Anticonvulsant Effects of the SocialWasp Polybia ignobilis Venom on Chemically Induced Seizures. 

Alexandra Olimpio Siqueira Cunha, Márcia Renata Mortari, Luciana de Oliveira and Wagner Ferreira dos Santos.

Neurobiology and Venoms Laboratory– Department of Biology - FFCLRP/USP

In this work we describe the anticonvulsant effects of the denatured venom of the Brazilian social wasp Polybia ignobilis in rats. Venom sacs were dissecated from the wasps crushed and centrifuged at 5000 g for 10 min, the supernatant collected was added acetonitrile (1:1), boiled for 10 minutes and lyophilized. The denatured venom was then dissolved in saline 15 mM and the final solutions were then referred to as acetonitrile boiled P. ignobilis venom (PiDv). Bioassays were conducted using Male Wistar rats (200-250g), which were anaesthetized, placed in a stereotaxic frame where stainless steel guide cannulas were implanted into the lateral ventricle. The animals were allowed to recover for 5-7 days from surgery, after which they were injected with PiDv and convulsant agents in a volume of 3 ml/min. It was determined the spontaneous locomotor activity of the animals by counting the line crossings along 4 time windows (0-5; 5-10; 10-15 and 15-20 min) in the open field. A dose response curve was made with: bicuculline, picrotoxin, kainic acid and PTZ in progressive dilutions (n = 6-10/dose). Diazepam was used as positive control and saline alone was used before the convulsant drugs. Seizures were evaluated by Racine (1972) score modified by Pinel and Rovner (1978) and the latency to seizure onset was noted. Latencies were analyzed using one-way analysis of variance (ANOVA) followed by Tukey test. Anticonvulsant activity was measured as the frequency of protected animals and it was analyzed using the chi-square test (p<0.05 and p<0.001). When injected via i.c.v., PiDv inhibited the locomotor activity in first analyzed period. The injection of PiDv blocked seizures induced by i.c.v.-bicuculline 3, 1 and 0.3 mg/ml (57, 55 and 87% of the animals). Seizures induced by picrotoxin (28 mg/ml) and kainic acid (0.8 mg/ml) were also blocked by PbDv (57 e 90% of the animals, respectively), but was ineffective against seizures caused by pentylenetetrazole, applied sistemically. All the latencies to seizure of the unprotected animals were raised by PiDv pretreatment.

Conclusion: These findings inidicate that the venom of P. ignobilis might contain active neurotoxins that can be used as pharmacological sources for anticonvulsant drug design.

Financial support: CNPq.

Correspondence to: alecunha@usp.br