Developmental exposure to 17-α-hydroxyprogesterone caproate disrupts decision-making in adult female rats: A potential role for a dopaminergic mechanism.

The synthetic progestin, 17α-hydroxyprogesterone caproate (17-OHPC), is administered to pregnant individuals at risk for preterm birth and is likely transferred from mother to fetus. Yet, there is little information regarding the potential effects of 17-OHPC administration on behavioral and neural development in offspring. In rats, neonatal 17-OHPC exposure altered dopaminergic fiber distribution and density in the prelimbic medial prefrontal cortex (mPFC) in neonates and adolescents, respectively. Additionally, neonatal 17-OHPC exposure in male rats increased response omissions in a delay discounting task of impulsive decision-making. Because developmental 17-OHPC exposure has differential effects in males and females, investigating the effects of 17-OHPC on impulsive decision-making in female rats is necessary. The present study tested the effects of developmental 17-OHPC exposure (P1-P14) in a delay discounting task in which female rats chose between a small immediate reward and a larger delayed (0, 15 30, or 45 s) reward. 17-OHPC-exposed females made more omissions than controls. There was no effect of 17-OHPC on large reward preference nor on response time, and omissions were similar during both free- and forced-choice trials. The present study also aimed to investigate the neural mechanisms underlying omissions in 17-OHPC-exposed female rats. The dopamine transporter inhibitor, methylphenidate (MPH), was administered prior to delay discounting testing. MPH treatment did not reduce omissions in 17-OHPC-exposed females. If anything, MPH increased omissions in control females nearly fourfold during the longest delays. These results suggest that developmental 17-OHPC exposure increased omissions without affecting impulsivity or slowing decision-making. Furthermore, omissions may be regulated, at least in part, by dopaminergic mechanisms.

Implications of Developmental 17-OHPC Exposure on the Mesocorticolimbic Serotonergic and Dopaminergic Pathways and Adolescent Mood-Related Behavior in Rats.

The synthetic progestin, 17-α-hydroxyprogesterone caproate (17-OHPC), is administered to pregnant individuals at risk for recurrent preterm birth during a critical period of fetal mesocorticolimbic serotonergic and dopaminergic pathway development. These pathways play an important role in regulating cognitive behaviors later in life. Despite this, there has been very little research regarding the potential long-term effects of 17-OHPC on the behavioral and neural development of exposed children. In rodents, developmental exposure to 17-OHPC disrupts serotonergic and dopaminergic innervation of the medial prefrontal cortex and impairs decision-making in complex cognitive tasks in adulthood. The present study tested the hypothesis that developmental exposure to 17-OHPC similarly disrupts the development of serotonergic and dopaminergic pathways within limbic targets and subsequent mood-related behaviors. Developmental 17-OHPC exposure significantly increased the density of serotonin transporter-IR fibers in CA1, CA2/3, and the suprapyramidal blade of dentate gyrus in hippocampus and significantly reduced the density of TH-IR fibers within the nucleus accumbens shell in males but had no effect in females during adolescence. Irregular microglia activational phenotype and number were also observed in the hippocampus of 17-OHPC-exposed males. Developmental 17-OHPC reduced the latency to immobility in males in the forced swim test but did not affect sucrose consumption in a sucrose preference test. These findings suggest that 17-OHPC exerts sex-specific effects on the development of mesocorticolimbic pathways and mood-related behavior in adolescence and highlight the need to investigate effects in adolescent children.