Top-Down Effect of Direct Current Stimulation on the Nociceptive Response of Rats

Autor(es)

Dimov, Luiz Fabio ^[1] ; Franciosi, Adriano Cardozo ^[1] ; Pinheiro Campos, Ana Carolina ^[1] ; Brunoni, Andre Russowsky ^{[2, 3, 4]} ; Pagano, Rosana Lima ^[1]

Afiliação do(s) autor(es)

^[1] Hosp Sirio Libanes, Lab Neuromodulat & Expt Pain, Rua Prof Daher Cutait 69, BR-01308060 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Fac Med, SIN, Dept & Inst Psychiat, Lab Neurosci LIM27, Rua Doutor Ovidio Pires Campos 785, BR-05403000 Sao Paulo, SP - Brazil

^[3] Univ Sao Paulo, Ctr Clin & Epidemiol Res, Univ Hosp, Ave Prof Lineu Prestes 2565, Ext 3, BR-05508000 Sao Paulo, SP - Brazil

^[4] Univ Sao Paulo, Interdisciplinary Ctr Appl Neuromodulat CINA, Univ Hosp, Ave Prof Lineu Prestes 2565, Ext 3, BR-05508000 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: PLoS One; v. 11, n. 4 APR 12 2016.
• Citações Web of Science: 4

Resumo

Transcranial direct current stimulation (tDCS) is an emerging, noninvasive technique of neurostimulation for treating pain. However, the mechanisms and pathways involved in its analgesic effects are poorly understood. Therefore, we investigated the effects of direct current stimulation (DCS) on thermal and mechanical nociceptive thresholds and on the activation of the midbrain periaqueductal gray (PAG) and the dorsal horn of the spinal cord (DHSC) in rats; these central nervous system areas are associated with pain processing. Male Wistar rats underwent cathodal DCS of the motor cortex and, while still under stimulation, were evaluated using tail-flick and paw pressure nociceptive tests. Sham stimulation and naive rats were used as controls. We used a randomized design; the assays were not blinded to the experimenter. Immunoreactivity of the early growth response gene 1 (Egr-1), which is a marker of neuronal activation, was evaluated in the PAG and DHSC, and enkephalin immunoreactivity was evaluated in the DHSC. DCS did not change the thermal nociceptive threshold; however, it increased the mechanical nociceptive threshold of both hind paws compared with that of controls, characterizing a topographical effect. DCS decreased the Egr-1 labeling in the PAG and DHSC as well as the immunoreactivity of spinal enkephalin. Altogether, the data suggest that DCS disinhibits the midbrain descending analgesic pathway, consequently inhibiting spinal nociceptive neurons and causing an increase in the nociceptive threshold. This study reinforces the idea that the motor cortex participates in the neurocircuitry that is involved in analgesia and further clarifies the mechanisms of action of tDCS in pain treatment. (AU)

• Processo FAPESP: 12/20911-5 - Escitalopram e estimulação transcraniana por corrente contínua no transtorno depressivo maior: um ensaio clínico randomizado, duplo-cego, placebo-controlado de não-inferioridade
• Beneficiário: Andre Russowsky Brunoni
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 11/21631-3 - Efeito da estimulação direta de corrente contínua transcraniana sobre a resposta nociceptiva
• Beneficiário: Luiz Fabio Dimov
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
• Processo FAPESP: 09/50772-4 - Doença de Parkinson e dor: mecanismos envolvidos na neuroplasticidade nociciptiva e no efeito da estimulação do córtex motor em ratos
• Beneficiário: Rosana de Lima Pagano
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores