Ocimum basilicum (Basil) Modulates Apoptosis and Neurogenesis in Olfactory Pulp of Mice Exposed to Chronic Unpredictable Mild Stress

Nasra N Ayuob; Maha J Balgoon; Soad Ali; Ibrahim S Alnoury; Hailah M ALmohaimeed; Amany A AbdElfattah

doi:10.3389/fpsyt.2020.569711

Ocimum basilicum (Basil) Modulates Apoptosis and Neurogenesis in Olfactory Pulp of Mice Exposed to Chronic Unpredictable Mild Stress

Front Psychiatry. 2020 Sep 11:11:569711. doi: 10.3389/fpsyt.2020.569711. eCollection 2020.

Authors

Nasra N Ayuob^{1

2}, Maha J Balgoon³, Soad Ali^{2

4

5}, Ibrahim S Alnoury⁶, Hailah M ALmohaimeed⁷, Amany A AbdElfattah⁸

Affiliations

¹ Department of Medical Histology, Faculty of Medicine, Delta University for Science and Technology, Mansoura, Egypt.
² Yousef Abdullatif Jameel, Chair of Prophetic Medical Applications (YAJCPMA), Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.
³ Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
⁴ Department of Anatomy, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.
⁵ Department of Histology, Faculty of Medicine, Assuit University, Assuit, Egypt.
⁶ Department of ENT, H&N Surgery, Faculty of Medicine, King Abdul Aziz University Hospital, Jeddah, Saudi Arabia.
⁷ Department of Basic Science, Medical College, Princess Noruh bint Abdulrahman University (PNU), Riyadh, Saudi Arabia.
⁸ Department of Histology and Cell Biology, Faculty of Medicine, Mansoura University, Mansoura, Egypt.

Abstract

Background: Ocimum basilicum (O. basilicum) was described to have antidepressant and anxiolytic activities. Although the relationship between the main olfactory bulb (MOB) and depression was recently reported, the chronic stress-induced dysfunction of the MOB is not clearly described.

Objectives: This study aimed to assess the efficacy of inhalation of O. basilicum essential oils in improving chronic unpredictable mild stress (CUMS)-induced changes in MOB of mice and understand the mechanism underlying such effect.

Materials and methods: Adult male mice (n=40) were assigned into four groups included the control, CUMS-exposed, CUMS + fluoxetine (FLU), CUMS + O. basilicum. Behavioral changes, serum corticosterone level, and gene expression of GFAP, Ki 67, and caspase-3 were assessed using real-time PCR (RT-PCR). Histopathological and immunochemical examination of the MOB was performed.

Results: FLU and O. basilicum significantly down-regulated (p = 0.002, p<0.001) caspase-3 gene expression indicating reduced apoptosis and up-regulated (p = 0.002, p < 0.001) Ki67 gene expression indicating enhanced neurogenesis in MOB, respectively. FLU and O. basilicum-treated mice markedly improved MOB mitral cell layer distortion and shrinkage induced by CUMS.

Conclusion: O. basilicum relieved both biochemically and histopathological chronic stress-induced changes in the main olfactory bulb possibly through up-regulation of gene expression of GFAP and Ki67 and down-regulation of caspase-3 in the MOB.

Keywords: Ocimum basilicum; anti-glial fibrillary acidic protein; caspase-3; chronic stress; neurogenesis; olfactory bulb.