Antidepressant and Anxiolytic Effect of Echium amoenum in Restraint Stress Model: The Role of Neuroinflammation in the Prefrontal Cortex and Hippocampus

Echium amoenum (E. amoenum) is an Iranian medicinal plant with mood-enhancing effects.

This study was designed to investigate the effect of standardized E. amoenum hydroalcoholic extract on restraint stress (RS)-evoked anxiety- and- depressive-like behaviors in mice.

This experimental study was conducted at the Tabriz University of Medical Sciences, Tabriz, Iran, in 2018. Doses of the hydroalcoholic extract of E. amoenum were optimized for rosmarinic acid (> %2 w/w) concentration of the extract. Other phytochemical indices, including total phenolic and flavonoid contents and radical scavenging activity, were also measured. For behavioral studies, 65 mice were randomly assigned into five groups (n = 13) of control, RS, RS + E75, RS + E150, and RS + E300. Animals in the RS group were subjected to the RS (3 h/day for 14 days) and treated with normal saline, while treatment groups received E. amoenum extract (75, 150, and 300 mg/kg, p.o.) concomitantly with RS exposure. Anxiety-like behaviors were assessed by Elevated Plus Maze (EPM) and Open Field Test (OFT). Depression was assessed by the forced swim test (FST) and Tail Suspension Test (TST). Western blotting was performed to determine the protein levels of IL-1β, NF-κB, TNF-α, and IL-6 in the prefrontal cortex (PFC) and hippocampus (HIP). The concentrations of corticosterone, alanine aminotransferase, aspartate aminotransferase, and alanine phosphatase were also measured in serum.

Moderate and high doses of the extract ameliorated RS-induced anxiety- (P < 0.05 in OFT and EPM) and depressive-like (P < 0.05 and P < 0.01 in FST; P < 0.01 and P < 0.001 in TST) behaviors. These results were approved by decreased serum corticosterone levels (P < 0.05 and P < 0.001). Furthermore, E. amoenum reduced the protein expression of neuroinflammatory markers in the HIP and PFC subregions (significant at least at P < 0.05 for IL-1β, NF-κB, and TNF-α). Although RS slightly increased the serum levels of liver enzymes, no histopathological changes were seen in the liver of the RS or E. amoenum-treated groups.

E. amoenum can be an effective and safe complementary strategy for the treatment of stress-associated inflammation and behavioral changes.