Electrical stimulation of the posterior insular cortex induces opioid and cannabinoid-dependent antinociception and regulates glial cells in the spinal cord

• Autor(a) principal: Gonçalves,Elizamara Santos
• Data de Publicação: 2022
• Outros Autores: Matielo,Heloísa Alonso, Teixeira,Manoel Jacobsen, Andrade,Daniel Ciampi de, Hamani,Clement, Dale,Camila Squarzoni
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: BrJP (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2595-31922022000300239
• topic: Chronic pain; Electric stimulation; Neuroglia

ABSTRACT BACKGROUND AND OBJECTIVES: Half of neuropathic pain patients still end up failing clinical treatments. Electrical stimulation of the posterior insular cortex (ESI) modulates sensory and nociceptive circuits. This study evaluated the effects of a range of frequencies of ESI proposed to improve neuropathic pain. METHODS: Male Sprague Dawley rats, 280-340 g, submitted to the chronic constriction of the right sciatic nerve were tested for mechanical sensitivity using the paw pressure and von Frey flaments tests, and for thermal sensitivity using the hot plate test. The rats were submitted to ESI 10, 60 or 100 Hz (one, five or seven ESI, 15 min, 210 µs, 1V), applied to the posterior insular cortex, and were evaluated in the tests before and after ESI, or in follow-up of 48, 72 and 168h. The open field evaluated general activity after ESI 5. The involvment of opioid and cannabinoid testes were evaluated through treatment with naloxone and SR1416A - antagonist and inverse agonist/antagonist of the receptors, respectively, after ESI 5, while activation of astrocytes, marked by glial fibrillary acid protein (GFAP), and of microglia, marked by IBA-1 (glial marker), in the spinal cord evaluated by immunohistochemistry. RESULTS: Data demonstrate that 10, 60, and 100 Hz ESIs modulate mechanical and thermal sensitivity. ESI 5 increased immunoreactivity of GFAP in the spinal cord, without altering IBA-1 (glial marker). Naloxone and SR141716A reversed the antinociception of 60 Hz ESI 5. 60 Hz ESI 7 induced antinociception up to 72h. CONCLUSION: 60 Hz ESI induces opioid and cannabinoid-dependent antinociception and regulates glia. HIGHLIGHTS 60 Hz-delivered ESI was the best analgesic protocol for the insular stimulation. Data showed a prolonged analgesic effect up to 72h after repetitive ESI. ESI regulates glia activation in pain modulatory system.