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High- and low-frequency transcutaneous electrical nerve stimulation delay sciatic nerve regeneration after crush lesion in the mouse

Authors

  • Abrahão F. Baptista,

    1. Universidade Federal do Rio de Janeiro, Departamento de Histologia e Embriologia, Instituto de Ciências Biológicas, Centro de Ciências da Saúde, Cidade Universitária, Rio de Janeiro
    2. Fundação Oswaldo Cruz – Centro de Pesquisas Gonçalo Moniz, Unidade de Microscopia Eletrônica, Salvador
    3. Fundação Bahiana para Desenvolvimento das Ciências, Grupo de Pesquisas em Dinâmica do Sistema Neuromusculoesquelético, Salvador, Brazil
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  • Joyce R. S. Gomes,

    1. Fundação Bahiana para Desenvolvimento das Ciências, Grupo de Pesquisas em Dinâmica do Sistema Neuromusculoesquelético, Salvador, Brazil
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  • Júlia T. Oliveira,

    1. Fundação Bahiana para Desenvolvimento das Ciências, Grupo de Pesquisas em Dinâmica do Sistema Neuromusculoesquelético, Salvador, Brazil
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  • Soraia M. G. Santos,

    1. Fundação Bahiana para Desenvolvimento das Ciências, Grupo de Pesquisas em Dinâmica do Sistema Neuromusculoesquelético, Salvador, Brazil
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  • Marcos A. Vannier-Santos,

    1. Fundação Oswaldo Cruz – Centro de Pesquisas Gonçalo Moniz, Unidade de Microscopia Eletrônica, Salvador
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  • Ana M. B. Martinez

    Corresponding author
    1. Universidade Federal do Rio de Janeiro, Departamento de Histologia e Embriologia, Instituto de Ciências Biológicas, Centro de Ciências da Saúde, Cidade Universitária, Rio de Janeiro
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Ana Maria Blanco Martinez, MD, PhD, Universidade Federal do Rio de Janeiro, Departamento de Histologia e Embriologia, Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Bloco F, sala F012, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, CEP 21.949-900, Brazil. Tel/Fax: 55 71 2562-6431; E-mail: martinez@histo.ufrj.br

Abstract

Abstract  The stimulation of peripheral nerve regeneration has been studied in different ways, including the use of electrical fields. The capacity of this modality to enhance nerve regeneration is influenced by the parameters used, including current type, frequency, intensity, and means of administration. Transcutaneous electrical nerve stimulation (TENS) is a frequently used form of administering electrical current to the body, but its effects on peripheral nerve regeneration are not known. This study assessed the influence of TENS on sciatic nerve regeneration, using a model of crush lesion in the mouse. Mice were stimulated 30 min a day, 5 days a week, for 5 weeks with both high- (100 Hz) and low- (4 Hz) frequency TENS. Control animals had the sciatic nerve crushed but were not stimulated. Assessment was performed weekly by functional analysis using the Static Sciatic Index for the mouse and at the end of the experiment by light and electron microscopy. The results showed that although there were no differences between the groups regarding the Static Sciatic Index values, TENS led to nerves with morphological signs of impaired regeneration. At light microscopy level, TENS nerves presented more axons with dark axoplasm, signs of edema, and a less organized cytoarchitecture. Electronmicrographs showed fewer and thinner thick myelinated fibers and increased number of Schwann cell nuclei. Myelinated axon diameters and density and diameter of nonmyelinated fibers were not affected by TENS, leading to the conclusion that this regimen of electrical stimulation leads to a delayed regeneration after a crush lesion of the sciatic nerve in the mouse. All these effects were more pronounced on high-frequency TENS nerves.

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