Recovery of the early cellular changes induced by lead in rat peripheral nerves after withdrawal of the toxin.
A morphological and quantitative investigation was carried out in the peripheral nerves of adult rats, which were first exposed to 4% lead acetate in the drinking water and then restored to standard laboratory conditions. After six weeks of continuous lead exposure, the only cells involved were Schwann cells (SC) and endothelial cells (EC). As compared to age-matched controls, the most conspicuous changes observed by light and electron microscopy in these cells included the presence of nuclear inclusion bodies (NIB), cytoplasmic hypertrophy, mitochondrial abnormalities, an increased number of myelin-derived SC intracytoplasmic structures, and vesiculation of myelin sheaths. By counting the number of nuclear profiles containing NIB in semithin sections stained with basic fuchsin and methylene blue, we found that SC from predominantly cutaneous (sural) nerves were less vulnerable to lead than SC from mixed (peroneal) and muscular (tibial) nerves. With respect to EC, however, no significant differences were found among these three nerves. After termination of lead exposure, we observed a gradual decrease of most of the above cellular changes, which finally disappeared at day 30 post-intoxication. However, the number of myelin-related SC cytoplasmic bodies still remained above normal levels at the time of the termination of the experiment (60 days post-intoxication). The nature of the changes induced by lead in peripheral nerve cells as well as the rapid and nearly complete recovery suggest that they reflect a compensatory response to overcome the adverse effects of the lead on cell metabolism.
Coria
F
F
Department of Medicine, Faculty of Medicine, University of Santander, Spain.
Montón
F
F
D000818:Animals; D004727:Endothelium / Q000473:pathology; D005260:Female; D007855:Lead Poisoning / Q000473:pathology*; D010525:Peripheral Nerves / Q000648:ultrastructure; D010523:Peripheral Nervous System Diseases / Q000473:pathology*; D051381:Rats; D011919:Rats, Inbred Strains; D012583:Schwann Cells / Q000473:pathology