P-Opioid receptor

Klebsiella pneumoniae infection in mice after intravenous treatment (Meisel and Schlimme, 1996). The mechanism by which milk protein derived peptides exert their immunomodulatory effects is not yet defined. However, opioid peptides may affect the immunoreactivity of lymphocytes via the opiate receptor. There is a remarkable relationship between the immune system and opioid peptides, because opioid p, receptors for endorphins are present on T lymphocytes and human phagocytic leukocytes (Meisel, 1998). 

Morphine will be described in detail and other opioid analgesics principally in so far as they differ. Morphine acts mainly on the opioid p,-receptor (analgesia, euphoria, dependence) and p ceptors (respiratory depression, reduced gut motility). The principal actions of morphine may be summarised ... 

Codeine has only about one tenth the analgesic potency of morphine this is a consequence of the blocked phenolic hydroxyl group, which prohibits binding to opioid p-receptors. A small amount of codeine (10%) is converted to morphine (see Figure 34 36), which accounts for the... 

Although morphine is a classical p opioid receptor agonist, its intrinsic activity is known to be lower than that of a representative full p opioid receptor agonist, DAMGO. Moreover, recent reports showed that morphine was a partial agonist for the opioid p receptor in some pharmacological assays. See [34-38]. 

Fentanyl Duragesic Actiq Fentora Sublimaze Opioid p-receptor agonist mp 87.5 °C Treatment of severe pain spinal and epidural anesthesia 0 s Ph... 

Susceptibilify factors Genetic In an observational study in 212 pregnant women, epidural morphine 2 mg bd was administered for postcesarean analgesia [140 ]. There were three different polymorphisms of the human opioid p receptor A118G gene— AA, AG, and GG. The authors suggested that the recessive G allele may protect against the development of pruritus, since the GG polymorphism was associated with a lower incidence of pruritus (in 4.8%) compared with the dominant AA (53%) and AG (42%). 

Picenadol opioid analgesic (-r)-isomer (3.S,4R) p-receptor agonist (-)-isomer (3R.4.5) weak p-receptor antagonist... 

Pasternak GW (2001) Incomplete cross tolerance and multiple p opioid peptide receptors. Trend Pharmacol Sci 22 67-70... 

The GABAB-receptors, the muscarinic M2- and IVU-receptors for acetylcholine, the dopamine D2-, D3-and D4-receptors, the a2-adrenoceptors for noradrenaline, the 5-HTiA F-receptors for serotonin, and the opioid p-, 8- and K-receptors couple to G proteins of the Gi/o family and thereby lower [1] the cytoplasmic level of the second messenger cyclic AMP and [2] the open probability ofN- andP/Q-type Ca2+ channels (Table 1). The muscarinic Mr, M3- and M5-receptors for acetylcholine and the ai-adrenoceptors for noradrenaline couple to G proteins of the Gq/11 family and thereby increase the cytoplasmic levels of the second messengers inositol trisphosphate and diacylglycerol (Table 1). The dopamine Dr and D5-receptors and the (3-adrenoceptors for noradrenaline, finally, couple to Gs and thereby increase the cytoplasmic level of cyclic AMP. 

Major gastrointestinal effects include decreased gut motility and changes in secretion of gastric and intestinal fluids. Morphine and most p receptor agonists cause pupillary constriction. Some tolerance to this effect may develop, but addicts with high opioid levels will still have miosis. Respiratory depression is the usual cause of death from opioid overdose. 

Three distinct opioid receptor genes have been identified, namely the MOR (p), KOR (k), and DOR (8) genes. Although only one p receptor gene... 

The intoxicating effects of opioids appear to be due to their action as agonists on mu (p) receptors of the opioid neurotransmitter system. Competitive p opioid antagonists such as naloxone and naltrexone acutely reverse many of the adverse effects of opioids. To date we do not have specific antagonists for most other abused substances, so rapid pharmacologic reversal of intoxication is usually not possible. 

Schiller PW, Nguyen TM-D, Maziak LA, Lemieux C. A novel cyclic opioid peptide analog showing high preference for p-receptors. Biochem Biophys Res Commun 1985 127 558-564. 

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