The Roles of Opioid Receptors and Agonists in Health and Disease Conditions
Ibegbu, A. O.
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Ibegbu, A., Mullaney, I., Fyfe, L. & McBean, D. (2011) The Roles of Opioid Receptors and Agonists in Health and Disease Conditions, British Journal of Pharmacology and Toxicology, vol. 2, , pp. 84-91,
Opioid receptors are found in the Central Nervous System (CNS) and are classified as mu (_), kappa (6), delta (*) and sigma (F) opioid receptors. Opioid receptors belong to the large family of G Protein Coupled Receptors (GPCRs), and have diverse and important physiological roles. The aim of the present review is to discuss the roles played by opioid receptors, their agonists and antagonists in health and disease conditions. Opioid receptors are not uniformly distributed in the CNS and are found in areas concerned with pain, with the highest concentration in the cerebral cortex, followed by the amygdala, septum, thalamus, hypothalamus, midbrain and spinal cord. Activated delta opioid receptors are coupled to Gi1 while activated mu opioid receptors are coupled to Gi3 in neuroblastoma cells. Mu opioid receptors are activated by mu receptor agonists and are coupled through the Gi1 and GoA. Both mu and kappa opioid receptors are coupled via both Gi and Gz and opioid receptors are important targets for thousands of pharmacological agents. GPCRs typically require activation by agonists for their signalling activity to be initiated but some of the GPCRs may display basal or spontaneous signalling activity in the absence of an agonist. The stimulation of these receptors triggers analgesic effects and affects the function of the nervous system, gastrointestinal tract and other body systems. Hundreds of analogs of opioid peptides have been synthesized in an effort to make the compounds more active, selective, and resistant to biodegradation than the endogenous ligands. All these modifications resulted in obtaining very selective agonists and antagonists with high affinity at mu-, delta-, and kappa-opioid receptors, which are useful in further studies on the pharmacology of opioid receptors in a mammalian organism.
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Morphological changes induced by opioid receptor agonist treatment of B50 neuronal cells cultured in hypoxia Ibegbu, A. O.; McBean, Douglas; Fyfe, Lorna; Mullaney, I. (Brazilian Society of Anatomy and, 2013-04)Introduction: Hypoxia has been implicated in nerve cell deaths that occur in a variety of neurological disorders. Opioid receptor agonists have been shown to have some positive benefits on the nervous system. The aim of ...
The Effects of Hypoxia and Opioid Receptor Agonists Treatment in Cortical B50 Neuronal Cells in Culture Ibegbu, A. O.; Fyfe, Lorna; McBean, Douglas; Mullaney, I. (Uludag University Applied Research Center for Agriculture (ARCA) and Applied Research Center for Environmental Problems (ARCEP), Uludag University Gorukle Campus, 16059 Bursa-Turkey, 2012-12)Hypoxia has been implicated in nerve cell deaths in many neurological disorders and opioid receptor agonists have some positive benefits on the nervous system. The aim of the present work was to investigate the effects of ...
Oxidative stress does not predispose neuronal cells to changes in G protein coupled (opioid) receptor gene expression in cortical B50 neurons in culture Ibegbu, A. O.; Mullaney, I.; Fyfe, Lorna; McBean, Douglas (Kamla-Raj Enterprises, 2012-12)Oxidative stress adversely affects neuronal cells in which they may die when oxygen supply is reduced or eliminated and opioid receptor agonists elicit several central nervous system effects. The aim of this study was to ...