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TY - GEN ID - cogprints5800 UR - http://cogprints.org/5800/ A1 - Tarapacki, J. A. A1 - Thompson, A. C. A1 - Kristal, Dr. Mark B. Y1 - 1992/// N2 - Ingestion of amniotic fluid or placenta by rats has been shown to enhance opioid-mediated analgesia induced by morphine injection, footshock, vaginal/cervical stimulation, or late pregnancy. This enhancement by ingestion appears to be specific to the central actions of opioids. The present study was designed to examine the possibility that information traveling via the vagus nerve might be involved in mediating this effect. Rats that had undergone either selective gastric vagotomy or sham vagotomy were injected with either morphine sulfate or vehicle and fed either placenta or a meat control. Enhancement was observed in rats that had undergone sham vagotomy but not in those that had undergone gastric vagotomy. These results support an interpretation of vagal involvement in the enhancement of opioid-mediated analgesia by placenta. PB - Pergamon Press KW - placenta KW - opioids KW - morphine KW - POEF KW - vagotomy KW - placentophagia KW - pain KW - analgesia KW - antinociception KW - tail-flick latency KW - vagus KW - rat TI - Gastric vagotomy blocks opioid analgesia enhancement produced by placenta ingestion SP - 179 AV - public EP - 182 ER -