Cannabidiol induces systemic analgesia through activation of the PI3Kγ/nNOS/NO/KATP signaling pathway in neuropathic mice. A KATP channel S-nitrosylation-dependent mechanism.

BACKGROUND: Cannabidiol (CBD) is the second most abundant pharmacologically active component present in Cannabis sp. Unlike Δ-9-tetrahydrocannabinol (THC), it has no psychotomimetic effects and has recently received significant interest from the scientific community due to its potential to treat anxiety and epilepsy. CBD has excellent anti-inflammatory potential and can be used to treat some types of inflammatory and neuropathic pain. In this context, the present study aimed to evaluate the analgesic mechanism of cannabidiol administered systemically for the treatment of neuropathic pain and determine the endogenous mechanisms involved with this analgesia. METHODS: Neuropathic pain was induced by sciatic nerve constriction surgery, and the nociceptive threshold was measured using the paw compression test in mice. RESULTS: CBD produced dose-dependent antinociception after intraperitoneal injection. Selective inhibition of PI3Kγ dose-dependently reversed CBD-induced antinociception. Selective inhibition of nNOS enzymes reversed the antinociception induced by CBD, while selective inhibition of iNOS and eNOS did not alter this antinociception. However, the inhibition of cGMP production by guanylyl cyclase did not alter CBD-mediated antinociception, but selective blockade of ATP-sensitive K+ channels dose-dependently reversed CBD-induced antinociception. Inhibition of S-nitrosylation dose-dependently and completely reversed CBD-mediated antinociception. CONCLUSION: Cannabidiol has an antinociceptive effect when administered systemically and this effect is mediated by the activation of PI3Kγ as well as by nitric oxide and subsequent direct S-nitrosylation of KATP channels on peripheral nociceptors.

Chronic inflammatory periapical diseases: a Brazilian multicenter study of 10, 381 cases and literature review

Abstract The aim of this study was to investigate the epidemiological and clinical characteristics of chronic inflammatory periapical diseases in different regions of Brazil and to compare with data from the literature. A multicenter study was carried out in four Brazilian referral centers in oral diagnosis. Histopathological records were reviewed, and all cases diagnosed microscopically as periapical granuloma, radicular cyst, and periapical abscess were included. Demographic and clinical data were collected. Descriptive statistics and Pearson's chi-square test were performed. A total of 10,381 cases of chronic inflammatory periapical diseases were found (13.8% of 74,931 archived specimens) over a period of 65 years. Radicular cysts were the most common lesion (59.9%). Women (56.1%) with a mean age of 37.01 years old (range 13 to 100 ± 14.42) and people of white skin color (59.2%) were the most affected individuals by chronic inflammatory periapical diseases. The lesions were generally asymptomatic (28.1%), located in the maxilla (60.1%), and posterior region (49.8%). The radicular cysts were larger when compared to periapical granulomas (p < 0.001). The disagreement between the clinical and histopathological diagnoses was higher when the final diagnosis was a periapical granuloma (p < 0.001). Chronic inflammatory periapical diseases continue to be common lesions affecting mainly adults. This should be a consequence of the burden of untreated caries in permanent teeth. Women are more affected and radicular cyst was the most common lesion.