Effects of morphine and naloxone on the release of oxytocin and on milk ejection in dairy cows.

摘要: The aim of this study was to investigate the action opioids (the mu receptor agonist morphine) and antagonist naloxone on inhibition oxytocin release milk let-down in response milking dairy cows. In first experiment, cows were injected with 0, 21, 70 210 mg morphine 10 min before four successive days. Plasma levels after 1 manual stimulation udder reduced by morphine, inhibited at latter dose. second a control (or 350 following day if not effective) inhibit flow. On inhibiting dose given naloxone. Naloxone injection had no effect plasma concentrations, but abolished potentiated milking. alone increased during milking, suggesting involvement opioid system A model has been developed for effects Morphine suppressed dose-dependent manner reversible