The effects of cisplatin on rat spinal ganglia: a study by light and electron microscopy and by morphometry.

Cisplatin given in doses of 0.5-2 mg to Wistar and to Sprague-Dawley rats produced nucleolar segregation of the dense fibrillar from the granular component in spinal root ganglion cells. The nucleolar segregation, found to the same extent in large and small neurons, was confirmed by specific silver staining and by electron microscopy. After repeated doses of 1 mg or 0.5 mg, up to 40% of affected nucleoli were observed by light microscopy. Focal clearing of the nucleoplasm of nuclei also occurred. Disorganisation of ribosomes was found in more severely intoxicated animals, especially in large light cells with shrinkage of the Nissl substance and apparent increase in neurofilaments, the latter occasionally distending the initial segment of the axon, but never extending further. Hypertrophy of the satellite cells with increase in the perineuronal intercellular spaces, often associated with irregular, scalloped nuclear and cell outlines, suggested that neuron shrinkage had occurred. This was confirmed by morphometry and marked alterations were found in nucleolar-to-nuclear and nucleolar-to-cell diameter ratios, nuclear and cell diameters were also somewhat reduced without change in the nucleus-to-cell ratios. Peripheral sensory nerve degeneration was not seen, and the animals died from non-neural causes. The probable role of these events in the production of sensory neuropathy is discussed.