Alterations in enzyme activities in muscles and nerve cord of Periplanata americana induced by sublethal administration of cypermethrin, carbaryl and monocrotophos

Periplanata americana were exposed with sublethal dose (less than the LD₅₀ value for 96 hours) of cypermethrin (2.0x10⁻³ mg), carbaryl (5.0x10⁻² mg) and monocrotophos (1.8x10⁻¹ mg) for 24 and 98 hours. An elevation of aspartate aminotransferase (AAT) activity was noticed in the muscles and nerve cord of cockroaches exposed with all the three insecticides. The observed increase in AAT activity was time-dependent with the exception of monocrotophos treated insects in which there was a decline in activity at 96 hours. However, the carbaryl-treated cockroaches showed pronounced increase in AAT activity as compared to cypermethrin and monocrotophos. Elevated levels of alanine aminotranferase (ALAT) activity were also observed in cypermethrin and carbaryl treated cockroaches at 24 and 96 hours. However, a decline in ALAT activity was observed at 24 hours of monocrotophos exposure. A significant elevation in acid phosphatase (ACP) and alkaline phosphatase (ALP) activities in both the tissues were observed in treated cockroaches. This elevation was time-dependent. However, after 96 hours of treatment, there was a slight decline in ACP activity in cypermethrin- and monocrotophos-treated cockroaches as compared to 24 hours of the treatments. Na⁺/K⁺-ATPase as well as Mg²⁺-ATPase activities declined significantly in both the tissues of cockroaches treated with all the three pesticides. This indicates that cypermethrin, carbaryl and monocrotophos are potent inhibitors of Na⁺/K⁺-ATPase and Mg²⁺-ATPase activities in the cockroach.