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Description
The maternal separation (MS) paradigm is an animal model of early life stress. Animals subjected to MS during the first two weeks of life display altered behavioral and neuroendocrinological stress responses as adults. MS also produces altered responsiveness to and self-administration (SA) of various drugs of abuse including cocaine, ethanol,

The maternal separation (MS) paradigm is an animal model of early life stress. Animals subjected to MS during the first two weeks of life display altered behavioral and neuroendocrinological stress responses as adults. MS also produces altered responsiveness to and self-administration (SA) of various drugs of abuse including cocaine, ethanol, opioids, and amphetamine. Methamphetamine (METH) causes great harm to both the individual user and to society; yet, no studies have examined the effects of MS on METH SA. This study was performed to examine the effects of MS on the acquisition of METH SA, extinction, and reinstatement of METH-seeking behavior in adulthood. Given the known influence of early life stress and drug exposure on epigenetic processes, group differences in levels of the epigenetic marker methyl CpG binding protein 2 (MeCP2) in the nucleus accumbens (NAc) core were also investigated. Long-Evans pups and dams were separated on postnatal days (PND) 2-14 for either 180 (MS180) or 15 min (MS15). Male offspring were allowed to acquire METH SA (0.05 mg/kg/infusion) in 15 2-hr daily sessions starting at PND67, followed by extinction training and cue-induced reinstatement of METH-seeking behavior. Rats were then assessed for MeCP2 levels in the NAc core by immunohistochemistry. The MS180 group self-administered significantly more METH and acquired SA earlier than the MS15 group. No group differences in extinction or cue-induced reinstatement were observed. MS15 rats had significantly elevated MeCP2-immunoreactive cells in the NAc core as compared to MS180 rats. Together, these data suggest that MS has lasting influences on METH SA as well as epigenetic processes in the brain reward circuitry.
ContributorsLewis, Candace (Author) / Olive, Micheal F (Thesis advisor) / Conrad, Cheryl (Committee member) / Neisewander, Janet (Committee member) / Arizona State University (Publisher)
Created2013
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Description
The goal of this study is to contribute to the understanding of Mexican-American three- to five-year-old children’s effortful control (EC) and negative emotionality (NE) development by examining whether Mexican-American adolescent mothers’ parenting transacts with their three- to five-year-old children’s EC and NE and by exploring whether mothers’ familism acts as

The goal of this study is to contribute to the understanding of Mexican-American three- to five-year-old children’s effortful control (EC) and negative emotionality (NE) development by examining whether Mexican-American adolescent mothers’ parenting transacts with their three- to five-year-old children’s EC and NE and by exploring whether mothers’ familism acts as a protective factor. I hypothesized that mothers’ harshness and warmth would transact with EC and NE over time. I further hypothesized that mothers’ familism values would (a) positively predict mothers’ warmth and negatively predict mothers’ harshness, and (b) act as a buffer between low EC and high NE, and high harshness and low warmth. These hypotheses were tested within a sample of Mexican-American adolescent mother-child dyads (N = 204) and assessed longitudinally when children were 36, 48, and 60 months. Mothers were predominantly first generation (i.e., mothers’ parents were born in Mexico; 67%) and spoke English (65%). When children were 36 months, average family income (i.e., wages, public assistance, food stamps) was $24,715 (SD = $19,545) and mothers had started community college (13%) or completed high school/GED (30%), 11th grade (19%), 10th grade (8%), or less than 9th grade (14%). In this sample, transactions between harshness or warmth and EC or NE were not found, but a bidirectional association between NE and harshness was found. Familism marginally negatively predicted harshness, but not warmth. Familism moderated the relation between NE and harshness such that there was only a negative relation between NE and harshness when familism was high. However, familism did not moderate the relations between NE and warmth, or EC and harshness or warmth. The results of this study are discussed with respect to (a) current methodological limitations in the field, such as the need to test or develop parent-report measures of Mexican-American children’s temperament and value-driven socialization goals, (b) future avenues for research, such as person-centered studies of clusters of mothers’ values and how those relate to clusters of parenting behaviors, and (c) implications for interventions addressing parenting behavior of adolescent mothers.
ContributorsBerger, Rebecca H (Author) / Wilkens, Natalie (Thesis advisor) / Spinrad, Tracy (Committee member) / Updegraff, Kimberly (Committee member) / Crnic, Keith (Committee member) / Arizona State University (Publisher)
Created2018
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Description
Evidence from the 20th century demonstrated that early life stress (ELS) produces long lasting neuroendocrine and behavioral effects related to an increased vulnerability towards psychiatric illnesses such as major depressive disorder, post-traumatic stress disorder, schizophrenia, and substance use disorder. Substance use disorders (SUDs) are complex neurological and behavioral psychiatric illnesses.

Evidence from the 20th century demonstrated that early life stress (ELS) produces long lasting neuroendocrine and behavioral effects related to an increased vulnerability towards psychiatric illnesses such as major depressive disorder, post-traumatic stress disorder, schizophrenia, and substance use disorder. Substance use disorders (SUDs) are complex neurological and behavioral psychiatric illnesses. The development, maintenance, and relapse of SUDs involve multiple brain systems and are affected by many variables, including socio-economic and genetic factors. Pre-clinical studies demonstrate that ELS affects many of the same systems, such as the reward circuitry and executive function involved with addiction-like behaviors. Previous research has focused on cocaine, ethanol, opiates, and amphetamine, while few studies have investigated ELS and methamphetamine (METH) vulnerability. METH is a highly addictive psychostimulant that when abused, has deleterious effects on the user and society. However, a critical unanswered question remains; how do early life experiences modulate both neural systems and behavior in adulthood? The emerging field of neuroepigenetics provides a potential answer to this question. Methyl CpG binding protein 2 (MeCP2), an epigenetic tag, has emerged as one possible mediator between initial drug use and the transition to addiction. Additionally, there are various neural systems that undergo long lasting epigenetics changes after ELS, such as the response of the hypothalamo-pituitary-adrenal (HPA) axis to stressors. Despite this, little attention has been given to the interactions between ELS, epigenetics, and addiction vulnerability. The studies described herein investigated the effects of ELS on METH self-administration (SA) in adult male rats. Next, we investigated the effects of ELS and METH SA on MeCP2 expression in the nucleus accumbens and dorsal striatum. Additionally, we investigated the effects of virally-mediated knockdown of MeCP2 expression in the nucleus accumbens core on METH SA, motivation to obtain METH under conditions of increasing behavioral demand, and reinstatement of METH-seeking in rats with and without a history of ELS. The results of these studies provide insights into potential epigenetic mechanisms by which ELS can produce an increased vulnerability to addiction in adulthood. Moreover, these studies shed light on possible novel molecular targets for treating addiction in individuals with a history of ELS.
ContributorsLewis, Candace (Author) / Olive, M. Foster (Thesis advisor) / Hammer, Ronald (Committee member) / Neisewander, Janet (Committee member) / Sanabria, Federico (Committee member) / Arizona State University (Publisher)
Created2015
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Description
Theoretical models support conceptualizing parent-child relationships as reciprocal and transactional with each person exerting influence on the other’s behaviors and the overall quality and valence of the relationship across time. The goals of this study were twofold: 1) determine whether there were reciprocal relations in maternal hostility and child negativity

Theoretical models support conceptualizing parent-child relationships as reciprocal and transactional with each person exerting influence on the other’s behaviors and the overall quality and valence of the relationship across time. The goals of this study were twofold: 1) determine whether there were reciprocal relations in maternal hostility and child negativity across early and middle childhood, and 2) investigate whether individual characteristics (i.e., child temperamental anger and frustration and maternal neuroticism) moderated relations found in goal one. Data were from the Study of Early Child Care and Youth Development. Empirical support was found for conceptualizing mother-child interactions as reciprocal. Maternal hostility was related to a decrease in the probability children would exhibit negative behaviors during mother-child interactions measured approximately two years later. Child negativity was also associated with a significant decrease in the probability mothers would display future hostility.

Child temperamental anger and frustration was found to moderate reciprocal relations across all three parent-to-child cross-lagged paths. Children scoring high on a dispositional proclivity to react with anger and frustration were more likely to avoid maternal hostility, via a significant decrease in negativity, across time. Moderation was also supported in two of three child-to-parent lagged paths. Finally, maternal neuroticism moderated the reciprocal effects during early childhood, such that more neurotic mothers were more likely to demonstrate a decrease in the probability of hostility relative to mothers scoring lower on neuroticism. This affect was attenuated in middle childhood, with patterns becoming similar between mothers scoring high and low on neuroticism. Moreover, children of less neurotic mothers were more likely to demonstrate a decrease in the probability of exhibiting negativity from 36 to 54 months compared to children of more neurotic mothers. This effect also attenuated with patterns becoming negative at the grade 1 to grade 3 lag. Overall, the results from this study supported a transactional model of parent-child relationships, were consistent with the motivation literature, did not support a coercive process of interaction when the sample and measurement paradigm were low-risk, and generally suggested parents and children have an equal influence on the relational processes investigated from early to middle childhood.
ContributorsPennar, Amy LaRae (Author) / Bradley, Robert H (Thesis advisor) / Iida, Masumi (Committee member) / Spinrad, Tracy (Committee member) / Taylor, Michelle (Committee member) / Arizona State University (Publisher)
Created2016
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Description
The theory of biological sensitivity to context (BSC; Boyce & Ellis, 2005) posits that specific biological characteristics, such as vagal tone, may confer risk for physical and mental health outcomes for some children but promote health for others. High levels of resting respiratory sinus arrhythmia (RSA), an index of vagal

The theory of biological sensitivity to context (BSC; Boyce & Ellis, 2005) posits that specific biological characteristics, such as vagal tone, may confer risk for physical and mental health outcomes for some children but promote health for others. High levels of resting respiratory sinus arrhythmia (RSA), an index of vagal tone, may confer susceptibility to the effects of the caregiving environment on child development. Consistent with BSC, I expected that, relative to infants with lower RSA, infants with higher RSA would demonstrate fewer behavior problems if their mothers reported fewer postpartum depressive symptoms, but more behavior problems if their mothers reported more postpartum depressive symptoms. I also evaluated whether observed child social engagement with their mothers mediated children's biological sensitivity to the effects of postpartum depressive symptoms on behavior problems in early childhood. I evaluated a mediated moderation model among a sample of 322 low-income Mexican American mother-infant dyads. As expected, the RSA x maternal depressive symptoms interaction, controlling for covariates, was a significant predictor of internalizing, externalizing and total behavior problems, and high vagal tone conferred susceptibility for externalizing behavior problems. Contrary to my hypothesis, children with low RSA may be more susceptible to the effects of maternal postpartum depressive symptoms on children's internalizing and total behavior problems, and child social engagement did not account for these effects. Among infants in economically disadvantaged families, lower RSA and fewer maternal depressive symptoms may promote resilience, and more research is needed to understand behavioral mediators of biological sensitivity.
ContributorsSomers, Jennifer (Author) / Luecken, Linda (Thesis advisor) / Crnic, Keith (Committee member) / Spinrad, Tracy (Committee member) / Arizona State University (Publisher)
Created2017