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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

Casoxin 4 antagonism of morphine inhibition of electrically driven contraction in the mouse pre-incubated with 0.1 μmol/L ibuprofen (▪) and guinea pig ileum (•). The concentrations of morphine used to induce approximately 50% of contraction were 1 μmol/L for the mouse and 0.1 μmol/L for the guinea pig. This is a representative graph of three determinations on different animals in duplicate. The IC50 values for casoxin 4 for n = 3 determinations in duplicate for the guinea pig and n = 3 determinations in duplicate for the mouse were 2.1 ± 0.2 μmol/L and 11.3 ± 0.5 μmol/L, respectively, which were significantly different by two-tailed Student’s t-test (P < 0.001).Abbreviations: GP, guinea pig; IC50, half maximal inhibitory concentration; Mo, mouse.
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f3-ceg-4-023: Casoxin 4 antagonism of morphine inhibition of electrically driven contraction in the mouse pre-incubated with 0.1 μmol/L ibuprofen (▪) and guinea pig ileum (•). The concentrations of morphine used to induce approximately 50% of contraction were 1 μmol/L for the mouse and 0.1 μmol/L for the guinea pig. This is a representative graph of three determinations on different animals in duplicate. The IC50 values for casoxin 4 for n = 3 determinations in duplicate for the guinea pig and n = 3 determinations in duplicate for the mouse were 2.1 ± 0.2 μmol/L and 11.3 ± 0.5 μmol/L, respectively, which were significantly different by two-tailed Student’s t-test (P < 0.001).Abbreviations: GP, guinea pig; IC50, half maximal inhibitory concentration; Mo, mouse.

Mentions: Concentrations of morphine required to inhibit electrically driven contractions by approximately 50% in the guinea pig and mouse were 0.1 and 1.0 μmol/L respectively. The μ-specific opioid antagonist, casoxin 4, one of the smallest and most potent opioid antagonist peptides yet described, is a synthetic tetrapeptide fragment of casoxin 6.24,25 The potency of casoxin 4 to antagonize morphine inhibition of electrically driven contractions is shown in Figure 3. The IC50 for casoxin 4 reversal of morphine inhibition is 2.1 ± 0.2 μmol/L for the guinea pig and 11.3 ± 0.5 μmol/L for the mouse, respectively, which were significantly different by Student’s t-test (P < 0.001). Using the electrical regimes employed here, the guinea pig was far more sensitive and had a higher maximal inhibition to morphine compared with the mouse. Furthermore, casoxin 4 overcame only 50% of the morphine inhibition of electrically driven contraction in the mouse. It was found that all inhibition of contractility could be antagonized by 0.1–1.0 μmol/L naloxone (results not shown).


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)

Casoxin 4 antagonism of morphine inhibition of electrically driven contraction in the mouse pre-incubated with 0.1 μmol/L ibuprofen (▪) and guinea pig ileum (•). The concentrations of morphine used to induce approximately 50% of contraction were 1 μmol/L for the mouse and 0.1 μmol/L for the guinea pig. This is a representative graph of three determinations on different animals in duplicate. The IC50 values for casoxin 4 for n = 3 determinations in duplicate for the guinea pig and n = 3 determinations in duplicate for the mouse were 2.1 ± 0.2 μmol/L and 11.3 ± 0.5 μmol/L, respectively, which were significantly different by two-tailed Student’s t-test (P < 0.001).Abbreviations: GP, guinea pig; IC50, half maximal inhibitory concentration; Mo, mouse.
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Related In: Results  -  Collection

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f3-ceg-4-023: Casoxin 4 antagonism of morphine inhibition of electrically driven contraction in the mouse pre-incubated with 0.1 μmol/L ibuprofen (▪) and guinea pig ileum (•). The concentrations of morphine used to induce approximately 50% of contraction were 1 μmol/L for the mouse and 0.1 μmol/L for the guinea pig. This is a representative graph of three determinations on different animals in duplicate. The IC50 values for casoxin 4 for n = 3 determinations in duplicate for the guinea pig and n = 3 determinations in duplicate for the mouse were 2.1 ± 0.2 μmol/L and 11.3 ± 0.5 μmol/L, respectively, which were significantly different by two-tailed Student’s t-test (P < 0.001).Abbreviations: GP, guinea pig; IC50, half maximal inhibitory concentration; Mo, mouse.
Mentions: Concentrations of morphine required to inhibit electrically driven contractions by approximately 50% in the guinea pig and mouse were 0.1 and 1.0 μmol/L respectively. The μ-specific opioid antagonist, casoxin 4, one of the smallest and most potent opioid antagonist peptides yet described, is a synthetic tetrapeptide fragment of casoxin 6.24,25 The potency of casoxin 4 to antagonize morphine inhibition of electrically driven contractions is shown in Figure 3. The IC50 for casoxin 4 reversal of morphine inhibition is 2.1 ± 0.2 μmol/L for the guinea pig and 11.3 ± 0.5 μmol/L for the mouse, respectively, which were significantly different by Student’s t-test (P < 0.001). Using the electrical regimes employed here, the guinea pig was far more sensitive and had a higher maximal inhibition to morphine compared with the mouse. Furthermore, casoxin 4 overcame only 50% of the morphine inhibition of electrically driven contraction in the mouse. It was found that all inhibition of contractility could be antagonized by 0.1–1.0 μmol/L naloxone (results not shown).

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