The Mechanism of Anxiolytic Effects of Moringa oleifera Leaf Extracts Associated with Significant Differential Expression of Crhb, Faah2a, Mao, and Pah Genes in Danio rerio

The search and development of new therapeutic agents from medicinal plants to alleviate anxiety is well justified due to the increasing cases of anxiety disorder and lack of effective treatment. Moringa oleifera has been used traditionally to treat anxiety. However, there is still lack of understanding on the mechanism for its anxiolytic effect. The purpose of this study was to investigate the anxiolytic effects and the mechanism of ethanolic extracts of the leaves of M. oleifera (MOLE) by observing behavioural changes of the Danio rerio and the differential gene expression analysis using custom RT2 Profiler PCR array. A 14-day chronic behaviour study was conducted using three concentrations of MOLE (500 mg/L, 1000 mg/L and 2000 mg/L) fluoxetine as the positive control. Stress-induced D. rerio treated with 1000 mg/L MOLE showed the lowest level of anxiety compared to other groups as evidenced by a decrease in freezing episodes and freezing time, increased entries into the light region. The fish also showed significant changes in the expression of crhb, faah2a, mao, and pah genes. MOLE with the presence of quercetin and kaempferol are believed to exert its anxiolytic effects through differential expression of gene (i) modulating the function of GABAA receptor (crhb), (ii) inhibiting the expression of nitric oxide synthase (NOS) and the production of nitric oxide, (iii) increasing the AEA levels in the brain (faah2a), (iv) increasing the level of dopamine levels in the brain (mao). These findings provide valuable insights into the potential use of MOLE as a treatment for anxiety-related disorders as well as the significance of the molecular pathways involved in its anxiolytic properties.