Endomorphin peptides: pharmacological and functional implications of these opioid peptides in the brain of mammals. Part one
| Autor: | Philippe Leff Gelman, Norma Estela González Herrera, Maura Epifanía Matus Ortega, Lenin Pavón Romero, Carlos Téllez Santillán, Alberto Salazar Juárez, Benito Antón Palma |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | Instituto Politécnico Nacional IPN Redalyc-IPN Salud Mental (México) Num.2 Vol.33 |
| Popis: | "The present paper describes several aspects of the biological activities, physiological and behavioral responses displayed by the most recent discovered opioid peptides: endomorphins. Endormorphins comprise two endogenous C-terminal amide tetrapeptides, named as endomorphin-1 (EM1; Tyr-Pro-Trp-Phe-NH2) and endomorphin-2 (EM2; Tyr-Pro-Phe-Phe-NH2), which were discovered a decade ago (1997) by Zadina¿s group. Initially, they reported the identification of two endogenous opioid peptides that displayed high binding affinities and selectivities for the ¿-opioid receptor among other identified and cloned opioid receptors. These led authors to support the hypothesis that endomorphin peptides represent the endogenous ligand agonists for the ¿-opioid receptor. Both peptides were identified and isolated from bovine and human brains. They consist of four amino acids that share a 75% structural homology among amino acids, and which display the structural ¿-amidated form of C-terminal -Phe- residue, as demonstrated for many other bioactive neuropeptides. These peptides are structurally distinct from other endogenous opioid substances identified in the brain of mammals, although they share some similarities with other amide terapeptides such as Tyr-WMIF- 1, found also in the mammalian brain. Here, we review the structure-relationship activity of both endomorphin molecules comparing their binding properties to different opioid receptors. Both EM1/EM2 peptides appear to be vulnerable to enzymatic degradation when exposed to the activities of different proteolytic enzymes, as occurs with many other neuroactive peptides found in the SNC of mammals. Immunohistochemical studies showed the wide and asymmetric distribution of both EM1-2 peptides in the brain, leading to the extensive pharmacological, cellular, and physiological studies that demonstrated the wide and varied bioactivities displayed by these peptides at both central and peripheral tissues. These studies led several authors to suggest the potential endogenous role of these peptides in major physiological processes (e.g. analgesia or antinociception). Based on the generation of specific (rabbit) polyclonal antibodies and the use of combined radioimmunoassay (RIA) techniques and immunohistochemical procedures, it was shown the wide distribution of EM1-2-LI (endomorphin1-2-like immunoreactivities) throughout the brain of different species (e.g. rat, primate, human), particularly co-localized in specific areas where ¿-opioid receptor has been shown to be expressed. IHC mapping of endomorphin material in the CNS showed a parallelism with the neuroanatomical distribution of other endogenous opioid peptides (e.g. Met/Leu-enk, Dynorphin A, ¿-endorphin) previously reported..." |
| Databáze: | OpenAIRE |
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