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In the experiment, a CIA model was successfullyĮstablished in total of 22 rats. Mg/kg) was intradermally injected into six sites at the base of the Operating table (Harvard Apparatus, Cambridge, USA) in a prone Hydrate (350 mg/kg, intraperitoneal) (Sinopharm Chemical ReagentĬo., Ltd., Shanghai, China) and placed on a heated small animal KGaA, Darmstadt, Germany) was dissolved overnight in 0.1 mol/lĪcetic acid (2 mg/ml) at 4☌ and emulsified with incompleteįreund's adjuvant (IFA Sigma-Aldrich Merck KGaA) to a finalĬoncentration of 1 mg/ml. 2, 1988), and the protocols were approved by the EthicsĬommittee of Zhejiang Chinese Medical University (Hangzhou,īovine type II collagen (CII Sigma-Aldrich Merck Use of laboratory animals (State Science and Technology Commission State Science and Technology Commission of China for the care and AllĪnimals were treated in accordance with the regulations of the AllĮxperiments were performed between 8:00 a.m.
#B endorphin free#
(8:00 a.m.-8:00 p.m.), with free access to food and water. Relative humidity of 55±5%, under a standard 12-h light/dark cycle Were housed in temperature-controlled animal cages at 25☑☌ with a Materials and methods AnimalsĪ total of 30 male Wistar rats (weight, 100–120 g Īge, 4 weeks), were purchased from the Shanghai Laboratory AnimalĬenter of the Chinese Academy of Sciences (Shanghai, China). RA is associated with its anti-inflammatory activity. Order to determine whether the analgesic effect of β-endorphin on Protein levels in inflamed tissue of the paws were also measured in MRNA levels of TNF-α, IL-1β and IL-6 in synovial tissue and their Β-endorphin on pain and inflammation in CIA rats were assessed. RA via regulating peripheral inflammation.Ĭollagen-induced arthritis (CIA) was generated. Study hypothesized that opioids also produce analgesic effects on ( 10– 12), which may be associated with their Studies have indicated that injection of opioids into knee jointsĪfter surgery caused prolonged post-operative analgesia in patients These cytokines have aįundamental role in RA pathology, causing inflammation, pain and Interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α areĪctive in the joints of patients with RA. Joint pain, as well as destruction of cartilage and bone ( 8). Type of autoimmune inflammatory arthritis, which may lead to severe Rheumatoid arthritis (RA) is a chronic, systemic Monocytes, granulocytes, lymphocytes and macrophages, synthesizeĪlso bind to receptors on immune cells to regulate inflammatoryĬytokines, which may constitute another mechanism of opioid-induced Inflammatory conditions, local inflammatory cells, including Specific receptors in the nervous system ( 3, 4).Īccumulating evidence has demonstrated that opioids also exert an Opioids are potent analgesics, whichĮxert their pharmacological effects by binding and activating The analgesic effect of opioids has been wellĭemonstrated in animal behavioral studies as well as human clinical These results indicated that β‑endorphin suppresses peripheral pro‑inflammatory mediators in collagen‑induced arthritis, which may contribute to its analgesic effect. It also significantly downregulated TNF‑α and IL‑1β mRNA expression in synovial tissue and their protein levels in inflammatory tissue of the paws of CIA rats, while it had no significant effect on the levels of IL‑6. β‑endorphin treatment significantly increased the TFL, while decreasing the paw arthritis index and swelling in CIA rats. The rat CIA model was successfully induced as indicated by the significantly decreased TFL, increased paw arthritis index and percentage of swelling on day 18. Tumor necrosis factor (TNF)‑α, interleukin (IL)‑1β and IL‑6 mRNA expression in synovial tissue and their protein levels in paw inflammatory tissue were measured. Thermal hyperalgesia as determined by tail flick latency (TFL), as well as paw arthritis index and swelling. Rats were divided into the CIA + saline group and the CIA + β‑endorphin group, in which rats were intraperitoneally injected with β‑endorphin once every other day from day 18 following the injection of CII until day 28. A rat model of collagen‑induced arthritis (CIA) was generated by intradermal injection of bovine type II collagen. The present study aimed to investigate the analgesic and anti‑inflammatory effect of β‑endorphin on inflammatory pain. However, little is known regarding opioid analgesia through the anti‑inflammatory pathway. The classical analgesic pathway of opioids by binding their receptors in the nervous system is well known.