Animal Behavior Models: Increased Sensitivity to Stressors and Other Environmental Experiences after Prenatal Cocaine Exposure

Neural compensations occurring after prenatal cocaine exposure may often permit some functional recovery, although the cost of this reorganization may be a decrease in adaptability. As we have seen in our rodent model of prenatal cocaine exposure, latent deficits may become unmasked when offspring are exposed to cognitive and environmental demands and stressors. In adolescence and adulthood, offspring exposed gestationally to cocaine exhibit characteristic decreases in stress-induced immobility along with increases in aggression under the demands of social competition. Recently, we observed that cocaine-exposed offspring are also unusually sensitive to the long-term effects of early manipulation (noninvasive heart rate testing at 16 days of age). When tested in adulthood, cocaine-exposed offspring not receiving this early experience exhibited less immobility when tested in the presence of intermittent footshock or when subsequently examined in an open field as well as more locomotion in the open field than control offspring, findings reminiscent of previous work. By contrast, these effects were normalized (shock-induced immobility) or reversed (open field immobility and locomotion) in cocaine-exposed animals given the early experience. This marked susceptibility to the effects of early manipulation was less evident in control offspring and even in a group of stunted nutritional controls. Thus, cocaine-exposed offspring may exhibit increased sensitivity not only to environmental demands and stressors, but also to the potential moderating or beneficial effects of early experiences.