Neuropharmacologic effects of whole plant extract of Digitaria horizontalis in mice

Abstract

Digitaria horizontalis Willd (Poaccae) is used in traditional African medicine in the treatment of various ailment including neurological disorders. In this study, an attempt was made to investigate the neuropharmacological activities of the hydrocthanolic whole plant extract of Digitaria horizontal is (DM) in mice. Methodology: DH (12.5, 25, 50 or 100 mg/kg, p.o.) was administered 1 h before the behavioural assays. The formalin, open field, picrotoxin/ pentylenetetrazol, elevated plus maze (EPM), hexobarbitone-induced hypnosis and tail suspension tests (TST) were used to assay for antinociceptive, spontaneous locomotor, anticonvulsant, anxiolytic, hypnotic and antidepressant activities of DM in mice, respectively. Results: Intraplantar injection of formalin (1% in saline, 20 µl) into the right hind paw induced biphasic nociceptive behaviours which was prevented by DH pretreatment in both the early and late phases, DH induced antinociception was reversed by naloxone (opioid receptor antagonist). No significant change in spontaneous locomotor activity in the open field test |OFT]. DH prevented the occurrence and reduced the duration of seizure in picrotoxin and pentylenetetrazol models. Conversely, DM failed to increase the time spent by mice in open arms of the EPM. DM reduced latency to sleep but not the duration of sleep in hypnotic assay. Interestingly, DH dose dependency and significantly reduced the immobility time in TST in mice. DM showed potent antioxidant capacity due to its richness in phenolic, flavonoid, and tannins. DH possesses wide margin of safety, the extract up to 4000 mg/kg, p.o. did not induce mortality, however, a median lethal dose (LD50) of 1259 mg/kg was obtained following intraperitoneal injection. Conclusion: Findings from this study showed that D. horizontal is possesses antinociceptive, sedative and antidepressant effects. The anticonvulsant activity could involve enhancement of GABAergic