Effects of oxytocin and oxytocin receptor antagonist atosiban on nociception and morphine analgesia in rats
Objective: Oxytocin is a peptide-based hormone released from the supraoptic nucleus and paraventricular nucleus in the hypothalamus and consisting of nine amino acids. It has been shown that oxytocin may have an effect on opiate receptors. Atosiban is a oxytocin receptor antagonist. Our aim in this study was to investigate thee ffects of oxytocin and atosiban on nociception and morphine analgesia.
Method:In our study, 48 Wistar Albino 230-260 g male rats were used. The animals were divided into eight groups (control, 200 μg/kg oxytocin, 3 mg/kg atosiban, oxytocin+ atosiban, 5 mg/kg morphine, morphine+ oxytocin, morphine+atosiban and morphine+ oxytocin+ atosiban). Serum physiologic to the control group, oxytocin and atosiban were given intraperitoneally(i.p.) at the indicated doses to the other groups. Morphine was administered subcutaneously(s.c.). Analgesic effects were assessed by hot plate and tail flick analgesia tests. The resulting analgesic effect was measured and recorded at the 15th, 30th, 60th, 90th and 120th minutes. Assessment of analgesic effect was formulated as% analgesia (MPE) (% analgesia = 100x [post drug reaction time-pre drug reaction time]/[cut off time-pre drug reaction time]).
Results: Oxytocin showed analgesic activity (p<0,05). Atosiban showed hyperalgesic activity and decreased the analgesic activity of oxytocin when given with oxytocin (p<0,05). Oxytocin increased the analgesic activity of morphine (p<0.05). In addition, although atosiban did not alter the analgesic activity of morphine, morphine analgesia increased by oxytocin was reduced (p<0.05).
Conclusion: According to these results, it can be said that although atosiban does not effect on the analgesic effect of morphine alone, it blocks the effect of oxytocin on morphine analgesia.
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