Tabernaemontana arborea and ibogaine induce paroxysmal EEG activity in freely moving mice Involvement of serotonin 5-HT
Several Apocynaceae species, most notably Tabernanthe iboga, Voacanga africana and many Tabernaemontana species, produce ibogan-type alkaloids. Although a large amount of information exists about the Tabernaemontana genus, knowledge concerning chemistry and biological activity remains lacking for several species, especially related to their effects on the central nervous system (CNS). The aim of this study was to evaluate the effect of Tabernaemontana arborea Rose ex J.D.Sm. (T. arborea) hydroalcoholic extract (30, 56.2 and 100 mgkg, i.p.) and two of its main alkaloids (ibogaine and voacangine, 30 mgkg, i.p.) on electroencephalographic (EEG) activity alone and in the presence of the chemical convulsant agent pentylenetetrazole (PTZ, 85 mgkg, i.p.) in mice. EEG spectral power analysis showed that T. arborea extract (56.2 and 100 mgkg) and ibogaine (30 mgkg, i.p.) promoted a significant increase in the relative power of the delta band and a significant reduction in alpha band values, denoting a CNS depressant effect. Voacangine (30 mgkg, i.p.) provoked an EEG flattening pattern. The PTZ-induced seizures were not modified in the presence of T. arborea, ibogaine, or voacangine. However, sudden death was observed in mice treated with T. arborea extract at 100 mgkg, i.p., combined with PTZ. Because T. arborea extract (100 mgkg, i.p.) and ibogaine (30 mgkg, i.p.), but not voacangine (30 mgkg, i.p.), induced paroxysmal activity in the EEG, both were explored in the presence of a serotonin 5-HT