Which statement correctly describes the GABA receptor types?

Which statement correctly describes the GABA receptor types?

• A. GABA-A is metabotropic; GABA-B is ionotropic
• B. GABA-A is ionotropic; GABA-B is metabotropic
• C. GABA-A is ionotropic; GABA-B is ionotropic
• D. GABA-A is metabotropic; GABA-B is metabotropic

Answer: (B)

Two main types of GABA receptors mediate inhibition in the brain, and they work through different mechanisms. GABA-A receptors are ionotropic, forming a ligand-gated chloride channel. When GABA binds, chloride ions flow into the neuron, hyperpolarizing it and producing fast, brief inhibitory postsynaptic potentials. GABA-B receptors are metabotropic, meaning they are G-protein-coupled receptors that influence ion channels and intracellular signaling through second messengers, typically opening potassium channels or reducing calcium influx, which leads to slower, longer-lasting inhibition. Therefore, the statement that GABA-A is ionotropic and GABA-B is metabotropic is the correct description. The other pairings would imply opposite or double-mechanism roles that aren’t accurate.

Two main types of GABA receptors mediate inhibition in the brain, and they work through different mechanisms. GABA-A receptors are ionotropic, forming a ligand-gated chloride channel. When GABA binds, chloride ions flow into the neuron, hyperpolarizing it and producing fast, brief inhibitory postsynaptic potentials. GABA-B receptors are metabotropic, meaning they are G-protein-coupled receptors that influence ion channels and intracellular signaling through second messengers, typically opening potassium channels or reducing calcium influx, which leads to slower, longer-lasting inhibition. Therefore, the statement that GABA-A is ionotropic and GABA-B is metabotropic is the correct description. The other pairings would imply opposite or double-mechanism roles that aren’t accurate.