Evaluation of Anxiolytic and Antidepressant-like Activity of Aqueous Leaf Extract of Nymphaea Lotus Linn. in Mice

The search for psychoactive plants possessing therapeutic potential in the treatment of anxiety and depression has attracted growing interest. One such plant, Nymphaea lotus (commonly known as water lily), is used in traditional medicine for analgesic and sedative effects. The present study sought to assess the anti-anxiety and antidepressant activities of crude leaf extract of N. lotus and determine possible mechanisms of action. Barbiturate sleep induction, rota-rod, light/dark box, elevated plus maze, forced swimming test (FST) and open field test (OFT) were conducted. Male Albino Swiss mice were treated orally with vehicle 10 mL/kg, imipramine 15 mg/kg (reference drug in the FST), diazepam 1 or 5 mg/kg (reference drug in the OFT) or N. lotus extract (CEN) 20, 60 or 180 mg/kg. Mice were pretreated with p-chlorophenylalanine methyl ester (PCPA) 100 mg/kg, α-methyl-p-tyrosine (AMPT) 100 mg/kg, prazosin (PRAZ) 0.5 mg/kg or yohimbine (YOH) 1 mg/kg prior to oral administration of vehicle 10 mL/kg or CEN 20 mg/kg to determine potential mechanisms of action. Monoamine oxidase (MAO) assay and quantification of brain derived neurotrophic factor (BDNF) were performed. CEN potentiated sodium pentobarbital-induced hypnotic effect and anxiolytic-like effect without altering immobility time in FST. Both MAO activity and BDNF level remained unchanged. These results suggest anxiolytic-like effect of CEN and involvement of noradrenergic mechanism due to the blockade of anxiolytic-like effect by AMPT and PRAZ.