Our study sought to evaluate the anxiolytic and antidepressant activities of oleanolic acid as well as the neural mechanisms involved. Animal models such as barbiturate sleep-induction, light-dark box, elevated plus maze, forced swimming test, tail suspension test and open field test were conducted. Male Albino Swiss mice were treated orally with vehicle 10 mL/kg, fluoxetine 20 mg/kg, imipramine 15 mg/kg, diazepam 1 mg/kg or oleanolic acid 5-40 mg/kg. Pretreatment (intraperitoneal) of animals with pentylenetetrazole (PTZ) 20 mg/kg, 1-(2-methoxyphenyl)-4-[4- (2-phthalimido) butyl]piperazine hydrobromide (NAN-190) 0.5 mg/kg, p-chlorophenylalanine methyl ester (PCPA) 100 mg/kg or α-methyl-p-tyrosine (AMPT) 100 mg/kg, WAY100635 (WAY) 0.3 mg/kg, prazosin (PRAZ) 1 mg/kg, yohimbine 2 mg/kg as well as monoamine oxidase assay and hippocampal brain-derived neurotrophic factor (BDNF) quantification were carried out. Oleanolic acid potentiated the hypnotic effect of barbiturate and demonstrated an anxiolytic effect in both the light-dark box and elevated plus maze. This effect was not reversed by PTZ. Acute and/or chronic oral treatment of mice with oleanolic acid (5-20 mg/kg) elicited an antidepressant effect in the forced swimming test and the tail suspension test without interfering with the locomotor activity. The antidepressant effect of oleanolic acid was attenuated by NAN-190, AMPT, PCPA, WAY and PRAZ. Although monoamine oxidase activity remained unaltered by oleanolic acid, chronic administration of oleanolic acid augmented hippocampal BDNF level. These findings demonstrate multiple mechanisms of the anxiolytic and antidepressant effect of oleanolic acid.
Keywords: Oleanolic acid; antidepressant; anxiolytic; metabolic enzymes; monoamine; neurotrophic factor.
© The Author(s) 2014.