Investigation of Antidepressant, Anxiolytic and Sedative Activities of the Aqueous Leaf Extract of Musa sapientum Linn. (Banana; Musaceae)

Datura stramonium abrogates depression- and anxiety-like disorders in mice: possible involvement of monoaminergic pathways in its antidepressant activity

OBJECTIVES

Ethno-botanical surveys uncovered the use of Datura stramonium in the management of mental health abnormalities. Antidepressant- and anxiolytic-like activities of hydroethanol leaf extract of D. stramonium (HLDS) in mice and its possible mechanism of action were investigated in this study.

METHODS

The hole-board test (HBT), open field test (OFT), elevated plus maze test (EPMT), and social interaction test (SIT) were used to investigate the anxiolytic-like activity while forced swim test (FST) and tail suspension test (TST) were employed for the antidepressant effect. Mice were pre-treated orally with purified water (10 mL/kg), bromazepam (1 mg/kg), fluoxetine (20 mg/kg) and D. stramonium (25, 50, 100 and 200 mg/kg). One hour post-treatment, mice were subjected to the various tests.

RESULTS

In HBT, D. stramonium increased the head dips and sectional crossings turnover. D. stramonium increased the number of square crossed and rearings/assisted rearings in OFT. DS increased the time spent in open arms of EPM. In SIT, D. stramonium increased the frequency/duration of interactions. In FST and TST, D. stramonium decreased the duration of immobility which were reversed by doxazosin (α₁ adrenoceptor antagonist) and ondasentron (5-HT₃ receptor antagonist).

CONCLUSIONS

HLDS has anxiolytic- and antidepressant-like activities through modulation of serotoninergic and adrenergic neurotransmissions.

Adrenergic α2 receptors are implicated in seizure-induced respiratory arrest in DBA/1 mice

AIMS

Sudden unexpected death in epilepsy (SUDEP) is a serious and underestimated public health burden. Both clinical and animal studies show that seizure-induced respiratory arrest (S-IRA) is the primary cause of death in SUDEP. Our previous studies demonstrated that atomoxetine, a norepinephrine reuptake inhibitor (NRI), suppresses S-IRA in DBA/1 mice, suggesting that noradrenergic neurotransmission modulates S-IRA. However, it remains unclear which adrenoceptors are implicated in S-IRA in DBA/1 mice.

MATERIALS AND METHODS

Naïve DBA/1 mice exhibit a low incidence of S-IRA, but after primed by acoustic stimulation, they become consistently susceptible to S-IRA. Atomoxetine, adrenoceptor agonists, antagonists or vehicle was intraperitoneally (i.p.) administered alone or in combination, and the effects of drug treatments on S-IRA incidence and seizure behaviors were examined.

KEY FINDINGS

The incidence of S-IRA in primed DBA/1 mice was significantly reduced by clonidine, an α2 adrenoceptor agonist, as compared with that of the vehicle control. However, compared with the vehicle control, S-IRA was not altered by cirazoline, an α1 agonist. Consistent with previous reports, atomoxetine reduced S-IRA in primed DBA/1 mice. The suppressing effect of atomoxetine on S-IRA was prevented by injection of an α2 adrenoceptor antagonist, yohimbine or atipamezole, but not by prazosin, an α1 antagonist. Administration of α1 or α2 antagonists alone did not promote the incidence of S-IRA in nonprimed DBA/1 mice.

SIGNIFICANCE

These data demonstrate that noradrenergic neurotransmission modulates S-IRA predominantly via α2 adrenoceptors in DBA/1 mice, indicating that selective activation of α2 adrenoceptors can potentially prevent SUDEP.

Anxiolytic- and antidepressant-like activities of hydroethanol leaf extract of Newbouldia laevis (P.Beauv.) Seem. (Bignoniaceae) in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Newbouldia laevis (Bignoniaceae) is a woody tropical plant commonly found in southwest Nigeria. Ethnobotanical survey and literature revealed its application in the management of CNS disorders e.g. psychosis, insomnia, convulsions and associated anxiety and depression. This study evaluated the anxiolytic and antidepressant activities of the hydroethanol leaf extract of N. laevis in mice.

MATERIALS AND METHODS

The hole-board (HBT), elevated plus maze (EPMT), light/dark exploration (LDET), open field (OFT), social interaction (SIT) (anxiolytic activity), forced swim (FST) and tail suspension (TST) (antidepressant property) tests were employed in this investigation. Mice randomly allotted to different groups were treated orally with distilled water (10 ml/kg), diazepam (1 and 3 mg/kg), imipramine (20 mg/kg) and N. laevis (25-200 mg/kg). The mice were subjected to the various tests 60 min post-treatment.

RESULTS

In the HBT, N. laevis (25 and 100 mg/kg) increased the number of sectional crossings significantly (p < 0.05). In the OFT, N. laevis (25-200 mg/kg) increased the number of general square crossings, centre square crossings, rearings and assisted rearings (p < 0.05). In the EPMT, the extract (25 and 50 mg/kg) increased the open arms time spent, number of head dips and entry (p < 0.05). In the LDET, N. laevis increased the number of transitions at 100 and 200 mg/kg (p < 0.05). For the SIT, N. laevis (25 and 200 mg/kg) increased the frequency and duration of interaction respectively (p < 0.05). In the FST and TST, N. laevis (25-200 mg/kg) increased the latency and reduced the total duration of immobility (p < 0.05). The effect of the extract on duration of immobility was significantly reversed by sulpiride (Dopamine D₂ receptor antagonist).

CONCLUSION

The hydroethanol leaf extract of N. laevis possesses anxiolytic- and antidepressant-like activities, the later possibly mediated by dopaminergic enhancement(s).