Guinea-pigs treated with beta-endorphin fragments DTgammaE and DEgammaE exhibit reduced morphine inhibition of electrically-induced contractions.
Prog Neuropsychopharmacol Biol Psychiatry
; 24(1): 51-9, 2000 Jan.
Article
in En
| MEDLINE
| ID: mdl-10659983
ABSTRACT
The effect exerted by two gamma-endorphin derivatives (DTgammaE and DEgammaE) was investigated on morphine-induced inhibition on the electrically contractions of guinea pig ileum in vitro. Morphine (1x10(-8)-5x10(-8)-1x10(-7) M) dose dependently and significantly reduced the E.C. of guinea pig ileum, IC50=6.5x10(-8) M (Confidence limits 3.7x10(-8)-9.1x10(-8)). DTgammaE and DEgammaEper se (1x10(-6)-5x10(-6)-1x10(-5) M) did not modify significantly the E.C. of guinea pig ileum. Furthermore, DTgammaE or DEgammaE injection 10-30-60 min before morphine, did not affect the inhibitory effect of morphine on the E.C. of guinea pig ileum. By contrast, ilea from guinea-pigs treated for 4 days with DTgammaE or DEgammaE (1 mg/Kg/i.p.) resulted less sensitive to the inhibitory effect of morphine, IC50=8.3x10(-7) M (Confidence limits 1.4x10(-6)-3.5x10(-7)) for DTgammaE and IC50=7.7x10(-7) M (Confidence limits 2.7x10(-6)-8.7x10(-7)) for DEgammaE. Our results indicate that chronic treatment of guinea pigs with DTgammaE or DEgammaE induces a significant reduction of the inhibitory effect of morphine on the E.C. of guinea-pig ileum thus confirming an important functional interaction between gamma-endorphin derivatives and opioid system.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Peptide Fragments
/
Beta-Endorphin
/
Endorphins
/
Analgesics, Opioid
/
Morphine
/
Muscle Contraction
Limits:
Animals
Language:
En
Journal:
Prog Neuropsychopharmacol Biol Psychiatry
Year:
2000
Document type:
Article
Affiliation country: