Many studies have demonstrated that the hereditary nature of drug abuse is due to both genetic and environmental factors. Recent findings demonstrate that one mechanism regulating interactions between genes and the environment are epigenetic modifications. The term epigenetics refers to DNA and histone protein modifications that regulate gene expression and which are transmitted from a mother cell to a daughter cell or from a parent to a progeny, but which do not change the underlying DNA sequence. While it is clear that epigenetic modifications can be passed from one generation to the next, the mechanisms involved in the transmission of these effects are not fully understood. Several recent findings indicate that the maternal environment, both pre- and postnatal, may play a critical role in epigenetic transfer. To date, the role of epigenetics in familial patterns of drug abuse has not been well studied. Prescription narcotics use by adolescent females has increased dramatically in the past decade. We have developed an animal model of adolescent morphine exposure in female rats to examine the long-term consequences of opiate use during this unique developmental period. Our findings demonstrate that in addition to significant alterations in gene expression in adult female rats exposed to morphine during adolescence, the offspring of adolescent-exposed females demonstrate enhanced responsiveness to morphine. These offspring effects suggest adolescent morphine exposure increases the risk of drug abuse in the next generation. One of important aspect of this model is that adolescent morphine-exposed females are drug-free for at least 10 days prior to mating. Thus, developing offspring are never directly exposed to morphine. This means that any effect observed in the offspring is maternally-derived. The purpose of the present proposal is to determine the role of epigenetics in the long-term effects of adolescent morphine exposure on both the female and her offspring. The current proposal will identify transgenerational epigenetic modifications in the adult offspring of females exposed to morphine during adolescent development (Specific Aim 1). It will also examine possible changes in the maternal environment which may play a role in the transmission of these offspring effects (Specific Aim 2). Finally, we will test whether postnatal manipulations can ameliorate or prevent the transgenerational effects of adolescent morphine exposure (Specific Aim 3). Understanding how drug-induced alterations in morphine sensitivity may be passed from one generation to the next will help identify basic mechanisms underlying familial patterns of drug abuse as well as possible interventions.

Public Health Relevance

The goal of this project is to understand how mothers who are exposed to narcotics during adolescence increase the probability of drug abuse in their future offspring. These studies will provide a foundation for understanding the role of maternal factors in familial patterns of drug abuse.

National Institute of Health (NIH)
National Institute on Drug Abuse (NIDA)
Research Project (R01)
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Study Section
Biobehavioral Regulation, Learning and Ethology Study Section (BRLE)
Program Officer
Satterlee, John S
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Tufts University
Veterinary Sciences
Schools of Veterinary Medicine
United States
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Vassoler, Fair M; Wright, Siobhan J; Byrnes, Elizabeth M (2016) Exposure to opiates in female adolescents alters mu opiate receptor expression and increases the rewarding effects of morphine in future offspring. Neuropharmacology 103:112-21
Vassoler, F M; Byrnes, E M; Pierce, R C (2014) The impact of exposure to addictive drugs on future generations: Physiological and behavioral effects. Neuropharmacology 76 Pt B:269-75
Ravenelle, R; Santolucito, H B; Byrnes, E M et al. (2014) Housing environment modulates physiological and behavioral responses to anxiogenic stimuli in trait anxiety male rats. Neuroscience 270:76-87
Vassoler, Fair M; Johnson-Collins, Nicole L; Carini, Lindsay M et al. (2014) Next generation effects of female adolescent morphine exposure: sex-specific alterations in response to acute morphine emerge before puberty. Behav Pharmacol 25:173-81
Pierce, R Christopher; Vassoler, Fair M (2014) Reduced cocaine reinforcement in the male offspring of cocaine-experienced sires. Neuropsychopharmacology 39:238
Vassoler, Fair M; Johnson, Nicole L; Byrnes, Elizabeth M (2013) Female adolescent exposure to cannabinoids causes transgenerational effects on morphine sensitization in female offspring in the absence of in utero exposure. J Psychopharmacol 27:1015-22
Ravenelle, Rebecca; Byrnes, Elizabeth M; Byrnes, John J et al. (2013) Environmental enrichment effects on the neurobehavioral profile of selective outbred trait anxiety rats. Behav Brain Res 252:49-57
Byrnes, John J; Johnson, Nicole L; Carini, Lindsay M et al. (2013) Multigenerational effects of adolescent morphine exposure on dopamine D2 receptor function. Psychopharmacology (Berl) 227:263-72
Byrnes, John J; Johnson, Nicole L; Schenk, Marian E et al. (2012) Cannabinoid exposure in adolescent female rats induces transgenerational effects on morphine conditioned place preference in male offspring. J Psychopharmacol 26:1348-54
Byrnes, John J; Babb, Jessica A; Scanlan, Victoria F et al. (2011) Adolescent opioid exposure in female rats: transgenerational effects on morphine analgesia and anxiety-like behavior in adult offspring. Behav Brain Res 218:200-5

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