AGE-RELATED DIFFERENCES IN THE INHIBITION OF BRAIN ACETYLCHOLINESTERASE ACTIVITY OF HETEROPNEUSTES-FOSSILIS (BLOCH) BY MALATHION

The objective of this study is to determine whether there are differences in the sensitivity of brain acetylcholinesterase between juvenile and adult fish exposed to malathion. Air-breathing catfish, Heteropneustes fossils were used. The exposure concentration was 1.2 mg/l (sublethal), and exposure durations were 24, 48, 72, and 96 hr. A reduction in the mean acetylcholinesterase activity is seen at all exposure durations in the juveniles. It also indicates a significant difference between the control and exposure groups-24, 48, 72 and 96 hr in group A. However, in the adults, a reduction is seen, only at the 72 hr exposure duration, T-value and two-tail probability show that only control and 72 hr exposed ones are significantly different, In the higher weight group, there is a recovery in AChE activity at the 96 hr exposure level. This indicates that the detoxification capacity of the fish increases with age. The results show that the juveniles are much more susceptible than the adults.