Morphological Analysis of the Effect of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin on the Peripheral Nervous System of Mouse / 대한해부학회지

ABSTRACT

Toxicity of TCDD on the peripheral nerve has not yet been clear even though there are many reports about its toxicity on various organs of human and other animals. This study was designed to clarify the effect of TCDD on the peripheral nerve by the morphometric and electron microscopic analysis. Fourty mg/kg of TCDD was injected to 4 week-old C57BL/6J mice intraperitoneally. At the 1st, 4th and 16th weeks after TCDD injection, the 4th lumbar segments of the spinal cord, the same level of spinal ganglia, and the sciatic nerves were taken. They were used for the light and electron microscopic examination and morphometric analysis. The nerve cell bodies of the anterior horn and the spinal ganglia did not show the difference between the TCDD-treated and control groups. Neuronal population of the ganglia of the TCDD-treated group did not differ from that of the control group. Unusually thickened myelin was frequently observed in the TCDD-treated groups, while axonal degeneration was not found in the sciatic nerves of both groups. The cross sectional area of myelin sheaths in the TCDD-treated group of all age was larger than that of the control group. Under the trasmission electron microscope, the myelin of the TCDD-treated group showed that it lost the regular compact arrangement and its lamellar was disrupted. In conclusion, we suggest that TCDD slows down the nerve conduction velocity via the disruption of the myelin structure of the peripheral nerve.