DIELDRIN AND PICROTOXININ MODULATION OF GABA(A) RECEPTOR SINGLE CHANNELS

THE insecticide dieldrin is known to suppress the GABA(A) receptor-cha nnel complex in a manner similar to that of picrotoxin. To elucidate t he more detailed mechanisms of dieldrin and picrotoxin interactions wi th the GABA system, single-channel patch clamp experiments were perfor med using rat dorsal root ganglion neurons in primary culture. Dieldri n did not alter the open time distribution and mean current amplitude or the distribution of burst duration and the mean burst duration. How ever, the mean closed time was prolonged indicating that dieldrin decr eased the channel open probability. Previous studies have demonstrated that dieldrin and picrotoxin share the common binding site on the GAB A receptor. Thus, the effects of picrotoxinin on the GABA(A) receptor single channels were also examined. Dieldrin and picrotoxinin had simi lar effects at the single-channel level. These changes of single-chann el parameters explain the suppressive effects of these chemicals on GA BA-induced whole-cell currents. (C) 1998 Lippincott Williams & Wilkins .