Background: Electroacupuncture (EA) can produce analgesia by increasing the β-endorphin level and activation of peripheral μ-opioid receptors in inflamed tissues. Endogenous cannabinoids and peripheral cannabinoid CB2 receptors (CB2Rs) are also involved in the antinociceptive effect of EA on inflammatory pain. However, little is known about how peripheral CB2Rs interact with the endogenous opioid system at the inflammatory site and how this interaction contributes to the antinociceptive effect of EA on inflammatory pain. In this study, we determined the role of peripheral CB2Rs in the effects of EA on the expression of β-endorphin in inflamed skin tissues and inflammatory pain.Results: Inflammatory pain was induced by injection of complete Freund's adjuvant into the left hindpaw of rats. Thermal hyperalgesia was tested with a radiant heat stimulus, and mechanical allodynia was quantified using von Frey filaments. The mRNA level of POMC and protein level of β-endorphin were quantified by real-time PCR and Western blotting, respectively. The β-endorphin-containing keratinocytes and immune cells in the inflamed skin tissues were detected by double-immunofluorescence labeling. The CB2R agonist AM1241 or EA significantly reduced thermal hyperalgesia and mechanical allodynia, whereas the selective μ-opioid receptor antagonist β-funaltrexamine significantly attenuated the antinociceptive effect produced by them. AM1241 or EA significantly increased the mRNA level of POMC and the protein level of β-endorphin in inflamed skin tissues, and these effects were significantly attenuated by pretreatment with the CB2R antagonist AM630. AM1241 or EA also significantly increased the percentage of β-endorphin-immunoreactive keratinocytes, macrophages, and T-lymphocytes in inflamed skin tissues, and these effects were blocked by AM630.Conclusions: EA and CB2R stimulation reduce inflammatory pain through activation of μ-opioid receptors. EA increases endogenous opioid expression in keratinocytes and infiltrating immune cells at the inflammatory site through CB2R activation.

Annexin 1 (ANXA1) has analgesic effects in inflammatory pain. We aimed to investigate the anti-nociceptive role of ANXA1, at the dorsal root ganglion (DRG) level, through an interaction with formyl-peptide-receptor-like 1 (FPR2/ALX). Inflammatory pain was evoked by injecting complete Freund's adjuvant (CFA, 50 μl) into the hindpaw of male Sprague-Dawley rats. The distribution of ANXA1 and FPR2/ALX in L4/5 DRGs was evaluated by immunofluorescence. The expression of ANXA1 was measured by western blot. The involvement of FPR2/ALX in the anti-nociception of ANXA1 was investigated by thermal (irradiant heat) and mechanical (von Frey filament) pain tests with intrathecal (i.t.) ANXA1-derived peptide (Anxa1(2-26)), FPR2/ALX agonist 5(S)-6(R)-7-trihydroxyheptanoic-acid-methyl-ester (BML-111), and antagonist N-t-Boc-Phe-Leu-Phe-Leu-Phe (Boc1). ANXA1 and FPR2/ALX localized in the satellite glial cells and neurones in L4/5 DRGs. CFA treatment (n=20) increased ANXA1 expression in L4/5 DRGs within 7 days (P<0.01). I.T. Anxa1(2-26) (20 and 100 µg µl(-1)) and BML-111 (10 and 100 nmol) reduced CFA-induced thermal and mechanical nociception within 48 h (n=40) (P<0.05). However, i.t. Boc1 10 µg intensified inflammatory pain (P<0.05) and reversed the anti-nociceptive effect of Anxa1(2-26) (n=25) (P<0.05). Moreover, ANXA1 expression increased in L4/5 DRGs after i.t. Anxa1(2-26) (20 µg µl(-1)) (P<0.05) and BML-111 (10 nmol) (P<0.01) but decreased after i.t. Boc1 (10 and 100 µg) alone (P<0.01) or Boc1 (10 µg) co-injection with Anxa1(2-26) (20 µg µl(-1)) (P<0.05). Endogenous ANXA1 expression at the DRG level is involved in CFA-induced inflammatory pain, and i.t. ANXA1 20 µg µl(-1) produces its anti-nociceptive effect through FPR2/ALX.

Objective: GLUT1 deficiency syndrome (GLUT1-DS) is a rare, treatable neurometabolic disorder. However, its diagnosis may be challenging due to the various and evolving phenotypes. Here we report the first Chinese familial cases with genetically confirmed GLUT1-DS and analyze the characteristics of Chinese children with GLUT1-DS from clinical, laboratory, and genetic aspects.Methods: We reported a Chinese family with three members affected with GLUT1-DS and searched for relevant articles up to September 2020 from PubMed, WOS, CNKI, and WanFang databases. A total of 30 Chinese patients diagnosed with GLUT1-DS (three newly identified patients in one family and 27 previously reported ones) were included and analyzed in this study.Results: The median age of onset of the 30 patients (male: 18, female: 12) was 8.5 months (range, 33 days to 10 years). Epileptic seizures were found in 25 patients, most with generalized tonic–clonic and focal ones. Movement disorders were found in 20 patients—frequently with ataxia and dystonia, developmental delay in 25 patients, and microcephaly only in six patients. The cerebrospinal fluid (CSF) analysis showed decreased CSF glucose (median: 1.63 mmol/L, range: 1.1–2.6 mmol/L) and glucose ratio of CSF to blood (median: 0.340; range: 0.215–0.484). The genetic testing performed in 28 patients revealed 27 cases with pathogenic variations of the SLC2A1 gene, including 10 missense, nine frameshift, three nonsense, three large fragment deletions, and two splice-site mutations. Most patients had a good response to the treatment of ketogenic diet or regular diet with increased frequency. Although three patients in this Chinese family carried the same pathogenic mutation c.73C > T (p.Q25X) in the SLC2A1 gene, their symptoms and responses to treatment were not exactly the same.Conclusion: The clinical manifestations of GLUT1-DS are heterogeneous, even among family members sharing the same mutation. For children with unexplained epileptic seizures, developmental delay, and complex movement disorders, detection of low CSF glucose or SLC2A1 gene mutations is helpful for the diagnosis of GLUT1-DS. Early initiation of ketogenic diet treatment significantly improves the symptoms and prognosis of GLUT1-DS.

Autism spectrum disorder (ASD) is a serious neurodevelopmental disorder and characterized by early childhood-onset impairments in social interaction and communication, restricted and repetitive patterns of behavior or interests. So far there is no effective treatment for ASD, and the pathogenesis of ASD remains unclear. Genetic and epigenetic factors have been considered to be the main cause of ASD. It is known that endocannabinoid and its receptors are widely distributed in the central nervous system, and provide a positive and irreversible change toward a more physiological neurodevelopment. Recently, the endocannabinoid system (ECS) has been found to participate in the regulation of social reward behavior, which has attracted considerable attention from neuroscientists and neurologists. Both animal models and clinical studies have shown that the ECS is a potential target for the treatment of autism, but the mechanism is still unknown. In the brain, microglia express a complete ECS signaling system. Studies also have shown that modulating ECS signaling can regulate the functions of microglia. By comprehensively reviewing previous studies and combining with our recent work, this review addresses the effects of targeting ECS on microglia, and how this can contribute to maintain the positivity of the central nervous system, and thus improve the symptoms of autism. This will provide insights for revealing the mechanism and developing new treatment strategies for autism.