Editing Placentophagy (section)

=== In rats ===
Placentophagia has been studied most commonly in rodents, specifically rats. There have been multiple conclusions drawn from the available literature. One major finding is that the consumption of the afterbirth and associated materials increases the onset and intensity of maternal behavior in rats.<ref name=":22" /> The increased contact between the adult and the infant is what enhances the adoption of parental behavior. In addition to increasing the parenting tendencies of mother rats, it has been seen that placentophagia by female weanling laboratory rats when the mother births a subsequent litter, elevates [[alloparenting]] behavior toward their siblings.<ref>{{Cite journal|last1=Harding|first1=Kaitlyn M.|last2=Lonstein|first2=Joseph S.|date=2014|title=Placentophagia in weanling female laboratory rats: Placentophagia in Weanling Females|journal=Developmental Psychobiology|language=en|volume=56|issue=6|pages=1290–9|doi=10.1002/dev.21208|pmc=4119531|pmid=24604548}}</ref> Additional research has shown that ingestion of the placenta and amniotic fluid influences the pain tolerance in pregnant rats via elevation of naturally occurring opioid-mediated analgesia.<ref name=":22" /> Production of endogenous opioids produced by the central nervous system, is increased during the birthing process which raises the pain threshold of the mother. When coupled with the ingestion of placenta or amniotic fluid, there is a drastic increase in the opioid effect. A test whereby rats were given meat rather than placenta supported the contribution of the afterbirth components to the enhanced opioid effect by showing no increase in the pain threshold of the post-partum mother.<ref name=":22" /><ref name=":3" />