Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study male Swiss-Webster mice were used to examine the effects of cysteine (ICV), a precursor in the biosynthesis of taurine, on ethanol-induced loss of the righting reflex. The interaction of ethanol with gamma-aminobutyric acid (GABA) and isethionic acid, a metabolite of taurine, was also investigated on ethanol-induced central nervous system depression as measured by loss of the righting reflex experiments. Immediately after the animals regained the righting reflex following ethanol injection (IP) mice received an ICV injection of saline, cysteine (1, 15 or 25 mumol/kg), GABA (1, 15 or 25 mumol/kg) or isethionic acid (25 or 50 mumol/kg). Upon ICV administration of cysteine or GABA the mice again lost the righting reflex. This effect occurred immediately and in a dose-dependent manner. The compound, isethionic acid, failed to cause a second loss of the righting reflex following ethanol administration (IP). In the absence of ethanol cysteine or GABA (25 mumol/kg, ICV) did not produce a substantial loss of the righting reflex in mice. In another experiment mice were pretreated (IP) with L-2-oxothiazolide-4-carboxylate (OTC) 2 hr prior to ethanol administration (IP). OTC is a compound which can be converted to cysteine in the body. In the presence of ethanol OTC (15 mmol/kg) caused an enhancement of ethanol-induced central nervous system depression under certain conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The interaction between ethanol and cysteine on the central depressant effects of ethanol in mice. 237 62

The effects of acute and chronic administration desipramine (DMI) and the potential antidepressant, MDL 26,479 (2,4-dimethyl-5-(3-fluorophenyl)-3H-1,2,4-triazole-3-thione) were compared on the sensitivity of Purkinje neurons in the cerebellum of the rat to iontophoretically applied norepinephrine (NE) and gamma-aminobutyric acid (GABA). Neither compound, administered acutely at 10 mg/kg (i.p.), altered the spontaneous firing rate of Purkinje neurons or the depression of the rate caused by iontophoresed NE. However, MDL 26,479 did significantly reduce the enhancement of inhibitory responses to GABA, produced by NE. Administered chronically (10 mg/kg x 21 days, i.p.), neither compound altered the slowing of Purkinje neurons evoked by NE. Chronic treatment with MDL 26,479, but not with DMI, produced a small but significant decrease in average spontaneous firing rate of Purkinje neurons. Both compounds substantially attenuated the enhancement of the inhibitory responses to GABA produced by NE, with MDL 26,479 having a more marked effect than DMI. These effects of MDL 26,479 on the activity of Purkinje neurons are consistent with the compound having antidepressant potential and further suggest, since similar effects were seen after a single dose, that the compound may have a rapid onset of antidepressant action.
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PMID:The effects of a potential antidepressant, 2,4-dimethyl-5-(3-fluorophenyl)-3H-1,2,4-triazole-3-thione, in an electrophysiological model responsive to desipramine. 238 27

Using internally dialyzed neurons of Helix, we have examined the effects of sodium-pump activity and intracellular ATP concentration on transmembrane currents induced by acetylcholine (ACh) and gamma-aminobutyric acid (GABA). We also report on the effects of pump activity and levels of intracellular ATP on binding by Helix ganglia of 3H-alpha-bungarotoxin (3H-alpha-BT) and 3H-GABA. Both ouabain-containing and potassium-free solutions depressed the neurotransmitter-induced transmembrane current of one type of dialyzed neurons. An increase in the intracellular ATP concentration led to a depression of ACh-induced currents and to the disappearance of the blocking effect of ouabain on these currents. Intracellular ADP had a similar but smaller effect on transmitter-induced currents, and intracellular AMP was ineffective. The depressing effect of internal ATP on ACh-induced currents was absent in the presence of an inhibitor of membrane phosphorylation (dinitrophenol). The binding of tritium-labeled alpha-BT and GABA to the membranes was depressed by both ouabain-containing and K-free solutions and also by compounds (theophylline and NaF) which increase the levels of intracellular ATP. The results suggest that the Na pump modulates the affinity of ACh and GABA membrane receptors by the regulation of the phosphorylated state of membrane receptors.
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PMID:Further study of the correlation between Na-pump activity and membrane chemosensitivity. 241 57

Both baclofen and gamma-aminobutyric acid (GABA) induced a dose-dependent depression of cholinergic twitch contractions in the transmurally stimulated guinea-pig isolated ileum. Over a range of 0.6-2.4 mM Ca2+, the degree of depression was inversely related to the Ca2+ concentration, with an increased sensitivity and sinistral shift of the dose-response curve at lower Ca2+ concentrations. Partial occupation of Ca2+ channels by Ruthenium Red (0.1 microM) also potentiated the depressive responses to baclofen and GABA. It is concluded that these agonists, acting through GABAB receptors, limit the availability of Ca2+ required for neurotransmitter release in myenteric motor nerves.
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PMID:Calcium dependence of baclofen- and GABA-induced depression of responses to transmural stimulation in the guinea-pig isolated ileum. 243 28

The rat olfactory bulb is an area displaying a particularly high density of substance P receptors in the glomerular cell layer whose functions are unknown. In pilot in vivo experiments we discovered that iontophoretically administered substance P potently depressed the spontaneous firing rate of most unidentified neurons of the rat olfactory bulb. To further elucidate the mechanism of this unexpected depressant effect, we studied the peptide's action in vitro on coronal sections of this brain region. Bath applied and microiontophoretically administered substance P depressed the spontaneous discharge of unidentified glomerular neurons in a dose-dependent fashion. This inhibiting effect is mediated indirectly via the release of another transmitter because it was abolished completely if the standard perfusion medium was replaced by a medium containing zero calcium and high magnesium. It appears that substance P acts by means of releasing GABA which in turn evokes the observed cell depression because the depressant effects were completely abolished by bath-applied bicuculline (10 microM) and picrotoxin (100 microM). In conclusion we propose that substance P indirectly depresses neuronal activity in the glomerular cell layer of the rat olfactory bulb by releasing gamma-aminobutyric acid.
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PMID:Substance P depresses neuronal activity in the rat olfactory bulb in vitro and in vivo: possible mediation via gamma-aminobutyric acid release. 244 May 22

Studies were carried out in chloralose-anesthetized cats while monitoring respiratory (tidal volume and respiratory rate) and cardiovascular (arterial pressure and heart rate) activity. Midazolam applied bilaterally to the intermediate area of the ventral surface of the medulla in doses of 0.75, 7.5 and 75 micrograms/side reduced tidal volume by -6 +/- 3, -10 +/- 1 and -11 +/- 1 ml, respectively. A dose of 250 micrograms/side produced apnea in each animal tested. Corresponding changes in arterial pressure were -35 +/- 9, -44 +/- 6, -43 +/- 9 and -64 +/- 17 mm Hg, respectively. Larger doses of chlordiazepoxide (e.g., 1000 micrograms/side) were required to produce similar effects. Intravenous administration of midazolam in doses of 1.5 to 150 micrograms had no significant effect on cardiorespiratory activity. However, larger doses of midazolam given i.v. produced cardiorespiratory depression that was similar to that observed with centrally applied drug. Pretreatment or treatment with centrally applied flumazenil or bicuculline counteracted the cardiorespiratory effects of centrally applied midazolam. Most importantly, ventral surface application of flumazenil counteracted the cardiorespiratory depressant effects of i.v. midazolam. Central administration of ethyl-beta-carboline-3-carboxylate produced cardiorespiratory effects opposite to those seen with midazolam, and these stimulatory effects were also counteracted by centrally applied flumazenil. These results indicate that alterations in cardiorespiratory activity can be produced by drugs interacting with gamma-aminobutyric acid/benzodiazepine receptors at the ventral surface of the medulla.
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PMID:Drug interaction with gamma-aminobutyric acid/benzodiazepine receptors at the ventral surface of the medulla results in pronounced changes in cardiorespiratory activity. 253 19

1. The effects of gamma-aminobutyric acid (GABA), 3-aminopropane sulphonic acid (3-APS) and baclofen on spontaneous, electrically-induced and propulsive motility were investigated in rabbit distal colon. 2. In unstimulated longitudinal (LMPs) and circular muscle strip preparations (CMPs) 3-APS (10-200 microM) and GABA caused a clear-cut relaxation susceptible to desensitization. Baclofen (10-200 microM) caused relaxation in a minority (30%) of preparations. The 3-APS response was sensitive to tetrodotoxin (TTX; 1 microM), SR 95531 (a novel competitive GABAA-receptor antagonist) (10 microM), picrotoxinin (30 microM), and insensitive to hyoscine (1 microM) and to a combination of prazosin (1 microM) and propranolol (1 microM). The baclofen response was antagonized by 5-aminovaleric acid (DAVA, 500 microM), TTX and hyoscine and resistant to GABAA-receptor and adrenoceptor blockade. GABAA-receptors were therefore associated with non-adrenergic non-cholinergic (NANC) inhibitory nerve activation while GABAB-receptors were involved in depression of cholinergic tone of smooth muscle. GABA (10-200 microM) elicited both above mentioned effects. 3. In LMPs, baclofen (10-200 microM) dose-dependently inhibited submaximal responses to both cholinergic and NANC inhibitory nerve stimulation. This effect was resistant to SR 95531 and picrotoxinin and prevented by DAVA and baclofen desensitization. GABA (10-200 microM) mimicked the action of baclofen. GABA inhibitory effects persisted in the presence of GABAA-receptor blockade. 4. In segments of distal colon, GABA and baclofen (1-200 microM), but not 3-APS (1-200 microM), dose-dependently decreased the velocity of propulsion of an intraluminally-distended balloon. This effect was antagonized by DAVA and GABA or baclofen desensitization and resistant to SR 95531 and picrotoxinin. These antagonists per se had no effect on propulsion. In preparations in which propulsion was slowed by hyoscine (1 microM), baclofen caused no consistent further depression of propulsive activity. 5. Our results show that GABAA- and GABAB-receptors are present in rabbit colon. GABAA-receptor stimulation activates NANC inhibitory nerves without apparently affecting propulsion. GABAB-receptors are associated with a reduction of neural (mainly cholinergic) activity subserving muscular tone and peristalsis and appear to be located on both cholinergic and NANC inhibitory nerves. However, the persisting propulsive activity during suppression of GABAA- and GABAB-receptor function suggests that GABA in enteric neurones is not crucial for the neural circuitry subserving colonic peristalsis in this species.
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PMID:An in vitro study of the relationship between GABA receptor function and propulsive motility in the distal colon of the rabbit. 255 56

The effect of gamma-aminobutyric acid (GABA) on basal and bombesin (BBS)-stimulated release of somatostatin (SLI) and gastrin from isolated perfused rat stomach was examined. In the control study, BBS at a dose of 10 nM significantly stimulated release of SLI and gastrin. Infusion of GABA (1-1000 nM) caused a depression of SLI release induced by BBS (10 nM) in a dose-dependent fashion. However, at doses used in this study GABA had no effect on either basal level of SLI and gastrin or BBS-elicited gastrin release. These results indicate that GABA can specifically modulate BBS-induced SLI release from rat stomach.
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PMID:Effect of gamma-aminobutyric acid on bombesin-evoked release of somatostatin and gastrin from isolated rat stomach. 256 10

1. Iontophoretic application of the veterinary tranquilizer xylazine suppressed the spontaneous firing of 134/137 neurons tested, an effect not antagonized by adenosine receptor and alpha-adrenergic receptor blocking agents. 2. Depressions in neuronal activity evoked by norepinephrine, gamma-aminobutyric acid or adenosine failed to be potentiated by xylazine. 3. However, the excitatory effects of acetylcholine and glutamate were both inhibited by xylazine. 4. Thus, the depressant effect of locally applied xylazine may involve a decrease in the excitability of the neuronal membrane.
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PMID:Xylazine-evoked depression of rat cerebral cortical neurons: a pharmacological study. 256 68

The concentrations of 3 putative neurotransmitters (glutamate, aspartate and gamma-aminobutyrate), 4 related amino acids and 5 non-transmitter-related amino acids have been measured in neurosurgical samples (frontal cortex) from patients with intractable depression and controls. In addition, the glutamate receptor agonist 2-amino-4-sulpho-butanoic acid (homocysteic acid) has been identified in human brain and measured in these samples. There were no changes in the concentrations of amino acids in depressed patients compared to control with the exception of aspartic and homocysteic acids which were elevated in a sub-group of patients with depression compared to control. The Ca2+-dependent release (K+-stimulated) of putative neurotransmitters has been demonstrated for the first time from brain tissue of depressed patients. Glutamate release was unaltered from the control value. Aspartate values showed unexplained variability but it's release and that of gamma-aminobutyrate were elevated in some depressed subjects. These results do not support the hypothesis of reduced amino acid function in depressive illness.
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PMID:Brain amino acid concentrations and Ca2+-dependent release in intractable depression assessed antemortem. 257 Jun 24


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