?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Ingestion+of+amniotic+fluid+enhances+the+facilitative+effect+of+VTA+morphine+on+the+onset+of+maternal+behavior+in+virgin+rats&rft.creator=Neumann%2C+Anne&rft.creator=Hoey%2C+Robert+F.&rft.creator=Daigler%2C+Lindsey+B.&rft.creator=Thompson%2C+Dr.+Alexis+C.&rft.creator=Kristal%2C+Dr.+Mark+B.&rft.subject=Behavioral+Biology&rft.subject=Neuroendocrinology&rft.subject=Psychobiology&rft.subject=Physiological+Psychology&rft.subject=Neuropharmacology&rft.subject=Behavioral+Neuroscience&rft.description=Previous+research+has+shown+that+injection+of+morphine+into+the+ventral+tegmental+area(VTA)+facilitates+the+onset+of+maternal+behavior+in+virgin+female+rats%2C+and+injection+of+the+opioid+antagonist+naltrexone+into+the+VTA+disrupts+the+onset+of+maternal+behavior+in+parturient+rats.+Placentophagia+%E2%80%93+ingestion+of+placenta+and+amniotic+fluid%2C+usually+at+parturition+%E2%80%93+modifies+central+opioid+processes.+Ingestion+of+the+active+substance+in+placenta+and+amniotic+fluid%2C+Placental+Opioid-Enhancing+Factor+(POEF)%2C+enhances+the+hypoalgesic+effect+of+centrally+administered+morphine%2C+and+more+specifically%2C+enhances+%CE%B4-+and+%CE%BA-opioid-receptor-%0D%0Amediated+hypoalgesia+and+attenuates+%CE%BC-opioid-receptor-mediated+hypoalgesia.+POEF+(in+placenta+or+amniotic+fluid)+ingestion+does+not%2C+by+itself%2C+produce+hypoalgesia.+In+the%0D%0Apresent+study%2C+we+tested+the+hypothesis+that+ingestion+of+amniotic+fluid+enhances+the+facilitative+effect+of+opioid+activity+(unilateral+morphine+injection)+in+the+VTA+on+the+rate+of+onset+of+maternal+behavior.+Virgin+female+Long-Evans+rats+were+given+one+intra-VTA+injection+of+morphine+sulfate+(0.0%2C+0.01%2C+or+0.03+%CE%BCg%2C+in+saline)+and+an+orogastric+infusion+of+0.25+ml+amniotic+fluid+or+saline+once+each+day+of+the+first+three+days+of+the+10-day+testing%0D%0Aperiod.+Subjects+were+continuously+exposed+to+foster+pups+that+were+replaced+every+12+h%3B+replacement+of+pups+was+followed+by+a+15-min+observation+period.+Maternal+behavior%0D%0Alatency+was+determined+by+the+first+of+two+consecutive+tests+wherein+the+subject+displayed+pup+retrieval%2C+pup+licking+in+the+nest%2C+and+crouching+over+all+foster+pups%2C+during+the+15-min+observation.+We+confirmed+the+previous+finding+that+the+VTA+injection%2C+alone%2C+of+0.03+%CE%BCg+morphine+shortened+the+latency+to+show+maternal+behavior+and+that+0.0+%CE%BCg+and+0.01+%CE%BCg+morphine+did+not.+Ingestion+of+amniotic+fluid+(and+therefore+POEF)+facilitated+the+onset+of%0D%0Amaternal+behavior+in+rats+receiving+an+intra-VTA+microinjection+of+an+otherwise+subthreshold+dose+of+morphine+(0.01+%CE%BCg).&rft.publisher=Elsevier&rft.date=2009&rft.type=Journal+(Paginated)&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F6385%2F1%2FPOEF-VTA-maternal.pdf&rft.identifier=++Neumann%2C+Anne+and+Hoey%2C+Robert+F.+and+Daigler%2C+Lindsey+B.+and+Thompson%2C+Dr.+Alexis+C.+and+Kristal%2C+Dr.+Mark+B.++(2009)+Ingestion+of+amniotic+fluid+enhances+the+facilitative+effect+of+VTA+morphine+on+the+onset+of+maternal+behavior+in+virgin+rats.++%5BJournal+(Paginated)%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F6385%2F