Anxiolytic- like Effects by trans-Ferulic Acid Possibly Occur through GABAergic Interaction Pathways

Abstract

Numerous previous studies reported that ferulic acid exerts anxiolytic activity. However, the mechanisms have yet to be elucidated. The current study aimed to investigate the anxiolytic effect of trans-ferulic acid (TFA), a stereoisomer of ferulic acid, and evaluated its underlying mechanism using in vivo and computational studies. For this, different experimental doses of TFA (25, 50, and 75 mg/kg) were administered orally to Swiss albino mice, and various behavioral methods of open field, hole board, swing box, and light-dark tests were carried out. Diazepam (DZP), a positive allosteric modulator of the GABA_A receptor, was employed as a positive control at a dose of 2 mg/kg, and distilled water served as a vehicle. Additionally, molecular docking was performed to estimate the binding affinities of the TFA and DZP toward the GABA_A receptor subunits of α2 and α3, which are associated with the anxiolytic effect; visualizations of the ligand-receptor interaction were carried out using various computational tools. Our findings indicate that TFA dose-dependently reduces the locomotor activity of the animals in comparison with the controls, calming their behaviors. In addition, TFA exerted the highest binding affinity (-5.8 kcal/mol) to the α2 subunit of the GABA_A receptor by forming several hydrogen and hydrophobic bonds. Taken together, our findings suggest that TFA exerts a similar effect to DZP, and the compound exerts moderate anxiolytic activity through the GABAergic interaction pathway. We suggest further clinical studies to develop TFA as a reliable anxiolytic agent.

Keywords: GABAergic system; anxiolytic effect; in silico; molecular docking; trans-ferulic acid.

Figure 1

(a) Number of square cross (NSC), (b) number of grooming (NG), and (c) rearing (NR) observed in test and control groups. (Values are the mean ± standard error of the mean (SEM); one-way ANOVA and t-Student–Newman–Keuls post hoc test with multiple comparisons at 95% confidence intervals; * p < 0.05 when compared to the NC (vehicle) group; ^a p < 0.05 when compared to the TFA-50 group; NC: negative control; DZP: diazepam (2 mg/kg); TFA: trans-ferulic acid (25, 50 or 75 mg/kg)).

Figure 2

(a) Number of holes cross (NHC), (b) number of swing (NS), (c) dark residence time (DRT) observed in test and/or control groups. (Values are the mean ± standard error of the mean (SEM); one-way ANOVA and t-Student–Newman–Keuls post hoc test with multiple comparisons at 95% confidence intervals; * p < 0.05 when compared to the NC (vehicle) group; ^a p < 0.05 when compared to the TFA-50 group; NC: negative control; DZP: diazepam (2 mg/kg); TFA: trans-ferulic acid (25, 50 or 75 mg/kg)).

Figure 3

Ramachandran plot of the homology modeled GABA_A receptor: (a) α2 subunit; (b) α3 subunit.

Figure 4

Schematic of 2D and 3D views of the receptor binding site with names of non-bond interactions and interacted amino acid residues between GABA_A receptor subunits (α2 and α3) and selected ligands.

Figure 4

Schematic of 2D and 3D views of the receptor binding site with names of non-bond interactions and interacted amino acid residues between GABA_A receptor subunits (α2 and α3) and selected ligands.

Figure 5

Proposed molecular anxiolytic mechanisms of trans-ferulic acid and diazepam with the GABA_A receptor. (↑) indicates an increase, and the green arrow shows the binding of the ligands (trans-ferulic acid and diazepam) to the positive allosteric sites of different GABA_A receptor subunits.

Figure 6

Chemical structures of standard and test compounds.