Perinatal hypoxia: different effects of the inhibitors of GABA transporters GAT1 and GAT3 on the initial velocity of [3H]GABA uptake by cortical, hippocampal, and thalamic nerve terminals

Abstract

AimTo analyze the effects of highly selective blocker GAT1, NO-711, and substrate inhibitor GAT3, β-alanine, on the initial velocity of [3H]GABA uptake by cortical, hippocampal, and thalamic nerve terminals (synaptosomes) after perinatal hypoxia.MethodsAnimals were divided into two groups: control (n = 17) and hypoxia (n = 12). Rats in the hypoxia group underwent hypoxia and seizures (airtight chamber, 4% O2 and 96% N2) at the age of 10-12 postnatal days and were used in the experiments 8-9 weeks after hypoxia.ResultsIn cortical synaptosomes, the effects of NO-711 (30 μΜ) and β-alanine (100 μΜ) on [3H]GABA uptake were similar in control and hypoxia groups. In hippocampal synaptosomes, NO-711 inhibited 84.3% of the initial velocity of [3H]GABA uptake in normal conditions and 80.1% after hypoxia, whereas the effect of β-alanine was increased after hypoxia from 14.4% to 22.1%. In thalamic synaptosomes, the effect of NO-711 was decreased by 79.6% in controls and by 70.9% in hypoxia group, whereas the effect of β-alanine was increased after hypoxia from 20.2% to 30.2%.ConclusionsThe effectiveness of β-alanine to influence GABA uptake was increased in hippocampal and thalamic nerve terminals as a result of perinatal hypoxia and the effectiveness of NO-711 in thalamic nerve terminals was decreased. These results may indicate changes in the ratio of active GAT1/GAT3 expressed in the plasma membrane of nerve terminals after perinatal hypoxia. We showed a possibility to modulate non-GAT1 GABA transporter activity in different brain regions by exogenous and endogenous β-alanine.

Synthesis of new fluorinated analogs of GABA, Pregabalin bioisosteres, and their effects on [3H]GABA uptake by rat brain nerve terminals

“…[1][2][3] After release, GABA is rapidly removed from the extracellular space by high-affinity sodium-and chloride-dependent GABA transporters, which terminate inhibitory synaptic transmission. [4][5][6] GABA transporters are responsible for the maintenance of proper extracellular concentration of GABA between episodes of exocytotic release. Four types of GABA transporters are expressed in the plasma membrane of neurons and glial cells, that is, GAT1, GAT2, GAT3, and GAT4, which belong to the SLC6 superfamily of Na + -dependent transporters, the activity of which is regulated by the extracellular Na + and Cl À levels.…”

Permanent dynamic transporter-mediated turnover of glutamate across the plasma membrane of presynaptic nerve terminals: arguments in favor and against

“…GABA, glycine, and possibly dopamine, whereas the physiological significance of these gradients is different from that of glutamate. It is so because in our experiments, the extracellular level of [ 3 H]GABA in synaptosomes is also maintained at a definite and non-negligible level (Pozdnyakova et al, 2014;Borisova et al, 2015). The extracellular level of [ 14 C]glycine is unstable, presumably because of its very intensive diffusion through the plasma membrane (unpublished data).…”

Glutamate transport in rat cerebral hemisphere nerve terminals under conditions of deep and profound hypothermia

“…Радіоактивність визначали на сцинтиляційному лічильнику «Tracor Analytic Delta 300» (США) зі сцинтиля-ційною сумішшю ACS (aqueous counting scintillate -сцинтиляційна рідина для водних зраз-ків) (1,5 мл) [9,25,29]. Дані одержували неза-лежними експериментами, що повторювалися тричі з різними препаратами синаптосом.…”