Neurobehavioural Mechanism of Antidepressant Effect of Methanol Stem Bark Extract of Adansonia digitata (Linn) in Tail Suspension Test in Mice

Abstract

Aim: An earlier study has demonstrated the in-vivo antidepressant effect of methanol stem bark extract of Adansonia digitata, using soxhlet extraction protocol, but there is a lack of scientific data on its neurobehavioural mechanism of action. This study, therefore, investigated its antidepressant potentials, using cold maceration method, and determined the probable neurobehavioural mechanism of its antidepressant-like effect. Methodology: The antidepressant-like effect of the extract was evaluated in tail suspension test, at graded doses in mice. Subsequently, the probable neurobehavioural mechanism of the antidepressant-like effect of the extract was investigated by intraperitoneal pretreatment with adrenergic, serotonergic, dopaminergic, and muscarinic cholinergic receptor antagonists; GABA agonist; nitric oxide precursor and inhibitors; and using a putative neuromodulator at NMDA receptors prior to the extract administration. Results and discussion: The extract at all the doses used, significantly (p<0.05) and dose-dependently decreased the immobility time in tail suspension test without significant (p>0.05) alteration on locomotor behaviour in mice. However, the anti-immobility potential of the extract was significantly (p<0.05) reversed by prazosin, yohimbine, sulpiride, methylene blue, L-arginine and baclofen, suggesting the involvement of adrenergic, dopaminergic, GABAerargic and nitergic pathways. Conclusion: This study, therefore, concluded that the extract may possess antidepressant effect and its mechanism may involve multiple pathways.

Antidepressant-Like Activity of Solvent Fractions of the Root Bark of Carissa spinarum Linn. (Apocynaceae) in Rodents Involves Multiple Signaling Pathways

“…64 The fact that yohimbine, but not prazosin, was able to reverse the antidepressant-like activity of CSE suggests that the fraction mediates its effect via α2-adrenoceptors but not α1-adrenoceptors. This finding is consistent with reports indicating yohimbine 51,65 but not prazosin 66,67 that reversed the antidepressant-like activity of plant extracts. Collectively, these studies suggest that plant extracts preferentially interact with α2-adrenoceptors to produce antidepressant-like effects.…”

“…This was performed by assessing the involvement of noradrenergic, serotonergic, dopaminergic, nitric oxide, and cholinergic-muscarinic system using different drugs at doses that do not modify the locomotor behaviors of rats in FST. 51 , 52 Rats were randomly divided into nine different groups of 6 rats each. All drugs and the extract were dissolved in 0.5% v/v DMSO in normal saline.…”