Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: CAS:6893-26-1 (glutamate)
 73,096 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The occurrence and distribution of several neurochemical markers were investigated. Numerous nerve fibres were shown, using antibodies to protein gene product (PGP) 9.5, neurone-specific enolase, calcitonin gene-related peptide (CGRP), substance P. neurokinin A or protein S-100. The presence of vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine amide (PHI), neuropeptide tyrosine, dopamine-beta-hydroxylase (DBH), cholecystokinin/gastrin, glutamate and galanin was more scarce. Nerve fibres containing these above-mentioned markers were found at several locations, i.e. in the epithelium, connective tissue, and around blood vessels. In the taste buds, numerous PGP 9.5, neurone-specific enolase-, CGRP-, substance P-, neurokinin A- and protein S-100-containing structures were found, but few VIP and galanin ones. No immunoreactivity was found with antibodies against somatostatin, bombesin, enkephalin or dynorphin. These findings extend knowledge about the general as well as the neurochemical messenger-based innervation of rat fungiform papillae, forming a firm basis for future functional investigations of normal, experimental and also clinical materials.
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PMID:An immunohistochemical screening of neurochemical markers in fungiform papillae and taste buds of the anterior rat tongue. 913 26

The effect of sulphated cholecystokinin-8 (CCK-8S) on extracellular dynorphin B, aspartate, glutamate and GABA levels in the rat fronto-parietal cortex was investigated with in vivo microdialysis. The peptide was infused through the microdialysis probe trying to mimic local CCK-8S release. Basal levels of dynorphin B were around 20 pM, aspartate 100 nM, glutamate 600 nM and GABA 30 nM. CCK-8S (10 microM) induced a approximately 3-fold increase in extracellular dynorphin B, aspartate and glutamate levels, while GABA levels were only slightly increased. The effect of CCK-8S was restricted to the stimulated neocortex. Systemic pretreatment with the CCKB antagonist, L-365, 260, but not with the CCKA antagonist, L-364, 718, significantly antagonised the effect of CCK-8S on cortical dynorphin B and aspartate release. However, both CCKA and CCKB antagonists inhibited the increase in cortical glutamate levels. Thus, the present results indicate that cortical CCK release exerts a stimulatory modulation on cortical dynorphin B and aspartate release via the CCKB receptor subtype, and on glutamate release via both CCKA and CCKB receptor subtypes. Considering electrophysiological evidence that CCK increases neuronal firing rates in many brain regions, it may be suggested that CCK represents a stimulatory system modulating the function of the neocortex.
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PMID:Cholecystokinin-8S increases dynorphin B, aspartate and glutamate release in the fronto-parietal cortex of the rat via different receptor subtypes. 915 Dec 95

The neocortex is thought to exert a powerful influence over the functions of the basal ganglia via its projection to the striatum. It is not known, however, whether corticostriatal effects are similar across different types of striatal projection neurons and interneurons or are unique for cells having different functions within striatal networks. To examine this question, we developed a method for focal synchronous activation of the primary motor cortex (MI) of freely moving rats by local release of GABAergic inhibition. With this method, we monitored cortically evoked activation of two immediate-early gene protein products, c-Fos and JunB, in phenotypically identified striatal neurons. We further studied the influence of glutamate receptor antagonists on the stimulated expression of c-Fos, JunB, FosB, and NGFI-A. Local disinhibition of MI elicited remarkably selective induction of c-Fos and JunB in enkephalinergic projection neurons. These indirect pathway neurons, through their projections to the globus pallidus, can inhibit thalamocortical motor circuits. The dynorphin-containing projection neurons of the direct pathway, with opposite effects on the thalamocortical circuits, showed very little induction of c-Fos or JunB. The gene response of striatal interneurons was also highly selective, affecting principally parvalbumin- and NADPH diaphorase-expressing interneurons. The glutamate NMDA receptor antagonist MK-801 strongly reduced the cortically evoked striatal gene expression in all cell types for each gene examined. Because the gene induction that we found followed known corticostriatal somatotopy, was dose-dependent, and was selectively sensitive to glutamate receptor antagonists, we suggest that the differential activation patterns reflect functional specialization of cortical inputs to the direct and indirect pathways of the basal ganglia and functional plasticity within these circuits.
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PMID:Local release of GABAergic inhibition in the motor cortex induces immediate-early gene expression in indirect pathway neurons of the striatum. 916 35

The effect of dynorphin A(1-13) on N-methyl-D-aspartate (NMDA)-activated currents was investigated in the presence of low extracellular glycine concentrations in Xenopus oocytes expressing recombinant heteromeric NMDA receptors and in cultured hippocampal neurons with the use of voltage-clamp techniques. At an extracellular added glycine concentration of 100 nM, dynorphin A(1-13) (10 microM) greatly increased the amplitude of NMDA-activated currents for all heteromeric subunit combinations tested; on average, the potentiation was: epsilon1/zeta1, 3,377 +/- 1,416% (mean +/- SE); epsilon2/zeta1, 1,897 +/- 893%; epsilon3/zeta1, 4,356 +/- 846%; and epsilon4/zeta1, 1,783 +/- 503%. Potentiation of NMDA-activated current by dynorphin A(1-13) was concentration dependent between 0.1 and 10 microM dynorphin A(1-13), with a half-maximal concentration value of 2.77 microM and an apparent Hill coefficient of 2.53, for epsilon2/zeta1 subunits at 100 nM added extracellular glycine. Percentage potentiation by dynorphin A(1-13) was maximal at the lowest glycine concentrations tested (0.01 and 0.1 microM), and decreased with increasing glycine concentration. No significant potentiation was observed at glycine concentrations > 0.1 microM for epsilon1/zeta1, epsilon2/zeta1, and epsilon4/zeta1 subunits, or at > 1 microM for epsilon3/zeta1 subunits. Potentiation of NMDA-activated currents by dynorphin A(1-13) was not inhibited by 1 microM of the kappa-opioid receptor antagonist nor-binaltorphimine, and potentiation was not observed with 10 microM of the kappa-opioid receptor agonist trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl] benzene-acetamide. Potentiation of NMDA-activated current by dynorphin A(1-13) was inhibited by the glycine antagonist kynurenic acid (50 microM). NMDA-activated current was also potentiated at low glycine concentrations by 10 microM dynorphin A(2-13) or (3-13), both of which have a glycine as the first amino acid, but not by 10 microM dynorphin A(4-13), which does not have glycine as an amino acid. In hippocampal neurons, 10 microM dynorphin A(1-13) or (2-13) potentiated steady-state NMDA-activated current in the absence of added extracellular glycine. The extracellular free glycine concentration, determined by high-performance liquid chromatography, was between 26 and 36 nM for the bathing solution in presence or absence of 10 microM dynorphin A(1-13), (2-13), (3-13), or (4-13), and did not differ significantly among these solutions. The observations are consistent with the potentiation of NMDA-activated current at low extracellular glycine concentrations resulting from an interaction of the glycine amino acids in dynorphin A(1-13) with the glycine coagonist site on the NMDA receptor. Because dynorphin A is an endogenous peptide that can be coreleased with glutamate at glutamatergic synapses, the potentiation of NMDA receptor-mediated responses could be an important physiological regulator of NMDA receptor function at these synapses.
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PMID:Potentiation of NMDA receptor-mediated responses by dynorphin at low extracellular glycine concentrations. 930 96

We tested the effects of (3 R)-3-(1-pyrrolidinylmethyl)-4-[(1S)-5,6-dichloro-1-indancarbony l]-2,3,5,6-tetrahydro-1,4-thiazine hydrochloride (R-84760), a selective kappa-opioid receptor agonist, on the slow ventral root potential in the isolated spinal cord of neonatal rats. R-84760 at 10 nM decreased the slow ventral root potential to 35% of the control, leaving the monosynaptic reflex unaffected. The depressant effect of R-84760 progressed slowly for 60 min to the maximum and recovered slightly after removal of the drug from the perfusing solution. This contrasts with [D-Ala2, MePhe4, Gly-ol5]enkephalin (DAMGO) or [MeTyr1, MeArg7, D-Leu-NHEt8]dynorphin A-(1-8) (E-2078) which attained their maximum depressant effect within 15 min with recovery immediately after washout. Reversibility of the R-84760 effect was observed in vivo in antinociceptive tests in mice. R-84760 reduced the depolarization induced by substance P or L-glutamate in the normal solution, but not in the presence of tetrodotoxin at 0.3 microM. Naloxone inhibited the effect of R-84760 at a higher concentration (1 microM) than that (0.1 microM) needed to antagonize the effect of DAMGO. In contrast, R-84760 was more sensitive to nor-binaltorphimine than was DAMGO. The results show that R-84760 selectively inhibits the nociceptive response presynaptically through kappa-opioid receptors and that the inhibitory effect is characteristic, with long duration, in the neonatal rat spinal cord.
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PMID:Effects of R-84760, a selective kappa-opioid receptor agonist, on nociceptive reflex in isolated neonatal rat spinal cord. 957 Apr 65

Abnormal involuntary movements, or dyskinesias, plague current symptomatic approaches to the treatment of Parkinson's disease. The neural mechanisms underlying the generation of dyskinesia following repeated l-3,4-dihydroxyphenylalanine (L-DOPA) or dopamine agonist administration in Parkinson's disease remain unknown. However, de novo administration of bromocriptine or lisuride to either l-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned primates or patients can alleviate parkinsonian symptoms without the development of dyskinesia. In this study, we have investigated behavioral responses and alterations in the expression of opioid neuropeptide precursors preproenkephalin-A (PPE-A, encoding methionine- and leucine-enkephalin) and preproenkephalin-B (PPE-B), the precursor encoding dynorphins (dynorphin A1-17 and B1-13, leucine-enkephalin, and alpha-neoendorphin) in striatal output pathways of the 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease. Expression was assessed following repeated L-DOPA, bromocriptine, or lisuride administration. Given the functional organization of basal ganglia circuitry into anatomically discrete parallel circuits, we investigated alterations in peptide expression with reference to the detailed topography of the striatum. Following repeated L-DOPA administration (6.5 mg/kg, b.d., 21 days) in the 6-OHDA-lesioned rat a rotational response was observed. This became markedly enhanced with repeated treatment. We have previously characterized the pharmacology of this enhanced response and have suggested that it is a useful model for the elucidation of the cellular and molecular mechanisms underlying L-DOPA- and dopamine agonist-induced dyskinesia. In contrast to l-DOPA, de novo administration of bromocriptine (1 or 5 mg/kg, b.d., 21 days) or lisuride (0.01 or 0.1 mg/kg, b.d., 21 days) did not lead to an enhanced behavioral response. In vehicle-treated, 6-OHDA-lesioned animals, PPE-A expression was elevated rostrally and dorsally, while PPE-B expression was reduced in the striatum at all rostrocaudal levels. Repeated l-DOPA administration was accompanied by elevations in striatal PPE-B mRNA levels and a further elevation, above lesion-induced levels, in PPE-A expression. This further elevation was restricted to the dorsolateral striatum. However, following repeated bromocriptine or lisuride administration no increase in PPE-B expression was observed and the lesion-induced increase in PPE-A expression was normalized to prelesion levels. Increased PPE-A and PPE-B levels may, through decreasing GABA and glutamate release, respectively, in output nuclei of the basal ganglia, play a role in the development of L-DOPA- and dopamine-agonist induced dyskinesia in Parkinson's disease. These studies suggest that anti-parkinsonian treatments which are not associated with an elevation in PPE-B and/or normalize elevated PPE-A precursor expression, such as NMDA-receptor antagonists or long-acting dopamine D2 receptor agonists, e.g., cabergoline or ropinirole, may reduce dyskinesia in Parkinson's disease.
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PMID:Effect of repeated L-DOPA, bromocriptine, or lisuride administration on preproenkephalin-A and preproenkephalin-B mRNA levels in the striatum of the 6-hydroxydopamine-lesioned rat. 1007 96

The redox modulatory site of the N-methyl-D-aspartate (NMDA) receptor directly regulates NMDA receptor function. Sulfhydryl reducing agents, such as dithiothreitol (DTT), potentiate NMDA receptor-evoked currents in vitro, whereas oxidizing agents, such as 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB), attenuate these currents. In this study, we examined the effect of this redox manipulations on nociceptive spinal cord signaling in mice. Intrathecal (i.t.) administration of DTT (0.1-30 nmol), presumably reducing the NMDA receptor, dose-dependently enhanced NMDA-induced nociceptive behaviors, and this enhancement was blocked by the oxidizing agent, DTNB. Pretreatment with DTT (10 nmol, i.t.) enhanced NMDA-induced tail-flick thermal hyperalgesia and intraplantar formalin-induced nociceptive behaviors. Finally, DTT pretreatment enhanced the long lasting allodynia induced by i.t. administration of dynorphin, whereas post-treatment with DTNB reduced the permanent allodynia induced by dynorphin for 5 days. Potentiation of all four of these NMDA-dependent nociceptive behaviors by DTT suggests that the reduction of the NMDA receptor by endogenous reducing agents may contribute to augmented pain transmission in response to activation by endogenous glutamate. Moreover, blockade of in vivo NMDA receptor reducing agents or oxidation of the NMDA receptor redox site may prove therapeutically useful in the treatment of chronic pain.
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PMID:Redox manipulation of NMDA receptors in vivo: alteration of acute pain transmission and dynorphin-induced allodynia. 1020 16

Retrograde labelling has been combined with immunohistochemistry to localize neurons containing GABA, glutamate, choline acetyltransferase, leu-enkephalin, neurotensin and substance P-like immunoreactivity in the projection pathways from the midbrain tegmental nuclei to the mammillary nuclei in the rat. Injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the medial mammillary nucleus resulted in retrogradely labelled neurons in the ventral tegmental nucleus of Gudden, whereas injections into the lateral mammillary nucleus resulted in large numbers of retrogradely labelled neurons in the ipsilateral dorsal tegmental nucleus of Gudden and in the laterodorsal tegmental nucleus. In the ventral tegmental nucleus, moderate to small numbers of retrogradely labelled neurons were also immunolabelled for GABA and approximately ten to 18 WGA-HRP-labelled neurons per section were immunoreactive for leu-enkephalin. In addition, small numbers of WGA-HRP-labelled neurons in the principal subnucleus of the ventral tegmental nucleus were immunoreactive for Glu whereas small numbers of retrogradely labelled neurons in the compact subnucleus of the central superior nucleus displayed neurotensin-like immunoreactivity. In the ventral subnucleus of the dorsal tegmental nucleus, moderate to small numbers of retrogradely labelled neurons were also GABA-immunoreactive and approximately ten to 14 WGA-HRP labelled neurons per section were immunoreactive for leu-enkephalin. The ventral subnucleus of the dorsal tegmental nucleus also contained small numbers of retrogradely labelled neurons that displayed either glutamate or substance P-like immunoreactivity. In addition, moderate to small numbers of WGA-HRP-labelled neurons (five to 20 per section) in the laterodorsal tegmental nucleus were immunoreactive for choline acetyltransferase. These results are compatible with the possibility that tegmentomammillary projection neurons use several different neurochemicals as neurotransmitter(s) and/or neuromodulator(s).
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PMID:Localization of amino acids, neuropeptides and cholinergic neurotransmitter markers in identified projections from the mesencephalic tegmentum to the mammillary nuclei of the rat. 1022 11

Microinjection studies have found that although dynorphin peptides decrease dopamine release in the rat basal ganglia, the nonselective opiate antagonist naloxone produces the opposite effect. To investigate the contribution of the dynorphin pathways to a tonic modulation of dopamine release, a microdialysis study was undertaken, with probes implanted in the substantia nigra and the ipsilateral neostriatum. Perfusion of the substantia nigra with the nonselective antagonist naltrexone (NTX; 1-10 microM), the selective kappa-opoid receptor antagonist, nor-binaltorphimine (nor-BNI; 1-10 microM), and the selective mu-opioid receptor antagonist, D-Pen-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP; 1-10 microM) produced an increase in dopamine release, both in substantia nigra and neostriatum. nor-BNI also produced an increase in dynorphin B release, and a similar effect was observed with the higher concentration of NTX (10 microM). At the higher concentration of NTX and CTOP, an increase in glutamate release was also observed. Perfusion of the neostriatum with NTX, nor-BNI, or CTOP increased striatal dopamine, and dynorphin B release and increased dynorphin B in the ipsilateral substantia nigra. NTX and CTOP, but not nor-BNI, increased striatal glutamate and aspartate release. The kappa-opioid agonist U-50,488H (10 microM) induced a decrease in dopamine levels, both in the substantia nigra and neostriatum, and a paradoxical increase in striatal aspartate levels. Finally, systemic administration of NTX (4 mg/kg s.c.) in awake animals significantly increased striatal dopamine levels. The results suggest that opioid peptides, either dynorphins acting on kappa-opioid receptors or enkephalins acting on mu-opioid receptors, exert tonic inhibition on dopamine and dynorphin B release in both substantia nigra and neostriatum.
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PMID:Modulation of neurotransmitter release in the basal ganglia of the rat brain by dynorphin peptides. 1045 8

Vestibular receptors of the frog, Rana temporaria, were examined for the effect of bath-applied opioid peptide leu-enkephalin, its synthetic analogue dalargin and the specific opiate antagonist naloxone. Multiunit afferent activity of the whole vestibular nerve was recorded in an in vitro preparation. Leu-enkephalin (0.005-100 nM) and dalargin (0.1-100 nM) depress the resting discharge frequency. Naloxone (10 nM-1 microM) antagonizes responses induced by leu-enkephalin and dalargin that suggests a specific action of opioid peptides. Leu-enkephalin and delargin inhibit the excitatory action of L-glutamate. The effects of opioid peptides on L-glutamate-induced responses are unaffected by Co2+ block of transmitter release from hair cells that could speak in favour of the postsynaptic nature of these responses. At the same time, the other possible site of action of opioid peptides, such as efferent system, can not be excluded. The results indicate that opiate receptors are present in hair cells and that the neurotransmitter L-glutamate is involved in opiate action at the peripheral vestibular system of the frog. We suggest that opioid peptides may act as a neuromodulator in this system.
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PMID:Opioid peptides as possible neuromodulators of the afferent synaptic transmission in the frog semicircular canal. 1046 63


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