Neurochemical and behavioral effects of Nigella sativa and Olea europaea oil in rats

Abstract

Objectives: In the last few decades, therapeutic uses of medicinal compounds present in food as a normal constituent has risen substantially, largely because of their fewer side effects and adequate efficacy. This study is designed to investigate a role of brain serotonin (5-HT) and dopamine (DA) in the potential nootropic, anxiolytic, and other beneficial effects of Nigella sativa (NS) and Olea europaea (OE) oil in rat models.

Methods: Animals were treated with NS and OE oil orally at doses of 0.1 ml/kg and 0.25 ml/kg for 5 weeks. Food intake and body weight change, anxiety-like effects in elevated plus maze and activity in a novel and familiar environment were monitored weekly. Effects on learning and memory after 5 weeks treatment were monitored using Morris water maze test. Neurochemical analysis was carried using HPLC-ECD method.

Results: NS and OE oil administration enhanced learning and memory in Morris water maze test and the effects were greater in NS than OE oil-treated animals. Low dose of OE oil increased exploration in an open field, higher dose of OE oil and both doses of NS oil produced no consistent effect on open field exploration. Effects of both oils on anxiety-like behavior, food and water intake, and activity in activity box were either not consistent or did not occur. The treatment increased homovanillic acid (HVA). 5-HT levels increased in high dose of NS oil and low dose of OE oil-treated groups. Low dose NS oil decreased 5-HT.

Discussion: The present study suggests that active components in NS and OE oil may prove useful in treating impaired cognition. OE oil may produce psychostimulant-like effect. Modulation of DA and serotonin neurotransmission seems important in the pharmacological effect of these oils.

Keywords:

• Nigella sativa
• Olea europaea
• Anxiety
• Learning
• Memory
• Motor activity
• Dopamine
• Serotonin

Acknowledgments

The authors would like to thank Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), University of Karachi for providing faculty research grants.

Disclaimer statements

Contributors M. Atif Raza Cheema performed all the experiments and wrote major part of the manuscript. Shazia Nawaz helped in animal dissection. Sumera Gul helped in statistical analysis. Tabinda Salman helped in animal dissection. Sabira Naqvi helped in HPLC work. Ahsana Dar helped in HPLC work. Darakhshan J. Haleem designed the experiment and supervised the entire research.

Funding None.

Conflicts of interest None.

Ethics approval Animal handling and study protocol was conducted in accordance with international guidelines for ethical care and use of animals for research, which included the National Institute of Health Guidelines for Care and Use of Laboratory Animals. This study was approved by Institutional Animal Care and Use Committee, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi, Pakistan.

ORCID

M. Atif Raza Cheema http://orcid.org/0000-0002-0710-8554