What are the different nicotinic receptor subtypes?

• A. Skeletal muscle, peripheral neuronal, and central neuronal
• B. Peripheral neuronal and central neuronal only
• C. Skeletal muscle only
• D. Central nervous system only

Answer: (A)

Nicotinic receptors are ligand-gated ion channels with tissue-specific subtypes that arise from different subunit compositions and localizations. In skeletal muscle, the muscle-type nAChR sits at the neuromuscular junction and drives rapid depolarization that triggers muscle contraction. In the peripheral nervous system, nAChRs are present in autonomic ganglia and come in subtypes like α3β4 and α3β2, shaping autonomic neurotransmitter release and signaling. In the central nervous system, brain nAChRs include subtypes such as α4β2 and α7, which modulate neuronal excitability and cognitive functions. Because the question asks for the different nicotinic receptor subtypes, all three tissue categories—skeletal muscle, peripheral neuronal (autonomic ganglia), and central neuronal—need to be recognized. The other options miss one or more of these regions, so they don’t capture the full picture of nicotinic receptor diversity.