M1 receptor

The M1 receptor is a subtype of the muscarinic acetylcholine receptor, which is a type of G protein-coupled receptor (GPCR). It is primarily found in the central nervous system, particularly in the cerebral cortex, hippocampus, and striatum. The M1 receptor plays a crucial role in modulating cognitive functions, including learning and memory.

Structure

The M1 receptor is a member of the muscarinic receptor family, which consists of five subtypes: M1, M2, M3, M4, and M5. These receptors are characterized by their seven transmembrane alpha-helices, which are typical of GPCRs. The M1 receptor is encoded by the CHRM1 gene in humans.

Function

The primary function of the M1 receptor is to mediate the effects of the neurotransmitter acetylcholine in the brain. Upon binding of acetylcholine, the M1 receptor activates the Gq/11 protein, which in turn stimulates the phospholipase C (PLC) pathway. This leads to the production of inositol trisphosphate (IP3) and diacylglycerol (DAG), resulting in the release of calcium ions from intracellular stores and activation of protein kinase C (PKC).

The M1 receptor is involved in several physiological processes, including:

• Modulation of synaptic plasticity
• Enhancement of cognitive functions such as learning and memory
• Regulation of neuronal excitability

Clinical Significance

Dysfunction of the M1 receptor has been implicated in various neurological disorders, including Alzheimer's disease, schizophrenia, and Parkinson's disease. In Alzheimer's disease, there is a significant loss of cholinergic neurons, leading to reduced activation of M1 receptors, which contributes to cognitive decline.

Pharmacological agents that target the M1 receptor are being investigated for their potential therapeutic effects. Agonists of the M1 receptor may enhance cognitive function and are considered potential treatments for Alzheimer's disease and other cognitive disorders.

Pharmacology

M1 receptor agonists and antagonists are used in research to study the receptor's function and potential therapeutic applications. Some examples include:

• Agonists: Xanomeline, Talsaclidine
• Antagonists: Pirenzepine, Dicyclomine

Research

Ongoing research is focused on developing selective M1 receptor modulators that can cross the blood-brain barrier and have minimal side effects. These modulators hold promise for treating cognitive deficits in neurodegenerative diseases.

Also see

• Muscarinic acetylcholine receptor
• G protein-coupled receptor
• Acetylcholine
• Cognitive function
• Alzheimer's disease