Endogenous peptide opioids

Papaver somniferum Papaveraceae (opium poppy) has been used as an analgesic since 3000 BC [26]. The opium latex contains many alkaloids, including codeine, thebaine, papaverine and morphine - its main analgesic constituent [27]. Although morphine has found large clinical use, its analgesic mechanism was first elucidated only with the discovery of both endogenous peptide opioids (such as enkephalins, dynorphins, endorphins and nociceptin) and the opioid receptors, p, 8, k... 

Endogenous opioid peptides are the wide variety of endogenous peptides isolated since 1975 which are the natural ligands for the opioid receptors. The peptides... 

INTERACTION OF OPIOID RECEPTORS WITH ENDOGENOUS PEPTIDE LIGANDS... 

The mu, kappa, and delta opioid receptors have been found to interact with endogenous peptide ligands that share certain pharmacologic properties with opioid drugs. These peptide ligands are derived from at least three different prohormones located in both... 

Mizoguchi, H., Tseng, L. F., Suzuki, T., Sora, I. and Narita, M. Recent advances in the search for the p-opioidergic system differential mechanism of g-protein activation induced by endogenous p-opioid peptides, endomorphin and 5-endorphin. Jpn. J. Pharmacol. 89 239-244, 2002. 

Table 31-1 Opioid Receptor Subtypes, Their Functions, and Their Endogenous Peptide Affinities. ...

Three families of endogenous opioid peptides have been described in detail the endorphins, the pentapeptide enkephalins methionine-enkephalin (met-enkephalin) and leucine-enkephalin (leu-enkephalin), and the dynorphins. The three families of opioid receptors have overlapping affinities for these endogenous peptides (Table 31-1). 

There are dozens of presynaptic receptors for endogenous peptides. This review will focus on receptors for four peptides or peptide families the opioid peptides, neuropeptide Y and related peptides, adrenocorticotropic hormone (corticotropin, ACTH), and the orexins. This choice is representative, since part of the receptors inhibit and part of them facilitate transmitter release moreover, the receptors under consideration are coupled to the major G proteins, namely Gl/(), Gs and Gq (Table 1). 

Elevation in spinal dynorphin content has also been seen in condition of opioid-induced pain state (Vanderah et al., 2000). Although dynorphine was originally identified as an endogenous K-opioid agonist and may act as an endogenous antinociceptive peptide under certain conditions, considerable... 

The opioid alkaloids are classic examples of non-peptide ligands that have later been discovered to be mimetics of endogenous peptides. For example, morphine 5 (Figure 1.4.3) imitates the effect of flexible peptides, for example Met-enkephalin 4, at the common recognition site of the receptor for both compounds... 

Endogenous Peptides for Delta Opioid Receptors and Analogues... 

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