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Placenta ingestion by rats enhances d- and k-opioid antinociception, but suppresses m-opioid antinociception

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)]

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Abstract

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.

Item Type:Journal (Paginated)
Keywords:placentophagia, POEF, antinociception, opioid, parturition, DPDPE, DAMGO, spiradoline, rat, opioid receptor, delta, kappa, mu, pain
Subjects:Psychology > Psychobiology
Neuroscience > Neuropharmacology
Neuroscience > Behavioral Neuroscience
ID Code:5771
Deposited By:Kristal, Mark B.
Deposited On:22 Oct 2007 11:43
Last Modified:11 Mar 2011 08:56

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