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TY - GEN ID - cogprints5771 UR - http://cogprints.org/5771/ A1 - DiPirro, Jean M. A1 - Kristal, Dr. Mark B. Y1 - 2004/// N2 - Ingestion of placenta or amniotic fluid produces a dramatic enhancement of centrally mediated opioid antinociception in the rat. The present experiments investigated the role of each opioid receptor type (m, d, k) in the antinociception-modulating effects of Placental Opioid-Enhancing Factor (POEF?presumably the active substance). Antinociception was measured on a 52 C hotplate in adult, female rats after they ingested placenta or control substance (1.0 g) and after they received an intracerebroventricular injection of a d-specific ([D-Pen2,D-Pen5]enkephalin (DPDPE); 0, 30, 50, 62, or 70 nmol), m-specific ([D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAMGO); 0, 0.21, 0.29, or 0.39 nmol), or k-specific (U-62066; spiradoline; 0, 100, 150, or 200 nmol) opioid receptor agonist. The results showed that ingestion of placenta potentiated d- and k-opioid antinociception, but attenuated m-opioid antinociception. This finding of POEF action as both opioid receptor-specific and complex provides an important basis for understanding the intrinsic pain-suppression mechanisms that are activated during parturition and modified by placentophagia, and important information for the possible use of POEF as an adjunct to opioids in pain management. PB - Elsevier KW - placentophagia KW - POEF KW - antinociception KW - opioid KW - parturition KW - DPDPE KW - DAMGO KW - spiradoline KW - rat KW - opioid receptor KW - delta KW - kappa KW - mu KW - pain TI - Placenta ingestion by rats enhances d- and k-opioid antinociception, but suppresses m-opioid antinociception SP - 22 AV - public EP - 33 ER -