Evaluation of the biological response of propofol in zebrafish (Danio rerio): Focusing on biochemical, transcriptional, and molecular level.

Propofol, one of the most widely used intravenous anesthetic in clinical practice, has been reported to impair cognitive and memory function. However, the toxicological effects of propofol on aquatic organisms are still poorly understood. This study explored the toxic effects of chronic propofol exposure (0.008, 0.04, and 0.2 mg L) on adult zebrafish from biochemical, transcriptional, and molecular level after 7, 14, 21 and 28 days of exposure. Results indicated that the reactive oxygen species (ROS) levels were significantly upregulated during the 28 days exposure period, and excessive ROS caused lipid peroxidation, resulting in increased malondialdehyde (MDA) contents in the zebrafish brain. In order to relieve the oxidative damage induced by the excessive ROS, the activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT)) were significantly activated, and detoxification enzyme (glutathione S-transferase, GST) activities showed an "activation-inhibition" trend. However, the antioxidant enzymes and detoxification enzyme system could not eliminate the excessive ROS in time and thus caused DNA damage in zebrafish brain. The olive tail moment (OTM) values displayed a "dose-response" relationship with propofol concentrations. Meanwhile, the transcription of related genes of Nrf2-Keap1 pathway was activated. Further molecular simulation experiments suggested that propofol could directly combine with SOD/CAT to change the activity of its biological enzyme. These findings indicated that zebrafish could regulate antioxidant capacity to combat oxidative stress at the early exposure stage, but the activity of antioxidant enzymes were significantly inhibited with the increase of propofol exposure time. Our results are of great importance for understanding toxicological effects of propofol on aquatic organisms.