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The opioid epidemic has escalated in recent years and while this widespread usage is recognized as a public health crisis, a significant component of this epidemic that is understudied is opioid abuse during pregnancy. The fetal brain and placenta are permeable to opioids, so usage during gestation may have consequences for offspring. While studies have reported that animals prenatally exposed to opiates exhibit deficits in memory and learning, neither the onset nor the duration of these effects are known. Therefore, we assessed the effects of prenatal methadone exposure on learning and memory across ontogeny. Pregnant female Sprague Dawley rats were injected with methadone subcutaneously twice daily, from gestational days 3 through 20. Learning and memory were tested using Novel Object Recognition over 3 days (habituation, familiarization, and test day) on postnatal days (P) 27 (juveniles), 45 (adolescences), and 70 (adulthood) in both male and female offspring. At P45, it was found that the methadone exposed males exhibited decreased exploratory behavior overall, during their familiarization period. At P70, methadone exposed animals displayed preference to the known object, in contrast to control animals that preferred the novel object. These data suggest that prenatal exposure to methadone may have long-lasting effects on learning and memory.



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The Effects of Prenatal Methadone Exposure on Learning and Memory in Sprague Dawley Offspring