Practical Aspects of Assessing Toxic Lesions of the Peripheral Nervous System in Preclinical Studies in Rodents: A Review

Abstract

INTRODUCTION. In the current practice of preclinical safety studies of pharmacologically active substances, standard neurotoxicity assessment procedures are mainly aimed at diagnosing higher nervous activity and behavioural disorders. However, it is the structures of the peripheral nervous system that are particularly susceptible to drug-induced neurotoxicity, which renders these structures an easy target and leads to a high incidence of neurotoxic side effects. These circumstances dictate the importance of refining methodological approaches to the assessment of toxic injury in the peripheral nervous system.AIM. The study aimed to analyse the current methodological level of clinical and functional tests for assessing the toxic effects of pharmacologically active substances on the structures of the peripheral nervous system, as well as to formulate practical recommendations for using these tests in preclinical studies in rodents.DISCUSSION. Rodents are considered the optimal test system for preclinical studies of pharmacologically active substances, but it is impossible to reproduce the entire neurological examination that is conducted to identify clinical equivalents of neurotoxicity in humans using these animals. This article presents a systematic approach to using available diagnostic tests to increase the translatability of data. The article briefly describes the neurological deficits due to adverse drug reactions in humans, as well as the main toxidromes that can also occur in animals. Based on a literature review and experience, the authors provide practical recommendations for performing basic tests to study the strength and tone of muscles, the state of physiological reflexes, the coordination of movements, and various types of sensitivities in rodents. The article provides a brief overview of the diagnostic utility of electrophysiological testing for identifying toxic damage to the peripheral nervous system. The following tests are recommended as a minimum list of primary screening techniques for detecting neurotoxic side effects in study animals: a resting posture assessment, the beam walking test, the horizontal bar test, the digit abduction score assay, the tail flick test, and the Preyer reflex test.CONCLUSIONS. The results of a comprehensive assessment of neurological deficits in rodent experiments should be analysed from a clinically relevant perspective— that is, with a focus on topical diagnosis and common pathological process components. It is advisable to verify the pathological process at the level of the peripheral nervous system using a set of electrophysiological techniques.

Keywords

• neurotoxicity
• laboratory animals
• safety pharmacology
• clinical functional testing
• polyneuropathy
• myasthenic syndrome
• beam walking test
• horizontal bar test
• digit abduction score
• tail flick test
• preyer’s reflex
• rodents
• rodent studies