The effects of gamma-aminobutyric acid (GABA) on the electrophysiological properties of intracardiac neurones were investigated in the intracardiac ganglion plexus in situ and in dissociated neurones from neonatal, juvenile and adult rat hearts. Focal application of GABA evoked a depolarizing, excitatory response in both intact and dissociated intracardiac ganglion neurones. Under voltage clamp...

Cerebral ischemia is characterized by an early disruption of GABAergic neurotransmission contributing to an imbalance of the excitatory/inhibitory equilibrium and neuronal death, but the molecular mechanisms involved are not fully understood. Here we report a downregulation of GABA(A) receptor (GABA(A)R) expression, affecting both mRNA and protein levels of GABA(A)R subunits, in hippocampal neu...

?-Aminobutyric acid (GABA) and glucagon-like peptide-1 receptor agonist (GLP-1RA) improve rodent ?-cell survival function. In human ?-cells, GABA exerts stimulatory effects on proliferation anti-apoptotic effects, whereas GLP-1RA drugs have only limited proliferation. We previously demonstrated that sitagliptin (Sita), a dipeptidyl peptidase-4 inhibitor which increases endogenous GLP-1 levels, ...

Objective(s) In this study we investigated the expression of GABAA receptor subunits during brain development. These receptors may change in the embryonic chick forebrain. Materials and Methodes The expression levels of four types of GABAA receptor gamma subunits (γ1, γ2, γ3 and γ4) were quantified in the embryonic chick forebrain at 32 hr, 3, 7, 14, and 20 days of incubation and day one aft...

Evidence from toxicological studies suggested that an ionotropic GABA receptor of novel pharmacology (picrotoxin-insensitive, bicuculline-sensitive) exists in the chick embryo retina. In this report, we provide direct morphological and electrophysiological evidence for the existence of such an iGABA receptor. Chick embryo retinas (14-16 days old) incubated in the presence of kainic acid showed ...

Little is known about the properties of GABA receptors in the amphibian brain. The GABA(A) receptor is widespread in the mammalian brain, and can be specifically labeled with the receptor agonist [3H]muscimol. The binding of [3H]muscimol to membrane preparations from the brain of the bullfrog, Rana catesbeiana, was investigated in kinetic, saturation, and inhibition experiments to determine whe...

N,N'-Dicyclopentyl-2-methylsulfanyl-5-nitro-pyrimidine-4,6-diamine (GS39783) and structurally related compounds are described as novel allosteric enhancers of GABA(B) receptor function. They potentiate GABA-stimulated guanosine 5'-O-(3-[35S]thio)triphosphate ([35S]GTPgammaS) binding to membranes from a GABA(B)(1b/2)-expressing Chinese hamster ovary cell line at low micromolar concentrations, bu...

The inhibitory actions of picrotoxin (PTX) and zinc on the GABAC receptor in acutely isolated catfish cone horizontal cells were studied and compared using the whole-cell patch clamp technique. PTX blocked the GABAC current elicited by 30 microM GABA with IC50 = 0.64 microM. Over a PTX concentration range of 1-100 microM, simultaneous application of PTX with GABA (30 microM) produced current tr...

The GABA(B) receptor agonist baclofen enhances the epileptiform activity induced by 4-aminopyridine (4AP) in juvenile rat hippocampal slices. In this study, we used a similar experimental approach (i.e., field potential, intracellular, and [K+]o recordings in the CA3 area of slices obtained from 15-23-day-old rats) to establish whether antagonizing GABA(B) receptors could exert opposite (presum...

Neurons in the central amygdala express two distinct types of ionotropic GABA receptor. One is the classical GABA(A) receptor that is blocked by low concentrations of bicuculline and positively modulated by benzodiazepines. The other is a novel type of ionotropic GABA receptor that is less sensitive to bicuculline but blocked by the GABA(C) receptor antagonist (1,2,5,6-tetrohydropyridine-4-yl) ...