Protective Effects of Thymoquinone on the MDMA-induced Cerebrospinal Fluid Serotonin Depletion in Rats

3,4-methylenedioxymethamphetamine (MDMA; “ecstasy”) is an illicit drug belongs to the amphetamine-type stimulants (ATS) group. The long-term effect of MDMA includes depletion of extracellular serotonin or 5-hydroxytryptamine (5-HT). Hence, this study aimed to investigate the protective effects of thymoquinone (TQ) in preventing the 5-HT depletion induced by a single MDMA exposure in rats. This study was designed by dividing the rats randomly into four groups i.e: i) Control group, receiving 0.1 ml/kg saline, ii) MDMA group, receiving a single administration of 20 mg/kg MDMA, iii) MDMA-TQ group, receiving a single administration of 20 mg/kg MDMA and being treated with 40 mg/kg TQ for one week and, iv) TQ group, receiving 40 mg/kg TQ for one week. All compounds were administered through oral gavage. Percentage of weight gain was measured, and at the end of the experiment, cerebrospinal fluid was collected from the cisterna magna to evaluate the 5-HT level. Our results demonstrated a significant increased in 5-HT level in MDMA-TQ group as compared to the MDMA group. MDMA-TQ group also showed a higher percentage of weight gain as compared to the MDMA group. Our study suggested that the long-term MDMA induced 5-HT depletion in rats’ cerebrospinal fluid can be prevented by thymoquinone.