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Involvement of the opioid system in the analgesia induced by the electrical stimulation of the insular cortex

Grant number: 17/07411-7
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): July 01, 2017
Effective date (End): December 31, 2017
Field of knowledge:Biological Sciences - Physiology
Principal Investigator:Camila Squarzoni Dale
Grantee:Elizamara Santos Gonçalves
Home Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The insular cortex has connections with the analgesic downward pathway of pain and is the place where a painful sensation is interpreted by its intensity, in addition to being in contact with the emotional aspect of chronic pain. Neuropathic pain resulting from peripheral nerve injury is characterized by the presence of allodynia and hyperalgesia. Treatments for this type of pain are constantly ineffective due to misunderstanding of the molecular and cellular mechanisms involved. The encephalic electrical estimation induces mechanisms of pain suppression and endogenous analgesics, being, therefore, an alternative for patients refractory to conventional treatments. However, little is known about the mechanisms that involve this effect, proving a need for studies that go deeper in this field. Data obtained by our group demonstrate that an electrical estimate of the acute insular cortex (ECC) (only a 15 minute estimation session) induces antinociception in rats submitted to a neuropathic pain model, and this effect is dependent on opioid and cannabinoid receptors of the type I. In addition, a chronic ECM is capable of generating a mechanical antinociception that lasts for less than 24 hours after a last stimulation session without generating effects on a general locomotor activity of the animals. Thus, this project aims to investigate the effect of chronic ECSI (5 consecutive daily sessions of 15 minutes of estimation) on a mechanical pain sensitivity and to perform tests with a naloxone - a nonselective opioid antagonist to verify the involvement of the opioidergic system No antinociceptive effect induced by chronic ECSS in animals submitted to a peripheral neuropathy model. (AU)