Muscarinic acetylcholine receptor stimulation induces expression of the activity-regulated cytoskeleton-associated gene (ARC).

Muscarinic acetylcholine receptors (mAChR) are involved in learning and memory but their molecular function in these processes is not fully understood. In this study, the signal transduction pathway coupling mAChR activation to induction of the activity-regulated cytoskeleton-associated gene (ARC) was examined. ARC was first identified as an effector immediate early gene induced by neuronal activity and ARC protein is thought to play a role in synaptic plasticity. In rats, intraperitoneal injection of pilocarpine, a potent agonist of mAChR, led to increased ARC expression in the brain. In human SH-SY5Y neuroblastoma cells mAChR stimulation with carbachol caused a rapid and robust induction of ARC expression. This effect was inhibited by atropine, a nonselective muscarinic receptor antagonist as well as by M1/M3 subtype-specific antagonists. Analysis of mAChR downstream effectors revealed that protein kinase C (PKC) and tyrosine kinases of the src family are key molecules in the signal cascade leading to ARC expression. Our data suggest, for the first time, that a correlation exists among mAChR-controlled signal cascades, the induction of the effector immediate early gene ARC and synaptic plasticity.