Huilian Bu

Activation of spinal chemokine receptor CXCR3 mediates bone cancer pain through an Akt-ERK crosstalk pathway in rats

Previously, we showed that activation of the spinal CXCL9, 10/CXCR3 pathway mediated bone cancer pain (BCP) in rats. However, the cellular mechanism involved is poorly understood. Here, we found that the activated CXCR3 was co-localized with either neurons, microglia, and astrocytes in the spinal cord, or non-peptidergic-, peptidergic-, and A-type neurons in the dorsal root ganglion. The inoculation of Walker-256 mammary gland carcinoma cells into the rats tibia induced a time-dependent phosphorylation of Akt and extracellular signal-regulated kinase (ERK1/2) in the spinal cord, and CXCR3 was necessary for the phosphorylation of Akt and ERK 1/2. Meanwhile, CXCR3 was co-localized with either pAkt or pERK1/2. Blockage of either Akt or ERK1/2 prevented or reversed the mechanical allodynia in BCP rats. Furthermore, there was cross-activation between PI3K/Akt and Raf/MEK/ERK pathway under the BCP condition. Our results demonstrated that the activation of spinal chemokine receptor CXCR3 mediated BCP through Akt and ERK 1/2 kinase, and also indicated a crosstalk between PI3K/Akt and Raf/MEK/ERK signaling pathways under the BCP condition.

Inhibition of Glial Activation in Rostral Ventromedial Medulla Attenuates Mechanical Allodynia in a Rat Model of Cancer-induced Bone Pain

SummaryDescending nociceptive modulation from the supraspinal structures plays an important role in cancer-induced bone pain (CIBP). Rostral ventromedial medulla (RVM) is a critical component of descending nociceptive facilitation circuitry, but so far the mechanisms are poorly known. In this study, we investigated the role of RVM glial activation in the descending nociceptive facilitation circuitry in a CIBP rat model. CIBP rats showed significant activation of microglia and astrocytes, and also up-regulation of phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) and pro-inflammatory mediators released by glial cells (IL-1β, IL-6, TNF-α and brain-derived neurotrophic factor) in the RVM. Stereotaxic microinjection of the glial inhibitors (minocycline and fluorocitrate) into CIBP rats’ RVM could reverse the glial activation and significantly attenuate mechanical allodynia in a time-dependent manner. RVM microinjection of p38 MAPK inhibitor (SB203580) abolished the activation of microglia, reversed the associated up-regulation of pro-inflammatory mediators and significantly attenuated mechanical allodynia. Taken together, these results suggest that RVM glial activation is involved in the pathogenesis of CIBP. RVM microglial p38 MAPK signaling pathway is activated and leads to the release of downstream pro-inflammatory mediators, which contribute to the descending facilitation of CIBP.Descending nociceptive modulation from the supraspinal structures plays an important role in cancer-induced bone pain (CIBP). Rostral ventromedial medulla (RVM) is a critical component of descending nociceptive facilitation circuitry, but so far the mechanisms are poorly known. In this study, we investigated the role of RVM glial activation in the descending nociceptive facilitation circuitry in a CIBP rat model. CIBP rats showed significant activation of microglia and astrocytes, and also up-regulation of phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) and pro-inflammatory mediators released by glial cells (IL-1β, IL-6, TNF-α and brain-derived neurotrophic factor) in the RVM. Stereotaxic microinjection of the glial inhibitors (minocycline and fluorocitrate) into CIBP rats’ RVM could reverse the glial activation and significantly attenuate mechanical allodynia in a time-dependent manner. RVM microinjection of p38 MAPK inhibitor (SB203580) abolished the activation of microglia, reversed the associated up-regulation of pro-inflammatory mediators and significantly attenuated mechanical allodynia. Taken together, these results suggest that RVM glial activation is involved in the pathogenesis of CIBP. RVM microglial p38 MAPK signaling pathway is activated and leads to the release of downstream pro-inflammatory mediators, which contribute to the descending facilitation of CIBP.

Activation of CXCL10/CXCR3 Signaling Attenuates Morphine Analgesia: Involvement of Gi Protein

Morphine is a potent agonist of μ-opioid receptor and is widely used to relieve severe pain, including cancer pain. Some chemokines, for example, CX3CL1 and CCL2, participate in the regulation of opioid santinociception. In our previous study, we found overexpression of chemokine CXCL10/CXCR3 in spinal cord participated in the development of cancer-induced bone pain, so we supposed that CXCL10 may have influence in morphine analgesia in cancer pain relief. In this study, we found that a single dose of morphine could transiently increase the expression of CXCL10 in spinal cord. Blocking the function of CXCL10 enhanced morphine antinociception in cancer-induced bone pain rats. However, overexpression of CXCL10 induced acute algesia and decreased the analgesic effect of morphine in normal mice. The algesic effect of CXCL10 was blocked by inhibition of CXCR3 and Gi protein. These results suggested that CXCL10 in spinal cord serves as a novel negative regulator of morphine analgesia and provided evidence that activation of CXCL10/CXCR3 in spinal cord may attenuate antinociceptive potency of morphine in cancer pain relief.

Activation of spinal phosphatidylinositol 3-kinase/protein kinase B mediates pain behavior induced by plantar incision in mice.

The etiology of postoperative pain may be different from antigen-induced inflammatory pain and neuropathic pain. However, central neural plasticity plays a key role in incision pain. It is also known that phosphatidylinositol 3-kinase (PI3K) and protein kinase B/Akt (PKB/Akt) are widely expressed in laminae I-IV of the spinal horn and play a critical role in spinal central sensitization. In the present study, we explored the role of PI3K and Akt in incision pain behaviors. Plantar incision induced a time-dependent activation of spinal PI3K-p110γ and Akt, while activated Akt and PI3K-p110γ were localized in spinal neurons or microglias, but not in astrocytes. Pre-treatment with PI3K inhibitors, wortmannin or LY294002 prevented the activation of Akt brought on by plantar incision in a dose-dependent manner. In addition, inhibition of spinal PI3K signaling pathway prevented pain behaviors (dose-dependent) and spinal Fos protein expression caused by plantar incision. These data demonstrated that PI3K signaling mediated pain behaviors caused by plantar incision in mice.

Activation of PI3Kγ/Akt pathway mediates bone cancer pain in rats

Bone cancer pain (BCP) is one of the most common and severe complications in patients suffering from primary bone cancer or metastatic bone cancer such as breast, prostate, or lung, which profoundly compromises their quality of life. Emerging lines of evidence indicate that central sensitization is required for the development and maintenance of BCP. However, the underlying mechanisms are largely unknown. In this study, we investigated the role of PI3Kγ/Akt in the central sensitization in rats with tumor cell implantation in the tibia, a widely used model of BCP. Our results showed that PI3Kγ and its downstream target pAkt were up‐regulated in a time‐dependent manner and distributed predominately in the superficial layers of the spinal dorsal horn neurons, astrocytes and a minority of microglia, and were colocalized with non‐peptidergic, calcitonin gene‐related peptide‐peptidergic, and A‐type neurons in dorsal root ganglion ipsilateral to tumor cell inoculation in rats. Inhibition of spinal PI3Kγ suppressed BCP‐associated behaviors and the up‐regulation of pAkt in the spinal cord and dorsal root ganglion. This study suggests that PI3Kγ/Akt signal pathway mediates BCP in rats.

Stimulation for the compact parts of pedunculopontine nucleus: An available therapeutic approach in intractable epilepsy

Many studies have shown that susceptibility to epilepsy is increased during nonrapid eye movement (NREM, slow-wave) sleep whereas rapid eyemovement (REM) sleep suppresses seizure occurrence. Therefore, it is postulated that rapid eye movement sleep is a natural antiepileptogenic system in the body during the human wake–sleep cycle [1–3]. Because it is demonstrated that stimulation of the pedunculopontine tegmental nucleus (PPTg) can enhance REM sleep successfully [4], PPTg has been highlighted as a target for deep brain stimulation for seizure treatment of intractable epilepsy [2,5,6]; however, the exact location of the optimal brain site for stimulation is not fully understood [7,8]. Recently, some studies have suggested that the neurons innervating motor structures are predominantly situated in the caudal parts of the PPTg, which divide into the dissipated part (dp) and compact part (cp) of the PPTg [9–11]. Nevertheless, it is still unclear whether cpPPTg or dpPPTg is tightly linked to motor projections. There is unequivocal agreement on the high and specific value of neurotropic pseudorabies virus (PRV) tracing for synaptic connectivity and neuroanatomical pathways in CNS by propagating retrogradely through chains of functionally connected neurons [11–16]. It is well known that PRV can provide a highly specific method of mapping the motor and sympathetic pathways innervating a variety of targets [12,17–19]. We explore the hypothesis that the functional integrity of synapses in the cpPPTg is essential tomotor projections andnot sympathetic projections. We had characterized projections from the left gastrocnemius muscle to the PPTg of the midbrain tegmentum in surgically sympathectomized [20,21]mice by using retrograde tracing techniques of PRV-614, expressing a novelmonomeric red fluorescent protein (mRFP1) under control of the cytomegalovirus immediate early promoter for direct visualization with the fluorescence microscope [22–24]. We found that injections of PRV-614 into the left gastrocnemius muscle labeled neurons in the cpPPTg and dpPPTg (Fig. 1), which was in line with a previous report showing that the PPTg control of the lumbar epaxial muscle produced a special posture by transneuronal tracer PRV-Bartha [25], suggesting that a direct neuronal circuit from the cpPPTg and dpPPTg to gastrocnemius muscle exists via the motor pathway. Otherwise, PRV-614/tyrosine hydroxylase (TH) and PRV614/tryptophan hydroxylase (TPH) double-labeled neurons were detected in the dpPPTg and not in the cpPPTg (Fig. 1), which was in agreement with our previous immunohistochemical study in investigating that PRV-614/tryptophan hydroxylase and PRV-614/tyrosine hydroxylase double-labeled neurons in the cpPPTg were not detected

Enhancement of morphine analgesia and prevention of morphine tolerance by downregulation of β-arrestin 2 with antigene RNAs in mice

β-arrestin 2, a regulatory molecule of G protein-coupled receptor, has been proved to play an important role in regulating functions of mu opioid receptor. Changes of β-arrestin 2 expression might affect the function of mu opioid receptors and the effect of its agonists. In this study, antigene RNAs (agRNAs), which could selectively target gene transcription start sites and potently inhibit gene expression, were used to downregulate the expression of β-arrestin 2 to investigate its effects on morphine analgesia and tolerance in mice. After intracerebroventricular administration of recombinant lentivirus encoding β-arrestin 2 agRNAs to the mice, β-arrestin 2 expression was significantly decreased for more than 3 weeks. Mice treated with β-arrestin 2 agRNAs showed enhanced analgesic effects in response to morphine and failed to develop antinociceptive tolerance. These results suggest that inhibition of β-arrestin 2 in the brain with specific agRNAs can improve morphine efficacy, and consequently provide us a useful strategy for treatment of chronic intractable pain and morphine tolerance in vivo.

The mechanism of electroacupuncture for predicting the efficacy of deep brain stimulation in pharmacoresistant epilepsy may be involved in the melanocortinergic signal

Intractable epilepsy is still one of the most confusing and enigmatic neurological disorders [1,2]. Deep brain stimulation targeted at the subthalamic nucleus (STN-DBS) is an alternative treatment for patients with uncontrolled symptoms of epilepsy [3], but predicting outcome before the operation is not possible. Electrical stimulation at acupoints was also efficient in treating medically refractory epilepsy, and Yan et al. and Meng et al. suggested that electroacupuncture at acupoints could predict the curative effect of STN-DBS for refractory epilepsy [4,5]. However, but the mechanisms of electroacupuncture for predicting the efficacy of electrical stimulation in pharmacoresistant epilepsy are still unclear. It is interesting to note that previous studies have demonstrated that epileptic seizures are tightly linked to an imbalance between the excitatory [glutamate (Glu), aspartate (Asp)] and inhibitory [GABA, glycine (Gly), and taurine (Tau)] neuronal transmitters [6]. Otherwise, it has been verified that the therapeutic mechanism of STN-DBS and electroacupuncture at acupoints is associated with the balance between the excitatory and inhibitory neuronal transmitters [7,8]. Accordingly, some authors suggested that the mechanism of electroacupuncture for predicting the efficacy of deep brain stimulation in pharmacoresistant epilepsy involved the metabolism of amino acids [4,5]. We would like to further discuss the possible mechanism of electroacupuncture for predicting the efficacy of deep brain stimulation in MC4R-GFP transgenic mice [9–12]. As data have accumulated over the last two decades, STN-DBS is now identified as an importantmodification of energymetabolism as reflected by changes in daily energy metabolism after stimulation surgery [13]. The study of Batisse-Lignier et al. [14] indicated that STN-DBS in patients affected glucose disposal of endogenous glucose production, suggesting that a cross talk between the central subthalamic nucleus and peripheral tissues may regulate glucose homeostasis. In addition, clinical findings have demonstrated that the therapeutic mechanisms of STN-DBS are closely related to the changes in cerebral glucosemetabolism [15,16]. Some neuroimaging studies using functional magnetic resonance imaging, single-photon emission computed tomography (SPECT), and positron emission tomography (PET) had revealed that glucose metabolism significantly increased in the left superior medial frontal gyrus, the middle frontal gyrus, and the right superior medial frontal gyrus following electroacupuncture at Hegu (LI 4) and Quchi (LI 11) [17,18], suggesting that the clinical effect of electroacupuncture at acupoints is also related to the changes in cerebral glucose metabolism. Therefore, we presume that the possible mechanism of electroacupuncture for predicting the efficacy of deep brain stimulation in pharmacoresistant epilepsy may be involved in the changes in cerebral glucose metabolism.

Impact of malnutrition on propofol consumption and recovery time among patients undergoing laparoscopic gastrointestinal surgery.

Malnutrition is a major health problem, especially in hospitalized patients as it can be closely related to many post‐operative complications. However, research on malnutrition and its effect on the outcome of general anesthesia have been largely neglected. Here we investigated malnutrition status on propofol consumption and recovery time among patients undergoing laparoscopic gastrointestinal surgery under general anesthesia.