[Effect of dimethoate on serum monoamines neurotransmitters in rats].

OBJECTIVE: To study the effect of dimethoate on the monoamine Neurotransmitters, including norepinephrine (NE), epinephrine (E), serotonin (5-HT), dopamine (DA) and its metabolite (3, 4-hydroxyphenylacetic acid, DOPAC) in the serum of rats and furthermore to explore the non-cholinergic mechanism of organophosphate induced toxicity. METHODS: Groups of rats were treated with saline and 38.9, 83.7 and 180 mg/kg dimethoate respectively and were decapitated at the different time course from 0.5 to 24 hours after the administration. The monoamines neurotransmitters were determined by the reverse-phase high-performance liquid chromatography with the electrochemical detection. RESULTS: The serum concentrations of DA (8.42% - 248.42% of the control), DOPAC (17.22% - 68.21% of the control) increased, according with the DM dosage and the exposure time, while the levels of NE (9.65% - 38.26% of the control) and E (11.00% - 32.62% of the control) contents decreased at the same time. CONCLUSION: These findings indicate that dimethoate induced toxic effects can alter the monoamine levels at the different dosage and the time exposure in the serum of rats. It suggests that some non-cholinergic mechanisms may be involved in the dimethoate intoxication.

[Study on monoamine neurotransmitters in rat serum and brain tissue by high performance liquid chromatography with electrochemical detection].

OBJECTIVE: A rapid, reliable and simple method detecting monoamine neurotransmitters in rat serum and brain tissue by high performance liquid chromatography with electrochemical detector was developed. METHODS: An ODS column was selected as separation column at room temperature,and the mobile phase (pH4.50) consisted of 0.02 mol/L trisodium citrate and 0.05 mol/L disodium phosphate, containing 15% methanol (volume ratio)in distilled water. The mobile phase was pumped at a flow rate of 1.0 ml/min and the oxidation potential was set at +0.065 mV. Dihydroxybenzylamine was used as the internal standard for quantification. Four compounds, epinephrine (E), dopamine (DA) and 5-hydroxytryptamine(5-HT) in the brain tissue ((whole cerebral cortex, hippocampus, striatum, midbrain, cerebellum) and serum were simultaneously separated and determined under the above conditions. RESULTS: RSD of the retention times and peak areas of standard sample was in the range 0.29%-0.67% and 0.09%-0.36%. The recoveries of all analytes were over 85%. The detection limits of 0.083 ng/ml for NE, 0.51 ng/ml for E, 0.046 ng/ml for DA and 0.078ng/ml for 5-HT were achieved with standard solutions. The linearity is over the range 1.0-100 ng/ml for NE, 5.0-80 ng/ml for E,1.0-80 ng/ ml for DA and 1.0-60 ng/ml for 5-HT. CONCLUSION: The assay had been applied successfully to measure simultaneously cortex and serum concentrations of these four monoamines in rats.