Given the social and ethical issues surrounding maternal neglect and abuse in humans, an animal model of neglect provides an important method to study the bio-behavioral underpinnings of maternal neglect/abuse with more direct control over the confounding variables found in human research. Child abuse and maternal neglect has long been strongly correlated with drug abuse in women. Recently, lower levels of oxytocin and cocaine use during pregnancy have also been associated with general feelings of anger and hostility and difficulty with infant attachment in women. In a rodent model, the investigators have found that chronic cocaine treatment during pregnancy and acute cocaine treatment in postpartum dams both increase maternal neglect, defined as the disruption of pup-directed maternal behavior. Chronic cocaine treatment also increases postpartum maternal aggression towards intruders to the extent that pups are often injured, while acute cocaine treatment decreases protection of pups from intruders. They have also observed that chronic cocaine treatment reduces levels of oxytocin in the medial preoptic area and amygdala at the same time periods that maternal behavior and maternal aggression, respectively, are maximally affected. The investigators hypothesize that chronic and acute cocaine treatment will result in differential and significant patterns of maternal neglect/abuse of offspring at different times across the lactation period. They will measure the frequency, duration and latency of maternal behavior and maternal aggression in rat dams during lactation and unprovoked aggressive behavior (postweaning) towards other rats following chronic cocaine, acute cocaine, and saline treatment (Study 1). They also hypothesize that prenatal exposure to chronic cocaine and acute cocaine will result in altered patterns of maternal/parental behavior and aggression in offspring. Male and female rat offspring prenatally exposed to no treatment, chronic cocaine, acute cocaine or saline treatment will be tested for maternal behavior, parental behavior (males), maternal aggression, and unprovoked aggression towards other rats as juveniles and adults (Study 2). To determine if rearing conditions (neglect versus nurturing) ameliorate or exacerbate the effects of prenatal exposure to cocaine, they will study the offspring of chronic cocaine, acute cocaine, saline treated or untreated dams who are reared with their natural mothers or cross-fostered to other untreated, or cocaine or saline treated mothers. Males and females will be tested for maternal/parental behavior, maternal aggression and unprovoked aggression as juveniles and adults (Study 3). Study 4 will determine if oxytocin system changes in relevant brain areas are correlated with behavioral differences between groups of dams and offspring by sacrificing rats after behavioral testing and measuring oxytocin levels in these regions.
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