Juvenile hormone activity in Dysdercus cingulatus Fabr by juvenile hormone esterase inhibitor, OTFP.

Application of juvenile hormone esterase inhibitor 3-octylthio-1,1,1- trifluropropan-2-one (OTFP) to 5th instar nymphs and virgin females of D. cingulatus revealed the profound role played by juvenile hormone esterase (JHE) in metamorphosis and reproduction. The ability of OTFP to cause delay and the formation of malformed nymphs, suggests that inhibition of JHE in vivo maintains a higher than normal hemolymph JH titer. It is obvious that OTFP does inhibit in vivo JHE activity in late instar nymphs. Further, the application of JHE inhibitor, OTFP to virgin females demonstrates that substituted trifluropropanones can indirectly stimulate egg development by inhibiting JHE activity in virgin females.

A comparative study of delayed neurotoxicity in hens following repeated administration of organophosphorus compounds.

Hens treated with Mipafox (10 mg/kg, sc), sarin (50 micrograms/kg, sc) or parathion (1 mg/kg, sc) daily for 10 days exhibited severe, moderate and no ataxia respectively on 14th day after the start of exposure. The neurotoxic esterase (NTE) activity was significantly inhibited in the brain, spinal cord and platelets of hens treated with mipafox or sarin whereas no change was noticed with parathion treatment. All three compounds significantly inhibited acetylcholinesterase (AChE) activity in the platelets. Spinal cord of hens treated with mipafox, sarin or parathion showed axonal degeneration heavy, moderate and none respectively. It is concluded that repeated administration of equitoxic doses of mipafox, sarin and parathion to hens are marked, moderate and non-delayed neurotoxic respectively.

Tri-ortho-cresyl phosphate induced neurotarget esterase inhibition in brain and peripheral nerve effectively monitored by lymphocytes.

Tri-ortho-cresyl phosphate ester (TOCP: 10-100 mg/kg)--an organophosphorus compound (OP) inhibited brain, peripheral nerve and lymphocyte neurotarget esterase activities in a dose related and time-dependent manner. There was a good correlation of inhibition between brain, peripheral nerve and lymphocyte tissues taken from adult hens treated with 3 different doses of TOCP and sacrificed 24 and 48 hr after exposure. The results suggest that lymphocyte can effectively monitor OP compounds for investigating inhibition of neurotarget esterase activity in brain and peripheral nerve tissues.

Effect of tri-ortho-cresyl phosphate on hen nervous system.

Correlation of tri-ortho-cresyl phosphate (TOCP) toxicity with clinical symptoms and inhibition patterns of neurotoxic esterase (NTE) in different regions of the central nervous system was studied in hens. The total content of NTE in spinal cord and peripheral nerves was relatively much lower than that of the brain, about 29 and 4.8 per cent respectively. Brain and spinal cord NTE was inhibited to 75 and 67 per cent respectively on day 1 post-TOCP treatment, and 91 and 84 per cent respectively on day 2, while the activity of the enzyme in peripheral nerve was inhibited to 92 per cent on day 1. However, the clinical manifestations of paralysis appeared after 7-8 days of TOCP treatment. It can be concluded that the presence of NTE in very low quantities in the peripheral nerves and its almost complete inhibition as compared to that of brain and spinal cord, could be of great significance in the development of neurotoxicity.