The link between impaired maternal behavior (MB) and cocaine treatment could result from druginduced decreases in maternal reactivity to offspring, prenatal drug exposure (PDE) in offspring that could alter their ability to elicit MB, or the interaction of both, which could subsequently impair MB of the 1st-generation dams. Following chronic or intermittent cocaine or saline treatment during gestation, rat dams rearing natural or cross-fostered litters were compared along with untreated dams for MB. Untreated 1st-generation females with differentially treated rearing dams and PDE were tested for MB with their natural litters. The authors report disruptions in MB in dams and their 1st-generation offspring, attributable to main and interaction effects of maternal treatment, litter PDE, and rearing experience. Pregnant women who use cocaine perpetrate child abuse and neglect more often than women who do not use cocaine during pregnancy (Hawley, Halle, Drasin, & Thomas, 1995; Tyler, Howard, Espinosa, & Doakes, 1997; Wasserman & Leventhal, 1993). Maternal cocaine abuse during pregnancy has also been strongly associated with deficits in maternalinfant bonding (Burns, Chethik, Burns, & Clark, 1991), and mothers with a history of substance abuse often exhibit poor mother-infant interactions (Bauman & Dougherty, 1983;Bays, 1990; Howard, Beck-with, Espinosa, & Tyler, 1995;Johnson & Rosen, 1990). Though studies with human participants are helpful in understanding the connection between cocaine use and maternal neglect, these experiments are correlational. There is a necessary lack of control over many important variables that could confound the results, such as socioeconomic issues, lack of family support, multidrug abuse, and poor general prenatal care (Chasnoff et al., 1998;Koren et al., 1998). Studies that use numerous controls have shown a strong correlation between reported history of child maltreatment and the perpetration of maltreatment and/or neglect in next-generation mothers (Egeland, Jacobvitz, & Papatola, 1987;Hunter, Kilstrom, Kraybill, & Loda, 1978).In order to appropriately investigate and describe the characteristics of cocaine-induced disruption of maternal behavior and potential neglect, as well as possible intergenerational effects of such disruptions, a nonhuman cocaine abuse model offers several advantages. The laboratory rat is a particularly good model for the study of maternal behavior. Their offspring are born blind, unable to thermoregulate, defecate, urinate, or protect themselves from attack (Numan, 1994), thus needing considerable maternal care to survive (Stern, 1997). Behaviorally and neurologically, maternal behavior in the rat has also been relatively well characterized (Numan, 1994;Pedersen, Ascher, Monroe, & Prange, 1982;Pedersen, Caldwell, Walker, Ayers, & Mason, 1994) so that any insult to normal maternal behavior can be easily determined.Maternal separation studies also support a rat intergenerational model of behavior showing that cross-fostering results in behavior of offsp...

Studies using dopaminergic and serotonergic agonists or antagonists implicate involvement of these systems in various aspects of early maternal behavior and postpartum aggression towards an intruder in rats, both of which are associated with the presence of oxytocin in specific brain regions. It is unclear however, if or how long-term uptake inhibition of either neurotransmitter system alone or in combination, affects oxytocin system dynamics or maternal behavior/ aggression. Pregnant women frequently take drugs (antidepressants, cocaine) that induce longterm reuptake inhibition of dopamine and/or serotonin, thus it is important to understand these effects on behavior and biochemistry. Rat dams were treated throughout gestation with amfonelic acid, fluoxetine, or a combination of both, to investigate effects of reuptake inhibition of dopamine and serotonin systems respectively, on maternal behavior, aggression and oxytocin. The more appetitive aspects of maternal behavior (nesting, licking, touching) and activity were increased by the low dose of amfonelic acid, high dose of fluoxetine, or the high dose combination more than other treatments. Aggression was decreased by amfonelic acid and somewhat increased by fluoxetine. Dopamine uptake inhibition appears to have a strong effect on hippocampal oxytocin levels, while receptor dynamics may be more strongly affected by serotonin uptake inhibition.

Gestational cocaine treatment results in significantly increased maternal aggression towards an intruder by postpartum day six, while acute postpartum treatment dose dependently decreases maternal aggressive (MA) behavior. Both increased and decreased aggression in the cocainetreated dams are correlated with either decreased or increased levels of oxytocin in the amygdala, respectively. The current study was an effort to determine whether the effect of gestational cocaine on maternal aggression is transient or would continue into the postpartum period; whether an intermittent cocaine treatment regimen, which incorporates gestational and postpartum intermittent cocaine treatment, would differ from chronic daily gestational treatment; and finally, whether next generation female offspring of cocaine-treated or control dams would have altered MA behavior and oxytocin system changes attributable to either prenatal drug exposure, rearing condition or both. We now report no increase in maternal aggression following chronic gestational treatment and significantly lower levels of aggression in intermittently treated dams on postpartum day eight, with no significant effects in either group on postpartum day 12. Young adult female offspring of the cocaine-treated and control dams, who reared their own natural litters and were tested on postpartum day eight for maternal aggression, had higher levels of maternal aggression towards an intruder attributable to both prenatal cocaine exposure and rearing condition. Higher aggression in cocaine-reared next generation dams was associated with lower levels of oxytocin in the amygdala. Intergenerational effects of cocaine were apparent with respect to aggression and oxytocin system changes.

Cocaine administered chronically throughout gestation has been correlated with deficits in maternal behavior, increased maternal aggressive behavior and decreased oxytocin levels in rats. In addition to its effects on oxytocin levels, cocaine is a potent serotonergic, dopaminergic and noradrenergic reuptake inhibitor. Alterations in the dopaminergic and serotonergic systems have been suggested as possibly having a role in cocaine-induced maternal aggression. This study was in part, an attempt to understand some of the mechanisms by which cocaine increases postpartum aggression, particularly as they relate to changes in the oxytocin system.Oxytocin receptor number and binding affinity in the medial preoptic area of the hypothalamus, ventral tegmental area, hippocampus and amygdala were determined for lactating rat dams on postpartum day 6 (PPD 6) that were gestationally treated with cocaine, fluoxetine, saline or an amfonelic acid/fluoxetine drug combination. Cocaine and fluoxetine treatment both resulted in a significant up-regulation of oxytocin receptor number and lower receptor affinity in the amygdala of lactating rat dams compared to saline controls and the amfonelic acid/fluoxetine combination treatment group. Cocaine treatment also resulted in a significant down-regulation of oxytocin receptors in the medial preoptic area and both cocaine and fluoxetine treated dams had the highest affinity for oxytocin receptors in this brain region. Results of the present study support previous data indicating that alterations in oxytocinergic and perhaps serotonergic system dynamics in the amygdala may play a role in cocaine-induced postpartum aggression.

Impaired onset of maternal behavior in first generation rat dams was previously correlated with rearing by cocaine-treated dams and prenatal cocaine exposure. Pup-induced maternal behavior in non-lactating rats has not been examined with regard to cocaine exposure and rearing conditions. First generation male and female juveniles and young adult males reared by cocaine-treated or control dams and prenatally exposed to either cocaine or control conditions were tested for pup-induced maternal behavior at postnatal days 28 and 60. We now report disruptions in pup-induced maternal behavior in both 28 and 60 day old first generation offspring attributable to rearing condition and prenatal cocaine exposure.