title: Effect of dynorphin-(1-13) and related peptides on respiratory rate and morphine-induced respiratory rate depression.
abstract: Previous studies from our laboratory have shown that the opioid peptide dynorphin-(1-13), although not analgesic when given by itself, can inhibit morphine-induced analgesia in naive mice and potentiate it in morphine tolerant mice. In the present study, we examined the effect of dynorphin-(1-13) with two other dynorphin-like peptides, alpha-neoendorphin and dynorphin-(1-10) amide, on respiration. Our results show that none of the peptides studied had any significant activity on the respiratory rate in mice when given alone. However, in the presence of morphine, dynorphin-(1-13) antagonized the morphine-induced respiratory rate depression in morphine-tolerant animals; alpha-neoendorphin enhanced the morphine-induced respiratory rate depression in naive but had no effect in morphine-tolerant animals and dynorphin-(1-10) amide had no modulatory effect on the morphine-induced respiratory rate depression in either group of animals.
mesh_terms: D000818:Animals; D004361:Drug Tolerance; D004399:Dynorphins; D004723:Endorphins / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009020:Morphine / Q000037:antagonists & inhibitors*; D010446:Peptide Fragments / Q000494:pharmacology*; D011498:Protein Precursors / Q000494:pharmacology; D012119:Respiration / Q000187:drug effects*
chemical_list: D004723:Endorphins; D010446:Peptide Fragments; D011498:Protein Precursors; C025681:alpha-neoendorphin; C026843:dynorphin (1-13); D004399:Dynorphins; D009020:Morphine; C039666:dynorphin amide (1-10)