?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Ingested+placenta+blocks+the+effect+of+morphine+on+gut+transit+in+Long%E2%80%93Evans+rats&rft.creator=Corpening%2C+Dr.+James+W.&rft.creator=Doerr%2C+Dr.+Jean+C.&rft.creator=Kristal%2C+Dr.+Mark+B.&rft.subject=Behavioral+Neuroscience&rft.description=Opioids+produce+antinociception%2C+and+ingested+placenta+or+amniotic+fluid+modifies+that+antinociception.+More+specifically%2C+ingested+placenta+enhances+the+antinociception+produced+by+selective+activation+of+central+n-opioid+or+y-opioid+receptors+but+attenuates+that+produced+by+activation+of+central+A-opioid+receptors.+Opioids+also+slow+gut+transit+by+acting+on+central+or+peripheral+A-opioid+receptors.+Therefore%2C+we+hypothesized+that+ingested+placenta+would+reverse+the+slowing+of+gut+transit+that+is+produced+by+morphine%2C+a+preferential+A-opioid-receptor+agonist.+Rats+were+injected+with+morphine+either+centrally+or+systemically+and+fed+placenta%2C+after+which+gastrointestinal+transit+was+evaluated.+We+report+here+that+ingested+placenta+reversed+the+slowing+of+gut+transit+produced+by+centrally+administered+morphine+but+did+not+affect+the+slowing+of+gut+transit+produced+by+systemically+administered+morphine.+These+results+suggest+another+likely+consequence+of+placentophagia+at+parturition+in+mammals%E2%80%94reversal+of+opioid-mediated%2C+pregnancy-based+disruption+of+gastrointestinal+function%E2%80%94as+well+as+an+important+consideration+in+opioid-based+treatments+for+pain+in+humans%E2%80%94enhancement+of+desirable+effects+with+attenuation+of+adverse+effects.&rft.publisher=Elsevier&rft.date=2004&rft.type=Journal+(Paginated)&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F5728%2F1%2FCorpening.pdf&rft.identifier=++Corpening%2C+Dr.+James+W.+and+Doerr%2C+Dr.+Jean+C.+and+Kristal%2C+Dr.+Mark+B.++(2004)+Ingested+placenta+blocks+the+effect+of+morphine+on+gut+transit+in+Long%E2%80%93Evans+rats.++%5BJournal+(Paginated)%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F5728%2F