Brain GABA metabolism after chronic ethanol consumption and withdrawal in rats

Pharmacological Antagonism of T-Type Calcium Channels Constrains Rebound Burst Firing in Two Distinct Subpopulations of GABA Neurons in the Rat Ventral Tegmental Area: Implications for α-Lipoic Acid

The ventral tegmental area (VTA) is a midbrain region highly involved in motivation and reward. A large body of work has investigated synaptic plasticity and ion channel excitability in this area, which has strong implication in drug abuse. We recently provided electrophysiological and pharmacological evidence that the Ca_V3.1 isoform of T-type voltage-gated calcium channels contributes to the excitability of VTA dopamine (DA) neurons. However, the role of T-channels in excitability of VTA gamma-amino-butyric acid (GABA) neurons remained unaddressed. Here, with a population study of rat VTA GABA neurons, we provide evidence that T-channels contribute to rebound spiking activity in two phenotypically distinct subpopulations of GABAergic neurons, each with differing electrophysiological characteristics. Additionally, we provide the first study to investigate the effect of α-lipoic acid (ALA) on ion channels in mesolimbic reward circuitry. Taken together, our population study and pharmacology experiments implicate T-channels as a target for therapies aimed at tempering VTA and mesolimbic circuit excitability.

Exposure to polychlorinated naphthalenes affects GABA-metabolizing enzymes in rat brain

There is substantial evidence that polychlorinated naphthalenes (PCNs) are widespread global environmental pollutants, which accumulate in biota. The aim of our study was to characterize the effect of prolonged PCNs exposure on γ-aminobutyric acid (GABA) metabolism in rat brain regions with a high amount of GABAergic neurons (cerebellum, brain stem and basal ganglia). PCNs mixture was administered intragastrically for 7, 14 and 21 days in a dose 10mg/kg of body weight daily, and next the activity of glutamate decarboxylase (GAD), GABA-aminotransferase (GABA-T), succinic semialdehyde dehydrogenase (SDH) and succinate dehydrogenase (SSA-DH) was assayed. PCNs administration altered all examined activities in the selected brain areas, except GAD in basal ganglia. The results suggest the correlation between PCNs action and disturbance in GABA metabolism in rat brain. Moreover, the chronic PCNs intoxication increased SDH-mediated activation of TCA cycle, and it may be a kind of protective mechanism developed in nervous tissue in response to administration of toxic compounds.