Search results for "Gamma-Aminobutyric Acid"
showing 10 items of 142 documents
The endocannabinoid system controls key epileptogenic circuits in the hippocampus.
2006
SummaryBalanced control of neuronal activity is central in maintaining function and viability of neuronal circuits. The endocannabinoid system tightly controls neuronal excitability. Here, we show that endocannabinoids directly target hippocampal glutamatergic neurons to provide protection against acute epileptiform seizures in mice. Functional CB1 cannabinoid receptors are present on glutamatergic terminals of the hippocampal formation, colocalizing with vesicular glutamate transporter 1 (VGluT1). Conditional deletion of the CB1 gene either in cortical glutamatergic neurons or in forebrain GABAergic neurons, as well as virally induced deletion of the CB1 gene in the hippocampus, demonstrat…
The effects of low doses of pregabalin on morphine analgesia in advanced cancer patients
2012
Abstract OBJECTIVES: The aim of this study was to evaluate the opioid response in patients receiving morphine and pregabalin, independently from the presumed pain mechanisms, in comparison with patients receiving morphine treatment only. METHODS: A multicenter prospective randomized controlled study was carried out in a sample of 70 advanced cancer patients with pain requiring strong opioids. Thirty-five patients (group MO) were randomized to receive sustained-release morphine using initial doses of 60 mg/day. Thirty-five patients (group MO-PR) were randomized to start the same morphine doses and pregabalin in increasing doses, starting with 25 mg/day up to 150 mg/day in one week. The follo…
In vitro effects of putative neurotransmitters on synaptic ribbon numbers and N-acetyltransferase activity in the rat pineal gland
1992
The pineal contains a large number of classical transmitters and neuropeptides. Some of these neurochemicals are involved in the regulation of serotonin N-acetyltransferase (NAT) activity and hence in melatonin synthesis. Synaptic ribbons present in the pineal gland also exhibit a numerical day/night rhythm parallel to that of NAT activity. There is scarcity of information regarding the regulation of synaptic ribbon (SR) numbers. In the present study, we have investigated in vitro effects of a number of classical neurotransmitters and neuropeptides. NAT activity was used to monitor melatonin synthesis under the experimental conditions used. Norepinephrine (NE), Delta sleep-inducing peptide …
Cholinergic and GABAergic regulation of nitric oxide synthesis in the guinea pig ileum.
1999
Nitric oxide (NO) synthesis was examined in intact longitudinal muscle-myenteric plexus preparations of the guinea pig ileum by determining the formation of [3H]citrulline during incubation with [3H]arginine. Spontaneous [3H]citrulline production after 30 min was 80–90 dpm/mg, which constituted ∼1% of the tissue radioactivity. Electrical stimulation (10 Hz) led to a threefold increase in [3H]citrulline formation. Removal of calcium from the medium or addition of N G-nitro-l-arginine strongly inhibited both spontaneous and electrically induced production of [3H]citrulline. TTX reduced the electrically induced but not spontaneous [3H]citrulline formation. The electrically induced formation o…
Alzheimer's disease: amino acid levels and brain metabolic status.
2013
Abstract To study brain free amino acids and their relation with dementia we measured, by high-performance liquid chromatography (HPLC), the concentration of eight free amino acids, amines and related compounds. We used temporal cortex (TC) samples obtained from 13 Alzheimer’s disease (AD) patients and an equal number of agematched controls (AC). The patterns of free amino acids, amines and related compounds showed significant quantitative changes in AD conditions with respect to healthy ones. In Alzheimer patients, lower levels of GABA were found in the TC (-57 %). Amino acids glutamate (Glu), and aspartate (Asp) concentrations, also appeared significantly reduced in the TC of AD patients …
Impact of comorbidities on pharmacotherapy of painful diabetic neuropathy in clinical practice.
2014
Abstract Aims We evaluated the impact of baseline comorbidities on the effectiveness of duloxetine and anticonvulsants (pregabalin/gabapentin) in patients with painful diabetic neuropathy in clinical care. Methods Outcomes from a 6-month, observational study with 2575 patients initiating/switching DPNP treatment were analyzed post-hoc. Propensity scoring was used to adjust for baseline factors influencing treatment choice in 1523 patients receiving duloxetine or anticonvulsants. Analysis of covariance models with fixed effects for baseline pain, treatment, propensity score, baseline characteristics or comorbidities, and their interaction with treatment were used to estimate LSmean effects o…
Enhancement of guinea-pig intestinal peristalsis by blockade of muscarinic M1-receptors
1988
1. The effects of pirenzepine and hyoscine on the peristaltic reflex were investigated in the guinea-pig isolated small intestine. Peristalsis was induced by raising the intraluminal pressure and the volume of fluid propelled was taken as a measure of the efficiency of peristaltic activity. 2. Low concentrations of pirenzepine (0.1-1 nM) and of hyoscine (0.01 nM) significantly enhanced peristalsis, whereas larger concentrations of both drugs caused inhibition. Pirenzepine was about 6 times less potent than hyoscine in increasing peristalsis, but was about 100 times less potent in inhibiting it. 3. Neither tolazoline (1 microM) nor naloxone (0.3 microM) affected the stimulatory action of pir…
Environmental enrichment promotes neurogenesis and changes the extracellular concentrations of glutamate and GABA in the hippocampus of aged rats.
2005
The aim of the present study was to investigate the effects of environmental enrichment on the neurogenesis and the extracellular concentrations of glutamate and GABA in the hippocampus of freely moving young and aged rats. Male Wistar rats of 2 (young) and 25 (old) months of age were housed during 8 weeks in an enriched environment; control rats were kept in individual plastic cages during that same period of time. Rats were injected intraperitoneally with bromodeoxyuridine (BrdU; 40 mg/kg; 7 days) during the fourth week of the housing period to detect neurogenesis in the dentate gyrus (DG) of the hippocampus. Rats were sacrified 6 weeks after the last injection of BrdU. During the last we…
Opposite role played by GABAA and GABAB receptors in the modulation of peristaltic activity in mouse distal colon.
2014
We investigated the role of GABA on intestinal motility using as model the murine distal colon. Effects induced by GABA receptors recruitment were examined in whole colonic segments and isolated circular muscle preparations to analyze their influence on peristaltic reflex and on spontaneous and neurally-evoked contractions. Using a modified Trendelenburg set-up, rhythmic peristaltic contractions were evoked by gradual distension of the colonic segments. Spontaneous and neurally-evoked mechanical activity of circular muscle strips were recorded in vitro as changes in isometric tension. GABA, at low concentrations (10-50 µM), potentiated peristaltic activity and the neural cholinergic contrac…
GABAergic inhibition of nitric oxide-mediated relaxation of guinea-pig ileum
1999
The effects of GABA receptor agonists were investigated on guinea-pig isolated ileum longitudinal muscle with intact myenteric plexus. Electrical field stimulation (1 Hz, 10 s) of the histamine (1 microM)-precontracted preparation caused a contraction followed by a relaxation. Relaxations were inhibited by L-N(G)-nitroarginine (L-NA; EC50 3 microM) in a concentration-dependent manner. The inhibitory action of 10 microM L-NA was blocked by 10 microM L-arginine but not by D-arginine, which indicates that the relaxation was largely mediated by endogenous nitric oxide (NO). Tetrodotoxin (1 microM) reduced the relaxation only by about 50%. GABA and the GABA(B) agonist, baclofen, inhibited the fi…