ULTRASTRUCTURAL ASPECTS OF DRG SATELLITE CELL INVOLVEMENT IN EXPERIMENTAL CISPLATIN NEURONOPATHY

Different substances may induce neurological impairment, clinically ex pressed as peripheral neuropathies, due to damage of the neuronal bodi es (neuronopathy) of sensory or motor neurons. Neuronopathies have gen erally been studied referring to neurons, although other cellular comp onents may also be damaged. Cisplatin (CDDP) is known to be neurotoxic to the neurons of the dorsal root ganglia (DRG). The scarcity of info rmation as to the possible involvement and role played by dorsal root ganglion (DRG) satellite cells in neuronopathies prompted this study u sing the chronic DRG neuronopathy induced by the repeated administrati on of CDDP in rats as a model. Eighteen female Wistar rats were treate d to 3 different schedules of CDDP administration (6 rats for each gro up). Six further animals were used as controls. At the end of the expe riment the LA-L5-L6 dorsal root ganglia were examined at the light and electron microscope. Ag-NOR reaction was also examined in 4 further C DDP-treated rats and 4 controls. Pathological changes in satellite cel ls of animals treated with CDDP were remarkable in the nucleus where h eterochromatin clumps were reduced or even completely absent. Morphome tric analysis of the area occupied by heterochromatin indicated that t his nuclear component decreased in an exposure-time dependent manner. Frequently, nucleolar-like structures became apparent in the nucleus o f the rats treated with the higher doses of CDDP. Ag-NOR positive regi ons in the nuclei of treated rats were increased with respect to the c ontrols. Cytoplasmic changes in DRG satellite cells of CDDP treated ra ts were limited, being characterized by an increased electron-density of the matrix. In treated rats deep invaginations between satellite ce lls and the neuronal surface were evident, leading to the formation of vacuoli. The interstitial connective space often showed edematous are as. Our observations demonstrate that in chronic cisplatin neuronopath y, DRG satellite cells are also involved in the pathological changes i nduced by drug exposure, and that these changes may be interpreted as being mainly reactive.