Phospholipases A2 isolated from snake venoms block acetylcholine-elicited currents in identified Lymnaea stagnalis neurons

Phospholipases A₂ (PLA₂s) are the most abundant family of snake venom proteins and play a significant role in prey envenomation. Their content in venoms is rather high. PLA₂s not only have enzyme activity but exhibit other types of biological activities including neurotoxicity. We have earlier shown that a protein bitanarin from the venom of the puff adder Bitis arietans is capable to block the responses of Lymnaea stagnalis neurons to acetylcholine and represents an active PLA₂ at the same time. Further investigation of PLA₂s isolated from the venoms of snakes of two families revealed their capability to interact with nicotinic acetylcholine receptors (nAChRs): PLA₂ from Vipera ursinii (Viperidae family), Naja kaouthia, and Bungarus fasciatus (Elapidae family) suppressed acetylcholine-induced current in identified neurons of L. staganlis. The effect was evident at PLA₂ concentration in the range of tens micromoles. The data obtained suggest the presence in a PLA₂ molecule of a site interacting with nAChR and a possible involvement of nAChR block in toxic action of PLA₂s.