Effects of tri-ortho-cresyl phosphate on homeostasis of the glutamate-glutamine cycle and its key enzymes in the brains of hens

Zuo En-jun; Jiang Ying; Piao Feng-yuan

doi:10.3969/j.issn.2095-4344.2014.42.017

Abstract：BACKGROUND:Although incidents of organophosphate-induced delayed neurotoxicity have been documented for over a century, the molecular mechanisms underlying the axonopathy remain poorly understood. <br> OBJECTIVE:To discuss the effects of tri-ortho-cresyl phosphate (TOCP) on homeostasis of the glutamate-glutamine cycle and the expression of key enzymes in the brains of hens. <br> METHODS:Twenty-four adult hens were randomly divided into three groups (n=8). TOCP group was treated with TOCP by gavage at a single dosage of 1 000 mg/kg, and control group was given an equivalent volume vehicle by gavage, while hens in the phenylmethylsulfonyl fluoride (PMSF)+TOCP group were subcutaneously injected with 40 mg/kg PMSF fol owed by 1 000 mg/kg TOCP 24 hours later. The hens were kil ed on days 5 and 21 post-dosing. The brains were taken out quickly and preserved in a-80℃deep freezer. ELISA was used to determination the content of glutamine synthetase and glutaminase and the activity of glutamine synthetase. Corresponding kits were used to measure the level of glutamate and glutamine. Fluo3-AM was used to measure cytosolic calcium concentration. RESULTS AND CONCLUSION:The activity and content of glutamine synthetase and the concentration of glutamine were down-regulated, while the concentrations of the intracellular Ca2+and glutamate were up-regulated in the early stage after TOCP administration. It is also suggested that the downregulated expression of glutamine synthetase may be associated with organophosphate-induced delayed neurotoxicity through the disruption of homeostasis of the glutamate-glutamine cycle and cytosolic calcium concentration.