Quantitative Cytochemical Studies of RNA in Experimental Mercury Poisoning. I. Changes in RNA Content

Abstract

RNA content in single spinal ganglion neurons and anterior horn motoneurons from mercury intoxicated rats were analyzed by the cytochemical method of Edstrom. The cell volume of these nerve cells was measured by Mickelwright's method. It was found that in the spinal ganglion neurons, there was a continuous decrease in the RNA content after methylmercury poisoning. After inorganic mercury (HgCl₂) intoxication, there was in initial decrease in RNA content followed by a partial regaining of RNA after prolonged intoxication. These changes in RNA content were believed to be independent of the morphological changes produced by mercury in these neurons. Except for the cell swelling detected after the first week of methylmercury intoxication, there was a general decrease in cell volume after intoxication by either mercury compound. In the anterior horn motoneurons, there was a moderate increase in RNA after mercury poisoning (organic or inorganic). Since morphological lesions were only observed in the nerve fibers but not in the nerve cell bodies of these neurons, this increase in RNA level was thought to be a reparative response to the axonal injuries produced by the mercury compounds. Only a slight decrease in cell volume was observed at late stages of the intoxication.