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Results from a Survey of Current Practices for Sampling of Nervous System in Rodents and Non-rodents in General Toxicity Studies
Citation:
Andrews-Jones, L., A. Bradley, M. T. Butt, R. H. Garman, L. A. Gumprecht, K. F. JENSEN, J. McKay, I. Pardo, A. Radovsky, R. Sills, AND R. Switzer. Results from a Survey of Current Practices for Sampling of Nervous System in Rodents and Non-rodents in General Toxicity Studies. Presented at Society of Toxicologic Pathology Annual Symposium, Chicago, IL, June 20 - 24, 2010.
Impact/Purpose:
A survey of current practices for sampling and examination of the nervous system in rodents and non-rodents for general and neurotoxicity (NT) studies was conducted by the Nervous System Sampling subcommittee of hte STP.
Description:
A survey of current practices for sampling and examination of the nervous system in rodents and non-rodents for general and neurotoxicity (NT) studies was conducted by the Nervous System Sampling Subcommittee of the STP. For general toxicity studies most of those surveyed (>63%) have a standard approach for collection, trimming, and examination regardless of study duration, species, or test compound. Areas sampled in rodents and non-rodents include brain (>79%), spinal cord (3 levels) (>71%), sciatic (>64%) and optic nerves (>68%). Many of those surveyed (23%) felt that additional sampling should be done to include trigeminal nerve, dorsal root ganglia, and additional brain and spinal cord. Most (>77%) do immersion fixation in neutral buffered formalin (NBF), obtain a brain weight, trim brains freehand using landmarks, and examine all gross abnormalities histologically. In rodents 1-3 sections of brain are examined and in non-rodents 4-6 sections are examined. For the PNS, most examine a longitudinal section of one sciatic nerve in all species. About 40% of respondents conduct NT studies, and vary collection, trimming and examination by species and test compound, but not study duration. Histologically, for NT studies the following areas are examined in all species: cerebral cortex, basal ganglia, corpus callosum, thalamus, hippocampus, hypothalamus, cerebellum, pons, medulla oblongata, and spinal cord (3 levels). Additional areas include dorsal root ganglia, and sciatic and tibial nerve (rodents only). For NT studies, perfusion fixation (56%) with 10% NBF (44%) or paraformaldehyde (40%) is more common than immersion fixation (44%). In addition to hematoxylin and eosin staining, many also routinely use immunohistochemical or histochemical stains, most commonly GFAP, Luxol Fast Blue, and Fluoro-Jade. This abstract does not necessarily reflect EPA policy.