Voltage- and use-dependent inhibition by amphetamine of field potentials and Na⁺ current in rat nucleus accumbens neurons

The psychostimulant amphetamine (AMPH) is known to act as an indirect dopamine agonist by promoting dopamine release. Here we demonstrate direct AMPH inhibition of field potentials and Na⁺ currents in rat nucleus aocumbens (NAc) neurons. The experiments were done with field potential recordings from NAc slices and whole-cell recordings from isolated NAc neurons. In NAc slices, AMPH inhibited the field potentials. The inhibition increased when the NAc neurons were depolarized with higher extracellular K⁺ or when the field potentials were evoked at a higher rate. In isolated NAc neurons, AMPH inhibited the Na⁺ currents. The inhibition increased when Na⁺ currents were activated from more depolarized holding potentials or were activated more frequently. The voltage- and use-dependent inhibition of field potentials and Na⁺ currents by AMPH suggests a similar mechanism of AMPH action with local anesthetics and antiarrhythmic drugs.