?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Placenta+ingestion+by+rats+enhances+d-+and+k-opioid+antinociception%2C+but+suppresses+m-opioid+antinociception&rft.creator=DiPirro%2C+Jean+M.&rft.creator=Kristal%2C+Dr.+Mark+B.&rft.subject=Psychobiology&rft.subject=Neuropharmacology&rft.subject=Behavioral+Neuroscience&rft.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%2C+d%2C+k)+in+the+antinociception-modulating+effects+of+Placental+Opioid-Enhancing+Factor+(POEF%E2%80%94presumably+the+active+substance).+Antinociception+was+measured+on+a+52+C+hotplate+in+adult%2C+female+rats+after+they+ingested+placenta+or+control+substance+(1.0+g)+and+after+they+received+an+intracerebroventricular+injection+of+a+d-specific+(%5BD-Pen2%2CD-Pen5%5Denkephalin+(DPDPE)%3B+0%2C+30%2C+50%2C+62%2C+or+70+nmol)%2C+m-specific+(%5BD-Ala2%2CN-MePhe4%2CGly5-ol%5Denkephalin+(DAMGO)%3B+0%2C+0.21%2C+0.29%2C+or+0.39+nmol)%2C+or+k-specific%0D%0A(U-62066%3B+spiradoline%3B+0%2C+100%2C+150%2C+or+200+nmol)+opioid+receptor+agonist.+The+results+showed+that+ingestion+of+placenta+potentiated+d-+and+k-opioid+antinociception%2C+but+attenuated+m-opioid+antinociception.+This+finding+of+POEF+action+as+both+opioid+receptor-specific+and+complex%0D%0Aprovides+an+important+basis+for+understanding+the+intrinsic+pain-suppression+mechanisms+that+are+activated+during+parturition+and+modified+by+placentophagia%2C+and+important+information+for+the+possible+use+of+POEF+as+an+adjunct+to+opioids+in+pain+management.&rft.publisher=Elsevier&rft.date=2004&rft.type=Journal+(Paginated)&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F5771%2F1%2FDiPirro_and_Kristal.pdf&rft.identifier=++DiPirro%2C+Jean+M.+and+Kristal%2C+Dr.+Mark+B.++(2004)+Placenta+ingestion+by+rats+enhances+d-+and+k-opioid+antinociception%2C+but+suppresses+m-opioid+antinociception.++%5BJournal+(Paginated)%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F5771%2F