Damage to Astrocytes of Rat Due to Acute Paraquat Exposure

Objective To assess the acute neurotoxity of paraquat(PQ) using rat models.

Methods Sixty SD rats were assigned to four groups randomly: a saline control group(n=8) and three PQ treatment groups(n=16, 16, and 20 were sacrificed at 1^st, 3^rd and 7^th day after exposure respectively). The treatment groups received one intraperitoneal injection of PQ in a dose of 10.96 mg/kg body weight, while the control group received saline. The rats were anesthetized with 25% urethane and sacrificed for examinations. PQ concentrations in serum were tested by gas chromatography. Tissue samples of cortex of frontal lobe, hippocampus, substantia nigra, and striatum were treated by immunohistochemical staining to identify glial fibrillary acidic protein(GFAP) in astrocytes and the number of GFAP positive cells was counted. Ultrastructural changes in astrocytes were examined by transmission electron microscopy.

Results The serum PQ concentrations on the 1^st, 3^rd and 7^th day were(1.020±0.059), (0.564±0.087), and(0.067±0.045) mg/L, respectively(P < 0.05). The number of GFAP positive cells in substantia nigra and hippocampus CA1 on the 7^th day after PQ administration was significantly higher than that in the controls(P < 0.05). By transmission electron microscopy, astrocyte cytoplasm edema and apoptosis were observed in the hippocampus and striatum of PQ treated rats sacrificed on the 7^th day.

Conclusion Ascrocyte damages are observed in the rats with acute PQ poisoning, indicating neurotoxicity.