Arecoline inhibits and destabilizes agrin-induced acetylcholine receptor cluster formation in C2C12 myotubes

Areca nut (Areca catechu) is chewed as a medical and psychoactive food by roughly 10% of the world population. Areca nut chewing may lead to low birth weight, premature delivery and impaired muscle development. Our previous study showed that arecoline, a major alkaloid in the areca nut, inhibited the myogenic differentiation of C2C12 myoblastic cells. The clustering of acetylcholine receptors (AChRs) in the postsynaptic membrane at the neuromuscular junction (NMJ) by agrin, a signaling protein released by motor neurons, is critical for the development of functional muscles. Here, we further investigate whether arecoline affects the AChR clustering using cultured C2C12 myotubes. Rhodamine-conjugated α-bungarotoxin was used to detect the presence of AChR clusters. Our results showed that arecoline inhibited the formation of agrin-induced AChR clusters and destabilized agrin-induced or spontaneous AChR cluster formation. In addition, arecoline inhibited the expression of myogenin in C2C12 myotubes. These results shed light on the important role of arecoline on the detrimental effect of areca nut to muscle development.