The effect of Banisteriopsis caapi (B. caapi) on the motor deficits in the MPTP-treated common marmoset model of Parkinson's disease.

Banisteriopsis caapi (B.caapi) contains harmine, harmaline, and tetrahydroharmine, has monoamine oxidase inhibitory activity, and has reported antiparkinsonian activity in humans when imbibed as a tea; however, its effects are poorly documented. For this reason, motor function was assessed in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated common marmosets following administration of B.caapi extract (28.4-113.6mg/kg; po), harmine (0.1 and 0.3mg/kg; sc), and selegiline (10mg/kg; sc), alone or with a submaximal dose of L-3,4-dihydroxyphenylalanine (L-DOPA; 4-7mg/kg). L-DOPA reversed motor disability, increased locomotor activity, and induced moderate dyskinesia. B.caapi did not increase locomotor activity or induce dyskinesia but at 56.8 and 113.6mg/kg improved motor disability. The L-DOPA response was unaltered by co-administration of B.caapi. Harmine (0.1 and 0.3mg/kg) produced a mild improvement in motor disability without affecting locomotor activity or dyskinesia but had no effect on the L-DOPA-induced antiparkinsonian response. Selegiline (10mg/kg) alone improved motor function to the same extent as L-DOPA, but with only mild dyskinesia, and did not alter the response to L-DOPA, although dyskinesia was reduced. The findings suggest that B.caapi alone has a mild antiparkinsonian effect but does not enhance the L-DOPA response or reduce dyskinesia.