Effects of the Oxadiazine Insecticide, Indoxacarb, on Voltage-Gated Sodium Channels in Dorsal Unpaired Median Neurons Isolated from the American Cockroach, Periplaneta americana (Linnaeus) (Orhoptera: Blattidae)

Abstract

The effects of the oxadiazine insecticide, indoxacarb, and its N-decarbomethoxylated metabolite (DCJW) on voltage-gated sodium channels in dorsal unpaired median (DUM) neurons isolated from American cockroach, Periplaneta americana, were studied using a whole-cell patch clamp technique. Both indoxacarb and DCJW suppressed the peak sodium currents in a time dependent manner. Indoxacarb and DCJW at 1 μM blocked the sodium currents to 39.0±5.9% (n=3) and 3.2±0.2% (n=3) of the control after 25 min of bath application. Thus, indoxacarb was less potent than DCJW in blocking sodium currents in cockroach DUM neurons. However, the potency of indoxacarb in insect neurons observed in the present study was at least 100 times higher than that in rat dorsal root ganglion neurons reported previously.