Effects of prolyl-leucyl-glycinamide and cyclo(leucyl-glycine) on morphine-induced antinociception and brain mu, delta and kappa opiate receptors.
The effects of prolyl-leucyl-glycinamide and cyclo (leucyl-glycine) on morphine-induced antinociception in mice and on in vitro binding of 3H-ligands for opiate receptor subtypes (mu, delta and kappa) in the mouse brain homogenate were determined. Subcutaneous administration of either of the above peptides (1, 2, and 4 mg/kg) 10 min prior to the injection of morphine did not affect morphine-induced antinociception as evidenced by the identical ED50 values of morphine in vehicle and peptide treated groups. The binding of 3H-dihydromorphine and 3H-naloxone (mu receptors), 3H-D-Ala2-D-Leu5-enkephalin (delta receptors), and 3H-ethylketocyclazocine (kappa receptors) to opiate receptors in the mouse brain homogenate was also unaffected by both the peptides over a large concentration range. It is concluded that these peptides do not interact with brain opiate receptors.
D000698:Analgesia; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D004151:Dipeptides / Q000494:pharmacology*; D009075:MSH Release-Inhibiting Hormone / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D009479:Neuropeptides; D009619:Nociceptors / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D010456:Peptides, Cyclic; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu
D004151:Dipeptides; D009479:Neuropeptides; D010456:Peptides, Cyclic; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; C021166:cyclo(leucylglycine); D009020:Morphine; D009075:MSH Release-Inhibiting Hormone