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 differen ces in the sensitivity of brain acetylcholinesterase between juvenile and adult fish exposed to malathion. Air-breathing catfish, Heteropneu stes fossils were used. The exposure concentration was 1.2 mg/l (suble thal), and exposure durations were 24, 48, 72, and 96 hr. A reduction in the mean acetylcholinesterase activity is seen at all exposure dura tions in the juveniles. It also indicates a significant difference bet ween 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 exposur e duration, T-value and two-tail probability show that only control an d 72 hr exposed ones are significantly different, In the higher weight group, there is a recovery in AChE activity at the 96 hr exposure lev el. This indicates that the detoxification capacity of the fish increa ses with age. The results show that the juveniles are much more suscep tible than the adults.