Antipsychotic effects of ethanol extract of Blighia sapida (Sapindaecea) stem bark on pharmacological models of psychosis in Swiss mice

Abstract

Background: Blighia sapida is a common plant consumed as vegetable in southern part of Nigeria. The ackee plant has a long history of use as a medicinal plant by several ethnic groups to treat a wide variety of Central Nervous System (CNS) disorders. The present study was designed to evaluate the antipsychotic effect of ethanol extract of Blighia sapida (Sapindaecea) stem bark in ameliorating psychotic features in mice. Materials and methods: Graded doses of ethanol extract of Blighia sapida (EEBS) (10, 20,40, 80 mg/ kg, i.p) were administered 30 minutes prior to apormorphine (1 mg/kg, i.p) or ketamine (10 mg/ kg, i.p). The animals were subsequently subjected to forced swim test to determine the effect of EEBS on ketamine enhanced immobility. Catalepsy and ptosis in the experimental mouse model were also assessed for probable side effects associated with antipsychotics. Doses of EEBS being tested and haloperidol (1 mg/kg) were administered intraperitoneal^ to animals (i.p) 30 minutes prior to the catalepsy and ptosis observation. Catalepsy was measured using the bar test, ptosis for each animal was evaluated in a transparent observation chamber at 30-, 60-, and 90-minutes post-treatment with EEBS or haloperidol. Results: Ethanol extract of Blighia sapida stem bark (20, 40, 80 mg/kg, i.p) significantly decreased stereotyped behaviours induced by apomorphine (1 mg/kg, i.p) and ketamine (1 Omg/kg, i.p) in a dose-dependent manner, as 10 mg/kg EEBS failed to significantly inhibit ketamine induced stereotyped behaviours. EEBS showed differential effects against the ketamine induced hyperactivity compared to negative control. EEBS significantly (p< 0.05) reduced the ketamine enhanced immobility in the forced swim test and did not show extra-pyramidal side effects in the bar test of catalepsy. EEBS at higher doses induced ptosis that is commonly observed with most antipsychotics.