Glycyrrhiza glabra as an adjuvant in treatment of Parkinsonism and depression
The treatment of Parkinson's disease and depression is still far from satisfactory. The objective of the present study was to evaluate the potential of methanolic extract of Glycyrrhiza glabra (GGE) as an adjuvant in treatment of Parkinson's disease and depression. In acute study GGE (30 and 100mg/kg i.p.) significantly inhibited haloperidol-induced catalepsy in mice in dose dependent manner. Similar inhibitory effect of GGE was also observed in chronic study (15 days) indicating that there was no development of tolerance. The GGE reduced duration of catalepsy also. In mice treated with GGE (30mg/kg i.p.) for 6 days and given haloperidol on 7th day showed significantly (P<0.05) diminished catalepsy and the higher dose completely inhibited catalepsy. This indicated its ability to retain the anticataleptic effect. Further GGE in both the doses increased apomorphine-induced sniffing indicating stimulation of Dopamine D1 receptor stimulation.
In the tail suspension test, a widely used animal model of depression, GGE (30 and 100mg/kg i.p.) significantly reduced the duration of immobility and lower dose was found more effective. GGE significantly increased the antidepressant activity of imipramine (15mg/kg) and fluoxetine (20mg/kg). GGE (30mg/kg) also inhibited eticlopride-induced increase in the duration of immobility in tail suspension test (F5,24=50.04, P=0.0001) indicating dopamine D2/D3 receptor stimulation. The observations indicate that Glycyrrhiza glabra has a good potential as an adjuvant of anti-Parkinsonian and antidepressant drugs.
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