Which neurotransmitters are considered inhibitory?

The correct choice identifies glycine and gamma-aminobutyric acid (GABA) as inhibitory neurotransmitters. Both of these neurotransmitters play crucial roles in the central nervous system by hyperpolarizing neurons, making it less likely for them to fire action potentials.

GABA is the main inhibitory neurotransmitter in the brain. When GABA binds to its receptors, it typically allows chloride ions to enter the neuron, leading to hyperpolarization. This process dampens the excitatory signals and helps to regulate neuronal excitability, making it essential for maintaining a balance between excitation and inhibition in the brain.

Similarly, glycine functions primarily in the spinal cord and brainstem, acting similarly to GABA by facilitating the entry of chloride ions into the neuron, further contributing to inhibitory effects. This inhibitory action is vital for motor control and reflexes.

Understanding these neurotransmitters highlights the importance of inhibitory signaling in preventing excessive neuronal activity, which can result in conditions like anxiety disorders or epilepsy when disrupted.