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Neuropeptides and Social Behavior Development 179monly modified by modern obstetric practices; in these cases, OT has the potentialto influence physiology and behavior in both the mother and offspring(Pedersen et al., 2002).Pitocin (synthetic OT) is used to induce labor in approximately 30% of birthsin the United States, and in some hospitals the rate is much higher. For example,over 90% of the women giving birth at Northwestern University Hospital in Chicagoin 2005 received pitocin to either induce or augment labor (C. Wong, personalcommunication, 2005). Atosiban, an oxytocin antagonist, is approved foruse in 43 countries (although not in the United States) for the prevention of pretermlabor (Husslein, 2002). Both pitocin and atosiban have obvious applications inthe management of term and preterm labor. Atosiban has been shown to drasticallyreduce the risk of maternal cardiac complications in comparison to othercurrently available treatments for preterm labor (Cabrol et al., 2001; Husslein,2002; Romero et al., 2000). However, it is unclear how much pitocin/atosibancrosses the placental barrier and infant blood-brain barrier. A study in baboonsfound that atosiban crossed the placental barrier “relatively freely” (Nathanielszet al., 1997). Caesarian section has also been shown to alter endogenous OT inthe mother, which could affect OT exposure in the infant (Nissen, Gustavsson,Widstrom, & Uvnas-Moberg, 1998).Variations in child-rearing practices also hold the potential to influence OTsynthesis. OT is present in breast milk (Leake, Wietzman, & Fisher, 1981) and isreleased by warmth and touch (Uvnas-Moberg, 1998) . Animal studies have shownthat variation in maternal care in rats can affect OT and AVP receptor bindingin offspring (Champagne, Diorio, Sharma, & Meaney, 2001; Francis, Young,Meaney, & Insel, 2000; Francis, Young, Meaney, & Insel, 2002); while handling,especially during the first week of life, in voles can also affect OT and AVPpeptide levels in the hypothalamus (Carter et al., 2003). The effects of early experienceare often sexually dimorphic, and again raise the possibility that sex differencesin either peptides or the response of peptides to other treatment will beimportant in understanding their functions.Early exposure to AVP can also have long-lasting developmental effects. Inprairie voles, exposure to exogenous AVP or an AVP V1a receptor antagonist(AVPA) has long lasting, dose-dependent effects on aggression; extra AVP increasedaggression, especially in males, and animals treated with the AVPA exhibitedalmost no aggression in later life (Stribley and Carter, 1999). Animalsreceiving either AVP or AVPA treatments continued to show pair bonds and didnot differ in behavior in an elevated plus-maze, considered indicative of anxiety.Children may also face varying amounts of exposure to AVP through eithertreatment for bed-wetting (Moffatt, 1997) or through exposure to nicotine, whichreleases AVP (Andersson, Siegel, Fuxe, & Eneroth, 1983; Matta, Foster, & Sharp,1993). Almost nothing is known regarding the possible consequences of neonatalmanipulations of AVP in humans. However, nicotine experienced during pregnancy