Which neurotransmitter is released at parasympathetic postganglionic synapses?

Which neurotransmitter is released at parasympathetic postganglionic synapses?

• A. Norepinephrine
• B. Dopamine
• C. Acetylcholine
• D. GABA

Answer: (C)

Parasympathetic postganglionic neurons are cholinergic, meaning they release acetylcholine at their synapses with target tissues. This acetylcholine binds to muscarinic receptors on effectors to mediate rest-and-digest effects, such as slowing the heart rate and increasing digestive activity. The other options don’t fit because norepinephrine is the main transmitter of most sympathetic postganglionic fibers, not parasympathetic; dopamine isn’t used as a standard autonomic postganglionic transmitter; and GABA serves primarily as an inhibitory neurotransmitter in the central nervous system. So acetylcholine is the transmitter released at parasympathetic postganglionic synapses.

Parasympathetic postganglionic neurons are cholinergic, meaning they release acetylcholine at their synapses with target tissues. This acetylcholine binds to muscarinic receptors on effectors to mediate rest-and-digest effects, such as slowing the heart rate and increasing digestive activity. The other options don’t fit because norepinephrine is the main transmitter of most sympathetic postganglionic fibers, not parasympathetic; dopamine isn’t used as a standard autonomic postganglionic transmitter; and GABA serves primarily as an inhibitory neurotransmitter in the central nervous system. So acetylcholine is the transmitter released at parasympathetic postganglionic synapses.