Xu Dai

Lanzhou University, Lanzhou, Gansu Sheng, China

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Publications (5)14.26 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The opioid peptides modulate extensive bioactivities, including pain, cardiovascular response, development and further responses. In the present study, the stimulative effects of endogenous opioid peptides on angiogenesis are evaluated in the proliferation, migration, adhesion and tube formation assays of the human umbilical vein endothelial cell (HUVEC) for the first time. Endomorphin-1, endomorphin-2 and deltorphin I at physiological concentrations could stimulate HUVECs proliferation, migration, adhesion and tube formation in a dose dependent manner; whereas, they exhibited the cytotoxic effects on HUVECs at the higher doses in these assays. Naloxone, the nonselective opioid receptor antagonist, did not influence angiogenesis when it was administrated on its own; but it could antagonize the stimulative effects of the opioid peptides on angiogenesis when it was administrated in combination with the opioid peptides. Taken altogether, the results suggested that endogenous opioid peptides (endomorphin-1 and -2 and deltorphin I) stimulated angiogenesis at the cellular level, and these effects were mediated by the opioid receptors. These data are significant for potential clinical implementation in future.
    European journal of pharmacology 11/2009; 628(1-3):42-50. · 2.59 Impact Factor
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    ABSTRACT: The opioid peptides modulate extensive bioactivities, including pain, cardiovascular response, development and so on. The effects of endogenous opioid peptides on angiogenesis were evaluated in the chick embryo chorioallantoic membrane (CAM) assay for the first time in the present study. Endomorphin-1, endomorphin-2 and deltorphin I at the dosage of 1, 10, 100 nmol/embryo could stimulate angiogenesis dose-dependently, respectively. Naloxone, the nonselective opioid receptor antagonist, did not influence angiogenesis alone; but it could antagonize the stimulative effects of the opioid peptides on angiogenesis when it was administrated in combination with the opioid peptides. Taken altogether, the results suggested that endogenous opioid peptides (endomorphin-1 and -2 and deltorphin I) stimulated angiogenesis in the CAM assay, and these effects were modulated with the opioid receptors. These data are important for potential future clinical implementation.
    European Journal of Pharmacology 02/2008; 579(1-3):269-75. · 2.59 Impact Factor
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    ABSTRACT: The effects of melatonin (Mel) on the development of tolerance to antinociceptive actions induced by mu- and delta-opioid receptor agonists were determined in male Kunming mice. In the mouse tail-flick tests, selective mu and delta receptor agonists were repeatedly administered to mice supraspinally (intracerebroventricularly, i.c.v.) in the absence or presence of melatonin. Administration of endomorphin-1 (EM-1, a mu-opioid receptor agonist) or deltorphin I (del I, a delta-opioid receptor agonist) twice daily for 4 days produced antinociceptive tolerance compared with vehicle controls. Co-administration with melatonin prevented the development of tolerance to deltorphin I analgesia, and this effect was dose dependent. However, melatonin did not affect the development of antinociceptive tolerance to endomorphin-1. Additionally, the attenuation of deltorphin I tolerance by melatonin was reduced by chronic treatment with luzindole (luz), a selective antagonist on the MT(2) receptor subtype. Taken together, these data suggest that melatonin interferes with the neural mechanisms involved in the development of tolerance to delta-opioid agonist analgesia via its receptor.
    Behavioural Brain Research 09/2007; 182(1):21-7. · 3.33 Impact Factor
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    ABSTRACT: The pain modulatory properties of melatonin (MT) are generally recognized but the detail of the interaction between melatonin and opioid system in pain regulation is not fully understood. The present study was undertaken to investigate the modulatory effect of melatonin (MT) on the hyperalgesic effect of Orphanin FQ/Nociceptin (OFQ/NC, NC), a member of opioid peptide family. Intracerebroventricular (i.c.v.) administration of NC (10 microg/mouse) induced significant hyperalgesic effect in tail-flick test in mice; i.c.v. (5, 10, 50 microg/mouse) or intraperitoneal (i.p.) (5, 10, 50 mg/kg) co-injection of melatonin dose-dependently reversed NC-induced hyperalgesia and showed a profound analgesic effect. The antihyperalgesia effect of MT could be significantly antagonized by i.c.v. co-injection of luzindole (10 microg/mouse) (an antagonist of MT receptor) or naloxone (10 microg/mouse) (antagonist of traditional opioid receptor). Taken together, all the results suggested that MT could produce a luzindole and naloxone sensitive reversing effect on NC-induced hyperalgesia at supraspinal and peripheral level in mice. The augmentation effect of MT on the traditional opioid system may be one of the mechanisms of this antihyperalgesia action induced by MT. The present work will help to elucidate the mechanism of the pain modulation effect of MT, and also will help to represent new interesting modulating therapeutic targets for the relief of pain.
    Brain Research 05/2006; 1085(1):43-8. · 2.88 Impact Factor
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    ABSTRACT: This present study examines the effect of melatonin on antinociceptive action induced by opioid agonists in mice using the tail-flick test. When injected either by intraperitoneal (i.p.) (1, 5, 25 mg/kg) or by intracerebroventricular (i.c.v.) (0.25, 0.5, 1 mg/kg) routes, melatonin significantly enhanced the delta-opioid agonist deltorphin I induced antinociception, but not mu-opioid agonist endomorphin-1. Further investigation showed that i.c.v. luzindole (0.5 mg/kg) (an antagonist of melatonin receptor) significantly antagonized the enhanced antinociceptive effect of i.c.v. melatonin. These results demonstrated that melatonin can specifically enhance the antinociception induced by specific opioid receptor agonist (i.e., delta opioid agonist) acting on melatonin receptor and that melatonin may have augmentation effect on analgesia with delta-, but not mu-opioid agonists in mice.
    Brain Research 06/2005; 1043(1-2):132-8. · 2.88 Impact Factor

Publication Stats

64 Citations
14.26 Total Impact Points

Institutions

  • 2006–2009
    • Lanzhou University
      • School of Life Science
      Lanzhou, Gansu Sheng, China
  • 2008
    • The Hong Kong Polytechnic University
      • Department of Applied Biology and Chemical Technology
      Hong Kong, Hong Kong