@misc{cogprints5764,
          volume = {35},
          number = {4},
          author = {Dr. Mark B. Kristal and A. C. Thompson and H.L. Grishkat},
           title = {Placenta ingestion enhances opiate analgesia in rats.},
       publisher = {Pergamon Press},
         journal = {Physiology \& Behavior},
           pages = {481--486},
            year = {1985},
        keywords = {opiates, opioids, placentophagia, placenta, amniotic fluid, delivery, rat, POEF, naltrexone, analgesia, pain, tail-flick test, footshock, afterbirth, mammal},
             url = {http://cogprints.org/5764/},
        abstract = {Analgesia, produced by either a morphine injection or footshock, was monitored (using a tail-flick test) in nonpregnant female rats. Analgesia was induced within minutes of having the rats eat on of several substances. When the substance eaten was rat placenta, both the morphine- and shock-induced types of analgesia were significantly grater than in controls that ingested other substances (or nothing). When footshock (hind-paw) was administered in conjunction with the opiate antagonist naltrexone, the analgesia produced was attenuated but detectable; in this case, placenta ingestion did not enhance the analgesia, suggesting that the effect of placenta is specific to opiate-mediated analgesia. It is possible that this enhancement of analgesia is one of the principal benefits to mammalian mothers of ingesting placenta and birth fluids (placentophagia) at delivery.}
}

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