Hypotensive activity of thymoquinone in normotensive rats and its receptor mechanisms

• Main Authors: Marwan Saad, Abdulrahman Azzubaidi, Hussam, Mizher, Ahmed Ghazi, Alattraqchi
• Format: Article
• Language: English
• Published: 2017
• Subjects: R Medicine (General)
• Online Access: http://eprints.unisza.edu.my/5367/1/FH02-FP-17-10642.pdf; http://eprints.unisza.edu.my/5367/
• Institution: Universiti Sultan Zainal Abidin

Objective: The objectives of the current study were to confirm the blood pressure lowering effect of thymoquinone (TQ) and to investigate its mechanism through muscarinic and β-adrenergic receptors. Methods: Mean arterial blood pressure (MAP) was recorded using the non-invasive blood pressure tail-cuff technique. A dose-response relationship was obtained after using 3 TQ doses (2.5, 5 and 10 mg/kg) intraperitoneally to 3 different groups (n =5) of adult rats under pentobarbital anesthesia. MAP was then measured for another 2 animal groups pretreated either with atropine (P-at) or propranolol (P-pro) followed by 10 mg/kg TQ. Results: TQ produced a significant dose-dependent blood pressure and heart rate lowering effect. TQ-induced MAP reduction was significantly less pronounced in P-at (12±2.8 mmHg) than non-pretreated group (29±3.2 mmHg) with P<0.01. Conversely, TQ-induced MAP reduction in P-pro (28±3.4 mmHg) did not demonstrate a significant difference from the non-pretreated group (29±3.2 mmHg) with P>0.05. Conclusion: This study confirms the dose-related hypotensive effect of TQ and provides an evidence for the traditional use of Nigella sativa for the treatment of hypertension. The mechanism of TQ-induced hypotension involves at least in part activation of vascular muscarinic receptors, but not β-adrenergic receptors.