Insecticidal properties of 3-aminopropyl(methyl)phosphinic acid and its effect on K +-evoked release of acetylcholine from cockroach synaptosomes

Abstract

3-Aminopropyl(methyl)phosphinic acid (APMP), a potent agonist of mammalian GABA B receptors, caused prostration in houseflies ( Musca domestica L.) on injection into their thoraces, with an ED 50 value of 0.42 μg/fly. The 48-h LD 50 values of APMP were estimated to be 0.45 and 5.6 μg/fly in the presence and absence of piperonyl butoxide, a mixed-function oxidase inhibitor, respectively. Analogues of APMP, bearing a longer or shorter side chain by a CH 2 unit, or a phenyl group in the place of the methyl group, were without effects. In perfusion assays with synaptosomes prepared from the thoracic/abdominal nerve cords of cockroaches ( Periplaneta americana L.), 1 mM APMP reduced K +-evoked acetylcholine release to 10.4% of the control. These findings indicate that the physiologically important site of action of APMP, which might be implicated in neurotransmitter release, is present in insect neurons.