Muscarinic acetylcholine receptors, also known as mAChRs, are a type of cell membrane receptor that bind to the neurotransmitter acetylcholine. They are a subclass of acetylcholine receptors and are primarily found in the nervous system and smooth muscle tissues of the body.
The name "muscarinic" is derived from the fact that these receptors were originally discovered through their ability to be activated by muscarine, a natural compound found in certain mushrooms.
There are five subtypes of muscarinic receptors, which are designated as M1, M2, M3, M4, and M5. Each subtype has a unique distribution and function within the body, but they all share a common structure and mechanism of action.
When acetylcholine binds to a muscarinic receptor, it initiates a series of intracellular signaling events that regulate various physiological processes. These include the modulation of heart rate, smooth muscle contraction in the digestive and urinary systems, glandular secretions, and the regulation of cognitive functions in the brain.
Muscarinic receptors are the primary target for drugs that act as muscarinic agonists or antagonists. Agonists activate the receptor, mimicking the effects of acetylcholine, while antagonists bind to the receptor and prevent activation by acetylcholine. These drugs have various therapeutic applications, such as in the treatment of disorders like Alzheimer's disease, Parkinson's disease, urinary incontinence, and asthma.
