title: Placenta ingestion by rats enhances d- and k-opioid antinociception, but suppresses m-opioid antinociception
creator: DiPirro, Jean M.
creator: Kristal, Dr. Mark B.
subject: Psychobiology
subject: Neuropharmacology
subject: Behavioral Neuroscience
description: 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.
publisher: Elsevier
date: 2004
type: Journal (Paginated)
type: PeerReviewed
format: application/pdf
identifier: http://cogprints.org/5771/1/DiPirro_and_Kristal.pdf
identifier:   DiPirro, Jean M. and Kristal, Dr. Mark B.  (2004) Placenta ingestion by rats enhances d- and k-opioid antinociception, but suppresses m-opioid antinociception.  [Journal (Paginated)]     
relation: http://cogprints.org/5771/