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

doi:10.3969/j.issn.2095-4344.2014.42.017

Abstract

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.
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.
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 followed by 1 000 mg/kg TOCP 24 hours later. The hens were killed 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.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

全文链接：

Key words: phosphoric acid esters, organophosphorus compounds, glutamine, glutamic acid

CLC Number:

R318

Zuo En-jun, Jiang Ying, Piao Feng-yuan . Effects of tri-ortho-cresyl phosphate on homeostasis of the glutamate-glutamine cycle and its key enzymes in the brains of hens[J]. Chinese Journal of Tissue Engineering Research, 2014, 18(42): 6811-6816.

Figures/Tables 1

2.1 实验动物数量分析实验选用成年罗曼母鸡24只，实验过程无脱失，均进入结果分析。 2.2 TOCP暴露对鸡脑谷氨酰胺合成酶和谷氨酰胺酶含量的影响 TOCP染毒诱导OPIDN对鸡脑谷氨酰胺合成酶和谷氨酰胺酶含量的影响结果见图1A。TOCP染毒5 d时，TOCP组谷氨酰胺合成酶含量是对照组的0.76倍(P < 0.05)，是PMSF干预组的0.77倍(P < 0.05)。TOCP染毒 21 d时，TOCP组谷氨酰胺合成酶蛋白含量与对照组和PMSF干预组比较，无显著变化。TOCP染毒5 d和染毒21 d两个时间点，TOCP组谷氨酰胺酶含量与对照组和PMSF干预组比较，无显著变化(见图1B)。 2.3 鸡脑谷氨酰胺合成酶活性测定结果 TOCP染毒诱导OPIDN期间，鸡脑谷氨酰胺合成酶活性见图2。TOCP染毒5 d时，TOCP组脑谷氨酰胺合成酶活性是对照组的0.84倍(P < 0.05)，是PMSF干预组的0.825倍(P < 0.05)。TOCP染毒21 d时，TOCP组谷氨酰胺合成酶活性与对照组和PMSF干预组比较无显著变化。 2.4 TOCP暴露对鸡脑谷氨酸和谷氨酰胺浓度影响 TOCP染毒诱导OPIDN期间，鸡脑谷氨酸浓度见图3A。TOCP染毒5 d时，TOCP组谷氨酸浓度是对照组的 1.38倍(P < 0.05)，是PMSF干预组的1.28倍(P < 0.05)。TOCP染毒21 d时，TOCP组谷氨酸浓度与对照组和PMSF干预组相比较，无显著变化。TOCP染毒诱导OPIDN期间，鸡脑谷氨酰胺浓度见图3B。TOCP染毒5 d时，TOCP组谷氨酰胺浓度是对照组的0.84倍(P < 0.05)，是PMSF干预组的0.8倍(P < 0.05)。TOCP染毒21 d时，TOCP组谷氨酰胺浓度与对照组和PMSF干预组比较，无显著变化。 2.5 TOCP暴露对鸡脑细胞内钙离子浓度影响 TOCP染毒诱导OPIDN期间，鸡脑细胞内钙离子浓度测定结果见图4。TOCP染毒5 d时，TOCP组细胞内钙离子浓度是对照组的1.23倍(P < 0.05)，是PMSF干预组的1.12倍(P > 0.05)。TOCP染毒21 d时，TOCP组细胞内钙离子浓度与对照组和PMSF干预组相比较，无显著变化。"

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