Clozapine activates AMP-activated protein kinase (AMPK) in C2C12 myotube cells and stimulates glucose uptake

Aims: Clozapine has previously been implicated in the dysregulation of energy balance and glucose metabolism in the central nervous system, but its effects in the periphery have yet to be thoroughly elucidated. The objective of this study was to characterize the effects of clozapine on AMP-activated protein kinase (AMPK) activity in the skeletal muscles. Main methods: Myotube C2C12 cells were incubated under control conditions, or with clozapine. Expression levels of phosphorylation status of AMPK and its direct downstream Acetyl-CoA carboxylase (ACC) were analyzed by Western blot. Intracellular calcium concentration was measured with calcium indicator dye, fluo-3. AM. 2-deoxyglucose uptake was assessed via the scintillation count. Key findings: We reported that clozapine activated AMPK in mouse C2C12 myotubes and also stimulated glucose uptake. Clozapine also increased intracellular calcium concentrations of C2C12 cells, and pretreatment with either ethylenediaminetetraacetic acid (EDTA), an extracellular calcium chelator, or 1.8-naphthoylene benzimidazole-3-carboxylic acid (STO-609), a Ca²⁺/calmodulin-dependent protein kinase kinase (CaMKK) inhibitor, blocked clozapine-induced AMPK activation. Significance: These results demonstrate that clozapine increases glucose uptake through CaMKK-AMPK pathway in myotube C2C12 cells.