Memory-strengthening activity of Glycyrrhiza glabra in exteroceptive and interoceptive behavioral models

In the traditional system of medicine, the roots and rhizomes of Glycyrrhiza glabra have been employed clinically for centuries for their anti-inflammatory, anti-ulcer, expectorant, antimicrobial, and anxiolytic activities. The present study was undertaken to investigate the effects of G. glabra, popularly known as liquorice (Mulathi), on learning and memory. The elevated plus-maze and passive avoidance paradigm were employed to evaluate learning and memory parameters. Three doses (75, 150, and 300 mg/kg p.o.) of aqueous extract of G. glabra were administered for 7 successive days in separate groups of mice. The dose of 150 mg/kg of the aqueous extract of liquorice significantly improved learning and memory of mice. Furthermore, this dose reversed the amnesia induced by diazepam (1 mg/kg i.p.), scopolamine (0.4 mg/kg i.p.), and ethanol (1 g/kg i.p.). Anti-inflammatory and antioxidant properties of liquorice may be contributing favorably to the memory enhancement effect. Since scopolamine-induced amnesia was reversed by liquorice, it is possible that the beneficial effect on learning and memory may be because of facilitation of cholinergic transmission in brain. However, further studies are necessitated to identify the exact mechanism of action. In the present investigation, G. glabra has shown promise as a memory enhancer in both exteroceptive and interoceptive behavioral models of memory.