Question

Which one of the following acts as an inhibitory neurotransmitter?
A. GABA
B. Adrenaline
C. Norepinephrine
D. Acetylcholine

Answer 1

Hint: Inhibitory neurotransmitters help in producing inhibitory effects on the neuron. Inhibitory neurotransmitters function to slow down receptors on the postsynaptic membrane and diminish the effects of the action potential. Glutamate is the major excitatory transmitter of the CNS (central nervous system) and an important inhibitory transmitter is its derivative.

Complete answer:
> Option A is correct as GABA is secreted by brain cells and it is formed from glutamate, it belongs under the category of inhibitory neurotransmitter, its function is to inhibit or block nerve impulses. Its full form is Gamma-aminobutyric acid.

> Option B is incorrect because adrenaline is the hormone which is produced by the adrenal glands and it is excitatory neurotransmitters in nature. It is also considered as a hormone because it is secreted by the adrenal gland and functions outside the brain. It is also known as adrenaline.

> Option C is also incorrect because nor epinephrine which is also known as noradrenaline belongs to the type of excitatory neurotransmitter that is produced by the hypothalamus and adrenal glands. Hypo-secretion can elevate blood pressure, severe anxiety and sweating.

> Option C is also incorrect because acetylcholine belongs to the category of excitatory neurotransmitter that is released by nerve cells to transfer signals to other cells like muscles cells, ganglia, and postganglionic neurons of the sympathetic and also to parasympathetic nervous systems. Hypo-secretion can cause paralysis, body cramps, weakness of muscles, etc.

Hence, the correct answer is option (A).

Note: According to the chemical’s nature, neurotransmitters can be categorized into biogenic amines and amino acid based neurotransmitters. Adrenaline, nor-epinephrine, acetylcholine, dopamine comes under excitatory in nature and are biogenic amines whereas GABA, glutamate and glycine are amino acid based and inhibitory neurotransmitters.