Early single Aspirin-triggered Lipoxin blocked morphine anti-nociception tolerance through inhibiting NALP1 inflammasome: Involvement of PI3k/Akt signaling pathway.

Clinical usage of opioids in pain relief is dampened by analgesic tolerance after chronic exposure, which is related to opioid-associated neuroinflammation. In the current study, which is based on a chronic morphine tolerance rat model and sustained morphine treatment on primary neuron culture, it was observed that Akt phosphorylation, cleaved-Caspase-1-dependent NALP1 inflammasome activation and IL-1ß maturation in spinal cord neurons were significantly enhanced by morphine. Moreover, treatment with LY294002, a specific inhibitor of PI3k/Akt signaling, significantly reduced Caspase-1 cleavage, NALP1 inflammasome activation and attenuated morphine tolerance. Tail-flick tests demonstrated that pharmacological inhibition on Caspase-1 activation or antagonizing IL-1ß dramatically blocked the development of morphine tolerance. The administration of an exogenous analogue of lipoxin, Aspirin-triggered Lipoxin (ATL), caused a decline in Caspase-1 cleavage, inflammasome activation and mature IL-1ß production and thus attenuated the development of morphine tolerance by inhibiting upstream Akt phosphorylation. Additionally, treatment with DAMGO, a selective µ-opioid receptor peptide, significantly induced Akt phosphorylation, Caspase-1 cleavage and anti-nociception tolerance, all of which were attenuated by ATL treatment. Taken together, the present study revealed the involvement of spinal NALP1 inflammasome activation in the development of morphine tolerance and the role of the µ-receptor/PI3k-Akt signaling/NALP1 inflammasome cascade in this process. By inhibiting this signaling cascade, ATL blocked the development of morphine tolerance.

Mechanism of action of Shaoyao-Gancao decoction in relieving chronic inflammatory pain via Sema3G protein regulation in the dorsal root ganglion.

Objective: The purpose of this study was to analyze the impact of Shaoyao-Gancao decoction (SGD) on proteins with significant changes in the dorsal root ganglion (DRG) in rats and to explore the role of the Semaphorin 3G (Sema3G) protein in the DRG and its downstream factors, interleukin-6 (IL-6) and CC-motif chemokine ligand 2(CCL2), in the treatment of chronic inflammatory pain (CIP). Methods: We created a CIP rat model using 100 µL of complete Freund's adjuvant (CFA) that was injected into the left posterior plantar of rats. Then, we administered SGD intragastrically. We tested the animals for behavioral changes and protein expression levels in DRG pre- and post-drug intervention. Results: Rats in the SGD group showed significantly increased paw withdrawal threshold (PWT), paw withdrawal latency (PWL), and relative expression levels of the Sema3G protein in the DRG (all P < 0.05), while the relative mRNA expression levels of IL-6 and CCL2 in the DRG of the rats were significantly decreased (P < 0.05) when compared with the model group. Conclusion: In this study, we found that Shaoyao-Gancao decoction was effective in improving the PWT and PWL of rats with CIP. It reduced CIP by upregulating the expression of Sema3G in the DRG and inhibiting the relative mRNA expression levels of IL-6 and CCL2.

Lipoxins and aspirin-triggered lipoxin alleviate bone cancer pain in association with suppressing expression of spinal proinflammatory cytokines.

BACKGROUND: The neuroinflammatory responses in the spinal cord following bone cancer development have been shown to play an important role in cancer-induced bone pain (CIBP). Lipoxins (LXs), endogenous lipoxygenase-derived eicosanoids, represent a unique class of lipid mediators that possess a wide spectrum of anti-inflammatory and pro-resolving actions. In this study, we investigated the effects of intrathecal injection with lipoxin and related analogues on CIBP in rats. METHODS: The CIBP model was induced by intra-tibia inoculation of Walker 256 mammary gland carcinoma cells. Mechanical thresholds were determined by measuring the paw withdrawal threshold to probing with a series of calibrated von Frey filaments. Lipoxins and analogues were administered by intrathecal (i.t.) or intravenous (i.v.) injection. The protein level of LXA4 receptor (ALX) was tested by western blot. The localization of lipoxin receptor in spinal cord was assessed by fluorescent immunohistochemistry. Real-time PCR was carried out for detecting the expression of pro-inflammatory cytokines. RESULTS: Our results demonstrated that: 1) i.t. injection with the same dose (0.3 nmol) of lipoxin A4 (LXA4), lipoxin B4 (LXB4) or aspirin-triggered-15-epi-lipoxin A4 (ATL) could alleviate the mechanical allodynia in CIBP on day 7 after surgery. ATL showed a longer effect than the others and the effect lasted for 6 hours. ATL administered through i.v. injection could also attenuate the allodynia in cancer rats. 2) The results from western blot indicate that there is no difference in the expression of ALX among the naive, sham or cancer groups. 3) Immunohistochemistry showed that the lipoxin receptor (ALX)-like immunoreactive substance was distributed in the spinal cord, mainly co-localized with astrocytes, rarely co-localized with neurons, and never co-localized with microglia. 4) Real-time PCR analysis revealed that, compared with vehicle, i.t. injection with ATL could significantly attenuate the expression of the mRNA of proinflammatory cytokines (IL-1ß and TNF-α) in the spinal cord in CIBP. CONCLUSIONS: Taken together, the results of our study suggest that LXs and analogues exert strong analgesic effects on CIBP. These analgesic effects in CIBP are associated with suppressing the expression of spinal proinflammatory cytokines.

Involvement of spinal orexin A in the electroacupuncture analgesia in a rat model of post-laparotomy pain.

BACKGROUND: Orexin A (OXA, hypocretin/hcrt 1) is a newly discovered potential analgesic substance. However, whether OXA is involved in acupuncture analgesia remains unknown. The present study was designed to investigate the involvement of spinal OXA in electroacupuncture (EA) analgesia. METHODS: A modified rat model of post-laparotomy pain was adopted and evaluated. Von Frey filaments were used to measure mechanical allodynia of the hind paw and abdomen. EA at 2/15 Hz or 2/100 Hz was performed once on the bilateral ST36 and SP6 for 30 min perioperatively. SB-334867, a selective orexin 1 receptor (OX1R) antagonist with a higher affinity for OXA than OXB, was intrathecally injected to observe its effect on EA analgesia. RESULTS: OXA at 0.3 nmol and EA at 2/15 Hz produced respective analgesic effects on the model (P<0.05). Pre-surgical intrathecal administered of SB-334867 30 nmol antagonized OXA analgesia and attenuated the analgesic effect of EA (P<0.05). However, SB-334867 did not block fentanyl-induced analgesia (P>0.05). In addition, naloxone, a selective opioid receptor antagonist, failed to antagonize OXA-induced analgesia (P>0.05). CONCLUSIONS: The results of the present study indicate the involvement of OXA in EA analgesia via OX1R in an opioid-independent way.

Somatotopic Organization and Intensity Dependence in Driving Distinct NPY-Expressing Sympathetic Pathways by Electroacupuncture.

The neuroanatomical basis behind acupuncture practice is still poorly understood. Here, we used intersectional genetic strategy to ablate NPY+ noradrenergic neurons and/or adrenal chromaffin cells. Using endotoxin-induced systemic inflammation as a model, we found that electroacupuncture stimulation (ES) drives sympathetic pathways in somatotopy- and intensity-dependent manners. Low-intensity ES at hindlimb regions drives the vagal-adrenal axis, producing anti-inflammatory effects that depend on NPY+ adrenal chromaffin cells. High-intensity ES at the abdomen activates NPY+ splenic noradrenergic neurons via the spinal-sympathetic axis; these neurons engage incoherent feedforward regulatory loops via activation of distinct adrenergic receptors (ARs), and their ES-evoked activation produces either anti- or pro-inflammatory effects due to disease-state-dependent changes in AR profiles. The revelation of somatotopic organization and intensity dependency in driving distinct autonomic pathways could form a road map for optimizing stimulation parameters to improve both efficacy and safety in using acupuncture as a therapeutic modality.

[Effect of wrist-ankle acupuncture on the expression of glutamate and NMDA receptor of the spinal dorsal horn in rats with neuropathic pain].

OBJECTIVE: To observe the effect of wrist-ankle acupuncture (WA) stimulation at "R4"- "R5" - "R6" on the expression of glutamate (Glu) and phosphorylated protein NMDAR1(p-NMDAR1) of the spinal dorsal horn in spared nerve injury (SNI) rats, so as to explore its mechanism underlying improvement of SNI. METHODS: A total of 36 SD rats were randomly divi-ded into sham operation, model and WA groups, with 12 rats in each group. The SNI procedure comprised an axotomy and ligation of the tibial and common peroneal nerves leaving the sural nerve intact. Rats of the WA group were treated by acupuncture at "R4"-"R5"-"R6" points from the 5th day to the 14th day after modeling. The mechanical pain thresholds were measured before and 5, 10 and 14 d after SNI, respectively. The cold allodynia was dectected by Acetone solution dropped onto the lateral plantar surface of the paw. Glu content and p-NMDAR1 expression of spinal dorsal horn were detected by 1H-MRS, ELISA and immunohistochemistry Methods. RESULTS: Compared with the sham operation group, the mechanical pain threshold of the model group was significantly decreased (P<0.01), the duration of cold stimulation foot contraction was increased (P<0.01), and the Glu content and p-NMDAR1 expression in the spinal dorsal horn were significantly increased (P<0.05, P<0.01). After WA intervention, the mechanical pain threshold was significantly increased (P<0.01), the duration of cold stimulation was significantly shortened (P<0.01), and Glu content and p-NMDAR1 protein expression of spinal dorsal horn were decreased significantly (P<0.05, P<0.01) in the WA group compared with the model group. CONCLUSION: WA can reduce pain sensitivity in rats with neuropathic pain, possibly by inhibiting the expression of Glu and p-NMDAR1 in the spinal dorsal horn.

The Analgesic and Antineuroinflammatory Effect of Baicalein in Cancer-Induced Bone Pain.

Cancer-induced bone pain (CIBP) is a severe type of chronic pain. It is imperative to explore safe and effective analgesic drugs for CIBP treatment. Baicalein (BE), isolated from the traditional Chinese herbal medicine Scutellaria baicalensis Georgi (or Huang Qin), has been demonstrated to have anti-inflammatory and neuroprotective effects. In this study, we examined the effect of BE on CIBP and the mechanism of this effect. Intrathecal and oral administration of BE at different doses could alleviate the mechanical allodynia in CIBP rats. Intrathecal 100 µg BE could inhibit the production of IL-6 and TNF-α in the spinal cord of CIBP rats. Moreover, intrathecal 100 µg BE could effectively inhibit the activation of p-p38 and p-JNK MAPK signals in CIBP rats. The analgesic effect of BE may be associated with the inhibition of the expression of the inflammatory cytokines IL-6 and TNF-α and through the activation of p-p38 and p-JNK MAPK signals in the spinal cord. These findings suggest that BE is a promising novel analgesic agent for CIBP.

[Reversal of multidrug resistance property of carcinoma cells by down-regulating transcription of mdr-1].

OBJECTIVE: To reverse the multidrug resistance (MDR) property of carcinoma cells by blocking transcription of activating sites of mdr-1. METHODS: Breast carcinoma cells were transinfected with several antisense oligonucleotide (ASODN) complementary to mdr-1 by lipofectin. RT-PCR was used to detect the production of mdr-1mRNA. The expression of P-glycoprotein (gp) was then detected by immunohistochemistry and the function of P-gp was detected by rhodamine123 retention. RESULTS: Forty-eight hours after transfection, mdr-1 index of cells treated by ASODN complementary to MA zone (major initiation start zone), MI (minor initiation start zone), C zone (CAAT box), G zone (GC box) of mdr-1 gene was 1.4, 1.9, 1.6 and 2.1 respectively. The rate of P-gp protein expression in treated cells was 14%, 43%, 26% and 39% respectively. The intracellular Rh123 retention in treated cells was 125%, 83%, 102% and 77% respectively. There was significant difference between cells treated by ASODN complementary to MA zone and C zone and drug-resistant cells. CONCLUSIONS: The ASODN complementary to MA zone and C zone of mdr-1 gene can reverse MDR of drug-resistant cells to various extent, amongst which the former is more effective. Down-regulating transcription of mdr-1 by blocking transcription activating sites can reduce the expression of mdr-1mRNA and P-gp, and thus reversing MDR of carcinoma cells. The ASODN complementary to MI zone, G zone of mdr-1 however do not significantly reverse the MDR property.

Effects of chronic electroacupuncture on depression- and anxiety-like behaviors in rats with chronic neuropathic pain.

Growing evidence indicates that chronic neuropathic pain is frequently accompanied by an array of psychiatric diseases, such as depression and anxiety. Electroacupuncture (EA), as one therapy of traditional Chinese medicine, has displayed potent antidepressant-like effects in numerous clinical studies. The present study was designed to examine the possible effects of EA on the depressive and anxiety disorders induced by neuropathic pain. A classic rat model of neuropathic pain was produced by chronic constriction injury (CCI) of the sciatic nerve. EA was performed on acupoints "Bai-Hui" (GV20) and unilateral "Yang-Ling-Quan" (GB34). The antidepressive and anxiolytic effects of EA treatment were analyzed using the forced swimming test (FST) and the elevated plus maze (EPM) test, respectively. CCI resulted in remarkable depression- and anxiety-like behaviors, whereas the chronic EA treatment significantly improved the behavioral deficits of CCI rats. Moreover, the phosphorylation level of the NMDA receptor type 1 (NR1) subunit was decreased in the hippocampus of CCI rats. Intriguingly, continuous EA treatment effectively blocked this decrease in the levels of pNR1. These results suggested that EA has antidepressive and anxiolytic effects on rats with neuropathic pain and that this might be associated with restoring the phosphorylation of NR1 in the hippocampus.

Functional polymorphism in exon 5 and variant haplotype of the interleukin-1 receptor-associated kinase 1 gene are associated with susceptibility to and severity of sepsis in the Chinese population.

BACKGROUND: The interleukin-1 (IL-1) receptor-associated kinase 1 (IRAK1) is believed to play an important role in the pathogenesis of sepsis. Recent studies have suggested that the IRAK1 functional genetic variant could affect the severity of sepsis in Caucasians. In this report, we have investigated whether polymorphisms at the IRAK1 gene are associated with the susceptibility to and severity of sepsis among the Chinese population. METHODS: Haplotype-tagging single nucleotide polymorphisms (htSNPs) were selected from the HapMap database. They were genotyped in 255 patients with sepsis and 260 control subjects by PCR/restriction fragment length polymorphism (RFLP) analysis. The association between the selected htSNPs and the susceptibility to and severity of sepsis were estimated by Logistic regression with adjustments for age, sex, smoking, drinking, chronic disease status, Acute Physiology and Chronic Health Evaluation (APACHE) II score and primary diseases. RESULTS: rs1059702 was selected to represent the six linked htSNPs for IRAK1. Genotype frequencies of the htSNPs were in Hardy-Weinberg equilibrium for females, as were allele frequencies for both sex groups. Associations were observed in females between the htSNPs C/C genotype and increased susceptibility to sepsis (odds ratio (OR), 5.46; 95% confidence interval (CI), 1.12 - 26.67; P = 0.018), and such associations were also observed between the IRAK1 variant haplotype (CC/C-allele) and increased susceptibility to sepsis (OR, 1.68; 95% CI, 1.05 - 2.70; P = 0.031) when compared with the T/T + T/C genotype and the wild-type haplotype (TC + TT/T-allele). In the multiple organ dysfunction syndrome (MODS) subgroup, the variant haplotype was also associated with increased severity of sepsis (OR, 2.37; 95% CI, 1.13 - 4.94; P = 0.02) when compared with the wild haplotype. This association was not significant in male patients. CONCLUSIONS: The functional polymorphism in exon 5 and the variant haplotype of IRAK1 gene mediate susceptibility to and severity of sepsis. IRAK1 might be a genetic risk factor for the occurrence and development of sepsis in the Chinese population.

TRAF6 polymorphisms not associated with the susceptibility to and severity of sepsis in a Chinese population.

BACKGROUND: The tumor necrosis factor recepter associated factor (TRAF) 6 is an important intracellular adapter protein that plays a pivotal role in activating multiple inflammatory and immune related processes induced by cytokines. TRAF6 represents a strong candidate susceptibility factor for sepsis. We investigated whether polymorphisms at the TRAF6 gene are associated with the susceptibility to and severity of sepsis. METHODS: A hospital-based case-control study was conducted with 255 patients with sepsis and 260 controls who were recruited from Zhengzhou, China. Haplotype tagging single nucleotide polymorphisms (htSNPs) were selected from the HapMap database and genotyped using the SNPstream genotyping platform. The associations with the susceptibility and disease severity of sepsis were estimated by logistic regression, and adjusted for age, sex, smoking, drinking, chronic diseases status, APACHEII score and critical illness status. RESULTS: A total of 13 TRAF6 SNPs were tagged by 7 htSNPs. Five htSNPs (rs5030490, rs5030411, rs5030416, rs5030445 and rs3740961) were genotyped in the case control study. Genotype frequencies of the htSNPs were conformed to the Hardy-Weinberg equilibrium in both patients and controls. No significant association was found between the 5 htSNPs and the susceptibility to and severity of sepsis. Compared with the main haplotype -11120A/-10688T/-9423A/805G/12967G, no certain haplotype was associated with the significantly susceptibility to or severity of sepsis. CONCLUSION: TRAF6 gene polymorphisms might not play a major role in mediating the susceptibility to and severity of sepsis in the Chinese population. A larger population-based case-control study is warranted.

[Study on needling depth and direction from different acupoints to sphenopalatine ganglion].

OBJECTIVE: To observe and survey the location of Xiaguan (ST 7), "Die'e" and Quanliao (SI 18) on the surface, and the needling depth and direction from the 3 points to sphenopalatine ganglion. METHODS: Fifteen corpses (30 sides) of adult male were fixed by 10% formalin. The lateral areas of face were dissected from the surface to the deep on the 3 acupoints: the electric drill with the kirschner wire punctured towards the sphenopalatine ganglion and extended to the contralateral areas according to different directions of puncturing sphenopalatine ganglion from the 3 acupoints. The corresponding puncturing points of the 3 acupoints were measured by the coordinate location method. RESULTS: (1) Surface location: the distance between Quanliao (SI 18) and "Die'e" was 21 mm and the distance between Xiaguan (ST 7) and "Die'e" was 17 mm; (2) Inserting depth of each point to sphenopalatine ganglion: the depths of Xiaguan (ST 7), "Die'e" and Quanliao (SI 18) were 49.9 mm, 46.9 mm and 46.6 mm, respectively; (3) The coordinate location of the corresponding puncturing points: the puncturing direction of Xiaguan (ST 7) was anterointernal upper corresponding to the area of connecting center between contralateral Taiyang (EX-HN 5) and Tongziliao (GB 1), the distance between the corresponding inserting point of Xiaguan (ST 7) and Sizhukong (TE 23) was 17.6 mm; the puncturing direction of "Die'e" point was posterointernal upper, and the horizontal distance from the corresponding puncture point to the zygomatic arch was 33 mm and the vertical distance from the corresponding puncture point to the eyes' outer canthus was 42 mm; the puncturing direction of Quanliao (SI 18) was posteriointernal upper and the distance between the corresponding inserting point and the area of contralateral parietal tuber, the distance between the corresponding inserting point of Quanliao (SI 18) and the connecting line of bilateral external acoustic pore was 28 mm, the distance between the corresponding inserting point of Quan-liao (SI 18) and the medial line of the head was 62 mm. CONCLUSION: Understanding the surface location, inserting depths and the general puncturing directions of the 3 points can provide basis for puncturing the sphenopalatine ganglion in clinical practice.