Cholinergic Transmission Quiz

Methacholine is primarily used for the treatment of urinary bladder disorders

Methacholine is given by inhalation for the diagnosis of bronchial hyper-reactivity

Muscarinic receptor agonists can be classified into two classes: synthetic choline esters and cholinomimetic alkaloids

Bethanechol is contraindicated for the treatment of urine retention in the presence of organic obstruction

M1 and M4 receptor stimulation is of therapeutic interest for Alzheimer’s dementia and schizophrenia

Cholinergic Transmission in the Autonomic Nervous System

Acetylcholine (ACh) mediates neurotransmission at two distinct sites: ganglia and parasympathetic nerve endings.
In ganglia, ACh acts on neuronal nicotinic receptors (N).
In parasympathetic nerve endings, ACh acts on muscarinic receptors (M).

Nicotinic ACh Receptors

Nicotinic ACh receptors are ligand-gated cation channels, permeable to sodium and calcium ions.
Activation of these receptors causes rapid depolarization.
There are two categories of nicotinic ACh receptors:
- Neuronal nicotinic receptors (N)
- Muscular nicotinic receptors (N)

Muscarinic ACh Receptors

Five distinct subtypes of muscarinic ACh receptors exist.
Different subtypes exist in the same organ.
M3 is predominantly present in peripheral tissues.
Muscarinic receptors may be present in locations without parasympathetic innervation, such as blood vessels.
All muscarinic receptors are G-protein coupled.
There are no highly selective agonists or antagonists for muscarinic receptors.
Note: In contrast to muscarinic receptors, different subtypes of nicotinic receptors have selective agonists and antagonists.

Test your knowledge of cholinergic transmission in the autonomic nervous system and the role of acetylcholine in neurotransmission at different sites. This quiz covers topics such as cholinergic agonists, nicotinic and muscarinic receptors, and the classification of neuronal nicotinic receptors.