Permethrin decreased insulin-stimulated AKT phosphorylation dependent on extracellular signal-regulated kinase-1 (ERK), but not AMP-activated protein kinase α (AMPKα), in C2C12 myotubes

- Permethrin decreased membrane GLUT4 and inhibited insulin signaling in C2C12.
- Permethrin activated ERK without AMPKα activation in C2C12 myotubes.
- Permethrin decreased AKT phosphorylation via ERK activation in C2C12 myotubes.

Previously 10 μM permethrin (38.7% cis and 59.4% trans isomers), a pyrethroid insecticide widely used in agriculture and household products for pest control, was reported to reduce insulin-stimulated glucose uptake and phosphorylation of protein kinase B (p-AKT) in C2C12 mouse myotubes. The underlying mechanisms on how permethrin decreases insulin-stimulated AKT phosphorylation, however, are unknown. Thus, the goal of this study was to determine the possible mechanism(s) through which permethrin reduced insulin-stimulated AKT phosphorylation in C2C12 myotubes. Permethrin treatment, at 10 μM, decreased insulin-stimulated membrane glucose transporter type 4 (GLUT4) and AKT phosphorylation, and increased insulin receptor substrate 1 (IRS1) Ser307 phosphorylation in the presence of insulin. The inactivation of AKT by permethrin was independent of AMPKα. ERK inactivation by U0126, however, restored insulin-stimulated AKT phosphorylation, which was decreased by permethrin treatment. These results suggest that permethrin decreased insulin-stimulated AKT phosphorylation via ERK activation, but not by AMPKα inactivation.