The role of CA3-LS-VTA loop in the formation of conditioned place preference induced by context-associated reward memory for morphine.

Addiction-related behaviors, such as conditioned place preference (CPP), require animals to remember an association between environmental cue and drug treatment, and exposure to environmental cue is one of the key contributing factors to relapse. However, how central neural circuit participates in the formation of CPP induced by stimulus of morphine-paired environment remains unknown. In the present study, we found that reexposure to morphine-paired environment significantly increased the activity of hippocampal CA3 neurons, increased the excitability of GABAergic neurons and expression of glutamic acid decarboxylase 65/67 in the caudal lateral septum (LSc) and decreased the activity of GABAergic neurons and GAD65/67 expression in ventral tegmental area (VTA), leading to activation (disinhibition) of dopaminergic neurons. Inactivation of CA3 neurons attenuated GABAergic neurons activity and decreased the upregulation of GAD65/67 in LSc, prevented the dopaminergic neurons activation,and GAD65/67 downregulation in VTA and ameliorated the CPP behavior following exposure to morphine-paired context. Blockade of NMDA receptor in LSc also prevented the upregulation of GAD65/67 in LSc and formation of CPP induced by stimulus of morphine-paired environment. Suppression of GAD activity in LSc also remarkably attenuated the dopaminergic neurons activation and the GAD65/67 downregulation in VTA and prevented the formation of CPP induced by reexposure to morphine-associated context. Collectively, these results, for the first time, illustrated the involvement of neural circuitry of CA3-LSc-VTA, through integration of the contexts and reward information, participated in the reinstatement of CPP induced by exposure to morphine-associated context, which advanced our understanding on neurobiological basis for the context-associated memory and rewarding behavior.

Epigenetic upregulation of CXCL12 expression mediates antitubulin chemotherapeutics-induced neuropathic pain.

Clinically, Microtubule-targeted agents-induced neuropathic pain hampers chemotherapeutics for patients with cancer. Here, we found that application of paclitaxel or vincristine increased the protein and mRNA expression of CXCL12 and frequency and amplitude of miniature excitatory post synaptic currents (mEPSCs) in spinal dorsal horn neurons. Spinal local application of CXCL12 induced the long-term potentiation of nociceptive synaptic transmission and increased the amplitude of mEPSCs. Inhibition of CXCL12 using the transgenic mice (CXCL12) or neutralizing antibody or siRNA ameliorated the mEPSC's enhancement and mechanical allodynia. In addition, paclitaxel and vincristine both could increase the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and the acetylation of histone H4 in the CXCL12-expressing neurons. Immunoprecipitation and chromatin immunoprecipitation assays demonstrated that antitubulin chemotherapeutics increased the binding of STAT3 to the CXCL12 gene promoter and the interaction between STAT3 and p300, and contributed to the enhanced transcription of CXCL12 by increasing the acetylation of histone H4 in CXCL12 gene promoter. Inhibition of STAT3 by intrathecal injection of adeno-associated virus encoding Cre and green fluorescent protein into STAT3 mice or inhibitor S3I-201 into rats suppressed the CXCL12 upsurge by decreasing the acetylation of histone H4. Finally, blockade of CXCR4 but not CXCR7 ameliorated the paclitaxel- or vincristine-induced mechanical allodynia. Together, these results suggested that enhanced interaction between STAT3 and p300 mediated the epigenetic upregulation of CXCL12 in dorsal horn neurons, which contributed to the antitubulin chemotherapeutics-induced persistent pain.

The inhibition of spinal synaptic plasticity mediated by activation of AMP-activated protein kinase signaling alleviates the acute pain induced by oxaliplatin.

Our recent findings demonstrated that oxaliplatin entering CNS may directly induce spinal central sensitization, and contribute to the rapid development of CNS-related side effects including acute pain during chemotherapy. However, the mechanism is largely unclear. In the current study, we found that the amplitude of C-fiber-evoked field potentials was significantly increased and the expression of phosphorylated mammalian AMP-activated protein kinase α (AMPKα) was markedly decreased following high frequency stimulation (HFS) or single intraperitoneal injection of oxaliplatin (4mg/kg). Spinal local application of AMPK agonist metformin (25µg) prevented the long term potentiation (LTP) induction and the activation of mTOR/p70S6K signal pathway, and significantly attenuated the acute thermal hyperalgesia and mechanical allodynia following single oxaliplatin treatment. Importantly, we found that incubation of low concentration oxaliplatin at dose of 6.6nM (the detected concentration in CSF following a single intraperitoneal injection of oxaliplatin) also significantly inhibited the AMPKα activation and increased the amplitude of sEPSCs, the number of action potential, and the expression of p-mTOR and p-p70S6K in spinal cord slices. Metformin (25µg) or rapamycin (2µg) inhibited the increased excitability of dorsal horn neurons and the decrease of p-AMPKα expression induced by low concentration oxaliplatin incubation. Furthermore, spinal application of AMPK inhibitor compound C (5µg) induced the spinal LTP, thermal hyperalgesia and mechanical allodynia, and rapamycin attenuated the spinal LTP, the thermal hyperalgesia and mechanical allodynia following oxaliplatin treatment (i.p.). Local application of metformin significantly decreased the mTOR and p70S6K activation induced by tetanus stimulation or oxaliplatin (i.p.). These results suggested that the decreased AMPKα activity via negatively regulating mTOR/p70S6K signal pathway enhanced the synaptic plasticity and contributed to acute pain induced by low concentration of oxaliplatin entering CNS.

mir-500-Mediated GAD67 Downregulation Contributes to Neuropathic Pain.

UNLABELLED: Neuropathic pain is a common neurobiological disease involving multifaceted maladaptations ranging from gene modulation to synaptic dysfunction, but the interactions between synaptic dysfunction and the genes that are involved in persistent pain remain elusive. In the present study, we found that neuropathic pain induced by the chemotherapeutic drug paclitaxel or L5 ventral root transection significantly impaired the function of GABAergic synapses of spinal dorsal horn neurons via the reduction of the GAD67 expression. We also found that mir-500 expression was significantly increased and involved in the modulation of GAD67 expression via targeting the specific site of Gad1 gene in the dorsal horn. In addition, knock-out of mir-500 or using mir-500 antagomir rescued the GABAergic synapses in the spinal dorsal horn neurons and attenuated the sensitized pain behavior in the rats with neuropathic pain. To our knowledge, this is the first study to investigate the function significance and the underlying molecular mechanisms of mir-500 in the process of neuropathic pain, which sheds light on the development of novel therapeutic options for neuropathic pain. SIGNIFICANCE STATEMENT: Neuropathic pain is a common neurobiological disease involving multifaceted maladaptations ranging from gene modulation to synaptic dysfunction, but the underlying molecular mechanisms remain elusive. The present study illustrates for the first time a mir-500-mediated mechanism underlying spinal GABAergic dysfunction and sensitized pain behavior in neuropathic pain induced by the chemotherapeutic drug paclitaxel or L5 ventral root transection, which sheds light on the development of novel therapeutic options for neuropathic pain.

Cerebrospinal Fluid Oxaliplatin Contributes to the Acute Pain Induced by Systemic Administration of Oxaliplatin.

BACKGROUND: Systemic administration of oxaliplatin has no effect on the tumors in the central nervous system (CNS) due to the limited concentration of oxaliplatin in the cerebrospinal fluid (CSF), while it was clinically reported that oxaliplatin can induce acute encephalopathy. Currently, the impairment of neuronal functions in the CNS after systemic administration of oxaliplatin remains uninvestigated. METHODS: The von Frey test and the plantar test were performed to evaluate neuropathic pain behavior after a single intraperitoneal administration of oxaliplatin (4 mg/kg) in rats. Inductively coupled plasma-mass spectrometry, electrophysiologic recording, real-time quantitative reverse transcription polymerase chain reaction, chromatin immunoprecipitation, Western blot, immunohistochemistry, and small interfering RNA were applied to understand the mechanisms. RESULTS: Concentration of oxaliplatin in CSF showed a time-dependent increase after a single administration of oxaliplatin. Spinal application of oxaliplatin at the detected concentration (6.6 nM) significantly increased the field potentials in the dorsal horn, induced acute mechanical allodynia (n = 12 each) and thermal hyperalgesia (n = 12 each), and enhanced the evoked excitatory postsynaptic currents and spontaneous excitatory postsynaptic currents in the projection neurokinin 1 receptor-expressing lamina I to II neurons. The authors further found that oxaliplatin significantly increased the nuclear factor-κB p65 binding and histone H4 acetylation in cx3cl1 promoter region. Thus, the upregulated spinal CX3CL1 markedly mediated the induction of central sensitization and acute pain behavior after oxaliplatin administration. CONCLUSIONS: The findings of this study suggested that oxaliplatin in CSF may directly impair the normal function of central neurons and contribute to the rapid development of CNS-related side effects during chemotherapy. This provides novel targets to prevent oxaliplatin-induced acute painful neuropathy and encephalopathy.

The possible involvement of JNK activation in the spinal dorsal horn in bortezomib-induced allodynia: the role of TNF-α and IL-1ß.

PURPOSE: Bortezomib (BTZ), a widely used chemotherapeutic drug, is closely associated with the development of painful peripheral neuropathy, but the mechanism underlying the induction of this disorder by BTZ remains largely unclear. To examine this association, we have evaluated the activation of mitogen-activated protein kinase (MAPK) family members in the spinal dorsal horn and the role of tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1ß) in BTZ-induced allodynia in rats. METHODS: Male Sprague-Dawley rats were used as the model animals. The paw withdrawal test, in which mechanical stimuli (von Frey hairs) is applied to the plantar surface of the hindpaw, was used to determine any changes in the paw withdrawal threshold of the treated rats. A PE-10 catheter was placed intrathecally to deliver TNF-α neutralizing antibody, IL-1 receptor antagonist (IL-1ra) or the c-Jun N-terminal kinase (JNK) inhibitor SP600125. The mRNA levels of various cytokines were measured by real-time quantitative PCR. The expression of TNF-α, IL-1ß and mitogen-activated protein kinase (MAPK) family members in the spinal dorsal horn was measured by western blot analysis and immunohistochemistry. All data were expressed as the mean ± standard error of the mean and analyzed using the SPSS version 13.0 software program. RESULTS: The BTZ treatment induced an upsurge in the mRNA and protein levels of TNF-α in the neurons and IL-1ß in the astrocytes in the spinal dorsal horn. It also significantly upregulated the phosphorylation of JNK but not of extracellular signal-regulated kinases (ERK) and p38-MAPK in astrocytes of the spinal dorsal horn. Inhibition of TNF-α or IL-1ß ameliorated JNK activation and mechanical allodynia induced by BTZ. Co-administration of thalidomide (TNF-α synthesis inhibitor) and IL-1ra prevented BTZ-induced mechanical allodynia. CONCLUSION: Our results suggest that the TNF-α or IL-1ß/JNK pathway in the spinal dorsal horn may play a critical role in the development of painful peripheral neuropathy induced by BTZ.

Orexin A-mediated AKT signaling in the dentate gyrus contributes to the acquisition, expression and reinstatement of morphine-induced conditioned place preference.

Accumulating evidence indicates that the hippocampal dentate gyrus (DG), a critical brain region contributing to learning and memory, is involved in the addiction and relapse to abused drugs. Emerging studies also suggest the role of orexin signaling in the rewarding behavior induced by repeated exposure to opiates. In the present study, we investigated the dynamic adaptation of orexin signaling in the DG and its functional significance in the acquisition, expression, maintenance of and relapse to rewarding behavior induced by morphine. Repeated place conditioning with morphine significantly increased the orexin A content released from the lateral hypothalamic area projecting neurons into the DG. Local infusions of orexin A into the DG sensitized the acquisition of and relapse to the conditioned place preference induced by morphine. The application of the orexin receptor type 1 (OXR1) antagonist SB334867 significantly abolished the acquisition, expression and maintenance of the conditioned place preference induced by repeated exposure to morphine. Furthermore, the significant increase of the phosphorylation of AKT in the DG was associated with preference for the morphine-paired chamber in rats, which was reversed by the local administration of an OXR1 antagonist. Thus, these findings suggested that the dynamic upregulation of orexin A signaling, via the AKT pathway in the DG, may promote the acquisition and maintenance of opioid-induced craving behaviors and may increase sensitivity to the rewarding effect of subsequent opioids.

Up-regulation of CX3CL1 via Nuclear Factor-κB-dependent Histone Acetylation Is Involved in Paclitaxel-induced Peripheral Neuropathy.

BACKGROUND: Up-regulation of CX3CL1 has been revealed to be involved in the neuropathic pain induced by nerve injury. However, whether CX3CL1 participates in the paclitaxel-induced painful peripheral neuropathy remains unknown. The aim of the current study was to elucidate the involvement of transcriptional factors nuclear factor-κB (NF-κB) and its causal interaction with CX3CL1 signaling in the paclitaxel-induced painful peripheral neuropathy. METHODS: Painful peripheral neuropathy induced by paclitaxel treatment was established in adult male Sprague-Dawley rats. The von Frey test were performed to evaluate neuropathic pain behavior, and real-time quantitative reverse transcription polymerase chain reaction, chromatin immunoprecipitation, Western blot, immunohistochemistry, and small interfering RNA were performed to understand the molecular mechanisms. RESULTS: The application of paclitaxel induced an up-regulation of CX3CL1 expression in the spinal neurons, which is reduced significantly by NF-κB inhibitor ammonium pyrrolidinedithiocarbamate or p65 small interfering RNA. Blockade of either CX3CL1 (n = 12 each) or NF-κB (n = 12 each) signaling pathway attenuated mechanical allodynia induced by paclitaxel. Chromatin immunoprecipitation further found that paclitaxel induced an increased recruitment of nuclear factor-κB (NF-κB)p65 to the Cx3cl1 promoter region. Furthermore, an increased acetylation level of H4, but not H3, in Cx3cl1 promoter region in spinal neurons was detected after paclitaxel treatment, which was reversed by inhibition of NF-κB with ammonium pyrrolidinedithiocarbamate or p65 small interfering RNA. CONCLUSIONS: These findings suggest that up-regulation of CX3CL1 via NF-κB-dependent H4 acetylation might be critical for paclitaxel-induced mechanical allodynia.

CX3CL1-mediated macrophage activation contributed to paclitaxel-induced DRG neuronal apoptosis and painful peripheral neuropathy.

Painful peripheral neuropathy is a dose-limiting side effect of paclitaxel therapy, which hampers the optimal clinical management of chemotherapy in cancer patients. Currently the underlying mechanisms remain largely unknown. Here we showed that the clinically relevant dose of paclitaxel (3×8mg/kg, cumulative dose 24mg/kg) induced significant upregulation of the chemokine CX3CL1 in the A-fiber primary sensory neurons in vivo and in vitro and infiltration of macrophages into the dorsal root ganglion (DRG) in rats. Paclitaxel treatment also increased cleaved caspase-3 expression, induced the loss of primary afferent terminal fibers and decreased sciatic-evoked A-fiber responses in the spinal dorsal horn, indicating DRG neuronal apoptosis induced by paclitaxel. In addition, the paclitaxel-induced DRG neuronal apoptosis occurred exclusively in the presence of macrophage in vitro study. Intrathecal or systemic injection of CX3CL1 neutralizing antibody blocked paclitaxel-induced macrophage recruitment and neuronal apoptosis in the DRG, and also attenuated paclitaxel-induced allodynia. Furthermore, depletion of macrophage by systemic administration of clodronate inhibited paclitaxel-induced allodynia. Blocking CX3CL1 decreased activation of p38 MAPK in the macrophage, and inhibition of p38 MAPK activity blocked the neuronal apoptosis and development of mechanical allodynia induced by paclitaxel. These findings provide novel evidence that CX3CL1-recruited macrophage contributed to paclitaxel-induced DRG neuronal apoptosis and painful peripheral neuropathy.

TNF-α-mediated JNK activation in the dorsal root ganglion neurons contributes to Bortezomib-induced peripheral neuropathy.

Bortezomib (BTZ) is a frequently used chemotherapeutic drug for the treatment of refractory multiple myeloma and hematological neoplasms. The mechanism by which the administration of BTZ leads to painful peripheral neuropathy remains unclear. In the present study, we first determined that the administration of BTZ upregulated the expression of TNF-α and phosphorylated JNK1/2 in the dorsal root ganglion (DRG) of rat. Furthermore, the TNF-α synthesis inhibitor thalidomide significantly blocked the activation of both isoforms JNK1 and JNK2 in the DRG and attenuated mechanical allodynia following BTZ treatment. Knockout of the expression of TNF-α receptor TNFR1 (TNFR1 KO mice) or TNFR2 (TNFR2 KO mice) inhibited JNK1 and JNK2 activation and decreased mechanical allodynia induced by BTZ. These results suggest that upregulated TNF-α expression may activate JNK signaling via TNFR1 or TNFR2 to mediate mechanical allodynia following BTZ treatment.

Effect of Chaiqinchengqi decoction on serum amyloid A in severe acute pancreatitis patients.

OBJECTIVE: To investigate the effect of Chaiqinchengqi decoction (CQCQD) on serum amyloid A (SAA) in severe acute pancreatitis (SAP) patients. METHODS: Thirty-five participants enrolled and were randomly assigned into either a treatment condition (n = 17, treated with CQCQD) or a control condition (n = 18, treated with placebo) 24 hours following the onset of the disease. No statistical difference was observed in either group at baseline. Upon admission, the Acute Physiology and Chronic Health Evaluation score II (APACHE II), SAA, serum C-reactive protein (CRP) and interleukin-6 (IL-6) were measured, as well as on the first, 3rd and 7th day and were compared between the two groups. Organ complications, infection, operation rate, mortality and hospital stay were also compared. RESULTS: The duration of acute respiratory distress syndrome, acute hepatitis, acute renal failure, gastrointestinal failure and blood coagulation dysfunction were shorter in the treatment group than in those in the control group (P < 0.05). The secondary infection rates and the hospital fees in the treatment group were lower than those in the control group (P < 0.05) as well as length of hospital stay (P < 0.01). After 3 days of hospitalization, the APACHEII, score SAA levels, serum CRP and IL-6 in the treatment group was lower than those in the control group (P < 0.05). SAA was positively correlated with serum CRP (R = 0.346, P = 0.042), Ranson score (R = 0.442, P = 0.008) and serum IL-6 (R = 0.359, P = 0.034). The area under the receiver operating characteristic curve of admission SAA predict pancreatic necrosis (PN) was 0.815 (95% CI: 0.625-0.954; P = 0.006). The best cut-off value of admission SAA was 7.85 mg/L with the sensitivity 84.6% and specificity 68.2%. CONCLUSIONS: The CQCQD can reduce the duration of organ damage through lowering the SAA in SAP patients and the SAA can early predict the PN and severity of SAP patients.

Effects of microbubbles on transcranial Doppler ultrasound-assisted intracranial urokinase thrombolysis.

INTRODUCTION: To evaluate the efficacy of microbubbles in transcranial Doppler ultrasound (TCD)-assisted urokinase thrombolysis. MATERIALS AND METHODS: Male New Zealand white rabbits (N=32) were randomly divided into 2 groups, a urokinase group and a combined urokinase plus microbubble group. The middle cerebral artery (MCA) was occluded by injecting autologous blood clots through the carotid artery. In the urokinase plus microbubble group, sulfur hexafluoride (SonoVue) microbubbles were injected intravenously immediately after intravenous injection of urokinase. The 2 groups were monitored by TCD from before until 2h after thrombolysis, and the hemodynamic changes and infarct size were recorded. RESULTS: The urokinase alone group had 1 case of complete recanalization and 4 cases of partial recanalization (recanalization rate, 31.3%). The urokinase plus microbubble group had 3 cases of complete recanalization and 6 cases of partial recanalization (recanalization rate, 56.3%). The average size of the infarction foci was 13.9% in the urokinase group and 9.1% in the urokinase plus microbubble group (P=0.025). Pathological examination revealed no cerebral hemorrhage in either group. CONCLUSIONS: The addition of microbubbles enhanced the effects of transcranial Doppler ultrasound-assisted urokinase thrombolysis.

[Effects of aging and decreased glomerular filtration rate on the prevalence of anemia in elderly population receiving body check from urban area of Hefei, China.].

OBJECTIVE: To investigate the effects of aging and the decreased glomerular filtration rate on the prevalence of anemia in elder receiving body check from urban area of Hefei, China. METHODS: A total of 4547 > 60 years subjects received healthy examination in Healthy Center of Anhui Provincial Hospital from January 2005 to December 2007 were enrolled in this study. Anemia was defined as hemoglobin < 120 g/L in men or < 110 g/L in women. RESULTS: The prevalence of anemia in the subjects was 4.40% (95%CI: 3.83% - 5.05%) and significantly increased with the aging process and the decline of estimated glomerular filtration rate (eGFR). With logistic analyses, increasing age, female, decreased eGFR were major risk factors for anemia. CONCLUSIONS: The morbidity of anemia is 4.40% in old population receiving body check from urban area of Hefei, China. Aging and the decline of eGFR are the independent risk factors of anemia.