Biopsychology of Parturition
Mark Kristal Principal Investigator
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Mothers of almost all nonaquatic, nonhuman mammalian species ingest amniotic fluid and placenta during delivery. Dr. Kristal has demonstrated that the increased contact, associated with this ingestion from the surface of the young, causes an accelerated onset of maternal behavior toward those young. Moreover, he has shown that this enigmatic behavior helps to relieve the mother's pain and discomfort during delivery. A substance contained in the afterbirth materials, which he has named the Placental Opioid-Enhancing Factor or POEF, seems to potentiate any ongoing opioid-mediated analgesia but does not by itself produce analgesia. The importance of this factor is that during labor and delivery, pregnancy-mediated analgesia can be maximized without so massive a release of endogenous opiates. Thus, it is possible to relieve pain with only a minimum brain opioid level. This is very important since too high a level of natural occurring opioids during and immediately after birth can detrimentally interfere with maternal behavior. A major problem that has prevented a thorough understanding of this fundamental behavior is the inability to prevent delivering mothers from ingesting any placenta or amniotic fluid without stressing the mother, disrupting delivery, or blocking the mother's natural behaviors. Dr. Kristal has overcome this obstacle by a clever series of experiments in which activated charcoal administration is used to block the utilization of subsequently ingested POEF. He can now determine its effects on pain threshold, maternal and other behaviors, as well as natural characteristics of delivery and fertility. These findings will enhance our knowledge of the physiological mechanisms of birth and postpartum behavior. Moreover, the research has importance for a broader range of mammalian taxa, since it could point the way toward the development of a new class of non-narcotic analgesics and shed new light on fundamental processes involved in pain and the body's reaction to it.