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

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 filaments 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 Electrical stimulation of the posterior insular cortex induces opioid and cannabinoid-dependent antinociception and regulates glial cells in the spinal cordA estimulação elétrica do córtex insular posterior induz antinocicepção opioide e canabinoide dependente e regula células da glia na medula espinal