EVOLUTION OF THE INTRACELLULAR CHANGES IN NEURONS CAUSED BY TRIMETHYLTIN

Abstract

Rats were given a single dose of trimethyltin (10 mg/kg) and the intracellular events were followed particularly in hippocampus, cerebral cortex, cerebellum and spinal ganglion cells. The earliest change visible occurs 12 h after this dose. Dense membrane-bound bodies, probably derived from branching tubulo-vesicular smooth endoplasmic reticulum [SER] formations were found. These occur in close connection with rough endoplasmic reticulum and polyribosomes and appear to have some association with the Golgi complex. At 24 h there is a general vacuolation of Golgi cisterns and SER membranes, and the membrane-bound bense body formation is greatly increased. SER abnormalities are particularly conspicuous in Purkinje cells. In spinal ganglion cells, while vacuolation of Golgi cisterns is intense, dense bodies are inconspicuous and are replaced by increased autophagosomes, often of great complexity. By 48 h vacuolation of Golgi cisterns has waned, but accumulation of dense bodies and secondary lysosomes has steadily increased. In spinal ganglion cells autophagosomes only are increased as the Golgi vacuolation declines. At later times steady increases of lysosomal dense bodies is seen generally accompanied in hippocampal pyramidal cells and dentate fascia cells by abundant cell death. The Golgi complex may be the seat of the critical metabolic lesion and disturbances to protein transfer and protein synthesis follow. No explanation for the selective loss of hippocampal h1-5 (CA1-CA4 except Sommer''s sector) pyramidal cells and of small dentate fascia neurons can be derived from these conclusions.