Nalbuphine attenuates morphine-induced scratching by inhibiting PKCß-dependent microglial activation and p38 phosphorylation in male mice.

Morphine-induced scratching (MIS) is a common adverse effect associated with the use of morphine as analgesia after surgery. However, the treatment of MIS is less than satisfactory due to its unclear mechanism, which needs to be enunciated. We found that intrathecal (i.t.) injections of morphine significantly enhanced scratching behavior in C57BL/6J male mice as well as increased the expressions of protein kinase C ß (PKCß), phosphorylated p38 mitogen-activated protein kinases (MAPK), and ionized calcium-binding adapter molecule 1 (Iba1) within spinal cord dorsal horn. Conversely, using the kappa opioid receptor antagonist nalbuphine significantly attenuated scratching behavior, reduced PKCß expression and p38 phosphorylation, and decreased spinal dorsal horn microglial activation, while PKCδ and KOR expression elevated. Spinal PKCß silencing mitigated MIS and microglial activation. Still, knockdown of PKCδ reversed the inhibitory effect of nalbuphine on MIS and microglial activation, indicating that PKCδ is indispensable for the antipruritic effects of nalbuphine. In contrast, PKCß is crucial for inducing microglial activation in MIS in male mice. Our findings show a distinct itch cascade of morphine, PKCß/p38MAPK, and microglial activation, but an anti-MIS pathway of nalbuphine, PKCδ/KOR, and neuron activation.

Combination of thoracic epidural analgesia with patient-controlled intravenous analgesia versus traditional thoracic epidural analgesia for postoperative analgesia and early recovery of laparotomy: a prospective single-centre, randomized controlled trial.

BACKGROUND: Thoracic epidural analgesia (TEA) has always been the first choice for postoperative pain treatment, but associated complications and contraindications may limit its use. Our study put forward a new analgesic strategy that combines TEA with patient controlled intravenous analgesia (PCIA) to optimize TEA. METHODS: Patients undergoing laparotomy were enrolled in this prospective randomized study. Patients were randomized to one of two groups: TEA/PCIA group and TEA group. Patients in TEA/PCIA group received TEA in the day of surgery and the first postoperative day and PCIA continued to use until the third postoperative day. Patients in TEA group received TEA for three days postoperatively. Visual analogue scale (VSA) pain scores at rest and on movement at 6, 24,48,72 h after surgery were recorded. In addition, the incidence of inadequate analgesia, adverse events, time to first mobilization, time to pass first flatus, time of oral intake recovery, time of urinary catheter removal, postoperative length of hospital stay, cumulative opioid consumption, and the overall cost were compared between the two groups. We examined VAS pain scores using repeated measures analysis of variance; P < 0.05 was considered as statistically significant. RESULTS: Eighty-six patients were analysed (TEA/PCIA = 44, TEA = 42). The mean VAS pain scores at rest and on movement in TEA/PCIA group were lower than TEA group, with a significant difference on movement and 48 h postoperatively (P < 0.05). The time to first mobilization and pass first flatus were shorter in TEA/PCIA group (P < 0.05). Other measurement showed no statistically significant differences. CONCLUSIONS: The combination of TEA with PCIA for patients undergoing laparotomy, can enhance postoperative pain control and facilitate early recovery without increasing the incidence of adverse effects and overall cost of hospitalization. TRIAL REGISTRATION: Chinese Clinical Trial Registry( www.chictr.org.cn ), ChiCTR 1,800,020,308, 13 December 2018.

Bone mesenchymal stem cells attenuate resiniferatoxin-induced neuralgia via inhibiting TRPA1-PKCδ-P38/MAPK-p-P65 pathway in mice.

Treatment of neuropathic pain (NP) resulting from nerve injury is one of the most complicated and challenging in modern practice. Pharmacological treatments for NP are not fully effectively and novel approaches are requisite. Recently, transplantation of bone mesenchymal stem cells (BMSCs) has represented a promising approach for pain relief and neural repair, but how it produces beneficial effects on resiniferatoxin (RTX) induced nerve injury is still unclear. Here, we identified the BMSCs' analgesic effects and their potential mechanisms of microglial cells activation on RTX induced neuralgia. Immunostaining, biochemical studies demonstrated that microglia rather than astrocyte cells activation involved in RTX induced mechanical hyperalgesia, whereas the GFP-labeled BMSCs alleviated this mechanical hyperalgesia. Moreover, pain-related TRPA1, PKCδ, CaMKIIɑ (Calcium/calmodulin dependent protein kinase II), P38/MAPK (mitogen-activated protein kinase), p-P65 activation and expression in the spinal cord were significantly inhibited after BMSC administration. In addition, BMSCs treated RTX mice displayed a lower density of mushroom dendritic spines. Our research suggested that activation of PKCδ-CaMKIIɑ-P38/MAPK-p-P65 pathway and mushroom dendritic spines abnormal increase in the spinal cord is the main mechanism of RTX induced neuropathic pain, and transplant of BMSCs to the damaged nerve may offer promising approach for neuropathic pain.