Analysis of Maternal Behavior in Oxycodone Exposed Rats transitioned to Methadone or Abstinence 

Supervised by: Dr. Elizabeth Byrnes and Kerri Budge, Department of Comparative Pathobiology, Tufts University Cummings School of Veterinary Medicine

Project Background

Opioid use disorder during pregnancy is a growing public health concern that affects both maternal and infant health. While synthetic opioid treatments, such as methadone or buprenorphine, are commonly used to manage opioid dependence during pregnancy, less is known about how different treatments influence maternal caregiving behaviors after birth. Maternal behavior plays a critical role in offspring development, affecting physical growth, stress regulation, and long-term behavioral outcomes. Therefore, understanding how opioid intervention treatments impact these behaviors is essential for improving health outcomes for both parents and children.

Previous work has established that opioid self-administration models in rats accurately portray human patterns of drug use and dependence. The Byrnes lab uses such models to analyze various aspects of neurobiology impacted by opioid use and interventions. A recent project examined the effects of prenatal methadone treatment in comparison to abstinence/withdrawal on the offspring of rats who were previously exposed to oxycodone (opioid). This research focused on the development and behaviors of the pups, determining that methadone treatment was associated with improved pup retrieval, full litter viability, and more regulated offspring vocalization patterns compared to the withdrawal group. 

My Goals 

To take this study further, I will investigate how gestational opioid exposure and treatment strategies influence maternal behavior during the early postpartum period. Maternal care encompasses a wide range of behaviors such as nursing, grooming, nest building, and time spent attending to offspring. In addition to behavioral changes, opioid exposure may alter neural pathways involved in caregiving. Neurotransmitters, hormones, and endogenous opioids also play a key role in regulating maternal behavior and may be disrupted by opioid exposure and withdrawal. We hypothesize that methadone treatment will improve the quality of maternal caregiving, in comparison to abstinence after opioid exposure. 

Methodology

My project will involve quantitatively analyzing home-cage video recordings collected from rat dams on postnatal days 3, 6, 9, and 12. I will score maternal behaviors by frequency, duration, and transitions. The data will be run through an R-script coding software to quantify and assess statistical significance. 

In addition to behavioral analysis, I will conduct literature reviews examining the neurobiological mechanisms underlying maternal care. This work will focus on neural systems involved in caregiving behavior, including the roles of oxytocin, dopamine, and endogenous opioid signaling. By integrating behavioral findings with current neuroscience literature, I hope to better understand how opioid exposure and withdrawal influence maternal caregiving at both behavioral and biological levels.

Impact

This research aims to provide a more comprehensive understanding of how opioid exposure during pregnancy affects maternal caregiving behaviors and offspring development. These findings may help inform clinical approaches to treating opioid use disorder during pregnancy. If methadone-treated rats demonstrate more consistent patterns of maternal care than those experiencing withdrawal, the results could provide additional evidence supporting treatment strategies that prioritize maternal stability and infant well-being. More broadly, this work contributes to the understanding of maternal health, fetal development, and the intergenerational effects of substance exposure.