Evaluation of the effect of thymoquinone treatment applied after stress exposure on learning and memory in rats and its relationship with nmda receptors

Stress, described as the disease of the modern age, is a reaction that involves the adaptation of many body systems in order to increase the chance of continuing life. N-methyl-D-aspartate (NMDA) receptors play a critical role in learning and memory processes. Stress can affect the functioning of these receptors, affecting our learning and memory abilities. Thymoquinone is a compound derived from the Nigella sativa plant that has neuroprotective properties. This study aims to understand the effects of stress on the brain and how thymoquinone modulates these effects and its possible ameliorative effects on learning and memory. In the study, 28 male Wistar albino rats were used. The rats were divided into 4 groups: control, thymoquinone, stress and thymoquinone-treated stress groups. In the experiment, open field test, elevated plus maze test, passive avoidance test and Morris water maze test were applied to evaluate the anxiety levels and learning-memory capacities of the rats. In the open field and elevated plus maze tests, a significant decrease in the anxiety levels of thymoquinone treated rats was observed (p<0.05). When the animals' time to find the platform was examined in the Morris water maze test, thymoquinone-treated rats showed better memory performance compared to non-stressed controls (p<0.01). Additionally, NMDA, brain derived neurothrophic factor (BDNF), gamma aminobutyric acid (GABA) and catalase (CAT) levels in the hippocampus tissue homogenate samples and cortisol levels in the serum samples were measured by ELISA There was a statistically significant (p<0.05) increase in cortisol levels in the thymoquinone group compared to the stress group, and a statistically significant (p<0.05) increase in serum epinephrine and CAT levels in the stress+thymoquinone group compared to the stress group.In the measurements of BDNF, NMDA, GABA and CAT levels in tissue homeogenate samples, a statistically significant (p<0.01) increase was found in the stress+thymoquinone group compared to the stress group, and a statistically significant (p<0.05) increase was found in the SOD and NMDA levels in the thymoquinone group compared to the stress group. These findings show that thymoquinone improves learning and memory especially by acting through NMDA receptors. This study indicates that the negative effects of stress on learning and memory can be alleviated by thymoquinone treatment and also indicates the potential use of thymoquinone in the treatment of neurological disorders.