The journal of pain : official journal of the American Pain Society
-
Morphine is a potent opioid analgesic used to alleviate moderate or severe pain, but the development of drug tolerance and dependence limits its use in pain management. Previous studies showed that cannabinoid type 2 (CB2) receptor ligands may modulate opioid effects. However, there is no report of the effect of CB2 receptor agonist on acute morphine tolerance and physical dependence. ⋯ Pretreatment with 3mg/kg AM1241 decreased the chronic morphine-induced Iba1 expression in spinal cord. Coadministration of AM1241 (3 mg/kg) reduced the production of interleukin-1β, tumor necrosis factor-α, and interleukin-6 induced by long-term and acute morphine treatment. Our findings suggest that the coadministration of the CB2 receptor agonist and morphine could increase morphine antinociception and reduce morphine tolerance and physical dependence in mice.
-
Facilitated pain mechanisms have been demonstrated in musculoskeletal pain, but it is unclear whether a recent painful injury leaves the pain system sensitized. Pain characteristics were assessed in individuals who recently recovered from ankle pain (recovered pain group; n = 25) and sex-matched control subjects (n = 25) in response to tonic pressure pain and saline-induced pain applied at the shin muscle. Pain intensity and pain referral patterns were recorded bilaterally after the painful muscle stimulus. ⋯ Compared with in control subjects, saline-induced and pressure-induced pain in the shin muscle were more frequently felt as referred pain in the previously painful ankle (P < .05), and the pain area within the previously affected ankle was larger after saline-induced pain (P < .05). In the recovered pain group, conditioned pain modulation responses and the cuff pressure needed to reach a 6-cm pain score on a 10-cm visual analog scale was higher in the previously painful leg compared with in the contralateral leg (P < .05). No group differences were found in pressure pain threshold, pain detection threshold, pain tolerance, and temporal summation of pain.
-
Postoperative pain after bone reconstruction is a serious complication that could jeopardize the global success of a surgery. This pain must be controlled and minimized during the first 3 to 4 postoperative days to prevent it from becoming chronic. In this study, a critical-size bone defect was created at the femoral distal end of rats and filled by an injectable calcium phosphate cement (CPC) loaded or not with local anesthetics (bupivacaine or ropivacaine). A functional evaluation of the gait was performed using the CatWalk system to compare the postoperative pain relief enhanced by the different CPCs after such a bone filling surgery. The results demonstrated significant pain relief during the short-term postoperative period, as shown by the print area and intensity parameters of the operated paw. At 24hours, the print area decreased by 65%, 42%, and 24%, and the intensity decreased by 25%, 9%, and 1% for unloaded, ropivacaine-loaded, and bupivacaine-loaded CPCs, respectively, compared with the preoperative values. Bupivacaine-loaded CPC provided an earlier return to full functional recovery than ropivacaine-loaded CPC. Moreover, the CPCs retained their biologic and mechanical properties. For all these reasons, anesthetic-loaded CPCs could be part of the global pain management protocol after bone reconstruction surgery such as iliac crest bone grafting procedures. ⋯ Bupivacaine-loaded CPC provided an earlier return to full gait function than ropivacaine-loaded CPC, with preserved bone filling properties. Such analgesic CPCs deserve further in vivo investigation and may be part of the global pain management protocol after bone reconstruction or bone augmentation surgery such as iliac crest bone grafting.
-
Chemotherapy-induced neuropathic pain is a common dose-limiting side effect of anticancerdrugs but lacks an effective treatment strategy. Scolopendra subspinipes has been used in traditional medicine to treat chronic neuronal diseases. Moreover, pharmacopuncture with S subspinipes (SSP) produces potent analgesia in humans and experimental animals. ⋯ The combination of SSP with a lower dose of clonidine (0.03 mg/kg) produced a comparable analgesic effect without side effects. Collectively, our findings demonstrate that SSP produces an analgesic effect in oxaliplatin-induced pain via neuronal conduction at the acupoint and activation of spinal α2-adrenoceptors. Moreover, acombination of low-dose clonidine with SSP represents a novel and safe therapeutic strategy for chemotherapy-induced chronic pain.