Abused inhalants enhance GABA-mediated synaptic inhibition
1Department of Anesthesia, Stanford University School of Medicine, Stanford, CA 94305-5117, USA. maciver@stanford.edu
Summary
Abused inhalants like toluene enhance inhibitory neurotransmission in the brain by increasing GABA release from nerve terminals. This mechanism, similar to anesthetics, may contribute to cognitive impairment from inhalant abuse.
Area of Science:
- Neuroscience
- Pharmacology
Background:
- Abused inhalants are prevalent among youth, acting as gateway drugs with poorly understood central nervous system effects.
- Inhalants share behavioral and chemical similarities with anesthetic drugs, suggesting a common target like GABA synapses.
Purpose of the Study:
- To investigate the neurobiological mechanisms underlying the effects of abused inhalants on the central nervous system.
- To examine the impact of abused inhalants on GABAergic synaptic transmission in the hippocampus.
Main Methods:
- Whole-cell patch clamp recordings were performed on CA1 pyramidal neurons in rat hippocampal slices.
- The study measured effects on neuronal excitability, action potential discharge, and GABA-mediated inhibitory responses.
- Specific inhalants (toluene, 1,1,1-trichloroethane, trichloroethylene) were applied in a concentration-dependent manner.
Main Results:
- Abused inhalants concentration-dependently and reversibly depressed CA1 neuronal excitability.
- This depression was mediated by enhanced GABA-ergic inhibition, indicated by reversal with a GABA receptor antagonist.
- Inhalants increased spontaneous inhibitory postsynaptic current frequency via a presynaptic action, involving intracellular calcium release.
Conclusions:
- Abused inhalants enhance GABAergic inhibition through a presynaptic mechanism involving calcium release from intracellular stores.
- This shared mechanism with inhaled anesthetics may explain altered behavioral effects, including potential disruption of learning and memory.
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