?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Opioid+stimulation+in+the+ventral+tegmental+area+facilitates+the+onset+of+maternal+behavior+in+rats&rft.creator=Thompson%2C+Alexis+C.&rft.creator=Kristal%2C+Mark+B.&rft.subject=Behavioral+Neuroscience&rft.subject=Behavioral+Biology&rft.subject=Comparative+Psychology&rft.subject=Neuroanatomy&rft.subject=Neurochemistry&rft.subject=Neuroendocrinology&rft.subject=Neuropharmacology&rft.subject=Neurophysiology&rft.subject=Physiological+Psychology&rft.subject=Psychobiology&rft.description=This+research+investigated+the+effect+of+an+increase+or+decrease+in+opioid+activity+in+the+ventral+tegmental+area+(VTA)+on+the+onset+of+maternal+behavior+in+rats.+In+Experiment+1%2C+the+latency+to+show+maternal+behavior+toward+foster+rat+pups+(sensitization+latency)+was+determined+in+maternally+naive+female+rats+given+either+nothing+or+a+unilateral+intra-VTA+injection+of+morphine+sulfate+(MS)+(0.0%2C+0.01%2C+0.03%2C+0.1+or+0.3+%C2%B5g)%2C+on+the+first+three+days+of+a+10-day+period+of+constant+exposure+to+pups.+Rats+treated+with+0.03+%C2%B5g+MS+had+significantly+shorter+sensitization+latencies+than+did+rats+treated+with+0.0+%C2%B5g+MS%2C+0.01+%C2%B5g+MS%2C+or+receiving+no+treatment+(higher+doses+of+morphine+produced+intermediate+results).+The+facilitating+effect+of+intra-VTA+MS+on+the+onset+of+maternal+behavior+was+blocked+by+pretreatment+with+naltrexone+hydrochloride+and+was+found+to+have+a+specific+site+of+action+in+the+VTA+(MS+injections+dorsal+to+the+VTA+were+ineffective).+In+Experiment+2%2C+sensitization+latencies+were+determined+in+periparturitional+rats+given+a+bilateral+intra-VTA+injection+of+either+the+opioid+antagonist+naltrexone+methobromide+(quaternary+naltrexone)%2C+its+vehicle%2C+a+sham+injection%2C+or+left+untreated+40+min+after+delivery+of+the+last+pup.+The+mothers'+own+pups+were+removed+at+delivery%3B+mothers+were+nonmaternal+at+the+time+of+testing.+Quaternary+naltrexone+treatment+produced+significantly+slower+sensitization+to+foster+pups+than+did+control+conditions.+Total+activity+and+pup-directed+activity+did+not+differ+significantly+with+treatment.+The+results+demonstrate+that+increased+opioid+activity+in+the+VTA+facilitates+the+onset+of+maternal+behavior+in+inexperienced+nonpregnant+female+rats%2C+and+decreased+opioid+activity+in+the+VTA+disrupts+the+rapid+onset+of+maternal+behavior+at+parturition.&rft.publisher=Elsevier&rft.date=1996&rft.type=Journal+(Paginated)&rft.type=PeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Fcogprints.org%2F6311%2F1%2FVTA.pdf&rft.identifier=++Thompson%2C+Alexis+C.+and+Kristal%2C+Mark+B.++(1996)+Opioid+stimulation+in+the+ventral+tegmental+area+facilitates+the+onset+of+maternal+behavior+in+rats.++%5BJournal+(Paginated)%5D+++++&rft.relation=http%3A%2F%2Fcogprints.org%2F6311%2F