Effects of the Areca nut constituents arecaidine and guvacine on the action of GABA in the cat central nervous system

Abstract

Arecaidine and guvacine, constituents of the nut of Areca catechu, inhibited the uptake of GABA and β-alanine, but not that of glycine, by slices of cat spinal cord. In cats anaesthetised with pentobarbitone, electrophoretic arecaidine enhanced the inhibitory actions of GABA and β-alanine, but not those of glycine or taurine, on the firing of spinal neurones. Similarly, electrophoretic guvacine enhanced the inhibition of spinal neurones by GABA but not that by glycine. The uptake of GABA by slices of cat cerebellum was inhibited by arecaidine, and the effect of electrophoretic GABA on the firing of cerebellar Purkinje cells was enhanced by electrophoretic arecaidine. When administered intravenously arecaidine failed to affect synaptic inhibitions considered to be mediated by GABA. Intravenous arecaidine had no effect on either spinal prolonged (presynaptic) inhibition (20 mg/kg), dorsal root potentials (20 mg/kg) or basket cell inhibition of Purkinje cells (250 mg/kg), although topical arecaidine (6.6–10 × 10 −3 M) blocked this latter inhibition. Large doses of arecaidine (1 g/kg subcutaneous) marginally reduced the lethal effects of bicuculline in mice but appeared to have little or no anticonvulsant activity.