Effects of prenatal methadone and buprenorphine exposure on motivated responding for sucrose and gene expression in adult male and female rats.

The opioid crisis has resulted in escalating rates of opioid use disorder in women of reproductive age and increased prevalence of fetal drug exposure. While medication for opioid use disorder (MOUD) - e.g., buprenorphine or methadone - improves maternal health outcomes, infants exposed to MOUD show a variety of physical and behavioral consequences. There are, however, few clinical or preclinical studies investigating long-term effects of MOUD exposure. The current work investigates the long-term effects of prenatal MOUD exposure on effort-based responding to a palatable food reward and gene expression in regions of the brain related to reward and feeding, including the nucleus accumbens and hypothalamus. Female Sprague Dawley rats were implanted with osmotic minipumps filled with methadone (10 mg/kg/day) or buprenorphine (1 mg/kg/day) or saline control (2.5 μL/hour for 28 days) and mated four days later. In adulthood, male and female offspring began sucrose pellet self-administration to assess the motivational strength of a food reward in MOUD-exposed animals compared to saline controls, followed by analysis of gene expression via RNAscope