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

Phospholipases A 2 (PLA 2 s) are the most abundant family of snake venom proteins and play a significant role in prey envenomation. Their content in venoms is rather high. PLA 2 s 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 PLA 2 at the same time. Further investigation of PLA 2 s isolated from the venoms of snakes of two families revealed their capability to interact with nicotinic acetylcholine receptors (nAChRs): PLA 2 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 PLA 2 concentration in the range of tens micromoles. The data obtained suggest the presence in a PLA 2 molecule of a site interacting with nAChR and a possible involvement of nAChR block in toxic action of PLA 2 s.