Dezocine exhibits antihypersensitivity activities in neuropathy through spinal μ-opioid receptor activation and norepinephrine reuptake inhibition

A retrospective study of the safety and efficacy of peritoneal dialysis catheter placement under combined local infiltration anesthesia and monitored anesthesia care

OBJECTIVE

Given the lack of global consensus on anesthesia selection for peritoneal dialysis catheter (PDC) placement via open surgery, this study investigates the safety and efficacy of combining local infiltration anesthesia (LIA) with monitored anesthesia care (MAC) in patients with end-stage renal disease (ESRD).

METHODS

This retrospective analysis of ESRD patients who underwent open surgical placement of PDC in the Department of Nephrology, the First Affiliated Hospital of the Army Medical University from 1 August 2020 to 31 May 2022. Patients were categorized into two groups based on anesthesia method: LIA group and LIA + MA group. MA was defined as preoperative sedation (0.2-0.7 µg/kg/h) with dexmedetomidine injection (Huidrican trade name, DEX), and intraoperative analgesia with dexrazoxane injection (Garonin trade name, DEZ) as appropriate according to the patients' pain scores. We compared the general clinical data of the two groups of patients, the changes in blood pressure and heart rate during the whole operation, the intraoperative and postoperative pain, the total duration of the operation and the immediate postoperative complications.

RESULTS

The study included 123 patients (59 in the LIA + MAC group and 64 in the LIA group). The LIA + MA group exhibited lower pain scores measured by Visual Analogue Scale(VAS) during surgery (skin incision, subcutaneous adipose tissue dissection, anterior fascia, muscle traction, posterior fascia, peritoneum, and catheterization) compared to the LIA group(p<0.05). In terms of surgical incisions, to intraoperative pain scores (VRS), the LIA + MA group showed higher score level I and lower score level II compared to the LIA group (p = 0.002, 0.004, respectively). The LIA + MA group experienced lower postoperative resting pain (NRS) and VAS than the LIA group (p = 0.001,0.003, respectively). The surgical duration for the LIA + MA group was shorter than that of the LIA group (p<0.001). Preoperative systolic and diastolic blood pressures (SBP and DBP) were higher in the LIA + MA group compared to the LIA group (p<0.001,<0.001, respectively). Postoperative heart rate and DBP were lower in the LIA + MA group (p<0.001, 0.004, respectively). The LIA + MA group exhibited greater changes in heart rate, SBP, and DBP during and after surgery compared to the LIA group (p = 0.009, <0.001,<0.001, respectively). In terms of immediate postoperative complications, the proportion of patients requiring analgesics within 24 h post-surgery was significantly lower in the LIA + MA group (p = 0.031).

CONCLUSION

Open surgery for PDC placement under LIA + MAC is both safe and effective.

Dezocine as preemptive analgesia alleviates ultrapulse CO2 fractional laser treatment induced pain in patients with acne scars

BACKGROUND

Ultrapluse CO2 fractional laser technology has emerged as an effective treatment for scar management. However, one drawback of this modality is the pain caused during the procedure. This study aims to explore the efficacy and safety of dezocine (DZC) as preemptive analgesia for reduction of pain induced by ultrapulse CO2 fractional laser treatment for acne scars.

METHODS

The study cohort included 78 outpatients with acne scars between February and April 2023. Patients were randomly assigned into three groups with intravenous injection (iv) of DZC prior to laser treatment: (1) control, iv of saline; (2) DZC group 1 (DZC_1), iv of DZC at 0.15 mg/kg; and (3) DZC_2, iv of DZC at 0.20 mg/kg. After 30 min, one session of ultrapulse CO2 fractional laser treatment on acne scars was performed. Hemodynamics, visual analogue scale (VAS), and anxiety visual analog test (AVAT) were monitored prior to, during, and after the procedure.

RESULTS

Operative success rates for patients in the control, DZC_1, and DZC_2 groups were 34.6%, 84.6%, and 100%, respectively. DZC administered with either dosage significantly reduced the VAS and AVAT scores of patients in treatment groups as compared with the subjects in the control group during the course of ultrapulse CO2 fractional laser treatment. Patients in DZC_1 and DZC_2 groups did not show any significant difference in hemodynamic parameters, VAS, and AVAT scores. Temporary adverse effects such as nausea and dizziness were observed in some subjects after treatment; the symptoms were quickly dissolved after a rest in supine position.

CONCLUSIONS

DZC as preemptive analgesia could effectively reduce pain and anxiety induced by ultrapulse CO2 fractional laser treatment in patients. This study provided an option of preemptive anesthesia to minimize the pain and discomforts associated with laser treatments in clinical practices.

Risk factors for postpartum posttraumatic stress disorder after emergency admission

BACKGROUND

Postpartum posttraumatic stress disorder (PTSD) can occur in women who give birth after emergency admission. The identification of risk factors for this condition is crucial for developing effective preventive measures. This retrospective study aimed to explore the incidence and risk factors for postpartum PTSD in women who give birth after emergency admission.

METHODS

Medical records of women who gave birth after emergency admission were collected between March 2021 and April 2023. The patients' general conditions and perinatal clinical indicators were recorded. The puerperae were divided into PTSD group and control group based on symptom occurrence at six weeks postpartum. Multivariate logistic regression analysis was performed to identify risk factors.

RESULTS

A total of 276 puerperae were included, with a PTSD incidence of 20.3% at six weeks postpartum. Multivariate logistic regression analysis identified emergency cesarean section (odds ratio [OR]=2.102; 95% confidence interval [CI]: 1.114-3.966, P=0.022), admission to the emergency department after midnight (12:00 AM) (OR=2.245; 95%CI: 1.170-4.305, P<0.001), and cervical dilation (OR=3.203; 95%CI: 1.670-6.141, P=0.039) as independent risk factors for postpartum PTSD. Analgesia pump use (OR= 0.500; 95%CI: 0.259-0.966, P=0.015) was found to be a protective factor against postpartum PTSD.

CONCLUSION

Emergency cesarean section, admission to the emergency department after midnight, and cervical dilation were identified as independent risk factors for postpartum PTSD, while analgesic pump use was a protective factor. These findings provide insights for developing more effective preventive measures for women who give birth after emergency admission.

The Effect of Dezocine on the Median Effective Dose of Sufentanil-Induced Respiratory Depression in Patients Undergoing Spinal Anesthesia Combined with Low-Dose Dexmedetomidine

Purpose

The application of sedation and analgesia in spinal anesthesia has many benefits, but the risk of respiratory depression (RD) caused by opioids cannot be ignored. We aimed to observe the effect of dezocine, a partial agonist of μ-receptor, on the median effective dose (ED50) of sufentanil-induced RD in patients undergoing spinal anesthesia combined with low-dose dexmedetomidine.

Patients and Methods

Sixty-two patients were randomly assigned to dezocine group (DS) and control group (MS). After spinal anesthesia, mask oxygen (5 L/min) and dexmedetomidine (0.1 ug/kg) were given. Five minutes later, patients in the DS group received an Intravenous (IV) bolus of sufentanil and 0.05mg/kg dezocine, while patients in the MS group only received an IV bolus of sufentanil.

Results

ED50 of DS group was 0.342 ug/kg, 95% confidence interval (CI) was (0.269, 0.623) ug/kg, and the ED50 of MS group was 0.291 ug/kg, 95% CI was (0.257, 0.346) ug/kg. There was no difference in the type and treatment measures of RD and hemodynamic changes between the two groups, and no serious adverse reactions occurred in either group.

Conclusion

Dezocine can improve RD induced by sufentanil in patients with spinal anesthesia combined with low-dose dexmedetomidine, and increase the safety window of sufentanil use.

The analgesic effects of dezocine in rats with chronic constriction injuries

Neuropathic pain (NP) is caused by diseases or dysfunction of nervous system and has a considerable negative impact on patients' quality of life. Opioid analgesics can be used for NP treatment. However, the effect of dezocine on NC remains unknown. In this study, we aimed to investigate the analgesic and intestinal effects of various doses of dezocine in rats with chronic constriction injuries (CCI). 100 rats were equally divided into 5 groups: the low (D1 group), medium (D2 group), and high (D3 group) doses of dezocine, and sham operation and model groups. The effects of dezocine on pain, analgesic effect, pain response, and tension and contraction frequencies of intestinal smooth muscles were assessed. With an increase in the dezocine dosage, the cumulative pain scores of rats decreased and analgesic effect significantly increased; mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) improved in varying degrees. The expression of the NP-related proteins glial fibrillary acidic protein (GFAP) and connexin 43 (Cx43) was also improved by dezocine treatment. The results of western blot and ELISA showed that IL-6, and monocyte chemotactic protein-1 (MCP-1) levels also decreased significantly with an increase in the dezocine dose, indicated that dezocine alleviated the inflammatory microenvironment. The dezocine exhibited no significant effect on the tension or contraction frequencies of intestinal smooth muscles of rats. In conclusion, the analgesic effect of dezocine on rats with CCI is dose-dependent and has little effect on the tension or contraction frequencies of intestinal smooth muscles. Our research proved the analgesic effect of dezocine in rats with CCI, and provided further insights into new therapies for NP treatment.

A randomized controlled study of a psycho-behavioral intervention combined with a non-benzodiazepine to improve perioperative sleep quality in patients undergoing knee arthroplasty

Objective

To clarify the effectiveness and safety of psycho-behavioral intervention combined with a non-benzodiazepine to improve perioperative sleep quality in patients undergoing knee arthroplasty, and also to explore the optimal dosage of non-benzodiazepine (oral zolpidem tartrate) to form a standardized sleep quality management process to promote accelerated recovery of patients.

Methods

240 patients undergoing initial unilateral total knee arthroplasty between January and December 2016 were prospectively included and randomly divided into blank control group (group A), psycho-behavioral intervention group (group B), zolpidem tartrate 10 mg group (group C), and psycho-behavioral intervention + zolpidem tartrate 5 mg group (group D). Sleep, pain, psychological, and knee function scores were compared.

Results

There were significant differences between the four groups with respect to Pittsburgh sleep quality index scores, sleep efficiency, Epworth Sleepiness Scale scores, inflammatory indices, pain, and enhanced recovery after surgery indices during hospitalization (P < 0.05).

Conclusion

Psychological behavioral intervention combined with non-benzodiazepine can improve the perioperative quality of sleep. Compared with drug intervention alone, it reduces the dosage of non-benzodiazepine, alleviates anxiety, improves patient satisfaction, and enhances the quality of life.

Monoaminergic mediation of hyperalgesic and analgesic descending control of nociception in mice

ABSTRACT

Descending control of nociception (DCN; also known as conditioned pain modulation [CPM], the behavioral correlate of diffuse noxious inhibitory controls) is the phenomenon whereby pain inhibits pain in another part of the body and is the subject of increasing study because it may represent a biomarker of chronic pain. We recently discovered that pain modulation upon application of a DCN paradigm involving low-intensity test stimuli occurs in the direction of hyperalgesia in healthy mice and rats, whereas the use of high-intensity stimuli produces analgesia. To elucidate the physiological mechanisms underlying hyperalgesic DCN, we administered agonists and antagonists of norepinephrine (NE) and serotonin (5-HT) receptors, key neurochemical players in the production of analgesic DCN. We find that three different monoamine reuptake inhibitors-the NE-selective reboxetine, the 5-HT-selective fluoxetine, and the dual NE/5-HT agonist duloxetine-all abolish hyperalgesic DCN when administered into the spinal cord (but not systemically), with no effect on heat or mechanical pain sensitivity. Reboxetine's attenuation of hyperalgesic DCN is mediated by α 2 -adrenergic receptors (i.e., blocked by atipamezole), and fluoxetine's effect is mediated by 5-HT 7 receptors (i.e., blocked by SB269970). In contrast, analgesic DCN was found to be reversed by atipamezole and SB269970 themselves, with no effect of reboxetine or fluoxetine. Thus, hyperalgesic DCN appears to be the neurochemical opposite to analgesic DCN. These data further validate and help elucidate a pre-clinical paradigm that mimics dysfunctional CPM, and thus may form the basis of translational experiments that aim to reveal preventative pharmacological strategies for individuals predisposed to persistent pain.

Dezocine as a potent analgesic: overview of its pharmacological characterization

Dezocine, a synthetic opioid, introduced in 1970s as an analgesic, was redeveloped for relieving moderate to severe pain by Yangtze River Pharmaceutical Group in China in 2009. To date, dezocine occupies 45% of China's opioid analgesic market. Along with dezocine being a dominated painkiller, a certain amount of research was conducted to elucidate dezocine's action. In this review we summarize the current knowledge on the receptor, preclinical and clinical pharmacology of dezocine. Briefly, preclinical data show that dezocine is effective under varying pain conditions, particularly chronic neuropathic pain and cancer pain, through activation of opioid receptors, and inhibition of norepinephrine reuptake. Clinical data establish the effectiveness of dezocine either as a primary analgesic for postoperative pain management or a supplement for balanced analgesia. The receptor profile of dezocine is different from known pure μ agonists, and allows it to be used in combination with other opioids for additivity in efficacy or lower incidence of adverse effects.

Dezocine Has the Potential to Regulate the Clinical and Biological Features of Tumors

Cancer is the second leading cause of death following ischemic heart disease in the world and the primary clinical, social and economic burden. Surgical resection is the main measure for the treatment of the vast majority of solid tumors. However, the recurrence and metastasis of tumors occur at different periods after surgery in many cases undergoing radical tumor surgery, which is the main cause of death of tumor patients. Moreover, tumor patients are prone to suffer from mental depression, which may increase the morbidity and mortality of tumors. Tumors have a series of clinical biological signs with the following five main features: postoperative pain and cancerous pain; suppression of antitumor immunity; angiogenesis in tumors; proliferation, growth and metastasis of tumors; and mental depression. Surgery is the first treatment in the majority of cancer patients with solid tumors. Opioids are required for anesthesia and postoperative analgesia. For cancerous pain control, patients undergo surgery, and their quality of life of is improved. However, traditional opioids, such as morphine, may inhibit antitumor immunity, induce vascular growth of tumors and promote the proliferation, invasion and migration of cancer cells, and traditional opioids can induce a risk of somatic dependence. However, studies have found that not all opioids share the effects of immunosuppression, tumor proliferation promotion and angiogenesis induction. Dezocine, a novel opioid with specific pharmacological mechanisms, has been demonstrated to regulate the five clinical and biological features of tumors. We reviewed the preclinical and clinical studies of dezocine on postoperative pain and cancer pain in tumor patients as well as the immune system, tumor angiogenesis, tumor proliferation, tumor growth, tumor metastasis and mental depression. We proposed that dezocine may be the best choice of opioids for anesthesia and analgesia in cancer patients.

Dezocine relieves the postoperative hyperalgesia in rats through suppressing the hyper-action of Akt1/GSK-3β pathway

The relieving role of dezocine in pain after surgery was previously reported, while the potential mechanism was not completely clear. Therefore, the current research probed into the regulatory mechanism of dezocine in pain after surgery. A postoperative pain model was established by performing plantar incision surgery on the juvenile Sprague-Dawley rats. After the rats were treated with dezocine or SC79 (Akt1 activator), the paw withdrawal threshold and paw withdrawal latency of rats were detected to evaluate the mechanical allodynia and thermal hyperalgesia. After the plantar tissue, dorsal root ganglions, and spinal cord of rats were collected, the expressions of Akt1, p-Akt1, GSK-3β, and p-GSK-3β in the tissues were determined by western blot to evaluate the activation state of the Akt1/GSK-3β pathway. After surgery, the paw withdrawal threshold and paw withdrawal latency of rats were lessened, whereas the ratios of p-Akt1/Akt1 and p-GSK-3β/GSK-3β were augmented in rat plantar tissue, dorsal root ganglions, and spinal cord. After treatment with dezocine alone, the paw withdrawal threshold and paw withdrawal latency of postoperative rats were elevated, but ratios of p-Akt1/Akt1 and p-GSK-3β/GSK-3β were reduced. After co-treatment with dezocine and SC79, SC79 reversed the effects of dezocine on elevating the paw withdrawal threshold and paw withdrawal latency, and reducing the ratios of p-Akt1/Akt1 and p-GSK-3β/GSK-3β in postoperative rats. Dezocine ameliorated the postoperative hyperalgesia in rats via repressing the hyper-action of Akt1/GSK-3β pathway.

Comparative study of dezocine, pentazocine and tapentadol on antinociception and physical dependence

AIMS

Dezocine and pentazocine, widely prescribed in China for postoperative pain, were initially considered as mixed agonist/antagonist targeting μ-opioid receptors (MORs) and κ-opioid receptors (KORs). However, dezocine has been revealed to alleviate chronic neuropathic pain through MOR activation and norepinephrine reuptake inhibition (NRI). This study investigated dezocine- and pentazocine-induced antinociception and physical dependence development, compared to the typical MOR-NRI opioid tapentadol.

MAIN METHODS

Calcium mobilization assay was conducted to assess the potency of the drugs while hot-plate test was performed to compare the antinociception. Physical dependence development was compared with morphine.

KEY FINDINGS

Treatment with dezocine, pentazocine and tapentadol stimulated calcium mobilization in HEK293 cells stably expressed MORs but not KORs, whereas dezocine and pentazocine inhibited KOR activities. Subcutaneously injected dezocine-, tapentadol- and pentazocine-induced antinociception dose-dependently, in hot-plate test. Intrathecally injected MOR antagonist CTAP, norepinephrine depletor 6-OHDA and α₂-adrenoceptor (α₂-AR) antagonist yohimbine partially antagonized dezocine, pentazocine and tapentadol antinociception. Whereas specific KOR antagonist GNTI did not alter their antinociception, the putative inverse KOR agonist nor-BNI reduced dezocine and pentazocine antinociception. Moreover, combined CTAP and 6-OHDA or yohimbine blocked dezocine and tapentadol antinociception but displayed the same partial inhibition on pentazocine antinociception as CTAP alone. Furthermore, compared to morphine and pentazocine, long-term treatment with dezocine and tapentadol produced much less physical dependence-related withdrawal signs, which were restored by spinal 6-OHDA or yohimbine treatment.

SIGNIFICANCE

Our findings illustrated that dezocine and tapentadol, but not pentazocine, exert remarkable antinociception in nociceptive pain with less abuse liability via dual mechanisms of MOR activation and NRI.

Nitric oxide modulates tapentadol antinociceptive tolerance and physical dependence

Tapentadol, an analgesic with a dual mechanism of action, involving both μ-opioid receptor agonism and noradrenaline reuptake inhibition (MOP-NRI), was designed for the treatment of moderate to severe pain. However, the widely acknowledged risk of analgesic tolerance and development of physical dependence following sustained opioid use may hinder their effectiveness. One of the possible mechanisms behind these phenomena are alterations in nitric oxide synthase (NOS) system activity. The aim of the study was to investigate the tolerance and dependence potential of tapentadol in rodent models and to evaluate the possible role of nitric oxide (NO) in these processes. Our study showed that chronic tapentadol treatment resulted in tolerance to its antinociceptive effects to an extent similar to tramadol, but much less than morphine. A single injection of a non-selective NOS inhibitor, NG-nitro-L-arginine (L-NOArg), reversed the tapentadol tolerance. In dependence studies, repeated administration of L-NOArg attenuated naloxone-precipitated withdrawal in tapentadol-treated mice, whereas a single injection of L-NOArg was ineffective. Biochemical analysis revealed that tapentadol decreased nNOS protein levels in the dorsal root ganglia of rats following 31 days of treatment, while no significant changes were found in iNOS and eNOS protein expression. Moreover, pre-treatment with L-NOArg augmented tapentadol antinociception in an opioid- and α2-adrenoceptor-dependent manner. In conclusion, our data suggest that the NOS system plays an important role in the attenuation of tapentadol-induced tolerance and withdrawal. Thus, inhibition of NOS activity can serve as a promising treatment option for long-term tapentadol use by extending its effectiveness and improving the side-effects profile.

Antidepressant-like effects of dezocine in mice: involvement of 5-HT1A and κ opioid receptors

Dezocine is an opioid with low efficacy at μ-opioid and κ-opioid receptors. It also inhibits the reuptake of norepinephrine and serotonin. Dezocine is an effective analgesic against various clinical painful conditions and is widely used in many Asian countries. Given the unique pharmacology of dezocine, the drug may also have antidepressant-like properties. However, no published preclinical study has explored this possibility. This study examined the potential antidepressant-like activity of dezocine in mice. Male ICR mice were used in the forced swimming test, the tail suspension test, the warm water tail withdrawal test and locomotor activity test to test the effects of dezocine (0.3-3.0 mg/kg). The 5-HT1A receptor antagonist WAY-100635 (1 mg/kg), the μ-opioid receptor antagonist β-funaltrexamine (2 mg/kg) and the κ-opioid receptor agonist U50488 (1 mg/kg) were also studied in combination with dezocine. Dezocine produced a dose-dependent decrease in the immobility time in the forced swimming test and tail suspension test at doses that did not alter the motoric activity as determined in the locomotion test. WAY-100635 and U50488 but not β-funaltrexamine pretreatment significantly blocked the effects of dezocine. Dezocine dose-dependently increased the latency in the tail withdrawal test which was blocked by WAY-100635 and β-funaltrexamine. Combined, these results suggest that dezocine may have antidepressant-like effects. Considering the well-documented analgesic property of dezocine, it may be useful to treat pain and depression comorbidity.

Microglial IL-10 and β-endorphin expression mediates gabapentinoids antineuropathic pain

Gabapentinoids are recommended first-line treatments for neuropathic pain. They are neuronal voltage-dependent calcium channel α2δ-1 subunit ligands and have been suggested to attenuate neuropathic pain via interaction with neuronal α2δ-1 subunit. However, the current study revealed their microglial mechanisms underlying antineuropathic pain. Intrathecal injection of gabapentin, pregabalin and mirogabalin rapidly inhibited mechanical allodynia and thermal hyperalgesia, with projected ED₅₀ values of 30.3, 6.2 and 1.5 µg (or 176.9, 38.9 and 7.2 nmol) and E_max values of 66%, 61% and 65% MPE respectively for mechanical allodynia. Intrathecal gabapentinoids stimulated spinal mRNA and protein expression of IL-10 and β-endorphin (but not dynorphin A) in neuropathic rats with the time point parallel to their inhibition of allodynia, which was observed in microglia but not astrocytes or neurons in spinal dorsal horns by using double immunofluorescence staining. Intrathecal gabapentin alleviated pain hypersensitivity in male/female neuropathic but not male sham rats, whereas it increased expression of spinal IL-10 and β-endorphin in male/female neuropathic and male sham rats. Treatment with gabapentin, pregabalin and mirogabalin specifically upregulated IL-10 and β-endorphin mRNA and protein expression in primary spinal microglial but not astrocytic or neuronal cells, with EC₅₀ values of 41.3, 11.5 and 2.5 µM and 34.7, 13.3 and 2.8 µM respectively. Pretreatment with intrathecal microglial metabolic inhibitor minocycline, IL-10 antibody, β-endorphin antiserum or μ-opioid receptor antagonist CTAP (but not κ- or δ-opioid receptor antagonists) suppressed spinal gabapentinoids-inhibited mechanical allodynia. Immunofluorescence staining exhibited specific α2δ-1 expression in neurons but not microglia or astrocytes in the spinal dorsal horns or cultured primary spinal cells. Thus the results illustrate that gabapentinoids alleviate neuropathic pain through stimulating expression of spinal microglial IL-10 and consequent β-endorphin.

"I'll Be Back": The Resurrection of Dezocine

Beginning with opium itself, natural and synthetic opioids have been used as analgesics for over 8000 years and were likely abused as drugs of recreation for that long as well. However, the "opioid crisis" resulted in attempts to avoid or limit opioid analgesics in favor of other therapies and methods. Mu opioid agonists can be effective analgesics but suffer from addiction, tolerance, and dangerous, sometimes fatal, side effects. One exception to this generalization is dezocine (Dalgan), a mixed mu/kappa opioid partial agonist. Dezocine is at least as effective as morphine in reducing acute pain in animal models and clinical applications such as postoperative pain. And while dezocine was discontinued in western markets in 2011, it has become the favored opioid analgesic in China, capturing over 40% of the market. Additionally, dezocine possesses norepinephrine uptake inhibitory activity, which may synergize with mu agonism in the case of acute pain treatment and possibly endow the drug with antinociceptive activity in neuropathic pain conditions. This Innovations article summarizes the history and properties of dezocine and presents evidence and rationale for why dezocine has undergone a resurrection.

Intracerebroventricular injection of propranolol blocked analgesic and neuroprotective effects of resveratrol following L5 spinal nerve ligation in rat

OBJECTIVES

Resveratrol as a natural polyphenolic agent can alleviate neuropathic pain symptoms. The mechanism of analgesic activity of resveratrol is far from clear. The current study examine whether analgesic activity of resveratrol is mediated by its neuroprotective and anti-oxidant activity in the neuropathic pain. We further examine whether analgesic activity of resveratrol is mediated by β-adrenoceptors in the brain.

METHODS

Neuropathic pain induced by L₅ spinal nerve ligation (SNL). Male Wistar rats assigned into sham, SNL, SNL + resveratrol (40 μg/5 μL), and SNL + resveratrol + propranolol (a non-selective β-adrenoceptor antagonist, 30 μg/5 μL) groups. Drugs injected intracerebroventricular (ICV) at day SNL surgery and daily for 6 days following SNL. Thermal allodynia and anxiety examined on days of -1, 2, 4, and 6 following SNL. Electrophysiological study performed on day 6 following SNL for evaluation of resveratrol effects on sciatic nerve conduction velocity (NCV). The activity of catalase (Cat) and superoxide dismutase (SOD) enzymes in the brain assessed on days 6 following SNL.

RESULTS

Resveratrol significantly decreased thermal allodynia (and not anxiety) in all experimental days. Additionally, resveratrol significantly increased NCV, and also normalized the disrupted Cat and SOD activities following neuropathic pain. Furthermore, propranolol significantly blocked the analgesic and neuroprotective effects of resveratrol.

CONCLUSIONS

It is suggested that the analgesic effects of resveratrol is mediated by its neuroprotective and antioxidant activities in the neuropathic rats. Furthermore, propranolol blocked the analgesic and neuroprotective effects of resveratrol.

Effect of patient-controlled intravenous analgesia combined with flurbiprofen axetil and dezocine on postoperative analgesia for lobectomy (EPIC-FAD): a trial protocol

BACKGROUND

The optimal analgesic strategy for surgical pain after lobectomy remains undefined. To compare the combination of flurbiprofen axetil and dezocine with flurbiprofen axetil alone and dezocine alone, in post-lobectomy patients.

METHODS

A single-center, parallel-design double-blind superiority trial, with 5 groups (1:1:1:1:1 ratio) with different combinations of flurbiprofen and dezocine. Patients scheduled for lobectomy will be recruited. The primary outcome is total sufentanil use in patient-controlled intravenous analgesia within the first 24 postoperative hours. Secondary outcomes include pain numeric rating scales at 6th, 12th, 24th, 48th, and 72th postoperative hours, and on the 1st, 3rd, and 6th postoperative months at rest and during coughing, adverse effects from experimental drug treatment, sufentanil use at other time points, analgesia cost, time to chest tube removal, length of hospital stay, time to pass first flatus, and serum level of cytokines. Doctors, patients, and nurses are blinded, and only the manager is unblinded. Analysis is intention-to-treat. Statistical analysis is pre-specified. Statistical comparison of the treatment groups includes one-way analysis of variance followed by Tukey's post hoc test.

DISCUSSION

Trial did not begin to recruit. Participant recruitment start date is planned to be June 1, 2020. Approximate recruitment end date is May 31, 2021. If successful, the trial may shed light on the use of certain analgesic combinations in post-lobectomy pain control.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR1800018563 . Registered on September 25, 2018.

Cynandione A Alleviates Neuropathic Pain Through α7-nAChR-Dependent IL-10/β-Endorphin Signaling Complexes

Cynandione A, an acetophenone isolated from Cynanchum Wilfordii Radix, exhibits antineuropathic pain effect. This study further explored the target molecule and signaling mechanisms underlying cynandione-A-induced antineuropathic pain. Intrathecal injection of cynandione A significantly attenuated mechanical allodynia in neuropathic rats and substantially increased spinal expression of IL-10 and β-endorphin but not dynorphin A. Cynandione A treatment also enhanced expression of IL-10 and β-endorphin but not α7 nicotinic acetylcholine receptors (nAChRs) in cultured microglia. The IL-10 antibody attenuated cynandione-A-induced spinal or microglial gene expression of β-endorphin and mechanical allodynia, whereas the β-endorphin antiserum blocked cynandione-A-induced mechanical antiallodynia but not spinal or microglial IL-10 gene expression. The α7 nAChR antagonist methyllycaconitine significantly reduced cynandione-A-induced mechanical antiallodynia and spinal or microglial expression of IL-10 and β-endorphin. Furthermore, cynandione A stimulated microglial phosphorylation of PKA, p38, and CREB in an α7-nAChR-dependent manner, and treatment with their inhibitors attenuated cynandione-A-induced mechanical antiallodynia and spinal or microglial expression of IL-10 and β-endorphin. In addition, cynandione A stimulated spinal phosphorylation of the transcription factor STAT3, which was inhibited by methyllycaconitine, the PKA activation inhibitor or IL-10 antibody. The STAT3 inhibitor NSC74859 also abolished cynandione-A-induced mechanical antiallodynia and spinal expression of β-endorphin. These findings suggest that cynandione A suppresses neuropathic pain through α7-nAChR-dependent IL-10/β-endorphin signaling pathway in spinal microglia.

Baicalin relieves neuropathic pain by regulating α2-adrenoceptor levels in rats following spinal nerve injury

In the present study, the ability of baicalin to relieve neuropathic pain due to spinal nerve ligation in rats was explored, and the relationship between baicalin and α₂-adrenoceptors (α₂-AR) was determined. The neuropathic pain model was established by ligating the L5-L6 spinal nerves in Sprague-Dawley rats. Several α₂-AR antagonists were injected into the intramedullary sheath to evaluate the role of baicalin in neuropathic pain. The antagonists included nonselective α₂-AR antagonist idazoxan, α_2a-AR antagonist BRL 44408, α_2b-AR antagonist ARC 239 and α_2c-AR antagonist JP 1302. The rats were divided into an untreated control group, saline group, baicalin group and baicalin + α₂-AR antagonist groups. Paw withdrawal threshold (PWT) was tested to assess the level of pain felt by the rats. The levels of α₂-AR mRNA were tested by reverse transcription-quantitative PCR. Inflammatory factors, including tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-17 and IL-1β, were analyzed by ELISA. The histopathological changes were assessed by hematoxylin and eosin staining. Flow cytometry was used to examine the percentage of CD4⁺ peripheral blood mononuclear cells (PBMCs). Compared with the saline group, the PWT value increased after treating with baicalin. However, intrathecal injection of α₂-AR antagonist reversed the antinociceptive effects of baicalin. Compared with the saline group, the expression of α_2a-AR and α_2c-AR mRNA was upregulated significantly in the baicalin group (P<0.05). Levels of α₂-AR mRNA were also decreased in the baicalin + idazoxan group compared with the baicalin group (P<0.05). The levels of TNF-α, IL-6, IL-17 and IL-1β were raised after treatment with baicalin. In addition, baicalin treatment ameliorated the histological damage in the spinal cord. The percentage of CD4⁺ PBMCs was increased in the saline group compared with the control group (P<0.05). Compared with the baicalin group, the percentage of CD4+ PBMCs was raised after treatment with the α₂-AR antagonists. In conclusion, intrathecal injection of baicalin produced an antiallodynic effect in a spinal nerve ligation-induced neuropathic pain model. The mechanism may be related to the regulation of a₂-AR expression.

Postoperative analgesia using dezocine alleviates depressive symptoms after colorectal cancer surgery: A randomized, controlled, double-blind trial

BACKGROUND

Postoperative depression is one of the most common mental disorders in patients undergoing cancer surgery and it often delays postoperative recovery. We investigated whether dezocine, an analgesic with inhibitory effect on the serotonin and norepinephrine reuptake, could relieve postoperative depressive symptoms in patients undergoing colorectal cancer surgery.

METHODS

This randomized, controlled, single-center, double-blind trial was performed in the Second Affiliated Hospital of the Army Medical University. A total of 120 patients were randomly assigned to receive either sufentanil (1.3 μg/kg) with dezocine (1 mg/kg) (dezocine group; n = 60) or only sufentanil (2.3 μg/kg) (control group; n = 60) for patient-controlled intravenous analgesia after colorectal cancer surgery. The primary outcome was the Beck Depression Inventory score at 2 days after surgery. The secondary outcomes included the Beck Anxiety Inventory, sleep quality, and quality of recovery scores.

RESULTS

Compared with those in the control group, patients in the dezocine group had lower depression scores (7.3±3.4 vs. 9.9±3.5, mean difference 2.6, 95% CI: 1.4-3.9; P<0.001) at 2 days after surgery and better night sleep quality at the day of surgery (P = 0.010) and at 1 day after the surgery (P<0.001). No significant difference was found in other outcomes between the two groups.

CONCLUSIONS

Intravenous analgesia using dezocine can relieve postoperative depression symptoms and improve sleep quality in patients undergoing colorectal cancer surgery.

The Use of Computational Approaches in the Discovery and Mechanism Study of Opioid Analgesics

Opioid receptors that belong to class A G protein-coupled receptors (GPCRs) are vital in pain control. In the past few years, published high-resolution crystal structures of opioid receptor laid a solid basis for both experimental and computational studies. Computer-aided drug design (CADD) has been established as a powerful tool for discovering novel lead compounds and for understanding activation mechanism of target receptors. Herein, we reviewed the computational-guided studies on opioid receptors for the discovery of new analgesics, the structural basis of receptor subtype selectivity, agonist interaction mechanism, and biased signaling mechanism.

Synergistic interaction between butorphanol and dexmedetomidine in antinociception

Opioid analgesics and the α2-adrenergic receptor (α2AR) agonists are found to produce synergistic antinociception when administered in combination. In this study interactions between butorphanol and dexmedetomidine were investigated in the thermal pain and autonomous locomotor activity. Butorphanol and dexmedetomidine were administered subcutaneously alone and in combination in a fixed-dose ratio (3:1) to assess the antinociceptive and sedative responses. Butorphanol produced antinociception in the hot-plate test via three major opioid receptor subtypes, i.e. MORs, KORs and DORs, while in the tail-immersion test the antinociception was produced by MORs and KORs, whereas dexmedetomidine exhibited antinociception by α2ARs in both tests. They exhibited dose- and time-dependent antinociception and inhibition of locomotor activity when administered alone, while their combination displayed enhanced therapeutic effects. Isobolographic analysis revealed that combined butorphanol and dexmedetomidine produced synergistic interactions in the hot-plate, tail-immersion and locomotor activity tests. Furthermore, the analgesic synergy was also approved to be modulated by MORs, KORs, DORs and α2ARs. Hence we concluded from this study that combined butorphanol and dexmedetomidine produced synergistic antinociception that may be helpful in facilitating clinical management of acute nociceptive pain.

Dezocine attenuates the remifentanil-induced postoperative hyperalgesia by inhibition of phosphorylation of CaMKⅡα

Remifentanil, ultra-short-acting μ-opioid receptor agonist, has the greatest advantage in analgesia but could increase postoperative pain scores and induces postoperative hyperalgesia. Dezocine is a mixed opioid receptor partial agonist/antagonist and has been used for postoperative hyperalgesia management in clinical patients,but the potential molecular mechanism is still unclear. Ca²⁺/calmodulin-dependent protein kinase Ⅱ(CaMKⅡ) has been reported involved in remifentanil-induced hyperalgesia (RIH) in previous studies, but the relationship between CaMKⅡ and dezocine in RIH is still unclear. To investigate the mechanism of dezocine in RIH, we used a remifentanil induced postoperative hyperalgesia (RIPH) in incisional pain model of mouse. We subcutaneously infused remifentanil (40 μg/kg) to induce postoperative hyperalgesia. Dezocine (1.5 mg/kg, 3.0 mg/kg, and 6.0 mg/kg) was infused subcutaneously with remifentanil using the apparatus pump for 30 min. Paw withdrawal thermal latency (PWTL) and paw withdrawal mechanical threshold (PWMT) were used to assess thermal hyperalgesia and mechanical allodynia. Western blotting analysis and immunohistochemistry analysis were used to assess the expression of phosphorylated CaMKⅡα (p-CaMKⅡα) in somatosensory cortex, hippocampus and spinal cord. Subcutaneous infusion of remifentanil enhanced postoperative pain induced by surgical incision and increased PWTL and PWMT. Dezocine dose-dependently decreased the PWTL and PWMT in RIPH model. Correlating with behavioral effects, dezocine inhibited remifentanil-induced up-regulation of p-CaMKⅡα expression in somatosensory cortex, hippocampus and spinal cord. Dezocine could attenuate RIPH by suppressing p-CaMKⅡα.

Endogenous opiates and behavior: 2017

This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

The role of the endogenous neurotransmitters associated with neuropathic pain and in the opioid crisis: The innate pain-relieving system

Neuropathic pain is a chronic pain caused by central and peripheral nerve injury, long-term diabetes or treatment with chemotherapy drugs, and it is dissimilar to other chronic pain conditions. Chronic pain usually seriously affects the quality of life, and its drug treatment may result in increased costs of social and medical care. As in the USA and Canada, in Europe, the demand for pain-relieving medicines used in chronic pain has also significantly increased, but most European countries are not experiencing an opioid crisis. In this review, the role of various endogenous transmitters (noradrenaline, dopamine, serotonin, met- and leu-enkephalins, β-endorphin, dynorphins, cannabinoids, ATP) and various receptors (α₂, μ, etc.) in the innate pain-relieving system will be discussed. Furthermore, the modulation of pain processing pathways by transmitters, focusing on neuropathic pain and the role of the sympathetic nervous system in the side effects of excessive opioid treatment, will be explained.

Dezocine Alleviates Morphine-Induced Dependence in Rats

BACKGROUND

Opioid dependence is a major public health issue without optimal therapeutics. This study investigates the potential therapeutic effect of dezocine, a nonaddictive opioid, in opioid dependence in rat models.

METHODS

Dezocine was administered intraperitoneally to a morphine-dependent rat model to investigate its effect on withdrawal and conditioned place preference (CPP). Effect of dezocine on morphine withdrawal syndrome and CPP was analyzed using 2-way analysis of variance (ANOVA) followed by Tukey's post hoc test. Buprenorphine and vehicle solution containing 20% (v/v) dimethyl sulfoxide were used for positive and negative control, respectively. The astrocytes activation in nucleus accumbens was assessed by immunofluorescence assay of glial fibrillary acidic protein. Effect of dezocine and buprenorphine on the internalization of κ opioid receptor (KOR) was investigated using Neuro2A expressing KOR fused to red fluorescent protein tdTomato (KOR-tdT). Buprenorphine and dezocine were screened against 44 G-protein-coupled receptors, ion channels, and transporter proteins using radioligand-binding assay to compare the molecular targets.

RESULTS

The mean withdrawal score was reduced in rats treated with 1.25 mg·kg dezocine compared to vehicle-treated control animals starting from the day 1 (mean difference: 7.8; 95% confidence interval [CI], 6.35-9.25; P < .0001 by 2-way ANOVA). Significance was observed at all treatment days, including day 7 (mean difference: 2.13; 95% CI, 0.68-3.58; P < .001 by 2-way ANOVA). Furthermore, dezocine inhibited the reinstatement of morphine-induced CPP (mean difference: 314; 95% CI, 197.9-430.1; P < .0001 by 2-way ANOVA) compared to the control group. Chronic morphine administration induced astrocytes activation in nucleus accumbens, which was attenuated by dezocine. Dezocine blocked the agonist-induced KOR internalization in vitro, 1 of the mechanisms involved in the downstream signaling and development of opioid dependence. Dezocine had affinity to norepinephrine and serotonin transporters and sigma-1 receptor, whereas buprenorphine showed no activity against these targets.

CONCLUSIONS

Dezocine could potentially be used to alleviate opioid dependence. Due to the unique molecular target profile different from buprenorphine, it might have important value in studying the mechanisms of morphine dependence and developing novel therapeutic approaches.

Effects of dezocine and sufentanyl for postoperative analgesia on activity of NK, CD4+ and CD8+ cells in patients with breast cancer

The effects of dezocine and sufentanyl on the activity of natural killer (NK), CD4⁺ and CD8⁺ cells in patients with breast cancer undergoing postoperative analgesia after radical mastectomy were compared. The clinical data of 76 female patients undergoing radical mastectomy in the Fudan University Shanghai Cancer Center from January 2015 to October 2017 were analyzed retrospectively. Forty-two patients treated with dezocine were group D and 34 patients with sufentanyl were group S. Visual analogue scale (VAS) was used to evaluate the analgesic effect at 3, 12, 24, 48 h after surgery. There was no significant difference in VAS score, NK cells, CD4⁺ cells, and CD8⁺ cell vitality at 3 h postoperatively between the two groups (P>0.05), and VAS score at 12, 24 and 48 h postoperatively in the S group was significantly lower than that in group D (P<0.05). The activity of NK cells and CD4⁺ cells at 3, 12, 24 and 48 h after surgery in group D was significantly higher than that in group S, and the difference was statistically significant (P<0.05). The activity of CD8⁺ cells at 3, 12, 24 and 48 h after surgery in group D was significantly lower than that in group S, and the difference was statistically significant (P<0.05). The analgesic effect of dezocine was slightly worse than that of sufentanyl, but it was more beneficial to the recovery of early postoperative immune function.

Effects of patient-controlled analgesia with hydromorphone or sufentanil on postoperative pulmonary complications in patients undergoing thoracic surgery: a quasi-experimental study

Objective

To compare the analgesic effects of patient-controlled intravenous analgesia (PCA) with hydromorphone and sufentanil after thoracic surgery on postoperative pulmonary complications (PPCs).

Methods

A total of 142 patients who were scheduled for thoracic surgery were randomly allocated to receive PCA with hydromorphone (group A: experimental group): hydromorphone 0.2 mg/kg + dezocine 0.5 mg/kg + ramosetron 0.6 mg diluted with normal saline to 200 mL; or with sufentanil (group B: control group): sufentanil 3.0μg/kg + dezocine 0.5 mg/kg + ramosetron 0.6 mg diluted with normal saline to 200 mL. The parameters of intravenous analgesia pump were set as background dose 4 ml/h, PCA dose 1 mL, locking time 15 min. Pain NRS (numerical rating scale), Ramsay sedation score, nausea or vomiting score were evaluated at 0 h, 6 h, 12 h, 24 h, 48 h after operation. The cases of PPCs (atelectasis, pulmonary infection, respiratory failure), CRP (C-reaction protein) and inflammatory cells (white cell count and percentage of neutrophils) and blood gas analysis at 12 h after operation, length of ICU and postoperative stay were recorded for each patient.

Results

Data of 136 patients were analyzed. Compared with group B (4[IQR:2,2]), the pain NRS in group A (2[IQR:4,4]) was significantly lower at 6 h after operation (P = 0.000). The CRP in group A (69.79 ± 32.13 mg/L) were lower than group B (76.76 ± 43.42 mg/L) after operation, but the difference was not significant (P = 0.427). No difference of nausea or vomiting was found between group A (7.3%) and group B (5.8%) postoperatively (P = 0.999). The PPCs were happened in 11 patients in group A (16.2%) and 22 patients in group B (32.4%) and the difference between two groups was significant (P = 0.027). Seven patients in group A (10.3%) and eighteen patients in group B (26.5%) had clinical evidence of pneumonia and the difference between two groups was significant (P = 0.014). The length of ICU and postoperative stay in group A were 2.73 h and 1.82 days less than group B respectively but the differences were not significant (P = 0.234, P = 0.186 respectively).

Conclusion

Compared with sufentanil, hydromorphone may provide better postoperative analgesic effect with less pulmonary complications for patients undergoing thoracic surgery, and it may accelerate patients’ rehabilitation.

Trial registration

Randomized Controlled Trials ChiCTR1800014282c. Registered 3 January 2018.

Spinal interleukin-10 produces antinociception in neuropathy through microglial β-endorphin expression, separated from antineuroinflammation

Interleukin 10 (IL-10) is antinociceptive in various animal models of pain without induction of tolerance, and its mechanism of action was generally believed to be mediated by inhibition of neuroinflammation. Here we reported that intrathecal IL-10 injection dose dependently attenuated mechanical allodynia and thermal hyperalgesiain male and female neuropathic rats, with ED₅₀ values of 40.8 ng and 24 ng, and E_max values of 61.5% MPE and 100% MPE in male rats. Treatment with IL-10 specifically increased expression of the β-endorphin (but not prodynorphin) gene and protein in primary cultures of spinal microglia but not in astrocytes or neurons. Intrathecal injection of IL-10 stimulated β-endorphin expression from microglia but not neurons or astrocytes in both contralateral and ipsilateral spinal cords of neuropathic rats. However, intrathecal injection of the β-endorphin neutralizing antibody, opioid receptor antagonist naloxone, or μ-opioid receptor antagonist CTAP completely blocked spinal IL-10-induced mechanical antiallodynia, while the microglial inhibitor minocycline and specific microglia depletor reversed spinal IL-10-induced β-endorphin overexpression and mechanical antiallodynia. IL-10 treatment increased spinal microglial STAT3 phosphorylation, and the STAT3 inhibitor NSC74859 completely reversed IL-10-increased spinal expression of β-endorphin and neuroinflammatory cytokines and mechanical antiallodynia. Silence of the Bcl3 and Socs3 genes nearly fully reversed IL-10-induced suppression of neuroinflammatory cytokines (but not expression of β-endorphin), although it had no effect on mechanical allodynia. In contrast, disruption of the POMC gene completely blocked IL-10-stimulated β-endorphin expression and mechanical antiallodynia, but had no effect on IL-10 inhibited expression of neuroinflammatory cytokines. Thus this study revealed that IL-10 produced antinociception through spinal microglial β-endorphin expression, but not inhibition of neuroinflammation.

Pharmacological Characterization of Dezocine, a Potent Analgesic Acting as a κ Partial Agonist and μ Partial Agonist

Dezocine is becoming dominated in China market for relieving moderate to severe pain. It is believed that Dezocine’s clinical efficacy and little chance to provoke adverse events during the therapeutic process are mainly attributed to its partial agonist activity at the μ opioid receptor. In the present work, we comprehensively studied the pharmacological characterization of Dezocine and identified that the analgesic effect of Dezocine was a result of action at both the κ and μ opioid receptors. We firstly found that Dezocine displayed preferential binding to μ opioid receptor over κ and δ opioid receptors. Dezocine, on its own, weakly stimulated G protein activation in cells expressing κ and μ receptors, but in the presence of full κ agonist U50,488 H and μ agonist DAMGO, Dezocine inhibited U50,488H- and DAMGO-mediated G protein activation, indicating that Dezocine was a κ partial agonist and μ partial agonist. Then the in intro results were verified by in vivo studies in mice. We observed that Dezocine-produced antinociception was significantly inhibited by κ antagonist nor-BNI and μ antagonist β-FNA pretreatment, indicating that Dezocine-mediated antinociception was via both the κ and μ opioid receptors. When co-administrating of Dezocine with U50,488 H or morphine, Dezocine was capable of inhibiting U50,488H- or morphine-induced antinociception. Finally, κ receptor activation-associated side effect sedation was investigated. We found that Dezocine displayed limited sedative effect with a ceiling effecting at a moderate dose. Thus, our work led to a better understanding of the analgesic mechanism of action of Dezocine in vivo.

Effect of preemptive dezocine before general anesthesia on postoperative analgesia in patients undergoing laparoscopic cholecystectomy: A prospective observational study

Dezocine is proposed as an adjunctive analgesic for postoperative pain control. This randomized, double-blind, controlled study aimed to investigate the effect of preoperative Dezocine therapy on postoperative pain following laparoscopic cholecystectomy as well as the underlying mechanisms.Eighty patients scheduled for laparoscopic cholecystectomy were randomly allocated into 2 groups as follows: patients in Group D received Dezocine 0.15 mg/kg before anesthesia induction and patients in Group S received same volume of saline. The pain intensity, sedation score, sufentanil-based patient-controlled analgesia (PCA) consumption were recorded for 24 hours after surgery. Plasma concentrations of norepinephrine and serotonin were also measured.During the first 24 hours after surgery, the patients in Group D experienced lower pain score assessed by numerical rating scale (NRS) at 3 hours (rest: P = .038; movement: P = .036), 6 hours (rest: P = .038; movement: P = .036), 12 hours (rest: P = .038; movement: P = .036), and 24 hours (rest: P = .038; movement: P = .036). Dezocine also decreased the sedation levels at 5 minutes (P = .031) after arrival at the PACU. Sufentanil-based PCA consumption in Group D was decreased when compared with Group S in the second to fourth phase after surgery (6-12 hours: P = .017; 12-18 hours: P = .003; 18-24 hours: P = .039). Plasma norepinephrine and serotonin concentrations were higher in the Group D at 24 hours after surgery (norepinephrine: P = .009, serotonin: P = .042). In addition, Group D showed less incidence of nausea/vomiting (P = .032) as well as a higher postoperative satisfaction score after surgery (P = .017).In conclusion, preemptive Dezocine administration is suggested to be useful for the management of postoperative pain in short-lasting surgery such as laparoscopic cholecystectomy.

Lappaconitine, a C18-diterpenoid alkaloid, exhibits antihypersensitivity in chronic pain through stimulation of spinal dynorphin A expression

Lappaconitine is a representative C18-diterpenoid alkaloid extracted from Aconitum sinomontanum Nakai and has been prescribed as a pain relief medicine in China for more than 30 years. This study evaluated its antihypersensitivity activity in the rat models of neuropathic and cancer pains and explored its underlying mechanisms. Subcutaneous injection of cumulative doses of lappaconitine produced dose-dependent mechanical antiallodynia and thermal antihyperalgesia in spinal nerve ligation-induced neuropathic rats. The cumulative dose-response analysis exhibited their E_max values of 53.3 and 58.3% MPE, and ED₅₀ values of 1.1 and 1.6 mg/kg. Single intrathecal lappaconitine dose in neuropathy also dose- and time-dependently blocked mechanical allodynia, with an E_max of 66.1% MPE and an ED₅₀ of 0.8 μg. Its multiple twice-daily intrathecal administration over 7 days did not induce mechanical antiallodynic tolerance. Subcutaneous cumulative doses of lappaconitine also produced dose-dependent blockade of mechanical allodynia in the rat bone cancer pain model induced by tibia implantation of cancer cells, with the E_max of 57.9% MPE and ED₅₀ of 2.0 mg/kg. Furthermore, lappaconitine treatment stimulated spinal dynorphin A expression in neuropathic rats, and in primary cultures of microglia but not neurons or astrocytes. Intrathecal pretreatment with the specific microglia depletor liposome-encapsulated clodronate, dynorphin A antibody, and κ-opioid receptor antagonist GNTI totally suppressed intrathecal and subcutaneous lappaconitine-induced mechanical antiallodynia. This study suggests that lappaconitine exhibits antinociception through directly stimulating spinal microglial dynorphin A expression. Graphical Abstract ᅟ.

Clinical and pharmacogenetics associated with recovery time from general anesthesia

AIM

Delayed recovery from general anesthesia is a well-known complication that requires predictive tools and approaches. This study aimed to determine significant factors associated with postanesthesia recovery and to develop an algorithm for estimating recovery time from general anesthesia.

MATERIALS & METHODS

The genotypes of patients were determined by SNaPshot or ARMS-qPCR. The algorithm was developed via machine-learning and tested by the worm plot.

RESULTS

Results showed that OPRM1 rs1799971 (p = 0.006) and ABCG2 rs2231142 (p = 0.041) were significantly associated with recovery time. Ten factors after random forest and stepwise selection were associated with recovery time. Ten factors after random forest and stepwise selection were associated with recovery time. Meanwhile, seven factors were associated with delayed recovery.

CONCLUSION

This study demonstrated that both clinical and pharmacogenetic data are significantly associated with recovery from general anesthesia and provide the basis for pre-emptive prediction tools.

Additive analgesic effect of dexmedetomidine and dezocine administered intrathecally in a mouse pain model

Background

It is known that dexmedetomidine can reduce opioid requirements and that there is a synergistic effect when dexmedetomidine and morphine (a full mu opioid receptor agonist) are administered together. However, it was unclear whether a synergistic or additive effect would be observed when dexmedetomidine was co-administered with a partial mu opioid receptor agonist. The present study was designed to elucidate such effects by intrathecally co-administering dexmedetomidine and dezocine, a partial mu receptor agonist, in a mouse pain model.

Methods

C57 mice (N = 165) were randomly divided into 19 groups. The tail flick test was adopted to measure the antinociceptive effects of the tested agents. The mice were divided into saline and drug groups to investigate the dose-dependent analgesic effects. Each drug was administered at fixed doses alone and in combination with one of three doses of a second drug.

Results

Dezocine (0.3125 - 1.25 μg) and dexmedetomidine (0.04 - 1 μg) both enhanced the tail withdrawal latency in dose-dependent fashions. Dexmedetomidine (0.04 - 1 μg) enhanced the analgesic effect of dezocine. Dezocine (0.3125 - 1.25 μg) enhanced the analgesic effect of dexmedetomidine. Compared with the individual drug effects, the combined effects of dezocine (0.625 μg) and dexmedetomidine (0.04 μg) were more potent 15 - 60 min after injection, but they remained similar to the sum of the effects of the two individual drugs.

Conclusions

Dexmedetomidine and dezocine produce an additive analgesic effect on acute nociception when administered simultaneously.