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3 results

  • In major depression, increased kappa and mu opioid receptor levels are associated with immune activation

  • Hussein Kadhem Al-Hakeim, Suhaer Zeki Al-Fadhel, Arafat Hussein Al-Dujaili, Michael Maes
  • Journal:
    Acta Neuropsychiatrica / Volume 32 / Issue 2 / April 2020
    Published online by Cambridge University Press:
    14 January 2020, pp. 99-108
  • Objective:

    This study was carried out to delineate differences between major depressive disorder (MDD) and healthy controls in dynorphin and kappa opioid receptor (KOR) levels in association with changes in the β-endorphin – mu opioid receptor (MOR) and immune-inflammatory system.

    Methods:

    The present study examines dynorphin, KOR, β-endorphin, MOR, interleukin (IL)-6 and IL-10 in 60 drug-free male participants with MDD and 30 age-matched healthy males.

    Results:

    Serum dynorphin, KOR, β-endorphin and MOR are significantly higher in MDD as compared to controls. The increases in the dynorphin/KOR system and β-endorphin/MOR system are significantly intercorrelated and are both strongly associated with increased IL-6 and IL-10 levels. Dynorphin, β-endorphin, KOR and both cytokines showed a good diagnostic performance for MDD versus controls with a bootstrapped (n = 2000) area under the receiver operating curve of 0.972. The dynorphin/KOR system is significantly decreased in depression with comorbid nicotine dependence.

    Conclusion:

    Our findings suggest that, in MDD, immune activation is associated with a simultaneous activation of dynorphin/KOR and β-endorphin/MOR signaling and that these opioid systems may participate in the pathophysiology of depression by (a) exerting immune-regulatory activities attenuating the primary immune response and (b) modulating reward responses and mood as well as emotional and behavioural responses to stress.

  • Chapter 21 - Cannabinoids

  • from Section 6 - The Management of Neuropathic Pain
  • Edited by Cory Toth, Dwight E. Moulin
  • Book:
    Neuropathic Pain
    Published online:
    05 December 2013
    Print publication:
    07 November 2013, pp 249-266

  • Summary

    Neuropathic pain after spinal cord injury (SCI) is a type of central neuropathic pain and is a frequent complication of spinal injury which is often refractory. Studies in animal models describe a number of peripheral and central pathophysiological processes after nerve injury that would be the basis of underlying neuropathic pain mechanisms. A major inhibitory system related to pain is opioid receptor mediated analgesia. In neuropathic pain, N-methyl-d-aspartate (NMDA) receptor activation increases excitation in the pain transmitting systems. Recent advances in pain research indicate multiple mechanisms, including many components of peripheral and central sensitization mechanisms, underlying the initiation and maintenance of neuropathic pain. Neurosurgical interventions may be treatment options in patients with poor pain control despite pharmacotherapy. Besides the effectiveness of a treatment, the adverse event profiles of these analgesics have to be considered before starting therapy or combining different agents.

  • Ontogeny of the opioid growth factor, [Met5]-enkephalin, and its binding activity in the rat retina

  • Tomoki Isayama, W. Jeffrey Hurst, Patricia J. McLaughlin, Ian S. Zagon
  • Journal:
    Visual Neuroscience / Volume 12 / Issue 5 / September 1995
    Published online by Cambridge University Press:
    02 June 2009, pp. 939-950

  • The endogenous opioid peptide [Met5]-enkephalin is a tonically active opioid growth factor (OGF) with an inhibitory action on DNA synthesis in the developing rat retina. In this study, the ontogeny of the spatial and temporal expression of OGF and its binding activity was examined. OGF-like immunoreactivity was detected in the retina at gestation day (E) 20, but not at E18, and was localized to ganglion cell and neuroblast layers; immunochemical reaction was no longer seen in the retina by postnatal day 6. Native OGF was further identified and characterized by high-performance liquid chromatography (HPLC) studies and immunodot assays, which revealed that [Met5]-enkephalin was present in the neonatal, but not adult, rat retina. OGF binding activity was detected as early as E18 using [125I]-[Met5]-enkephalin and in vitro receptor autoradiography. Little OGF binding activity was noted for prenatal retinas, but appreciable activity was observed from birth to postnatal day 4; no OGF binding could be detected after postnatal day 5 or in the adult. These results reveal the transient appearance of the OGF, [Met5]-enkephalin, and its receptor binding activity in the developing mammalian retina, and show that their ontogeny coincides with the timetable of DNA synthesis of retinal neuroblasts.