Placenta ingestion enhances analgesia produced by vaginal/cervical stimulation in rats.
Ingestion of placenta has previously been shown to enhance opiate-mediated analgesia (measured as tail-flick latency) induced either by morphine injection or by footshock. The present study was designed to test whether placenta ingestion would enhance the partly opiate-mediated analgesia produced by vaginal/cervical stimulation. Nulliparous Sprague-Dawley rats were tested for analgesia, using tail-flick latency, during and after vaginal/cervical stimulation; the tests for vaginal/cervical stimulation-induced analgesia were administered both before and after the rats ate placenta or ground beef. Placenta ingestion, but not beef ingestion, significantly heightened vaginal/cervical stimulation-induced analgesia. A subsequent morphine injection provided evidence that, as in a previous report, placenta ingestion, but not beef ingestion, enhanced morphine-induced analgesia.
D000653:Amniotic Fluid / Q000502:physiology*; D000818:Animals; D002584:Cervix Uteri / Q000503:physiopathology*; D004723:Endorphins / Q000502:physiology; D005260:Female; D005502:Food; D009020:Morphine / Q000627:therapeutic use; D010146:Pain / Q000503:physiopathology*; D010920:Placenta / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012684:Sensory Thresholds; D014621:Vagina / Q000503:physiopathology*
D004723:Endorphins; D009020:Morphine