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Effects of casoxin 4 on morphine inhibition of small animal intestinal contractility and gut transit in the mouse.

Patten GS, Head RJ, Abeywardena MY - Clin Exp Gastroenterol (2011)

Bottom Line: Chronic opioid analgesia has the debilitating side-effect of constipation in human patients.Using a polymeric dye, Poly R-478, the opioid antagonists casoxin 4 and lactoferroxin A were tested orally for blocking activity of morphine inhibition of gut transit in vivo by single or double gavage techniques.In contrast to naloxone, relatively high oral doses of the μ-opioid receptor antagonists, casoxin 4 and lactoferroxin A, applied before and after morphine injection were unable to antagonize morphine inhibition of gut transit.

View Article: PubMed Central - PubMed

Affiliation: CSIRO Preventative Health National Research Flagship, Adelaide, Australia;

ABSTRACT

Background and aims: Chronic opioid analgesia has the debilitating side-effect of constipation in human patients. The major aims of this study were to: 1) characterize the opioid-specific antagonism of morphine-induced inhibition of electrically driven contraction of the small intestine of mice, rats, and guinea pigs; and 2) test if the oral delivery of small milk-derived opioid antagonist peptides could block morphine-induced inhibition of intestinal transit in mice.

Methods: Mouse, rat, and guinea pig intact ileal sections were electrically stimulated to contract and inhibited with morphine in vitro. Morphine inhibition was then blocked by opioid subtype antagonists in the mouse and guinea pig. Using a polymeric dye, Poly R-478, the opioid antagonists casoxin 4 and lactoferroxin A were tested orally for blocking activity of morphine inhibition of gut transit in vivo by single or double gavage techniques.

Results: The guinea pig tissue was more sensitive to morphine inhibition compared with the mouse or the rat (IC(50) [half maximal inhibitory concentration] values as nmol/L ± SEM were 34 ± 3, 230 ± 13, and 310 ± 14 respectively) (P < 0.01). The inhibitory influence of opioid agonists (IC(50)) in electrically driven ileal mouse preparations were DADLE ([D-Ala(2), D-Leu(5)]-enkephalin) ≥ met-enkephalin ≥ dynorphin A ≥ DAMGO ([D-Ala(2), N-Me-Phe(4), Glyol(5)]-enkephalin) > morphine > morphiceptin as nmol/L 13.9, 17.3, 19.5, 23.3, 230, and 403 respectively. The mouse demonstrated predominantly κ- and δ-opioid receptor activity with a smaller μ-opioid receptor component. Both mouse and guinea pig tissue were sensitive to casoxin 4 antagonism of morphine inhibition of contraction. In contrast to naloxone, relatively high oral doses of the μ-opioid receptor antagonists, casoxin 4 and lactoferroxin A, applied before and after morphine injection were unable to antagonize morphine inhibition of gut transit.

Conclusions: Casoxin 4 reverses morphine-induced inhibition of contraction in mice and guinea pigs in vitro but fails to influence morphine inhibition of mouse small intestinal transit by the oral route.

No MeSH data available.


Related in: MedlinePlus

Effect of opioid agonists on inhibition of the electrically driven mouse ileum with 0.1 μmol/L ibuprofen. Opioids: (▪) morphine, (○) DAMGO, (▾) dynophin[1–13]-A, (•) met-enkephalin, (♦) DADLE, (□) morphiceptin. Each point represents the mean ± SEM at each dose tested on n = 3–4 mice in duplicate. On the graph, the letter “a” as determined by ANOVA and Bonferroni post tests, at 10−8 mol/L, the % inhibition of electrically driven contraction by DAMGO, DADLE, and met-enkephalin are significantly higher than morphine, dynophin[1–13]-A, and morphiceptin; for “b” at 10−7 mol/L, DAMGO, dynophin[1–13]-A, DADLE, and met-enkephalin are higher than morphine and morphiceptin; and “c” at 10−6 mol/L, DAMGO is higher than morphine (P < 0.05).Abbreviations: DADLE, [D-Ala2, D-Leu5]-enkephalin; DAMGO, [D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin; SEM, standard error of the mean.
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f2-ceg-4-023: Effect of opioid agonists on inhibition of the electrically driven mouse ileum with 0.1 μmol/L ibuprofen. Opioids: (▪) morphine, (○) DAMGO, (▾) dynophin[1–13]-A, (•) met-enkephalin, (♦) DADLE, (□) morphiceptin. Each point represents the mean ± SEM at each dose tested on n = 3–4 mice in duplicate. On the graph, the letter “a” as determined by ANOVA and Bonferroni post tests, at 10−8 mol/L, the % inhibition of electrically driven contraction by DAMGO, DADLE, and met-enkephalin are significantly higher than morphine, dynophin[1–13]-A, and morphiceptin; for “b” at 10−7 mol/L, DAMGO, dynophin[1–13]-A, DADLE, and met-enkephalin are higher than morphine and morphiceptin; and “c” at 10−6 mol/L, DAMGO is higher than morphine (P < 0.05).Abbreviations: DADLE, [D-Ala2, D-Leu5]-enkephalin; DAMGO, [D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin; SEM, standard error of the mean.

Mentions: The effect of a range of opioid receptor-specific agonists on the inhibition of electrically driven contractions in the mouse ileum is given in Figure 2. The relative order of potency (opioid receptor subtype, IC50 in nmol/L ± SEM) was DADLE (δ, 13.9 ± 2.1) ≥ met-enkephalin (δ, 17.9 ± 3.3) ≥ dynorphin[1–13] A (κ, 19.5 ± 4.0) ≥ DAMGO (μ, 23.3 ± 4.1) > morphine (μ, 230 ± 13) and morphiceptin (μ, 403 ± 19). The IC50 values for DADLE, met-enkephalin, and dynorphin[1–13] A were significantly lower than for morphine, and the morphine value was lower than for morphiceptin (P < 0.05). The differences between the various opioid agonists at 10−8, 10−7, and 10−6 mol/L are given in the legend to Figure 2. The μ-opioid receptor agonists (morphine and morphiceptin) had maximal inhibition of 48% and 50%, whereas the more active agents ranged between 64% and 76% maximal inhibition. It is of note that the dose response curve shapes of the various opioid agonists are different in Figure 2. However, similar variability in curve shapes has been observed for the inhibition of electrically driven contractions by enkephalins in vitro for the guinea pig ileum.7


Effects of casoxin 4 on morphine inhibition of small animal intestinal contractility and gut transit in the mouse.

Patten GS, Head RJ, Abeywardena MY - Clin Exp Gastroenterol (2011)

Effect of opioid agonists on inhibition of the electrically driven mouse ileum with 0.1 μmol/L ibuprofen. Opioids: (▪) morphine, (○) DAMGO, (▾) dynophin[1–13]-A, (•) met-enkephalin, (♦) DADLE, (□) morphiceptin. Each point represents the mean ± SEM at each dose tested on n = 3–4 mice in duplicate. On the graph, the letter “a” as determined by ANOVA and Bonferroni post tests, at 10−8 mol/L, the % inhibition of electrically driven contraction by DAMGO, DADLE, and met-enkephalin are significantly higher than morphine, dynophin[1–13]-A, and morphiceptin; for “b” at 10−7 mol/L, DAMGO, dynophin[1–13]-A, DADLE, and met-enkephalin are higher than morphine and morphiceptin; and “c” at 10−6 mol/L, DAMGO is higher than morphine (P < 0.05).Abbreviations: DADLE, [D-Ala2, D-Leu5]-enkephalin; DAMGO, [D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin; SEM, standard error of the mean.
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Related In: Results  -  Collection

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f2-ceg-4-023: Effect of opioid agonists on inhibition of the electrically driven mouse ileum with 0.1 μmol/L ibuprofen. Opioids: (▪) morphine, (○) DAMGO, (▾) dynophin[1–13]-A, (•) met-enkephalin, (♦) DADLE, (□) morphiceptin. Each point represents the mean ± SEM at each dose tested on n = 3–4 mice in duplicate. On the graph, the letter “a” as determined by ANOVA and Bonferroni post tests, at 10−8 mol/L, the % inhibition of electrically driven contraction by DAMGO, DADLE, and met-enkephalin are significantly higher than morphine, dynophin[1–13]-A, and morphiceptin; for “b” at 10−7 mol/L, DAMGO, dynophin[1–13]-A, DADLE, and met-enkephalin are higher than morphine and morphiceptin; and “c” at 10−6 mol/L, DAMGO is higher than morphine (P < 0.05).Abbreviations: DADLE, [D-Ala2, D-Leu5]-enkephalin; DAMGO, [D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin; SEM, standard error of the mean.
Mentions: The effect of a range of opioid receptor-specific agonists on the inhibition of electrically driven contractions in the mouse ileum is given in Figure 2. The relative order of potency (opioid receptor subtype, IC50 in nmol/L ± SEM) was DADLE (δ, 13.9 ± 2.1) ≥ met-enkephalin (δ, 17.9 ± 3.3) ≥ dynorphin[1–13] A (κ, 19.5 ± 4.0) ≥ DAMGO (μ, 23.3 ± 4.1) > morphine (μ, 230 ± 13) and morphiceptin (μ, 403 ± 19). The IC50 values for DADLE, met-enkephalin, and dynorphin[1–13] A were significantly lower than for morphine, and the morphine value was lower than for morphiceptin (P < 0.05). The differences between the various opioid agonists at 10−8, 10−7, and 10−6 mol/L are given in the legend to Figure 2. The μ-opioid receptor agonists (morphine and morphiceptin) had maximal inhibition of 48% and 50%, whereas the more active agents ranged between 64% and 76% maximal inhibition. It is of note that the dose response curve shapes of the various opioid agonists are different in Figure 2. However, similar variability in curve shapes has been observed for the inhibition of electrically driven contractions by enkephalins in vitro for the guinea pig ileum.7

Bottom Line: Chronic opioid analgesia has the debilitating side-effect of constipation in human patients.Using a polymeric dye, Poly R-478, the opioid antagonists casoxin 4 and lactoferroxin A were tested orally for blocking activity of morphine inhibition of gut transit in vivo by single or double gavage techniques.In contrast to naloxone, relatively high oral doses of the μ-opioid receptor antagonists, casoxin 4 and lactoferroxin A, applied before and after morphine injection were unable to antagonize morphine inhibition of gut transit.

View Article: PubMed Central - PubMed

Affiliation: CSIRO Preventative Health National Research Flagship, Adelaide, Australia;

ABSTRACT

Background and aims: Chronic opioid analgesia has the debilitating side-effect of constipation in human patients. The major aims of this study were to: 1) characterize the opioid-specific antagonism of morphine-induced inhibition of electrically driven contraction of the small intestine of mice, rats, and guinea pigs; and 2) test if the oral delivery of small milk-derived opioid antagonist peptides could block morphine-induced inhibition of intestinal transit in mice.

Methods: Mouse, rat, and guinea pig intact ileal sections were electrically stimulated to contract and inhibited with morphine in vitro. Morphine inhibition was then blocked by opioid subtype antagonists in the mouse and guinea pig. Using a polymeric dye, Poly R-478, the opioid antagonists casoxin 4 and lactoferroxin A were tested orally for blocking activity of morphine inhibition of gut transit in vivo by single or double gavage techniques.

Results: The guinea pig tissue was more sensitive to morphine inhibition compared with the mouse or the rat (IC(50) [half maximal inhibitory concentration] values as nmol/L ± SEM were 34 ± 3, 230 ± 13, and 310 ± 14 respectively) (P < 0.01). The inhibitory influence of opioid agonists (IC(50)) in electrically driven ileal mouse preparations were DADLE ([D-Ala(2), D-Leu(5)]-enkephalin) ≥ met-enkephalin ≥ dynorphin A ≥ DAMGO ([D-Ala(2), N-Me-Phe(4), Glyol(5)]-enkephalin) > morphine > morphiceptin as nmol/L 13.9, 17.3, 19.5, 23.3, 230, and 403 respectively. The mouse demonstrated predominantly κ- and δ-opioid receptor activity with a smaller μ-opioid receptor component. Both mouse and guinea pig tissue were sensitive to casoxin 4 antagonism of morphine inhibition of contraction. In contrast to naloxone, relatively high oral doses of the μ-opioid receptor antagonists, casoxin 4 and lactoferroxin A, applied before and after morphine injection were unable to antagonize morphine inhibition of gut transit.

Conclusions: Casoxin 4 reverses morphine-induced inhibition of contraction in mice and guinea pigs in vitro but fails to influence morphine inhibition of mouse small intestinal transit by the oral route.

No MeSH data available.


Related in: MedlinePlus