A pilot multiplex salivary transcriptomic analysis to understand the sex-specific effects of maternal opioid use in offspring.

Opioid use disorder affects males and females differently, yet the molecular mechanisms in neonates remain understudied. Our laboratory has demonstrated differential sex effects of opioids on select reward and inflammatory pathways related to neonatal feeding behavior that may affect growth and cardiometabolic outcomes. In this pilot observational study, we explored whether gene expression in the reward, energy homeostasis, inflammation, oxidative stress, and neuropathology pathways differed by prenatal opioid exposure and infant sex. Saliva from nine opioid-exposed and nine non-exposed neonates collected within 48 h after birth underwent a multiplex, high-throughput analysis of 72 genes using NanoString’s nCounter® system (NanoString Technologies, Seattle, WA, USA). Despite low RNA abundance in neonatal saliva, experimental conditions were optimized after several trials. Multiplex analysis showed sex-specific expression patterns related to maternal opioid use: male sex was associated with higher expression of genes annotated to reward, inflammation, oxidative stress, feeding, and energy homeostasis pathways, whereas female sex was associated with lower expression of inflammation- and cardiovascular-related transcripts. Future work in larger, independent cohorts will be needed to validate these sex-specific expression patterns and determine their relationships with short- and long-term health outcomes.