Olanzapine for the prevention of postoperative nausea and vomiting after gynecologic laparoscopic surgery: a randomized controlled trial.

Purpose: This study was designed to investigate the prophylactic effect of oral olanzapine in postoperative nausea and vomiting after gynecologic laparoscopic surgery. Methods: ASA I-II, aged 18-75 years, planned to undergo gynecologic laparoscopic surgery with general anesthesia in adult female patients. Using the randomized numbers table, the patients were placed in two groups. Oral olanzapine 5 mg or placebo was given 1 h before anesthesia. All patients received standard antiemetic prophylaxis with dexamethasone and granisetron. The primary outcome was nausea and/or vomiting in the 24 h after the postoperative. Results: A total of 250 patients were randomized, and 241 were analyzed. The primary outcome occurred in 10 of 120 patients (8.3%) in the olanzapine group and 23 of 121 patients (19.2%) in the placebo group (p = 0.014). According to Kaplan-Meier analysis, the probabilities of nausea and/or vomiting in the 24 h after the postoperative in the olanzapine group were lower than in the placebo group (log-rank p = 0.014). In a multivariate Cox analysis, the variables of use of olanzapine [hazard ratio (HR): 0.35, 95% confidence interval (CI): 0.16-0.79; p = 0.012] and use of vasoactive drugs (HR: 2.48, 95% CI: 1.07-5.75; p = 0.034) were independently associated with nausea and/or vomiting in the 24 h after the postoperative. Conclusion: Our data suggest that olanzapine relative to placebo decreased the risk of nausea and/or vomiting in the 24 h after gynecologic laparoscopic surgery. Trial registration: The trial was registered prior to patient enrollment at The Chinese Clinical Trial Registry (https://www.chictr.org.cn/showproj.html?proj=166900, link to registry page, Principal investigator: Nanjin Chen, Date of registration: 25 April 2022).

Preventing nausea and vomiting after laparoscopic gynecological surgery: the benefits of using olanzapine Why was this study done? Despite the use of antiemetics, postoperative nausea and vomiting remain prevalent. Furthermore, patients who undergo gynecological laparoscopic surgery are at an increased risk. Therefore, this study investigated whether oral Olanzapine could reduce the incidence of nausea and vomiting after gynaecological Laparoscopy? What did the researchers do? The research team examined patients who underwent gynecological laparoscopic surgery under general anesthesia. They observed the occurrence of nausea and vomiting within 24 hours after surgery in patients who either received or did not receive Olanzapine treatment. The goal was to assess the effectiveness of Olanzapine in reducing postoperative nausea and vomiting. What did the researchers find? The addition of Olanzapine, when combined with granisetron and dexamethasone, resulted in a decreased risk of nausea and/or vomiting within the 24 hours following gynecologic laparoscopic surgery, as compared to the placebo. Administering oral Olanzapine at a dosage of 5 mg reduced the incidence of nausea and vomiting after gynecological laparoscopy from 19.2% to 8.3%. What do the findings mean? This study has identified a safe and effective medication for preventing postoperative nausea and vomiting. Implementing Olanzapine as a preventive measure can significantly reduce the incidence of nausea and vomiting following surgery, thereby enhancing the overall medical experience for patients.

Triptolide Alleviates Neuropathic Pain by Inhibiting the Activation of Microglial Toll-Like Receptor 3.

BACKGROUND: Current data indicates the incidence of neuropathic pain after surgical nerve injury is as high as 50%, thus representing a major problem for patients and for the medical system. Triptolide, a traditional Chinese herb, has anti-inflammatory effects on various neurodegenerative and neuroinflammatory diseases. This agent also reduces peripheral nerve injury-induced neuropathic pain, although the mechanism underlying this effect is still unknown. MATERIALS AND METHODS: The effects of triptolide on spinal nerve ligation (SNL) injury-induced neuropathic pain was studied in an animal model using behavioral, morphological and molecular biological methods. RESULTS: Repeated administration of intrathecal triptolide was found to alleviate SNL- or Poly(I:C) (toll-like receptor 3 agonist) injection-induced mechanical allodynia without any motor impairment. The mechanism by which triptolide reduces SNL- and Poly(I:C) injection-induced microglial activation appears to be via the inhibition of OX42 expression, which is a microglial-specific marker. Intrathecal triptolide also suppressed SNL- and Poly(I:C) injection-induced expression of spinal TRIF. TRIF transmits signals from activated TLR3 and is the downstream adaptor of TLR3 in microglia. In addition, intrathecal triptolide inhibited the expression of spinal pro-inflammatory IL-1 ß following SNL or Poly(I:C) injection. CONCLUSIONS: Intrathecal triptolide can suppress the TLR3/TRIF/IL-1 ß pathway in spinal microglia following SNL. This could be the underlying mechanism by which triptolide alleviate neuropathic pain induced by peripheral nerve injury.

Pre-anesthetic clinic internship: new teaching method of pre-anesthesia evaluation for undergraduates.

BACKGROUND: This study aimed to observe the effect of internship in a pre-anesthetic clinic on the teaching quality of pre-anesthesia evaluation for undergraduates. METHODS: A total of 120 undergraduates from July 2017 to July 2018 in the anesthesia department of our hospital were randomly divided into two groups: pre-anesthetic clinic internship teaching group (n = 60) and traditional teaching group (n = 60). The knowledge in the pre-anesthesia evaluation teaching chapters was evaluated between the two groups of undergraduates. RESULTS: There were no significant differences in the demographic information between the two groups. The scores in the case analysis and theoretical knowledge test in the pre-anesthetic clinic internship teaching group were significantly higher than those in the traditional teaching group. In addition, the students' satisfaction with the curriculum design was significantly higher in the pre-anesthetic clinic internship teaching group than in the traditional teaching group. CONCLUSION: Pre-anesthetic clinic internships can improve the quality of pre-anesthesia assessment teaching for undergraduates.

Remifentanil up-regulates HIF1α expression to ameliorate hepatic ischaemia/reperfusion injury via the ZEB1/LIF axis.

Ischaemia/reperfusion (I/R)-induced hepatic injury is regarded as a main reason of hepatic failure after transplantation or lobectomy. The current study aimed to investigate how the opioid analgesic remifentanil treatment affects I/R-induced hepatic injury and explore the possible mechanisms related to HIF1α. Initially, an I/R-induced hepatic injury animal model was established in C57BL/6 mice, and an in vitro hypoxia-reoxygenation model was constructed in NCTC-1469 cells, followed by remifentanil treatment and HIF1α silencing treatment. The levels of blood glucose, lipids, alanine transaminase (ALT) and aspartate transaminase (AST) in mouse serum were measured using automatic chemistry analyser, while the viability and apoptosis of cells were detected using CCK8 assay and flow cytometry. Our results revealed that mice with I/R-induced hepatic injury showed higher serum levels of blood glucose, lipids, ALT and AST and leukaemia inhibitory factor (LIF) expression, and lower HIF1α and ZEB1 expression (P < .05), which were reversed after remifentanil treatment (P < .05). Besides, HIF1α silencing increased the serum levels of blood glucose, lipids, ALT and AST (P < .05). Furthermore, hypoxia-induced NCTC-1469 cells exhibited decreased HIF1α and ZEB1 expression, reduced cell viability, as well as increased LIF expression and cell apoptosis (P < .05), which were reversed by remifentanil treatment (P < .05). Moreover, HIF1α silencing down-regulated ZEB1 expression, decreased cell viability, and increased cell apoptosis (P < .05). ZEB1 was identified to bind to the promoter region of LIF and inhibit its expression. In summary, remifentanil protects against hepatic I/R injury through HIF1α and downstream effectors.

Systemic Injection of Thalidomide Prevent and Attenuate Neuropathic Pain and Alleviate Neuroinflammatory Response in the Spinal Dorsal Horn.

BACKGROUND AND OBJECTIVE: Thalidomide (Tha) has been shown to exert immunomodulatory and anti-inflammatory properties. Whether Tha can alleviate spinal nerve ligation (SNL)-induced neuropathic pain (NP) is still unclear. This study aimed to investigate the therapeutic effect of Tha on the SNL-induced NP and further explore the potential analgesic mechanisms of Tha. METHODS: The effects of Tha on SNL-induced mechanical allodynia were assessed by pain behavioral testing. The expressions of the astrocyte marker glial fibrillary acidic protein (GFAP) and the microglia marker Iba1 in the spinal dorsal horn were evaluated by immunofluorescence histochemistry. Protein expressions of the tumor necrosis factor alpha (TNF-α) in the spinal dorsal horn were tested by Western blot assay. Data were analyzed using one-way ANOVA or two-way ANOVA. RESULTS: By the pretreatment with a single intraperitoneal injection, the PWMT in SNL+Tha group was significantly increased from day 1 to day 2 after SNL (P < 0.05 compared with SNL+Veh group). By the posttreatment with a single intraperitoneal injection, the PWMT in SNL+Tha group was also significantly increased from day 3 to day 4 after SNL (P < 0.05 compared with SNL+Veh group). By the posttreatment with multiple intraperitoneal injection, both the PWMT and the PWTL in SNL+Tha group were similarly significantly increased from day 3 to day 14 after SNL (P < 0.05 compared with SNL+Veh group). Furthermore, the GFAP and Iba1 expressions and TNF-α levels of the ipsilateral spinal dorsal horn in SNL+Tha group were significantly weaker from day 3 to day 14 after SNL than those in SNL+Veh group (P < 0.05). CONCLUSION: Tha can significantly alleviate NP induced by SNL. The analgesic mechanism may be related to inhibition of astrocyte and microglia activation as well as down-regulation of TNF-α levels in the spinal dorsal horn.

Probenecid Relieves Cerebral Dysfunction of Sepsis by Inhibiting Pannexin 1-Dependent ATP Release.

Acute brain dysfunction and the following neurological manifestation are common complications in septic patients, which are associated with increased morbidity and mortality. However, the therapeutic strategy of this disorder remains a major challenge. Given the emerging role of a clinically approved drug, probenecid (PRB) has been recently identified as an inhibitor of pannexin 1 (PANX1) channel, which restrains extracellular ATP release-induced purinergic pathway activation and inflammatory response contributing to diverse pathological processes. In this study, we explored whether PRB administration attenuated neuroinflammatory response and cognitive impairment during sepsis. In mice suffered from cecal ligation and puncture (CLP)-induced sepsis, treatment with PRB improved memory retention and lessened behavioral deficits. This neuroprotective effect was coupled with restricted overproduction of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and interleukin (IL)-1ß in the hippocampus. Since this damped neuroinflammation was replicated by inhibition of ATP release, it suggested that PANX1 channel modulates a purinergic-related pathway contributing to the neurohistological damage. Therefore, we identified PRB could be a promising therapeutic approach for the therapy of cerebral dysfunction of sepsis.

The effect of pre- and after-treatment of sevoflurane on central ischemia tolerance and the underlying mechanisms.

In recent years, with continuous research efforts targeted at studying the effects of pre- and after-treatment of inhaled anesthetics, significant progress has been made regarding the common clinical use of low concentrations of inhaled sevoflurane and its effect on induced central ischemia tolerance by pre- and post-treatment. In this study, we collected, analyzed, classified, and summarized recent literature regarding the effect of sevoflurane on central ischemia tolerance and its related mechanisms. In addition, we provide a theoretical basis for the clinical application of sevoflurane to protect the central nervous system and other important organs against ischemic injury.

Hyperoxygenated hydrogen-rich solution suppresses shock- and resuscitation-induced liver injury.

BACKGROUND: It is not known whether simultaneous delivery of hydrogen and oxygen can reduce injury caused by hemorrhagic shock and resuscitation (HSR). This study investigated the therapeutic potential of hyperoxygenated hydrogen-rich solution (HHOS), a combined hydrogen/oxygen carrier, in a rat model of HSR-induced liver injury. MATERIALS AND METHODS: Rats (n = 60) were randomly divided into 5 groups (n = 6 per group at each time point). One group underwent sham operation, and the others were subjected to severe hemorrhagic shock and then treated with lactated Ringer's solution (LRS), hydrogen-rich solution, hyperoxygenated solution, or HHOS. At 2 and 6 h after resuscitation, blood samples (n = 6) were collected from the femoral artery and serum concentrations of alanine aminotransferase and aspartate aminotransferase (AST) were measured. Rats were then sacrificed, and histopathological changes in the liver were evaluated by quantifying the percentage of apoptotic cells by caspase-3 immunohistochemistry and terminal deoxynucleotidyl transferase dUTP nick-end labeling. Inflammation was assessed by assessing malondialdehyde content and tumor necrosis factor-α, and interleukin (IL)-6 expression. RESULTS: Compared to lactated Ringer's solution, hydrogen-rich solution, or hyperoxygenated solution groups, serum AST and alanine aminotransferase levels and IL-6, tumor necrosis factor-α, and malondialdehyde expression in liver tissue were decreased by HHOS treatment. The number of caspase-3- and terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells was decreased (P < 0.05) by HHOS treatment, 2 and 6 h after resuscitation. CONCLUSIONS: HHOS has protective effects against liver injury in a rat model of HSR.

Cause analysis, prevention, and treatment of postoperative restlessness after general anesthesia in children with cleft palate.

Cleft palate is one of the most common congenital malformations of the oral and maxillofacial region, with an incidence rate of around 0.1%. Early surgical repair is the only method for treatment of a cleft lip and palate. However, because of the use of inhalation anesthesia in children and the physiological characteristics of the cleft palate itself combined with the particularities of cleft palate surgery, the incidence rate of postoperative emergence agitation (EA) in cleft palate surgery is significantly higher than in other types of interventions. The exact mechanism of EA is still unclear. Although restlessness after general anesthesia in children with cleft palate is self-limiting, its effects should be considered by clinicians. In this paper, the related literature on restlessness after surgery involving general anesthesia in recent years is summarized. This paper focuses on induction factors as well as prevention and treatment of postoperative restlessness in children with cleft palate after general anesthesia. The corresponding countermeasures to guide clinical practice are also presented in this paper.

Neuron-restrictive silencer factor-mediated downregulation of µ-opioid receptor contributes to the reduced morphine analgesia in bone cancer pain.

Bone cancer pain has been reported to have unique mechanisms and is resistant to morphine treatment. Recent studies have indicated that neuron-restrictive silencer factor (NRSF) plays a crucial role in modulating the expression of the µ-opioid receptor (MOR) gene. The present study elucidates the regulatory mechanisms of MOR and its ability to affect bone cancer pain. Using a sarcoma-inoculated murine model, pain behaviors that represent continuous or breakthrough pain were evaluated. Expression of NRSF in the dorsal root ganglion (DRG) and spinal dorsal horn was quantified at the transcriptional and translational levels, respectively. Additionally, chromatin immunoprecipitation assays were used to detect NRSF binding to the promoter of MOR. Furthermore, NRSF was genetically knocked out by antisense oligodeoxynucleotide, and the expression of MOR and the effect of morphine were subsequently analyzed. Our results indicated that in a sarcoma murine model, NRSF expression is upregulated in dorsal root ganglion neurons, and the expression of NRSF mRNA is significantly negatively correlated with MOR mRNA expression. Additionally, chromatin immunoprecipitation analysis revealed that NRSF binding to the neuron-restrictive silencer element within the promoter area of the MOR gene is promoted with a hypoacetylation state of histone H3 and H4. Furthermore, genetically knocking down NRSF with antisense oligodeoxynucleotide rescued the expression of MOR and potentiated the systemic morphine analgesia. The present results suggest that in sarcoma-induced bone cancer pain, NRSF-induced downregulation of MOR is involved in the reduction of morphine analgesia. Epigenetically, up-regulation of MOR could substantially improve the effect of system delivery of morphine.

Dexmedetomidine Dose-Dependently Attenuates Ropivacaine-Induced Seizures and Negative Emotions Via Inhibiting Phosphorylation of Amygdala Extracellular Signal-Regulated Kinase in Mice.

Ropivacaine (Ropi), one of the newest and safest amino amide local anesthetics, is linked to toxicity, including the potential for seizures, changes in behavior, and even cardiovascular collapse. Dexmedetomidine (Dex), an α2-adrenergic receptor agonist, has been widely used in anesthesia and critical care practice. To date, the underlying mechanisms of the effects of Dex premedication on Ropi-induced toxicity have not been clearly identified. In the current study, we investigated the effects of increasing doses of Dex premedication on 50% convulsive dose (CD50) of Ropi. With increasing doses of intraperitoneal (i.p.) Dex 10 min prior to each i.p. RopiCD50, the latency and duration of seizure activity were recorded. Open-field (OF) and elevated plus maze (EPM) test were used to measure negative behavioral emotions such as depression and anxiety. Immunohistochemistry and Western blot were utilized to investigate phosphorylation-extracellular regulated protein kinases (p-ERK) expression in the basolateral amygdala (BLA) on 2 h and in the central amygdala (CeA) on 24 h after convulsion in mice. The results of our investigation demonstrated that Dex dose-dependently increased RopiCD50, prolonged the latency and shortened the duration of each RopiCD50-induced seizure, improved the negative emotions revealed by both OF and EPM test, and inhibited p-ERK expression in the BLA and the CeA.

Depressing interleukin-1ß contributed to the synergistic effects of tramadol and minocycline on spinal nerve ligation-induced neuropathic pain.

Our previous study indicated that coadministration of tramadol and minocycline exerted synergistic effects on spinal nerve ligation (SNL)-induced neuropathic mechanical allodynia. However, the underlying mechanisms are still unclear. Recent reports indicated that spinal proinflammatory factor interleukin-1ß (IL-1ß) contributed to the development of neuropathic pain and the positive feedback communication between neuron and glia. Therefore, the present research is to confirm whether spinal IL-1ß-related pathway response contributes to the synergistic effects of tramadol and minocycline on SNL-induced neuropathic pain. Real-time RT-PCR demonstrated IL-1ß up-expression in the ipsilateral spinal dorsal horn 3 days after lesion, which could be significantly decreased by tramadol and minocycline coadministration. Immunofluorescence and Western blot indicated that SNL-induced microglial phosphorylated p38 (p-p38) upregulation was also inhibited by tramadol and minocycline coapplication. Meanwhile, intrathecal administration of p38 inhibitor SB203580 markedly alleviated mechanical allodynia whilst reducing IL-1ß and Fos expression induced by SNL. Moreover, intrathecal neutralized antibody of IL-1ß could depress SNL-induced mechanical allodynia and Fos expression. These results suggest that depressing SNL-induced aberrant activation of the spinal dorsal horn IL-1ß-related pathway contributes to the underlying mechanism of the synergistic effects of tramadol and minocycline coadministration on SNL-induced neuropathic mechanical allodynia.

Antinociceptive effect of prostatic acid phosphatase in a rat model of cancer-induced bone pain.

BACKGROUND: Cancer-induced bone pain (CIBP) is a severe chronic pain that is less than adequately controlled by conventional analgesics. Prostatic acid phosphatase (PAP) has been considered as a diagnostic marker for prostate cancer and its transmembrane isoform has been reported to play an antinociceptive effect in neuropathic and inflammatory pain. However, it remains unknown whether it has an analgesic effect on CIBP and what are the underlying mechanisms. OBJECTIVE: In the present study, we tested whether PAP could alleviate the pain symptoms induced by bone cancer in a rat model. STUDY DESIGN: A randomized, double blind, and controlled rat animal trial. METHODS: We first established a rat CIBP model and observed the spinal expression of PAP by immunofluorescence histochemistry and Western blot. Then, PAP (0.1, 0.3, or 1 µg) was intrathecally administered in the CIBP rats in a repeated manner from 15 to 18 days (once per day) after inoculation of tumor cells. On postoperative day (POD) 18, the mechanical paw withdrawal threshold was tested for checking the dose-effect curve and ED50 of the antinociceptive effect of PAP. In an another test, a single dose of ED50 of PAP was intrathecally injected on POD 15 to observe the time course of its effect. Furthermore, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) (3 mg/kg), an adenosine A1 receptor antagonist, or dipyridamole (DIP) (10 µg), a nucleoside transporter inhibitor, was administered to the CIBP rats for exploring the analgesic mechanisms of PAP. The concentration of extracellular adenosine was also detected by microdialysis method after intrathecal injection of PAP (0.57 µg) and DIP (10 µg) in the CIBP rats. Finally, an in vivo electrophysiological study of the CIBP rats was performed to observe whether the electrically evoked response of spinal wide-dynamic-range (WDR) neurons could be affected by PAP (0.57 µg), DIP (10 µg), or DPCPX (10 µg). RESULTS: The expression of PAP in the spinal dorsal horn was significantly reduced in the CIBP rats, and intrathecal injection of PAP dose-dependently attenuated CIBP-induced mechanical allodynia via the adenosine A1 receptor. Simultaneously, intrathecal injection of PAP increased the extracellular concentration of spinal adenosine in the CIBP rats, as well as inhibited the neuronal responses of WDR neurons in deep layers within the spinal dorsal horn through the adenosine A1 receptor. Finally, the analgesic effect of PAP was potentiated by DIP, the nucleoside transporter inhibitor. LIMITATIONS: It's not clear whether PAP's antinociceptive effect is mediated by other signaling molecules besides the adenosine A1 receptor. In addition, the long-term antinociceptive effect of intrathecal PAP is still not clear. CONCLUSIONS: Our study demonstrated that PAP was involved in the maintenance of CIBP and could effectively suppress central sensitization by increasing spinal extracellular adenosine concentrations to exert a significant antinociceptive effect via the adenosine A1 receptor in CIBP rats. Therefore, our experiments suggest that the endogenous enzyme PAP may be a promising candidate for CIBP treatment.

Tramadol and propentofylline coadministration exerted synergistic effects on rat spinal nerve ligation-induced neuropathic pain.

Neuropathic pain is an intractable clinical problem. Drug treatments such as tramadol have been reported to effectively decrease neuropathic pain by inhibiting the activity of nociceptive neurons. It has also been reported that modulating glial activation could also prevent or reverse neuropathic pain via the administration of a glial modulator or inhibitor, such as propentofylline. Thus far, there has been no clinical strategy incorporating both neuronal and glial participation for treating neuropathic pain. Therefore, the present research study was designed to assess whether coadministration of tramadol and propentofylline, as neuronal and glial activation inhibitors, respectively, would exert a synergistic effect on the reduction of rat spinal nerve ligation (SNL)-induced neuropathic pain. Rats underwent SNL surgery to induce neuropathic pain. Pain behavioral tests were conducted to ascertain the effect of drugs on SNL-induced mechanical allodynia with von-Frey hairs. Proinflammatory factor interleukin-1ß (IL-1ß) expression was also detected by Real-time RT-PCR. Intrathecal tramadol and propentofylline administered alone relieved SNL-induced mechanical allodynia in a dose-dependent manner. Tramadol and propentofylline coadministration exerted a more potent effect in a synergistic and dose dependent manner than the intrathecal administration of either drug alone. Real-time RT-PCR demonstrated IL-1ß up-expression in the ipsilateral spinal dorsal horn after the lesion, which was significantly decreased by tramadol and propentofylline coadministration. Inhibiting proinflammatory factor IL-1ß contributed to the synergistic effects of tramadol and propentofylline coadministration on rat peripheral nerve injury-induced neuropathic pain. Thus, our study provided a rationale for utilizing a novel strategy for treating neuropathic pain by blocking the proinflammatory factor related pathways in the central nervous system.

Combination of tramadol with minocycline exerted synergistic effects on a rat model of nerve injury-induced neuropathic pain.

Neuropathic pain is a refractory clinical problem. Certain drugs, such as tramadol, proved useful for the treatment of neuropathic pain by inhibiting the activity of nociceptive neurons. Moreover, studies indicated that suppression or modulation of glial activation could prevent or reverse neuropathic pain, for example with the microglia inhibitor minocycline. However, few present clinical therapeutics focused on both neuronal and glial participation when treating neuropathic pain. Therefore, the present study hypothesized that combination of tramadol with minocycline as neuronal and glial activation inhibitor may exert some synergistic effects on spinal nerve ligation (SNL)-induced neuropathic pain. Intrathecal tramadol or minocycline relieved SNL-induced mechanical allodynia in a dose-dependent manner. SNL-induced spinal dorsal horn Fos or OX42 expression was downregulated by intrathecal tramadol or minocycline. Combination of tramadol with minocycline exerted powerful and synergistic effects on SNL-induced neuropathic pain also in a dose-dependent manner. Moreover, the drug combination enhanced the suppression effects on SNL-induced spinal dorsal horn Fos and OX42 expression, compared to either drug administered alone. These results indicated that combination of tramadol with minocycline could exert synergistic effects on peripheral nerve injury-induced neuropathic pain; thus, a new strategy for treating neuropathic pain by breaking the interaction between neurons and glia bilaterally was also proposed.

Triptolide prevents and attenuates neuropathic pain via inhibiting central immune response.

BACKGROUND: Current treatments for neuropathic pain are far from satisfactory. Considering the essential contribution of central immune factors to the pathogenesis of neuropathic pain, targeting inflammatory response is well accepted as an effective strategy for treating neuropathic pain. Triptolide has a long history in traditional Chinese medicine for treating inflammatory diseases and has been proven to inhibit cytokines released from glial cells. OBJECTIVE: In the present study, we tested whether systemic treatment with triptolide could prevent or attenuate nocifensive behaviors associated with neuropathic pain. We further tried to explore the underlying mechanism of the potential anti-allodynia effect of triptolide. STUDY DESIGN: A randomized, double blind, controlled animal trial. METHODS: Triptolide was administered systemically in a rat model of neuropathic pain induced by spinal nerve ligation (SNL) in the single bolus and repeated treatment manners. In the single bolus treatment experiment, triptolide (30 ug/kg, 100 ug/kg, 300 ug/kg) or vehicle was given to SNL and sham-operated rats once on day 1 or on day 10 after surgery (n = 6 each). In the repeated treatment study, prophylactic treatment with triptolide (30 ug/kg, 100 ug/kg, 300 ug/kg) was given to rats during the period of day -3 (3 days prior to SNL) to day 7 (7 days post-SNL) inclusively (n = 6 each). Another set of SNL and sham rats on postoperative day 10 received treatment with triptolide (30 ug/kg, 100 ug/kg, 300 ug/kg) or vehicle during the period of days 11-20 inclusively (n = 6 each), to assess potential reversal of established pain behavior. Mechanical allodynia of the rats was tested with von Frey filaments. Astrocytic and microglial activation in the spinal dorsal horn was evaluated with immunofluorescent histochemistry. Phosphorylation of mitogen-activated protein kinases (MAPKs), and expression of inflammatory cytokines (interleukin-6, interleukin-1beta, monocyte chemotactic protein-1, and tumor necrosis factor-alpha) were examined with Western blot analysis and real-time reverse transcription polymerase chain reaction study. RESULTS: A single bolus treatment with triptolide could neither prevent the induction nor reverse the maintenance of SNL-induced mechanical allodynia. However, repeated administration of triptolide dose-dependently inhibited neuropathic pain behavior in both preventative and interventional paradigms. Triptolide hampered SNL-induced activation of glial cells (astrocytes and microglia) in the spinal dorsal horn without influencing neurons. In addition, SNL-induced phosphorylation of MAPKs could be inhibited by triptolide. Furthermore, up-regulated expression of inflammatory cytokines in neuropathic pain states could be remarkably blocked by triptolide. LIMITATIONS: The direct target site (such as a specific receptor) of triptolide is still to be determined. In addition, triptolide could not completely block the SNL-induced mechanical allodynia. CONCLUSIONS: Our data suggest that triptolide may be a potential novel treatment for neuropathic pain through modulating immune response in the spinal dorsal horn.

The Inhibition of Spinal Astrocytic JAK2-STAT3 Pathway Activation Correlates with the Analgesic Effects of Triptolide in the Rat Neuropathic Pain Model.

Neuropathic pain (NP) is an intractable clinical problem without satisfactory treatments. However, certain natural products have been revealed as effective therapeutic agents for the management of pain states. In this study, we used the spinal nerve ligation (SNL) pain model to investigate the antinociceptive effect of triptolide (T10), a major active component of the traditional Chinese herb Tripterygium wilfordii Hook F. Intrathecal T10 inhibited the mechanical nociceptive response induced by SNL without interfering with motor performance. Additionally, the anti-nociceptive effect of T10 was associated with the inhibition of the activation of spinal astrocytes. Furthermore, intrathecal administration of T10 attenuated SNL-induced janus kinase (JAK) signal transducers and activators of transcription 3 (STAT3) signalling pathway activation and inhibited the upregulation of proinflammatory cytokines, such as interleukin-6, interleukin-1 beta, and tumour necrosis factor-α, in dorsal horn astrocytes. Moreover, NR2B-containing spinal N-methyl D-aspartate receptor (NMDAR) was subsequently inhibited. Above all, T10 can alleviate SNL-induced NP via inhibiting the neuroinflammation in the spinal dorsal horn. The anti-inflammation effect of T10 may be related with the suppression of spinal astrocytic JAK-STAT3 activation. Our results suggest that T10 may be a promising drug for the treatment of NP.

Intrastriatal manganese chloride exposure causes acute locomotor impairment as well as partial activation of substantia nigra GABAergic neurons.

Our previous studies showed chronic exposure to manganese chloride (Mn) causes locomotor impairment and lesion of dopaminergic neurons in substantia nigra (SN). But effects of acute Mn exposure on locomotor ability, SN dopaminergic and GABAergic neurons were not clear. In the current study, Mn was injected into the striatum of GAD(67)-GFP mice. Twenty-four hours after injection, locomotor ability was quantitatively evaluated with behavioral tests (rotarod test and open field test). Meanwhile, the numbers of dopaminergic and GABAergic neurons were counted through immunofluorescent staining for TH and GFP respectively, and activations of dopaminergic and GABAergic neurons were evaluated by double immunofluorescent labeling for TH/Fos and GFP/Fos, respectively. Behavioral tests showed a significant locomotor impairment 24h after Mn injection. The numbers of SN dopaminergic and GABAergic neurons were not altered significantly 24h after Mn injection; however, some of SN GABAergic neurons were activated and dopaminergic neurons were left inactivated. In addition, there were still a large number of Mn-activated neurons that fell into neither dopaminergic nor GABAergic criteria. Our data suggested that activation of SN GABAergic neurons but not lesion of dopaminergic neurons, which was found to play an important role in the Mn-induced chronic neurotoxicity in our previous studies, contributed partially to Mn-induced acute locomotor impairment. Therefore we come to the conclusion that Mn exposure can induce acute or chronic neurotoxicity via different neuronal elements.

Neuronal NR2B-containing NMDA receptor mediates spinal astrocytic c-Jun N-terminal kinase activation in a rat model of neuropathic pain.

Spinal N-methyl d-aspartate receptor (NMDAR) plays a pivotal role in nerve injury-induced central sensitization. Recent studies suggest that NMDAR also contributes to neuron-astrocyte signaling. c-Jun N-terminal kinase (JNK) is persistently and specifically activated (indicated by phosphorylation) in spinal cord astrocytes after nerve injury and thus it is considered as a dependable indicator of pain-related astrocytic activation. NMDAR-mediated JNK activation in spinal dorsal horn might be an important form of neuron-astrocyte signaling in neuropathic pain. In the present study, we observed that intrathecal injection of MK-801, a noncompetitive NMDA receptor antagonist, or Ro25-6981 and ifenprodil, which are selective antagonists of NR2B-containing NMDAR each significantly reduced nerve injury-induced JNK activation. Double immunostaining showed that NR2B was highly expressed in neurons, indicating the effect of NMDAR antagonists on JNK activation was indirect. We further observed that intrathecal injection of NMDA (twice a day for 3 days) significantly increased spinal JNK phosphorylation. Besides, NMDAR-related JNK activation could be blocked by a neuronal nitric oxide synthase (nNOS) selective inhibitor (7-nitroindazole sodium salt) but not by a nNOS sensitive guanylyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). Finally, real-time RT-PCR and immunostaining showed that nerve injury-induced interleukin-1beta expression was dependent on astrocytic JNK activation. Treatments targeting NMDAR-nNOS pathway also influenced interleukin-1beta expression, which further confirmed our hypothesis. Taken together, our results suggest that neuronal NMDAR-nNOS pathway could activate astrocytic JNK pathway. Excitatory neuronal transmission initiates astrocytic activation-induced neuroinflammation in this way, which contributes to nerve injury-induced neuropathic pain.