Guinea Pig Anti-CHRM3 Antibody

The action of the neurotransmitter acetylcholine is mediated through two types of receptors, the ionotrophic nicotinic receptors and the metabotrophic muscarinic receptors. The muscarinic receptors belong to the superfamily of 7-TM G-protein-coupled receptors. Five subtypes of muscarinic receptors have been cloned and named m1-m5.^1-2

The muscarinic receptors are widely distributed throughout the body, but are predominantly  expressed within the parasympathetic nervous system and exerts both excitatory and inhibitory control over central and peripheral tissues.^1-2 The m3 receptor is expressed in brain, heart, urinary bladder, salivary gland and airway smooth muscle.³

Muscarinic receptors participate in a number of physiologic functions such as regulation of heart rate,  muscle contraction, cognition, sensory processing and motor control.¹ They also participate in learning and memory processing.^4-5 The m1 receptors are the most abundant muscarinic subtype in the cortex and striatum. m1 receptors were also localized in the myenteric plexus where they function as autoreceptors to enhance the release of Ach from the nerves.^6-7 m2, found in heart, is coupled to and mediates the slowing of heart rate in response to acetylcholine.^3,8 m3 controls smooth muscle contraction and its stimulation causes secretion from glandular tissues.⁹

Involvement of muscarinic receptors in apoptosis and cell growth has been reported.^10-14  m1, m3 and m5, which are coupled to Gq/11 proteins, can protect cells from undergoing apoptosis induced by DNA damage. The signaling mechanism that mediates this anti-apoptotic response is still poorly understood. However, it was recently reported that a poly-basic motif in the C-terminus tail of the m3, m1 and m5 receptors is an essential element for the anti-apoptotic response of those receptors.¹⁰

Muscarinic receptors are also capable of promoting cell proliferation in many cell types, however, the signaling pathways are yet, unclear.^11-14 In the literature, m3 was reported to be involved in mitogenesis and proliferation of different cell types. Recently, it was reported that activation of the m3 muscarinic receptor induces significant proliferation of colon and prostate cancer cells.^11-14