AN EPILEPTOGENIC PEPTIDE FROM THE SEA ANEMONE Bunodosoma cangicum

Campêlo, P.A.; Santana, A.N.C.; Paiva, C.N.; Cavalheiro, E.A.; Ricart, C.A.O.; Cunha, R.B.; Treptow, W.L.; Sousa, M.V.; Cardi, B.A.;  Carvalho, K.M.

Laboratório de Neurofarmacologia, Universidade Estadual do Ceará, Fortaleza, CE and Universidade de Brasília, DF, Brazil.

Objectives: Sea anemones tentacles release toxins which may be used in the capture of prey or to protect then from predators. Several polypeptides with action on the voltage-sensitive sodium channel have been isolated from anemones. In this study, we demonstrated the isolation, the epileptogenic effects and the sequence of a new peptide (cangitoxin, CGX) from the anemone Bunodosoma cangicum.

Methods and Results: The specimens were immersed in distilled water (1:2, w:v) (30 min) and the suspension containing the discharged nematocysts was fractionated by HPLC using a C₁₈ column (25x250 mm)(5 ml/min) (acetonitrile 0-40%, 30 min). The effluent containing the peptide was lyophilized and stored at -80°C. The amino acid sequence (Edman, 1950) of CGX, performed by an Applied Biosystems sequencer, was GVACRCDSDGPTVRGNSLSGTLWLTGGCPSGWH NCRGSGPFIGYCCKK. Only CGX sequence and those of BgII and BcIII, contain Arg-05, Tre-12, Arg-35, Ser-37 and Fen-40, constituting a new subclass of Type 1 peptides. It is the only that joins Thr-12 and Val-13 in the region that interact with the sodium channel suggesting new peculiarities in the mechanism of action of CGX. The electroencephalographic recording (EEG) alterations following an intra hippocampal injection of CGX into the rat brain showed important seizure periods that evolved to status epilepticus that lasted 8-12 hr.

Conclusions:The epileptogenic effects of CGX are very similar to those of the acute phase of the pilocarpine model of temporal lobe epilepsy and they suggest that it may be a tool to develop a new experimental model of status epilepticus, opening new perspectives in the field of the sea anemone toxin study.

CORRESPONDENCE TO:

Patricia Campêlo do Amaral, Rua das Oiticicas - 659 Bloco 1B Apto.103, Fortaleza, CE, CEP: 60743-790, Brasil, Email: patricia.campelo@bol.com.br