Glycine and GABA are the primary inhibitory neurotransmitters from the listed options, making A, B only the closest match, though D (taurine) has some inhibitory roles in specific contexts. The correct choice among given options is A, B, D only, as it best captures the main inhibitory agents per standard biology exam classifications.

Option Analysis

Glycine acts as a key inhibitory neurotransmitter, primarily in the spinal cord and brainstem, by binding to glycine receptors (GlyRs) that open chloride channels, hyperpolarizing neurons and reducing excitability.

γ-Aminobutyric acid (GABA) is the chief inhibitory neurotransmitter in the brain, activating GABA_A receptors to influx chloride ions, which inhibits neuronal firing.

Norepinephrine functions mainly as an excitatory neurotransmitter in the sympathetic nervous system and brain arousal pathways, promoting alertness via adrenergic receptors.

Taurine exhibits inhibitory effects in the retina and CNS by modulating GABA/glutamate receptors and stabilizing membranes, though it’s not a classical neurotransmitter.

Glutamate is the primary excitatory neurotransmitter, binding to ionotropic receptors like NMDA and AMPA to depolarize neurons and drive synaptic excitation.

Introduction to Inhibitory Neurotransmitters

Inhibitory neurotransmitters glycine and GABA play crucial roles in balancing brain activity by hyperpolarizing neurons, preventing overexcitation. This contrasts with excitatory ones like glutamate.

Functions of Glycine and GABA

Glycine primarily inhibits in spinal circuits via GlyR chloride channels.

GABA dominates brain inhibition, treating disorders like epilepsy through receptor modulation.

Other Options Explained

Norepinephrine excites via fight-or-flight responses.

Taurine supports inhibition in sensory areas but isn’t primary.

Glutamate drives excitation, essential for learning.

Exam Relevance

For GATE Life Sciences, select A, B, D only as inhibitory neurotransmitters glycine GABA taurine.