Systemic treatment with canabidiol in a neuropathic pain model: evaluation of the sensorial-discriminative and emotional-motivacional components pain sensitivity

Abstract

The conditions of persistent or chronic pain are often accompanied by disordersemotional and cognitive. These dysfunctional or maladaptive changes in aversive/motivational circuits probably contribute to the challenges of treating neuropathic pain. However, experimental and methods used to measure the affective dimension of pain are still scarce in the literature. Considering the neurochemistry involved in nociceptive modulation, the cannabinoid system is an important endogenous system that participates in the circuit of pain sensitivity, functioning in parallel to the system and playing crucial roles in the development and resolution of pain states, as well as in the affective and cognitive aspects of pain. The distribution of the cannabinoid system in the neuraxis is extensive, with endogenous cannabinoids (CB) and their receptors found throughout the central nervous system. Still, recent studies suggest that cannabinoids act not only through action on cannabinoid receptors (CB), but also by modulation of vanilloid receptors (TRPV1). This study will if the systemic treatment with CBD modulates allodynia and hyperalgesia in a neuropathic pain model. In particular, it will be assessed whether CBD administration specifically alters the behavioral response (thermal and mechanical), that is to say, of the discriminating component of pain, and/or of the affective-motivational component. To achieve this, the von Frey Test (allodyniamechanics), hot plate and acetone test (heat and cold sensitivity the test of preference to the conditioned place (will evaluate the emotional affective component of the pain). In asecond stage, the expression of TRPV1 and CB1 receptors, as well as FOS encephalic components involved in the modulation of the affective-motivational component of pain. In particular, the following structures were evaluated: insular cortex, cingulate gyrus cortex, amygdala and hippocampus. Considering these objectives, we intend to understand the mechanisms that would be involved inmodulation of neuropathic pain and related to cannabinoid neurotransmission in brain areas addressed in this study. (AU)