Background: Desmodium adscendens extract (DAE) is used traditionally in Ghana for the management of psychosis. The present study aimed at providing pharmacological evidence for its ethnomedical use by testing the hypothesis that an ethanolic extract of Desmodium adscendens may possess antipsychotic properties.
Methods: The primary behavioral effects of DAE on the central nervous system of mice were investigated using Irwin's test paradigm. Novelty-induced and apomorphine-induced locomotor and rearing behaviors in mice were explored in an open-field observational test system. Apomorphine-induced cage climbing test in mice was used as the antipsychotic animal model. The ability of DAE to induce catalepsy and enhance haloperidol-induced catalepsy was also investigated in mice.
Results: The DAE produced sedation, cholinergic-, and serotonergic-like effects in mice when evaluated using the Irwin's test. No lethality was observed after 24 h post-treatment. The LD50 in mice was estimated to be greater than 3000 mg/kg. The DAE significantly decreased the frequency of novelty- and apomorphine-induced rearing and locomotor activities in mice. It also significantly lowered the frequency and duration of apomorphine-induced climbing activities in mice. It did not induce any cataleptic event in naïve mice but only significantly enhanced haloperidol-induced catalepsy at a dose of 1000 mg/kg.
Conclusions: The ethanolic extract of Desmodium adscendens exhibited antipsychotic-like activities in mice. Motor side effects are only likely to develop at higher doses of the extract.
Keywords: Desmodium adscendens; antipsychotic; apomorphine; chlorpromazine; haloperidol; stereotypy.