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Updated: Aug 11, 2026
Electrophysiological Recording in the Brain of Intact Adult Zebrafish
Published on: November 19, 2013
Sublethal effects of organophosphate diazinon on the brain of Cyprinus carpio
E Ozcan Oruç1, N Uner, Y Sevgiler
1Department of Biology, University of Cukurova, Faculty of Science and Letters, Balcali, Adana, Turkey.
Abstract:
Effects of diazinon, at different concentrations and exposure times, were investigated in freshwater fish, Cyprinus carpio, to elucidate the possible mode of action on lipid peroxidation together with the inhibitory effect of diazinon on acetylcholinesterase activity and changes in tissue protein levels. Cholinesterase inhibition is considered to be a specific biomarker of exposure to organophosphorus pesticides. Fish were exposed to 0.0036 microg/L, 0.018 microg/L, and 0.036 microg/L (sublethal) concentrations of diazinon for 5, 15, and 30 days, and biochemical measurements were carried out spectrophotometrically. Brain was chosen as an indicator tissue because it is a target system for the organophosphorus action. More than 20% decline in acetylcholinesterase activity relative to mean activity of the controls was observed in the diazinon-exposed groups. Protein content decreased significantly after 15 days of exposure to 0.018 microg/L and 0.036 microg/L diazinon and after 30 days of exposure to 0.036 microg/L. Malondialdehyde level declined markedly compared with the control levels. This study showed that prolonged exposures of C. carpio to diazinon had significant effects on brain acetylcholinesterase activity and that environmentally relevant concentrations of diazinon can significantly inhibit brain acetylcholinesterase activity. Altered protein content was probably due to the high energy demand under pesticide stress or inhibition of de novo enzyme synthesis. The decreased malondialdehyde content may reflect the possibility of better protection against oxidative stress.
Insights
Diazinon exposure significantly inhibits acetylcholinesterase activity in Cyprinus carpio, impacting protein levels and oxidative stress markers. Environmentally relevant concentrations pose a risk to freshwater fish health.
Area of Science:
- Environmental toxicology
- Fish physiology
- Biochemistry
Background:
- Organophosphorus pesticides like diazinon are widely used, posing risks to aquatic ecosystems.
- Acetylcholinesterase (AChE) inhibition is a key biomarker for organophosphorus pesticide exposure in fish.
- Understanding diazinon's effects on fish physiology is crucial for ecological risk assessment.
Purpose of the Study:
- To investigate the effects of sublethal diazinon concentrations on lipid peroxidation, acetylcholinesterase activity, and protein levels in Cyprinus carpio.
- To determine the impact of varying exposure durations on these biochemical parameters.
- To elucidate the potential mode of action of diazinon in freshwater fish.
Main Methods:
- Cyprinus carpio were exposed to three sublethal concentrations of diazinon (0.0036, 0.018, 0.036 microg/L) for 5, 15, and 30 days.
- Biochemical measurements, including acetylcholinesterase activity, protein content, and malondialdehyde levels, were performed spectrophotometrically.
- Brain tissue was analyzed as a primary target for organophosphorus pesticide action.
Main Results:
- A significant decline (over 20%) in brain acetylcholinesterase activity was observed in diazinon-exposed fish.
- Protein content decreased significantly after 15 and 30 days of exposure to higher diazinon concentrations.
- Malondialdehyde levels showed a marked decline compared to control groups, suggesting potential antioxidant effects.
Conclusions:
- Prolonged exposure to environmentally relevant concentrations of diazinon significantly affects brain acetylcholinesterase activity in Cyprinus carpio.
- Altered protein levels may result from increased energy demands or inhibited enzyme synthesis under pesticide stress.
- Decreased malondialdehyde suggests a possible adaptive response to oxidative stress, warranting further investigation.
