Anti-stress effects of essential oils detected by IBA 1 marker in brain tissue of experimental animals

Abstract

Background: Essential oils are secondary metabolites of plant substances that create the unique and luxurious scents of plants. In recent years, countries have widely used essential oils derived from aromatic plants such as Lavender (Lavandula angustifolia), Rose (Rosa damascena), and Orange tree (Citrus aurantium x L) in the treatment of chronic stress. During chronic stress, the activation of microglia plays a crucial role in neuronal growth and development by reducing Brain-derived neurotrophic factor (BDNF), which leads to inflammation and degeneration in nerve cells, resulting in memory disorder and cognitive dysfunction. Notably, exposure to chronic stress increases the M1 type inflammatory microglia cells, known as IBA 1. However, essential oils have been shown to reduce the activation of M1 microglial cells due to their anti-inflammatory effects. In our country, approximately 300 species of essential oil plants have been identified, but there has been a lack of research on their anti-stress effects. Therefore, we chose the essential oil of the aromatic plant Juniper sibirica, traditionally used for its luxurious scent, to investigate its potential anti-stress effects through the IBA 1 microglial cell marker in the brain tissue of experimental animals. This formed the basis of our research project. Aim: To investigate whether the essential oil of Juniper sibirica has anti-stress effects, we will identify the microglial cells using the IBA 1 marker in the brain tissue of experimental animals. Materials and Methods: Study was conducted at the Institute of Bio-Medical Sciences, MNUMS. The research was approved for conduct by the Ethics Review Board of the Mongolian National University of Medical Sciences during a meeting on November 24, 2023 (2023-03-09). Total of 25 male Balb/c mice, weighting approximately 22-28 gr, were randomly divided into 5 groups: control group, negative control group, Lavander group, and compound J.S essential oil’s low-dose group and high-dose group. After inducing a chronic stress model, mice were exposed to the essential oil scent for a week. Then all groups of mice were euthanized of perfusion fixation methods, brain tissue was taken, fixed in 4% paraformaldehyde solution, the tissue was prepared by frozen sectioning, immunohistochemical staining, and statistical calculations were performed using ImageJ software. Results: After chronic stress, IBA 1 microglial cells in brain tissue became amoeboid and activated. After finding the total area using ImageJ software, the number of IBA1 microglial cells in each group was counted and statistical calculations were performed on an area of 1,200,000 μm2: control group - 2±1, negative control group - 18±2, low dose group - 9±2, high dose group - 5±1, Lavender group - 11±1 number of IBA 1 positive microglial cells were stained. Conclusion: According to the results of the study, during chronic stress, essential oil has a protective effect on the brain tissue by reducing the number of microglial cells in the brain tissue.