Spinal Analgesia with Intrathecal Morphine versus Conventional Analgesia after Laparoscopic Colectomy: A Retrospective Cohort Study

Objective: Postoperative pain (POP) following abdominal surgery can vary from a few hours to several days. This acute, unrelieved pain can become chronic, requiring patients to take analgesics on an almost daily basis for comfort. Analgesia using general opioids has many side effects and intrathecal morphine is a good alternative. This study was conducted to evaluate the efficacy of intrathecal morphine (ITM) versus conventional analgesia in the management of postoperative pain in colectomy performed by laparoscopic surgery. Methods: Cohort study conducted at the Hôpital Nord in Marseille, from 01 January to 31 July 2021 in patients aged at least 18 years undergoing anaesthesia for scheduled colectomy by laparoscopic surgery. The primary endpoint was postoperative pain intensity and the secondary endpoints were morphine consumption, treatment side effects and length of hospital stay. Statistical analysis was performed using XLSTAT software. Results: We included 193 patients: 131 in the control group (conventional analgesia) and 62 in the ITM group. We observed: a significant decrease in pain (assessed by numerical scale) in favour of the ITM group in the post-anaesthetic care room, i.e. 3 (±4) vs 1 (±2), p 0 and H2: 2 (±2) vs. 1 (±2);p Conclusion: These results suggest that intrathecal morphine (ITM) in laparoscopic colectomy provides effective postoperative analgesia with low morphine consumption, and a reduction in morphine side-effects compared with conventional analgesia.

Monoclonal antibody targeting mu-opioid receptor attenuates morphine tolerance via enhancing morphine-induced receptor endocytosis

Morphine is a frequently used analgesic that activates the mu-opioid receptor(MOR),which has prominent side effects of tolerance.Although the inefficiency of morphine in inducing the endocytosis of MOR underlies the development of morphine tolerance,currently,there is no effective therapy to treat morphine tolerance.In the current study,we aimed to develop a monoclonal antibody(mAb)precisely targeting MOR and to determine its therapeutic efficacy on morphine tolerance and the underlying molecular mechanisms.We successfully prepared a mAb targeting MOR,named 3A5C7,by hybridoma technique using a strategy of deoxyribonucleic acid immunization combined with cell immunization,and identified it as an immunoglobulin G mAb with high specificity and affinity for MOR and binding ability to antigens with spatial conformation.Treatment of two cell lines,HEK293T and SH-SY5Y,with 3A5C7 enhanced morphine-induced MOR endocytosis via a G protein-coupled receptor kinase 2(GRK2)/b-arrestin2-dependent mechanism,as demonstrated by immunofluorescence staining,flow cytometry,Western blotting,coimmunoprecipitation,and small interfering ribonucleic acid(siRNA)-based knockdown.This mAb also allowed MOR recycling from cytoplasm to plasma membrane and attenuated morphine-induced phosphorylation of MOR.We established an in vitro morphine tolerance model using differentiated SH-SY5Y cells induced by retinoic acid.Western blot,enzyme-linked immunosorbent assays,and siRNA-based knockdown revealed that 3A5C7 mAb diminished hyperactivation of adenylate cyclase,the in vitro biomarker of morphine tolerance,via the GRK2/b-arrestin2 pathway.Furthermore,in vivo hotplate test demonstrated that chronic intrathecal administration of 3A5C7 significantly alleviated morphine tolerance in mice,and withdrawal jumping test revealed that both chronic and acute 3A5C7 intrathecal administration attenuated morphine dependence.Finally,intrathecal electroporation of silencing short hairpin RNA illustrated that the in vivo anti-tolerance and anti-dependence efficacy of 3A5C7 was mediated by enhanced morphine-induced MOR endocytosis via GRK2/b-arrestin2 pathway.Collectively,our study provided a therapeutic mAb,3A5C7,targeting MOR to treat morphine tolerance,mediated by enhancing morphine-induced MOR endocytosis.The mAb 3A5C7 demonstrates promising translational value to treat clinical morphine tolerance.

Analgesic Efficacy of Intrathecal Bupivacaine with or without Morphine in Lower Limb Orthopedic Surgery. A Comparative Study

Background: Lower limb orthopaedic surgeries are commonly associated with moderate to severe postoperative pain. Adequate pain relief is essential for patients undergoing such procedures, as uncontrolled pain can lead to delayed recovery, prolonged hospitalization, and increased morbidity. Intrathecal administration of bupivacaine, a long-acting local anesthetic, has been shown to provide effective analgesia after lower limb orthopaedic surgery. However, the duration of analgesia with bupivacaine alone is limited, and the addition of an opioid, such as morphine, can prolong the duration of analgesia. Objective: The objective of this study was to document the comparative effect of adding morphine to intrathecal bupivacaine or only intrathecal bupivacaine for lower limb trauma orthopedic surgeries in terms of onset of action, duration of analgesia, pain severity, and side effects. Methods: This was a comparative longitudinal study design conducted at the Orthopaedic Unit of the Tamale Teaching Hospital. A simple random sampling technique was used to recruit 60 patients. A standard structured questionnaire was also used to collect data on the socio-demographics, and clinical features of patients, drug used,side effects and severity of pain at 24,48 and 72 hrs after surgery. Results: Co-administration of intrathecal bupivacaine with morphine produced good and long-lasting postoperative analgesia with a mean time of 1004.25 ± 310.43 minutes, whiles using only bupivacaine produced shorter postoperative analgesia with a mean time of 294.75 ± 195.53 minutes. The p-value p values of p = 0.635 and p = 0.689 respectively. Conclusion: The study revealed that co-administration of intrathecal bupivacaine with morphine emerged as a better option for postoperative pain management after lower limb orthopedic surgeries as compared to administering only bupivacaine regarding the duration of analgesia. Milder side effects like pruritus, nausea, and vomiting were seen in group B than in group A and were promptly well managed to the patient’s satisfaction.

Systematic review on the risk-benefit ratio of morphine for acute heart failure

Objective:To evaluate morphine's risk-benefit profile in the treatment of acute heart failure.Method:Different electronic databases,including PubMed,MEDLINE,Cochrane Library,and Google Scholar,as well as clinicaltrails.gov,were searched for articles published between 2012 and 2022.The risk of bias in the present study was evaluated by employing randomized controlled trials(RCTs)checklist that assesses the effectiveness of new interventions through random assignment of participants to different treatment groups.The two-part tool was used to address the five specific domains such as selection bias,performance bias,detection bias,attrition bias,and selective reporting bias.Evaluation of the quality of diagnostic accuracy studies was conducted using the RevMan software(version 5.4),a quality assessment tool.Results:A total of 13 studies were included in the present review,in which there were 5 retrospective studies,3 randomized-control studies,2 prospective studies,1 multicenter pharmacodynamics study,1 multicenter cardiac magnetic resonance imaging study,and 1 open-label,cross-over study.The mortality of acute heart failure patients treated with morphine was higher compared to those without morphine.Conclusions:Acute heart failure patients who do not receive morphine have a lower mortality rate compared to those who receive morphine.Considering the adverse effects,including mortality associated with morphine,there is a pressing need for further research to explore alternative and effective treatment options in acute heart failure.

Suppressing high mobility group box-1 release alleviates morphine tolerance via the adenosine5'-monophosphate-activated protein kinase/heme oxygenase-1 pathway

Opioids,such as morphine,are the most potent drugs used to treat pain.Long-term use results in high tolerance to morphine.High mobility group box-1(HMGB1) has been shown to participate in neuropathic or inflammatory pain,but its role in morphine tolerance is unclear.In this study,we established rat and mouse models of morphine tolerance by intrathecal injection of morphine for 7 consecutive days.We found that morphine induced rat spinal cord neurons to release a large amount of HMGB1.HMGB1 regulated nuclear factor κB p65 phosphorylation and interleukin-1β production by increasing Toll-like receptor 4receptor expression in microglia,thereby inducing morphine tolerance.Glycyrrhizin,an HMGB1 inhibito r,markedly attenuated chronic morphine tole rance in the mouse model.Finally,compound C(adenosine 5’-monophosphate-activated protein kinase inhibitor) and zinc protoporphyrin(heme oxygenase-1 inhibitor)alleviated the morphine-induced release of HMGB1 and reduced nuclear factor κB p65 phosphorylation and interleukin-1β production in a mouse model of morphine tolerance and an SH-SY5Y cell model of morphine tole rance,and alleviated morphine tolerance in the mouse model.These findings suggest that morphine induces HMGB1 release via the adenosine 5’-monophosphate-activated protein kinase/heme oxygenase-1 signaling pathway,and that inhibiting this signaling pathway can effectively reduce morphine tole rance.

Pharmacokinetics of Controlled Release and Immediate Release Morphine Sulphate Tablets after a Single Dose and Multiple Doses in Chinese Volunteers

The pharmacokinetics of morphine sulphate was studied in 10 Chinese healthy volunteers after a single oral dose. Blood samples were collected before and after administration of controlled release tablets (CRMS, 30 mg) and immediate release tablets (IRMS, 20 mg). The plasma concentration of morphine was determined by GC MS. The pharmacokinetic parameters of controlled release tablets and immediate release tablets were calculated∶ C max was 19.38±3.80 and 21.27±6.21 ng/ml, t max was 2.36 ±0.37 h and 0.56±0.16 h, t 1/2β was 3.53±0.87 and 3.03±0.74 h, AUC was 145.15±17.65 and 93.08±16.65 ng/ml, respectively. The steady state plasma concentration of morphine sulphate in cancer patients after multiple doses was achieved, C max of CRMS and IRMS was 27.43±0.33 ng/ml and 22.68±0.16 ng/ml, C min of CRMS and IRMS was 19.45±1.44 ng/ml and 18.14±0.49 ng/ml, respectively.

Effects of 5-hydroxytryptophan on morphine-induced sensitization in mice

To investigate the involvement of central serotonergic system in behavioral sensitization to morphine in mice. Male Kunming mice were treated （i.p.） with saline or morphine 10 mg/kg twice daily for 3 d and then drug manipulation was suspended for 5 d. On day 9, a challenge dose of morphine （10 mg/kg） was given and the locomotor activity was measured for 60 rain to confkrm the establishment of behavioral sensitization in mice. Moreover, 5-hydroxytryptophan （5-HTP）, a precursor of serotonin, at the doses of 20-80 mg/kg was given i.p. in combination with daily morphine treatment （induction）, during the morphine treatment suspension （transfer） or prior to the challenge dose of morphine （expression） and locomotor activity was measured on day 9 after the challenge dose of morphine. Twice daily of morphine injection induced robust behavioral sensitization in mice as evidenced by significantly higher locomotion on day 9 for multiple treatment with morphine than saline in mice. 5-HTP treatment selec- tively and dose-dependently blocked the induction, but not the transfer nor the expression of morphine induced behavioral sensitization. This study provides clear evidence that up-regulation of central serotonergic system may suppress the induction of morphine sensitization in mice.

N-nitro-L-arginine Attenuates Morphine and Dihydroetorphine-induced Place Preference in Mice

Opiate dependence has become one of the most urgent problems of modernsociety. Opiate dependence involves physical and psychical dependence. Although many addicts can bedetoxified, the relapse ratio of 95% in 5 a demonstrates that opiate psychical dependence is aproblem more troublesome. It has been reported that acute and chronic administration of L- NNA canmarkedly retard the development of tolerance to physical dependence on morphine, and suppress theabstinence syndromes precipitated by naloxone in opiate dependent rodents, and even reverse theexisting morphine tolerance. However, the effect of L-NNA on the positive reinforcement ofpsychically active substances and its possible mechanism have not yet been reported. In presentstudy, the effect of L- NNA en the psychical dependence induced by opiates was evaluated on thebasis of conditioned place preference.

Sugar Derivatives of Morphine:A New Window for the Development of Potent Anesthetic Drugs

This review provides a short account of carbohydrate derivatives of an important natural drug,morphine,along with their comparative efficacies as anesthetic agent.Sugar derivatives are found to have more prospect as anesthetic drug than morphine itself owing to their enhanced bioavailability.Synthetic schemes of these sugar derivatives and information on related patents are also included in this manuscript.

Morphine analgesia in male inbred genetic diversity mice recapitulates the among-individual variance in response to morphine in humans

Morphine is a widely used analgesic, but its use in clinical precision medicine is limited by the variance in response among individuals. Although previous studies have shown that individual differences in morphine can be explained in terms of pharmacodynamics and pharmacokinetics, genetic polymorphisms also play an important role. However, the genetic basis of different sensitivity and tolerance susceptibility to morphine remains ambiguous. Using 15 strains of inbred Genetic Diversity(GD) mice,a new resource with wide genetic and phenotypic variation, we demonstrated great variance in sensitivity to morphine analgesia and susceptibility to morphine tolerance between different GD strains. Among-i ndividual variance in response to morphine analgesia in the population can be modeled in GD mice. Two loci respectively may be associated with the among-i ndividual variance in morphine sensitivity and tolerance,confirming the role of genetic factors in among-i ndividual different responses to morphine. These results indicate that GD mice may be a potential tool for the identification of new biomarkers to improve the clinical administration of morphine.

Effect of Co-administration of Morphine and Cholinergic Antagonists on Y-maze Spatial Recognition Memory Retrieval and Locomotor Activity in Mice

The interaction of morphine and cholinergic system was shown in previous studies. In the present study, we investigated whether morphine would interact with the cholinergic antagonists, scopolamine and atropine in a Y-maze spatial recognition memory. Pre-test treatments of morphine （5, 1.5, 0.5 mg/kg）, scopolamine （1, 0.1 mg/kg）, atropine （0.5, 0.1 mg/kg） were used in the experiments, relatively high or low doses were paired respectively as co-administration measures. The results showed that co-administration of morphine 0.Smg/kg ~ scopolamine 0.1 mg/kg and morphine 0.5 mg/kg ＋ atropine 0.1 mg/kg disturbed the inspective exploratory behavior （percent of arm duration） but not the inquisitive behavior （percent of arm visits） of the spatial memory retrieval, while the drugs didn＇t cause amnesia when single administered of the concerned low doses. Distinct interaction was found between scopolamine and morphine on increasing locomotor activity.

Effect of devazepide reversed antagonism of CCK-8 against morphineon electrical and mechanical activities of rat duodenum in vitro

AIM To study the antagonism of cholecystokinin octapeptide (CCK 8) against effect of morphine and its mechanism. METHODS The electrical and mechanical activities of rat duodenum in vitro were recorded simultaneously. RESULTS Acetylcholine (ACh) could increase the amplitude and the number of the spike potential (SPA and SPN) of rat duodenum in vitro , followed by the increase of the duodenal contraction amplitudes (CA), showing a positive correlation. Morphine, on the contrary, inhibited the potentiation of ACh, showing a negative correlation. CCK 8 could antagonize the effects of morphine, i.e. SPA and SPN were increased again, followed by the increase of CA. CCK A receptor antagonist Devazepide could reverse the antagonism of CCK 8 to the effect of morphine. CONCLUSION CCK 8 could antagonize the effect of morphine which inhibited the potentiation of ACh on the duodenal activities in vitro . The antagonistic effect of CCK 8 on morphine was mainly mediated by CCK A receptor.

Effect of crocin carotenoid on BDNF and CREB gene expression in brain ventral tegmental area of morphine treated rats

Objective: To investigate the effect of crocin carotenoid on BNDF and CREB gene expression in the brain ventral tegmental area(VTA) and the serum level of BDNF in morphine-treated rats compared to control. Methods: In this study, 40 male Wistar rats(200-250 g) were used in 5 experimental groups: 1) non morphine treat rats(control); 2) non morphine-treated rats with 25 mg/kg crocin carotenoid(i.p., for 21 d); 3) morphine treated rats(10 mg/kg twice a day, s.c., 21 d); 4 and 5) morphine-treated rats with 12.5 and 25 mg/kg crocin carotenoid, respectively. By the end of research, BDNF and CREB expression was determined by real-time-PCR method. ELISA analysis was also applied for assessing the serum BDNF level. Results: The data indicated that morphine treatment could cause a significant decrease in BDNF and CREB gene expression(P<0.01 and P<0.001, respectively) in brain VTA as well as serum level of BDNF(P<0.01) in comparison to control group. Treatment with 25 mg/kg crocin carotenoid caused a significant enhancement in BDNF and CREF gene expression(P<0.01 and P<0.05, respectively) and serum level of BDNF(P<0.01) in morphine-treated rats in comparison to morphine-treated group. Conclusions: Regarding to obtained results, crocin carotenoid can inhibit unfavorable effects of morphine on the neural system to some extent through enhancing BDNF and CREB gene expression in brain VTA and serum level of BDNF.

Effects of Morphine,Fentanyl and Tramadol on Human Immune Response

Summary： Morphine has been reported to suppress human immune response. We aimed to observe the effects of morphine, fentanyl and tramadol on NF- K B and IL-2 from both laboratory and clinical perspective. Jurkat cells were incubated with ten times clinically relevant concentrations of morphine, fentanyl and tramadol before being stimulated with PMA. NF- κB binding activity and IL-2 levels were measured, In the clinical study, 150 consenting patients were randomized into 3 groups according to the analgesics used in them, namely, group morphine （M）, group fentanyl （F） and group tramadol （T）. IL-2 was measured preoperatively and 1, 3 and 24 h after operation. Consequently, NF-κB activation was suppressed by morphine and fentanyl but not by tramadol. IL-2 was significantly decreased by morphine and fentanyl but not by tramadol in vitro. In the PCA patients, IL-2 was decreased in group M and increased in group F postoperatively. Whereas in group T, IL-2 was unchanged 1 h after operation but was significantly elevated 3 and 24 h after operation. Our results showed that the inhibition of morphine on IL-2 was most probably related to its suppression on NF-κB, Fentanyl had different effects on human immune response in vitro and in vivo. Tramadol may have immune enhancing effect.

Sex differences in morphine-induced behavioral sensitization and social behaviors in ICR mice

Gender and genetic strain are two prominent variants that influence drug abuse. Although certain sexrelated behavioral responses have been previously characterized in ICR mice, little is known about the effects of sex on morphine-induced behavioral responses in this outbred strain. Therefore, in this study, we investigated the sex differences of morphine-induced locomotion, anxiety-like and social behaviors in ICR mice. After morphine or saline exposure for four consecutive days（twice daily）, increased locomotion, more time spent in the central area, as well as attenuated rearing and self-grooming behaviors were found in morphine-treated females in an open field; no differences were found in locomotion and the time spent in the central area between male and female controls. When interacting with the samesex individuals, female controls were engaged in more social investigation, following, body contacting and self-grooming behaviors than controls; morphine exposure reduced contacting and self-grooming behaviors in females; in contrast, these effects were not found in males. These results indicate that female ICR mice are more prosocial and are more susceptible to morphine exposure than males.

Effect of morphine and M-cholinoceptor blocking drugs on human sphincter of Oddi during choledochofiberscopy manometry

OBJECTIVE: To evaluate the effects of morphine on the human sphincter of Oddi pressure and the antagonism of anticholinergic agents against morphine. METHODS: The action of these drugs on the sphincter of Oddi (SO) was evaluated by means of choledochofiberscopy manometry in 40 operated patients with T-tube. The patients were divided randomly into 4 groups: anisodamine, atropine, buscopan, and control. The following data were recorded: duodenal pressure (DP), basal pressure of the sphincter of Oddi (BPSO), contractive amplitude of the sphincter of Oddi (CASO), contractive frequency of the sphincter of Oddi (CFSO), contractive duration of the sphincter of Oddi (CDSO), and pressure of the common bile duct (PCBD). Both morphine and anticholinergic agents were given intramuscularly. RESULTS: After injection of 10 mg morphine, BPSO, CASO, CFSO, and PCBD increased significantly. After injection of 15 mg anisodamine or 0.75 mg atropine, CASO, BPSO declined obviously, and after injection of 20 mg buscopan, CASO, BPSO, CFSO declined obviously, but in anisodamine, atropine and buscopan groups, they differed insignificantly. CONCLUSIONS: The results illustrate that SO manometry via choledochofiberscopy is a new method for SO dynamic study. Morphine can increase DP, BPSO, CASO, PCBD, but anisodamine atropine and buscopan can antagonize the effect of morphine.

Effects of electro-acupuncture on brain tissue norepinephrine contents in a morphine withdrawal anxiety mouse model

BACKGROUND： Following morphine withdrawal, anxiety is associated with abnormal norepinephrine content change. However, increasing blood lactic acid content can induce anxiety or panic in patients with anxiety disorder or endogenous opioid peptide functional disorder. OBJECTIVE： This study was designed to observe the effects of electro-acupuncture, at the ＂Sanyinjiao＂ point （SP 6）, on brain tissue norepinephrine and blood lactic acid content in anxiety-model mice after morphine withdrawal. DESIGN： A randomized controlled animal experiment. SETTING： This study was performed in the Laboratory of Acupuncture, Electro-acupuncture ＆ Tuina College, Chengdu University of Traditional Chinese Medicine, from June to September 2001. MATERIALS： A total of 50 healthy Kunming male mice were provided by the Laboratory Animal Center of Chengdu University of Traditional Chinese Medicine. The protocol was performed in accordance with ethical guidelines stated in the Guide for the use and care of laboratory animals, approved by the Committee on the Care and Use of Laboratory Animals of the Institute of Laboratory Animal Resources Commission on Life Sciences, National Research Council, China （1985）. Experimental reagents and equipment used were as follows： morphine hydrochloride （Lot No. 930503, Shenyang No.1 Pharmaceutical Factory, China）, norepinephrine （Sigma Chemical Company, USA）, fluorospectrophotometer （RF-510, Shimadzu Corporation, Japan）, Han electro-acupuncture apparatus （WQ 1002, No. zun （91）-227270-588, Beijing Anlong Photoelectricity-Technique Company, China）, and T-maze （self-made）. METHODS： A total of 50 mice were randomly divided into 5 groups, with 10 mice in each group： blank control, T-maze, model, model ＋ electro-acupuncture, and electro-acupuncture groups. Establishment of anxiety model after morphine withdrawal： the mouse hot plate assay was used to detect the activity of morphine. The median effective dose of morphine, 2.95 mg/kg, was defined as the base. Mice were subcutaneously administered morphine, 3 times a day, for 4 days successively （initially 2.95 mg/kg, then increased day by day, as described below）. Interventions： In the model ＋ electro-acupuncture group, after model induction, mice were subjected electro-acupuncture at bilateral ＂Sanyinjiao＂ （SP6） points using a Han electro-acupuncture apparatus with sparse-dense waves and frequency of 2-100 Hz, once a day, for 6 days. In the model group, after anxiety-model induction, mice were subjected to fixation as same as model ＋ electro-acupuncture group within 6 days of model induction. In the electro-acupuncture group, the anxiety model was not induced and mice were subjected to fixation, electro-acupuncture and the T-maze test. In the T-maze group, the anxiety model was not induced and mice were subjected to fixation. The T-maze test was performed in the 4 groups after experiment. In the blank control group, the anxiety model was not induced and mice were subjected to fixation only. MAIN OUTCOME MEASURES： Brain tissue norepinephrine content of morphine-withdrawal anxiety mice was detected by fluorospectrophotometry after 6 days of electro-acupuncture. Blood lactic acid content was detected by visible spectrophotometry. RESULTS： A total of 50 mice were included in the final analysis. Brain norepinephrine content was significantly greater in the model group compared to the T-maze, blank control, electro-acupuncture and model ＋ electro-acupuncture groups, （P 〈 0.05-0.01）. Brain norepinephrine content was similar between the model ＋ electro-acupuncture and the blank control groups （P 〉 0.05）. There was no significant difference in blood lactic acid content among the groups （P 〉 0.05）. CONCLUSION： Electro-acupuncture lowers brain norepinephrine content but does not influence peripheral blood lactic acid content in morphine-withdrawn, anxiety-modeled mice. These results demonstrate that anxiety-inhibiting effects of electro-acupuncture, after morphine withdrawal, might be related to regulation of norepinephrine release.

Determination of trace amounts of morphine in human plasma by anodic adsorptive stripping differential pulse voltammetry

New adsorptive anodic differential pulse stripping voltammetry method for the direct determination of morphine at trace levels in human plasma of addicts is proposed.The procedure involves an adsorptive accumulation of morphine on a HMDE,followed by oxidation of adsorbed morphine by voltammetry scan using differential pulse modulation.The optimum conditions for the analysis of morphine are pH 10.5,Eacc of -100 mV（vs.Ag/AgCl）,and tacc of 120 s.The peak current is proportional to the concentration of morphine,and a Linear calibration graph is obtained at 0.01-3.10μg mL^-1.A relative standard deviation of 1.06%（n=5）was obtained,and the limit of detection was 3 ng mL^-1.The capabiLity of the method for the analysis of real samples was evaluated by the determination of morphine in spiked human plasma and addicts human plasma with satisfactory results.

Effect of Morphine and Naloxone on Release of the Excitatory Amino Acids of Spinal Astrocytes Induced by TNF-α

The effect of morphine and naloxone on release of the excitatory amino acids (EAAs) of spinal astrocytes induced by TNF-α was studied. Astrocytes were purified from 2- to 3-day old SD rats and divided into 8 groups: group 1 (without any stimulatants); group 2 (10 ng/ml TNF-α); group3 (10 ng/ml TNF-α+0.5 μmol/L morphine); group 4 (10 ng/ml TNF-α+1.0 μmol/L morphine); group 5 (10 ng/ml TNF-α+2.0 μmol/L morphine); group 6 (10 ng/ml TNF-α+0.5 μmol/L naloxone); group 7 (10 ng/ml TNF-α+1.0 μmol/L naloxone); group 8 (10 ng/ml TNF-α+2.0 μmol/L naloxone). In group 2, 3, 4 and 5, 0, 0.5, 1.0 or 2.0 μmol/L morphine was added to the cells cultured with serum-free Neurobasal/B27 medium containing 10 ng/ml TNF-α respectively, while in group 6, 7 and 8, 0.5, 1.0 or 2.0 μmol/L naloxone was added respectively to the cells cultured with serum-free Neurobasal/B27 medium containing 10 ng/ml TNF-α. After 30 min incubation, high-pressure liquid chromatography (HPLC) was used to measure the levels of EAAs in all cultured cells. The results showed the level of EAAs in group 2 was significant higher than in group 1 (P<0.01). As compared with group 2, the levels of EAAs in group 3, 4 and 5 were decreased with the difference being significant between group 5 and group 2 (P<0.01) or between group 4 and group 2 (P<0.05). The levels of EAAs in group 6, 7 and group 8 was significantly lower than in group 2 (P<0.05 or P<0.01). It was concluded that TNF-α could promote the release of glutamate and aspartate from astrocytes, and morphine and naloxone might reduce the release of EAAs in cultured spinal astrocytes induced by TNF-α.

Effect of morphine preconditioning on neuronal apoptosis following cerebral ischemia/reperfusion injury

Apoptosis, a form of neuronal damage, takes place following cerebral ischemia/reperfusion injury and caspase-3 plays an important role in apoptosis. Studies have shown that morphine preconditioning influences neuronal apoptosis and related protein expression following cerebral ischemia/reperfusion injury. In the present study, neuronal degeneration was attenuated, and the number of apoptotic cells and caspase-3 expression decreased following morphine preconditioning in a rat model of cerebral ischemia/reperfusion injury. Moreover, pathological changes were attenuated with increasing morphine doses, as well as the number of apoptotic cells and caspase-3 expression. Results from the present study revealed that morphine preconditioning reduced ischemic brain injury and improved cerebral ischemic tolerance in a dose-dependent manner. The anti-apoptotic mechanism of morphine is closely related to Caspase-3.