consisting of a lipid portion anchored in the plasma membrane and a carbohydrate portion on the outer cell surface containing one or more sialic acid residues. The hydrophihc carbohydrate portion is related to the regulation of Ca2+ channel. Exogenous ganglioside administration may have facilitatory effects on

SPINAL CORD POTENTIAL GENERATED BY SELECTIVE EXCITATION OF FINE CUTANEOUS AFFERENT FIBERS OF THE SURAL NERVE AND ITS SUPRASPINAL CONTROL IN CAT

Cord potentials in response to electrical stimulation of peripheral nerves have been investigated by a number of laboratories. It is commonly agreed that N1-and a later N2-waves reflect the excitation of interneurones in the dorsal horn by stimulation of the large myelinated afferent fibers, and that a following P-wave is due to the generation of primary afferent depolarization through the interneuronal path-

MODIFICATION OF PAIN REACTION BY ELECTRICAL STIMULATION OF NUCLEUS ACCUMBENS IN RABBITS

It has been reported by us that the analgesic effect of acupuncture was reduced following bilateral electrolytic lesions of nucleus accumbens in rats or local 6-hydroxydopamine (6-OH-DA) injection to the nucleus accumbens. In order to further elucidate the role played by nucleus accumbeus in the integration of pain information, in the present study the effect of electrical stimulation of nucleus accumbens on the pain reaction was observed in rabbits.

Kinetics of low threshold calcium channels of relay cells in cat lateral geniculate nucleus

Kinetics of the low threshold T-type Ca2+ channel is studied with single electrode voltage damp technique on brain slices of the cat lateral geniculate nucleus (LGN). Space damp is dramatically improved by blocking various K+ and Na+ channels, decreasing Ca2+ current and selecting proper holding potentials. Results from this study are similar to those obtained from acutely dissociated LGN neurons of the rat, indicating that the kinetics of T-Ca2+ channels of the cat LGN neurons is the same as that of the rat LGN. The result reported previously on the cat LGN may result from a defect in space damp.