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.

Expression and signifi cance of TLR4 and HIF-1α in pancreatic ductal adenocarcinoma

AIM:To investigate the expression of toll-like receptor(TLR) 4,nuclear factor-κB(NF-κB) p65 and hypoxiainducible transcription factor 1α(HIF-1α) in pancreatic ductal adenocarcinoma and their clinical significance.METHODS:The mRNA of TLR4 and HIF-1α were investigated by real-time polymerase chain reaction in 30 cases of pancreatic ductal adenocarcinoma and its adjacent tissues,and expression of TLR4,NF-κB p65 and HIF-1α protein were detected by immunohistochemistry in 65 cases of pancreatic ductal adenocarcinoma tissues and 38 cases of corresponding adjacent tissues.The relationship between TLR4 or HIF-1α and pathologic features,as well as the association between TLR4 and HIF-1α,were also analyzed.Kaplan-Meier method was used to assess the impact of expression of TLR4 and HIF-1α on survival of patients with pancreatic cancer.RESULTS:The relative quantif ication of TLR4 and HIF-1α mRNA in tumor tissues was 0.81±0.10 and 0.87±0.11,respectively,signif icantly higher than that in adjacent tissues(0.81±0.10 vs 0.70±0.16,P=0.002;0.87±0.11 vs 0.68±0.13,P=0.000).The protein expression of TLR4,NF-κB p65 and HIF-1α in tumor tissues was 69.20%,66.15% and 70.80%,respectively,being signif icantly higher than that in adjacent normal tissues(69.20% vs 39.50%,P=0.003;66.15% vs 31.58%,P=0.001;70.80% vs 36.80%,P=0.001).There was no signif icant correlation between TLR4 or HIF-1α expression and the age,gender,tumor location,the degree of tumor differentiation in the patients(P>0.05).However,there was signif icant correlation between the expression of TLR4 or HIF-1α and tumor size,lymph node metastasis,venous invasion and clinical staging(P<0.05).The expression of TLR4 and HIF-1α had a signif icant impact on survival of patients with pancreatic adenocarcinoma.CONCLUSION:TLR4,NF-κB p65 and HIF-1α are overexpressed in pancreatic adenocarcinoma,TLR4 may be partly involved in up-regulating HIF-1α,and both synergestically promote development of pancreatic adenocarcinoma.