Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0344307 (analgesia)
 28,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of taurine on the direct cortical response have been studied in immobilized cats (with local analgesia). The primary negative component of the response was inverted in polarity by the topical application of 25 mM taurine while the later slow negative component was considerably augmented. These effects are identical to those observed with 25 mM GABA. Pentobarbital anesthesia produced little qualitative change in the effects of taurine. With stronger stimuli in the presence of taurine, rhythmic waves followed each stimulus both at the cortical surface and at a depth of 1000 mum. An increase in the EEG amplitude following topical taurine was generally localized to the cortical surface but in certain experiments, could be recorded at cortical depths up to 1000 mum.
 ...
PMID:Modification of the direct cortical response by taurine. 5 Feb 28

The effect of GABA-ergic compounds on morphine-induced analgesia was studied to reveal probable interaction of GABA and opiates. As an index for morphine effect the reaction of vocalization in response to electrical stimulation of the rat tail was used. It was shown that thiosemicarbazide, the inhibitor of glutamate decarboxylase and bicuculline, GABA-ergic receptor blocking agent, which were proposed to be joined in a group of GABA-negative compounds, reduce and shorten the effect of morphine. Depakine, the inhibitor of alpha-ketoglutarate-GABA-transaminase, as well as GABA itself administered in high doses (GABA-positive actions) make morphine analgesia more pronounced and longer. Probable causes of the described interrelationship between GABA and opiates are discussed.
 ...
PMID:[Effect of GABA-ergic substances on the analgesic effect of morphine in rats]. 38 Jun 85

In chicks with cannulae chronically implanted into the III cerebral ventricle, the effects of a single dose (10 micrograms) of beta-endorphin on GABA and free glutamic acid content, GAD and GABA-T activities in the diencephalon, brain-stem and brain hemispheres were studied at the time of maximal behavioural stuporous state and analgesia. A significant decrease in GABA concentration both in the diencephalon and brain-stem, accompanied by a significant increase in GABA-T activity in the same areas, was shown to occur. No changes were observed in GAD activity and in glutamic acid content in the studied areas of the brain. In conclusion, present experiments suggest that some central effects of a beta-endorphin may be due to an interference with GABA-ergic transmission.
 ...
PMID:Effects of intraventricular beta-endorphin on GABA system in some areas of chick brain. 52 83

Effects of beta-(p-chlorophenyl)-GABA (baclofen), a muscle relaxant, on the response of mice and rats to various noxious stimuli were studied. In mice, 5 approximately 10 mg/kg i.p. of baclofen delayed the response time to tail-pinch and hot-plate stimuli but the relaxation was also apparent with this dose range. Mephenesin also delayed the response time to tail-pinch stimuli with the dose producing muscle relaxation. Baclofen, 3 mg/kg i.p., while producing no muscle relaxation, suppressed the acetic acid-induced writhing. The same effect, suppression of writhing and no muscle relaxation, was achieved with 50 mg/kg i.p. of mephenesin. In rats, baclofen (5 approximately 10 mg/kg i.p.) increased the response threshold in Randall-Selitto method and suppressed the bradykinin-induced symptoms, however, muscle relaxation was also produced with these same doses. Increase in response threshold in Randall-Selitto method was achieved with the dose of mephenesin producing muscle relaxation. The time courses of the depression of response to noxious stimuli and the muscle relaxation induced by baclofen and mephenesin were consistent in mice and rats. A small dose (3 mg/kg i.p. in mice, 2 mg/kg/h s.c. in rats) of baclofen reduced the antinociceptive effect of morphine but a larger dose (5 mg/kg i.p. in mice, 7 mg/kg/h s.c. in rats) of baclofen increased or did not alter the effect of morphine. It seems likely that the antinociceptive effect of baclofen may be nonspecific to analgesia.
 ...
PMID:[Effects of beta-(p-chlorophenyl)-GABA (baclofen) on response to noxious stimuli (author's transl)]. 59 82

From the following three lines of evidence, it is proposed that at least part of the convulsant activity of naloxone is a result of GABA receptor blockade. Firstly, iontophoretic naloxone reversibly antagonized GABA-evoked depression of firing rate in 21 of 27 neurons tested in the rat olfactory tubercle-nucleus accumbens region, without blocking inhibition evoked in the same cells by glycine (15 cells) or morphine (6 cells). Secondly, i.p. naloxone in high doses caused convulsions in mice, and potentiated the convulsant activity of bicuculline, but not that of strychnine. Diazepam, which protected mice against convulsions elicited by bicuculline, but not by strychnine, also protected mice against naloxone. Thirdly, naloxone, morphine, levorphanol and its non-analgesic enantiomer dextrorphan displaced 3H-GABA from GABA receptor sites in homogenates of human cerebellum, all with comparable low potencies (IC50 = 250--400 micron). There was no correlation with affinities at the stereospecific receptor sites that mediate opiate-induced analgesia, since the potent opiates etorphine and diprenorphine were relatively inactive (IC50 greater than 3 mM). In addition naloxone displaced 3H-GABA from receptor sites in rate forebrain and cerebellum, with similar low potency.
 ...
PMID:Naloxone as a GABA antagonist: evidence from iontophoretic, receptor binding and convulsant studies. 61 28

Muscimol, a very potent and specific GABA agonist, strongly depressed characteristic morphine-induced locomotor activity. Muscimol induced only a very weak increase in the morphine analgesia measured in the hot plate test which perhaps could be a result of a freezing reaction. No effect on morphine analgesia was observed in the wire grid test. These results indicate that GABA differentially influences morphine stimulation and analgesia.
 ...
PMID:Muscimol antagonizes morphine hypermotility without potentiation of analgesia. 64 89

Experiments were performed to evaluate the effects on the levels of aspartate, GABA and glutamate in the periaqueductal central gray matter, hypothalamus, midbrain reticular formation and cortex of mouse brain following various treatments. The results indicate that only glutamate among the 3 neurohumors is systematically altered relative to the experimental manipulations. Moreover, among the 4 brain areas examined, the data implicate only the periaqueductal central gray matter as a locus of morphine's antinociceptive action. Morphine also appears to produce a drug-specific effect in hypothalamus which, however, is not analgesia-related. There were no significant pain, stress or drug-related effects on the levels of glutamate in either the midbrain reticular formation or the cortex.
 ...
PMID:Morphine and pain: effects on aspartate, GABA and glutamate in four discrete areas of mouse brain. 93 43

Experiments were performed to determine 1) whether synergism existed between morphine and gamma-hydroxybutyrate in the production of analgesia and 2) the effect of each of these agents on pain-induced changes in brain amino acid content in mice. The analgetic ED50 for both agents was determined using hot plate and tail-flick procedures. The combination of one-half the ED50 of each agent produced an effect equivalent to the ED50 of either agent administered alone in the hot plate but not in the tail-flick test. Although both agents produced an unresponsiveness to noxious stimulation, only morphine prevented pain-induced alterations in brain GABA and glutamate levels.
 ...
PMID:An evaluation of the analgesia induced by morphine gamma-hydroxybutyrate. 114 17

Based on the data that diazepam, a benzodiazepine (BZP) receptor agonist, antagonized psychological (PSY)-stress induced analgesia (SIA) without prominent action on footshock (FS)- and forced swimming (SW)-SIA and that BZP receptors are coupled with GABA receptors, we examined how the GABAergic system participates in the production of various SIAs. Muscimol, a GABAA receptor agonist, at doses of 0.25 to 1.0 mg/kg, affected each SIA differently, suppressed PSY-SIA at 0.25 mg/kg but tended to potentiate it at 1.0 mg/kg, potentiated SW-SIA dose-dependently and did not affect FS-SIA at the doses employed. Both bicuculline, a GABAA receptor antagonist, 0.5 to 2.0 mg/kg, and picrotoxin, a Cl- channel blocker, 0.25 to 1.0 mg/kg, dose-dependently suppressed PSY- and FS-SIA. Meanwhile, the effects of both drugs on SW-SIA were less than those on PSY- and FS-SIA, namely, bicuculline slightly inhibited it only at 2.0 mg/kg, and picrotoxin did not produce any appreciable effect even at the highest dose. Baclofen, a GABAB receptor agonist, at 5.0 and 10.0 mg/kg had no influence on each SIA. On the contrary, CGP 35348, a GABAB receptor antagonist at 20 to 100 mg/kg caused the dose-dependent blockade of FS-SIA, but affected neither PSY- nor SW-SIA. The production of PSY- and SW-SIA is attributable to the GABAA receptors/Cl- channel mediated mechanism alone, while that of FS-SIA involves both GABAA and GABAB receptor mediated systems. Thus, GABAergic systems play an important role in the production of each SIA; however, the participation of the receptor subtypes in the mechanism was different from each other.
 ...
PMID:Participation of GABAergic systems in the production of antinociception by various stresses in mice. 133 79

Neuroanatomical, electrophysiological and pharmacological studies have provided indirect evidence indicating that GABAergic neurons play a key role in opiate analgesia mediated by the midbrain periaqueductal gray (PAG) and ventromedial medulla. Although these studies suggest that systemic administration of opiates inhibits GABA release in the PAG, there have been no investigations to date that have directly examined this issue. The present study was thus designed to determine whether systemic morphine injection inhibits GABA release in the PAG of awake, freely moving rats using in vivo microdialysis and subsequent HPLC analysis. Extracellular levels of GABA, glutamate, aspartate, glycine, homocysteic acid and taurine were monitored with the microdialysis technique in either the lateral or medial portion of the ventrocaudal PAG in unanesthetized, unrestrained rats. Amino acid release was induced by infusing veratridine (75 microM, a sodium channel activator) directly through the dialysis probe. The effect of veratridine alone and the effect of veratridine in the presence of systemic morphine on the concentrations of amino acids in the PAG dialysate were determined. There were no significant differences in the basal concentrations of GABA, taurine, aspartate, glutamate, homocysteic acid and glycine between dialysates collected from the medial versus the lateral ventrocaudal PAG. Glycine, taurine and glutamate were present in the highest concentrations in dialysis samples both before and after treatment with veratridine, whereas GABA, homocysteic acid and aspartate were present in the lowest concentrations. Perfusion of veratridine into the ventrocaudal PAG resulted in significant elevation of all amino acids investigated. Except for taurine, no significant difference in veratridine-induced release between the lateral and medial PAG was observed. Tetrodotoxin (TTX) significantly blocked veratridine-induced release of GABA, aspartate, glutamate, glycine and taurine but not homocysteic acid. When rats were injected with morphine (10 mg/kg i.p.), veratridine-induced release of GABA was selectively and significantly decreased in the lateral but not the medial PAG as compared to control rats injected with saline followed by veratridine perfusion. Systemic injection of morphine or saline caused no significant change in the basal concentration of amino acids in PAG dialysate samples. These findings are consistent with the proposed mechanism of action of morphine in the lateral ventrocaudal PAG and offer the first direct evidence that systemic opiates decrease GABA release in this midbrain region.
 ...
PMID:Systemic morphine reduces GABA release in the lateral but not the medial portion of the midbrain periaqueductal gray of the rat. 145 Sep 48


1 2 3 4 5 6 7 8 9 10 Next >>