Emerald Jewel Wasp Venom Adenosine Deaminase Antagonizes Purinergic Signaling in the Cockroach Brain

Abstract

Ampulex compressa injects venom directly into the cerebral ganglia of the cockroach (Periplaneta americana) to induce a reversable, but long‐term compliant state of hypokinesia, marked by an increase in escape threshold and a decrease in spontaneous walking. The venom is not paralytic as stung cockroaches can still stand, groom, eat and drink, and can even run if aggressively provoked. The venom is also not necrotic or cytotoxic, and despite its long‐lasting duration the venom’s effects are reversible, as the escape response returns to normal after several days. Previous work involved generation of a comprehensive venom apparatus transcriptome and venom proteome or “venome” and described several interesting signaling pathways that appear to be targeted by venom components. This includes adenosine deaminase (ADA), which may act to antagonize purinergic signaling in the brain.The substrates of venom ADA, adenosine (Ado) and adenosine monophosphate (AMP), are also the activating ligands of the cockroach adenosine receptor (AdoR). We hypothesize that the presence of ADA at the site of injection can reduce cell damage‐induced signaling by clearing Ado and AMP released from compromised cells. We have cloned, expressed, and characterized both venom ADA and cockroach brain AdoR and show that the presence of venom ADA can attenuate Ado induced calcium signaling in vitro. Antagonizing ADA or AdoR in vivo did not alter locomotory behavior. Thus, the action of ADA in the venom may be more neuroprotective than inhibitory of specific behaviors as is the case with other venom components.