IU Indianapolis ScholarWorks :: Browsing by Author "Chester, Julia A."

Browsing by Author "Chester, Julia A."

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Alcohol-preferring rats show decreased corticotropin-releasing hormone-2 receptor expression and differences in HPA activation compared to alcohol-nonpreferring rats
(Wiley Blackwell (Blackwell Publishing), 2014-05) Yong, Weidong; Spence, John Paul; Eskay, Robert; Fitz, Stephanie D.; Damadzic, Ruslan; Lai, Dongbing; Foroud, Tatiana; Carr, Lucinda G.; Shekhar, Anantha; Chester, Julia A.; Heilig, Markus; Liang, Tiebing; Department of Medicine, IU School of Medicine
BACKGROUND: Corticotropin-releasing hormone (CRH) and urocortins (UCNs) bind to corticotropin-releasing hormone type 2 receptor (CRF2 receptor ), a Gs protein-coupled receptor that plays an important role in modulation of anxiety and stress responses. The Crhr2 gene maps to a quantitative trait locus (QTL) for alcohol preference on chromosome 4 previously identified in inbred alcohol-preferring (iP) and-nonpreferring (iNP) F2 rats. METHODS: Real-time polymerase chain reaction was utilized to screen for differences in Crhr2 mRNA expression in the central nervous system (CNS) of male iP and iNP rats. DNA sequence analysis was then performed to screen for polymorphism in Crhr2 in order to identify genetic variation, and luciferase reporter assays were then applied to test their functional significance. Next, binding assays were used to determine whether this polymorphism affected CRF2 receptor binding affinity as well as CRF2 receptor density in the CNS. Finally, social interaction and corticosterone levels were measured in the P and NP rats before and after 30-minute restraint stress. RESULTS: Crhr2 mRNA expression studies found lower levels of Crhr2 mRNA in iP rats compared to iNP rats. In addition, DNA sequencing identified polymorphisms in the promoter region, coding region, and 3'-untranslated region between the iP and iNP rats. A 7 bp insertion in the Crhr2 promoter of iP rats altered expression in vitro as measured by reporter assays, and we found that CRF2 receptor density was lower in the amygdala of iP as compared to iNP rats. Male P rats displayed decreased social interaction and significantly higher corticosterone levels directly following 30-minute restraint when compared to male NP rats. CONCLUSIONS: This study identified Crhr2 as a candidate gene of interest underlying the chromosome 4 QTL for alcohol consumption that was previously identified in the P and NP model. Crhr2 promoter polymorphism is associated with reduced mRNA expression in certain brain regions, particularly the amygdala, and lowered the density of CRF2 receptor in the amygdala of iP compared to iNP rats. Together, these differences between the animals may contribute to the drinking disparity as well as the anxiety differences of the P and NP rats.
ALTERATIONS IN THE SEEKING AND SELF-ADMINISTRATION OF ETHANOL AND ANXIETY-LIKE BEHAVIOR FOLLOWING EXPOSURE TO YOHIMBINE IN RATS SELECTIVELY BRED FOR HIGH ALCOHOL INTAKE
(2011-08-16) Bertholomey, Megan Lee; Grahame, Nicholas J.; Czachowski, Cristine; Stewart, Robert; Chester, Julia A.
Stress has been shown to contribute to alcohol drinking; however, inconsistencies in both the clinical and pre-clinical literature speak to the need for better paradigms to study this interaction. The present experiments compared animal models of the propensity to consume ethanol, the selectively bred alcohol-preferring (P) and high-alcohol-drinking (HAD) rat lines, in their response to yohimbine on ethanol seeking and self-administration and anxiety-like behavior. The P and HAD lines consume similar amounts of ethanol, yet differ in apparent motivation to drink ethanol, in anxiety-like behavior, and response to stress in alcohol drinking. Therefore, it was of interest to determine whether stress may differentially affect ethanol-motivated behaviors between the P and HAD lines. Acute administration of yohimbine, an α-2 adrenoreceptor antagonist that increases anxiety and activate stress systems, increased operant ethanol self-administration and reinstatement of ethanol seeking in P rats, and free-choice ethanol drinking in both P and HAD rats. However, acute yohimbine administration decreased ethanol drinking when given limited access in the home cage, an effect that was diminished by extending the pre-treatment interval or increasing the number of ethanol exposure sessions. Yohimbine did not alter appetitive responding during a non-reinforced trial, nor did yohimbine alter the acquisition of free-choice ethanol drinking. Exposure to alcohol deprivation resulted in modest increases in ethanol intake, but yohimbine did not potentiate this effect. While acute yohimbine administration increased anxiety-like behavior, prior experience with repeated yohimbine exposures or with repeated deprivation periods did not. P rats were shown to be more active and less anxious and to display greater responding during a non-reinforced trial than HAD rats. Taken together, the results of these experiments demonstrate that the timing of yohimbine exposure relative to ethanol access is a critical component to determining its effects on ethanol seeking and self-administration and anxiety-like behavior. Further investigation into the parameters under which stress alters the motivation to seek and consume ethanol between these selectively bred lines is warranted, and future work that incorporates therapeutic agents aimed at reducing stress reactivity and alcohol drinking could elucidate effective strategies in the treatment of alcoholism.
Effects of nicotine on alcohol drinking in female mice selectively-bred for high or low alcohol preference
(Wiley, 2017) Weera, Marcus M.; Fields, Molly A.; Tapp, Danielle N.; Grahame, Nicholas J.; Chester, Julia A.; Psychology, School of Science
Background Studies show that repeated nicotine use associates with high alcohol consumption in humans, and that nicotine exposure sometimes increases alcohol consumption in animal models. However, the relative roles of genetic predisposition to high alcohol consumption, the alcohol drinking patterns, and the timing of nicotine exposure both with respect to alcohol drinking and developmental stage remain unclear. The studies here manipulated all these variables, using mice selectively bred for differences in free-choice alcohol consumption to elucidate the role of genetics and nicotine exposure in alcohol consumption behaviors. Methods In Experiments 1 and 2, we assessed the effects of repeated nicotine (0, 0.5 or 1.5 mg/kg) injections immediately before binge-like (drinking-in-the-dark; Experiment 1) or during free-choice alcohol access (Experiment 2) on these alcohol drinking behaviors (immediately after injections and during re-exposure to alcohol access 14 days later) in adult high- (HAP2) and low-alcohol preferring (LAP2) female mice (co-exposure model). In Experiments 3 and 4, we assessed the effects of repeated nicotine (0, 0.5 or 1.5 mg/kg) injections 14 days prior to binge-like and free-choice alcohol access on these alcohol drinking behaviors in adolescent HAP2 and LAP2 female mice (Experiment 3) or adult HAP2 female mice (Experiment 4). Results In Experiment 1, we found that repeated nicotine (0.5 and 1.5 mg/kg) and alcohol co-exposure significantly increased binge-like drinking behavior in HAP2 but not LAP2 mice during the re-exposure phase after a 14-day abstinence period. In Experiment 2, 1.5 mg/kg nicotine injections significantly reduced free-choice alcohol intake and preference in the 3rd hour post-injection in HAP2 but not LAP2 mice. No significant effects of nicotine treatment on binge-like or free-choice alcohol drinking were observed in Experiments 3 and 4. Conclusions These results show that the temporal parameters of nicotine and alcohol exposure, pattern of alcohol access, and genetic predisposition for alcohol preference influence nicotine's effects on alcohol consumption. These findings in selectively bred mice suggest that humans with a genetic history of alcohol-use disorders may be more vulnerable to develop nicotine and alcohol co-use disorders.
The FKBP5 Gene Affects Alcohol Drinking in Knockout Mice and Is Implicated in Alcohol Drinking in Humans
(MDPI, 2016-08) Qiu, Bin; Luczak, Susan E.; Wall, Tamara L.; Xu, Yuxue; Eng, Mimy Y.; Steward, Robert B.; Shou, Weinian; Boehm II, Stephen L.; Chester, Julia A.; Yong, Weidong; Liang, Tiebing; Kirchhoff, Aaron M.; Department of Psychology, School of Science
FKBP5 encodes FK506-binding protein 5, a glucocorticoid receptor (GR)-binding protein implicated in various psychiatric disorders and alcohol withdrawal severity. The purpose of this study is to characterize alcohol preference and related phenotypes in Fkbp5 knockout (KO) mice and to examine the role of FKBP5 in human alcohol consumption. The following experiments were performed to characterize Fkpb5 KO mice. (1) Fkbp5 KO and wild-type (WT) EtOH consumption was tested using a two-bottle choice paradigm; (2) The EtOH elimination rate was measured after intraperitoneal (IP) injection of 2.0 g/kg EtOH; (3) Blood alcohol concentration (BAC) was measured after 3 h limited access of alcohol; (4) Brain region expression of Fkbp5 was identified using LacZ staining; (5) Baseline corticosterone (CORT) was assessed. Additionally, two SNPs, rs1360780 (C/T) and rs3800373 (T/G), were selected to study the association of FKBP5 with alcohol consumption in humans. Participants were college students (n = 1162) from 21–26 years of age with Chinese, Korean or Caucasian ethnicity. The results, compared to WT mice, for KO mice exhibited an increase in alcohol consumption that was not due to differences in taste sensitivity or alcohol metabolism. Higher BAC was found in KO mice after 3 h of EtOH access. Fkbp5 was highly expressed in brain regions involved in the regulation of the stress response, such as the hippocampus, amygdala, dorsal raphe and locus coeruleus. Both genotypes exhibited similar basal levels of plasma corticosterone (CORT). Finally, single nucleotide polymorphisms (SNPs) in FKBP5 were found to be associated with alcohol drinking in humans. These results suggest that the association between FKBP5 and alcohol consumption is conserved in both mice and humans.
Intravenous Self-Administration of Alcohol in Selectively Bred High- and Low- Alcohol Preferring Mice
(2011-08-02) Green, Alexis Suzanne; Grahame, Nicholas J.; Goodlett, Charles R.; Murphy, James M.; Chester, Julia A.
Genetic vulnerability to alcoholism is theorized to be caused by multiple interacting genetic loci, each with a small to modest effect combining under certain environmental influences to contribute to vulnerability to ethanol dependence. Animal models such as selectively bred rodent lines can be used to address this hypothesis of genetic vulnerability. High-drinking lines are implicitly assumed by many to be evidence of high ethanol reinforcement without consideration for variables such as differential pre- and post ingestive effects, low response to alcohol or novelty-seeking. Therefore, it is an open question as to whether animal studies support the idea that genetic differences in free-choice drinking are correlated with genetic differences in other assessments of ethanol-reinforced behavior, including those utilizing operant and classical conditioning. Thus, the present study utilizes selectively bred High- and Low- Alcohol Preferring mice tested for operant intravenous alcohol administration to address the hypothesis that High Alcohol Preferring mice would show evidence of greater alcohol reinforcement than their selectively bred opposite, Low Alcohol Preferring mice. Evidence for greater reinforcement was supported by High Alcohol Preferring mice voluntarily pressing a lever to administer an intravenous dose of alcohol in a two lever choice paradigm, administering higher doses of intravenous alcohol, and tracking the location of the active alcohol lever during a lever reversal procedure in comparison to Low Alcohol Preferring mice. This study supports the High- and Low- Alcohol Preferring mice as a useful genetic model of alcohol-related vulnerability even when utilizing a route of administration that bypasses the digestive system.
Investigating reactivity to incentive downshift as a correlated response to selection for high alcohol preference and a determinant of rash action and alcohol consumption
(2014) Matson, Liana M.; Grahame, Nicholas J.; Czachowski, Cristine; Boehm, Stephen; Cyders, Melissa A.; Chester, Julia A.
Losing a job or a significant other are examples of incentive shifts that result in negative emotional reactions. The occurrence of negative life events is associated with increased drinking, and alleviation of negative emotions has been cited as a drinking motive for individuals with problematic drinking patterns (Keyes et al., 2011; Adams et al., 2012). Further, there is evidence that certain genotypes drink alcohol in response to stressful negative life events (Blomeyer et al., 2008; Covault et al., 2007). It is possible that shared genetic factors contribute to both alcohol drinking and emotional reactivity, but there is a critical need for this relationship to be understood. The first aim of this proposal will use an incentive downshift paradigm to address whether emotional reactivity is elevated in mice predisposed to drink alcohol. The second aim of this proposal will address if reactivity to an incentive shift can result in rash action using a differential reinforcement of low rates of responding task, and whether this response is also associated with a predisposition for high drinking. The third aim of this proposal will investigate if experimenter administered ethanol reduces contrast effects, and if an incentive shift increases ethanol consumption in a high drinking line. The overall goal of this proposal is to investigate whether reactivity to incentive shift is an important mechanism underlying alcohol drinking in these mice, and the role an incentive shift may play in producing rash action and influencing ethanol consumption.
Juvenile stress facilitates safety learning in male and female high alcohol preferring mice
(Elsevier, 2021) Müller, Iris; Adams, Demitra D.; Sangha, Susan; Chester, Julia A.; Psychology, School of Science
Adversities during juvenility increase the risk for stress-related disorders, such as post-traumatic stress disorder (PTSD) and alcohol use disorder. However, stress can also induce coping mechanisms beneficial for later stressful experiences. We reported previously that mice selectively bred for high alcohol preference (HAP) exposed to stress during adolescence (but not during adulthood) showed enhanced fear-conditioned responses in adulthood, as measured by fear-potentiated startle (FPS). However, HAP mice also showed enhanced responding to safety cues predicting the absence of foot shocks in adulthood. Here, we pursue these findings in HAP mice by investigating in further detail how juvenile stress impacts the acquisition of safety and fear learning. HAP mice were subjected to three days of juvenile stress (postnatal days 25, 27, 28) and discriminative safety/fear conditioning in adulthood. FPS was used to assess safety versus fear cue discrimination, fear learning, and fear inhibition by the safety cue. Both stressed and unstressed HAP mice were able to discriminate between both cues as well as learn the fear cue-shock association. Interestingly, it was only the previously stressed mice that were able to inhibit their fear response when the fear cue was co-presented with the safety cue, thus demonstrating safety learning. We also report an incidental finding of alopecia in the juvenile stress groups, a phenotype seen in stress-related disorders. These results in HAP mice may be relevant to understanding the influence of juvenile trauma for individual risk and resilience toward developing PTSD and how individuals might benefit from safety cues in behavioral psychotherapy.
Role of group II metabotropic glutamate receptor subtype 2 (MGluR2) in appetitive and consummatory aspects of ethanol reinforcement
(2014-12) Windisch, Kyle Allyson; Czachowski, Cristine; Lapish, Christopher; Neal-Beliveau, Bethany S.; Chester, Julia A.
Background: Group II metabotropic glutamate receptors (mGluR2/3) are predominately presynaptically located Gi/o coupled receptors that are highly expressed in the cortex, nucleus accumbens, amygdala, and hippocampus. Previous studies suggest that group II mGluRs are involved in regulating ethanol (EtOH) consumption and seeking following extinction (Backstrom and Hyytia, 2005; Kufahl, et al., 2011). The sipper tube model, which allows for procedural separation of seeking and consumption, was used to further clarify the role of mGluR2/3 in EtOH-seeking and consumption. The non-selective group II mGluR agonist LY379268 (LY37) and selective mGluR2 positive allosteric modulator (PAM) BINA were used to determine the relative contribution of mGlu2 and mGlu3 receptors on EtOH seeking and consumption. Following characterization of the agonist and PAM on EtOH reinforcement, a microinjection study was performed examining the effect of blockade of nucleus accumbens core mGluR2/3 on systemic agonist induced suppression of EtOH-seeking. Methods: For the systemic agonist/PAM experiments, separate groups of male Wistar rats [n=8-9 group; LY37 (0-2.0 mg/kg) and BINA (0-20 mg/kg)] were trained to complete a response requirement (RR) of 10 lever presses that resulted in access to 10% EtOH or 2% sucrose (in separate groups) for a 20-minute drinking period. For consummatory testing, animals received weekly drug injections with a RR1. The RR was then increased over sessions to a RR20. For appetitive testing, animals received weekly drug injections followed by a non-reinforced extinction session. To determine effects of blockade of NAc core mGluR2/3 receptors on agonist-induced suppression of EtOH-seeking, a separate group of male Wistar rats (n=15) was trained to complete a RR10 for access to 10% EtOH. Animals were surgically implanted with bilateral guide cannulae terminating 1mm above the NAc core. Following recovery, animals received four sets of microinjections in a balanced design (systemic vehicle + core vehicle, systemic LY37 + core vehicle, systemic LY37 + core LY34, and systemic vehicle + core LY34). A final non-balanced microinjection of LY37 was then performed. Results and Conclusions: Systemic administration of the mGluR2/3 agonist LY37 significantly reduced EtOH- and sucrose- seeking with no systematic effect on locomotion. Systemic administration of the selective mGluR2 PAM BINA had no significant effect on either seeking or consumption. These findings suggest that modulation of glutamatergic neurotransmission by a systemic mGluR2/3 agonist, but not allosteric modulation of mGluR2, significantly reduces reinforcer seeking. Intra- accumbens core administration of LY37 significantly reduced EtOH-seeking, suggesting a role of NAc core mGluR2/3 modulation in EtOH-seeking during maintenance drinking. Systemic administration of LY37 was also found to significantly reduce sucrose consumption and body weight 24-hours following systemic administration, meriting further examination of the role of mGluR2/3 receptors on feeding behavior.
USING SHORT-TERM BEHAVIORAL SELECTION TO EVALUATE THE HERITABILITY OF ETHANOL-INDUCED LOCOMOTOR SENSITIZATION AND ITS RELATIONSHIP TO ETHANOL’S POSITIVE MOTIVATIONAL EFFECTS IN MICE
(2013-08-14) Linsenbardt, David, N.; Boehm, Stephen; Grahame, Nicholas J.; Czachowski, Cristine; Chester, Julia A.
Sensitization to the locomotor stimulant effects of alcohol (ethanol) is thought to be a heritable risk factor for the development of alcoholism that reflects progressive increases in the positive motivational effects of this substance. However, very little is known about the genetic influences involved in this phenomenon or the extent to which ethanol’s positive motivational effects are altered in parallel to its development. The first goal of this work was to determine the heritability of ethanol-induced locomotor sensitization in mice using short-term behavioral selection. Genetically heterogeneous C57BL/6J (B6) x DBA/2J (D2) F2 mice were generated from B6D2F1 progenitors, phenotyped for the expression of locomotor sensitization, and bred for high (HLS) and low (LLS) expression of this behavior. A secondary goal was to characterize possible line differences in ethanol’s positive motivational effects using a conditioned place preference assay. There were large and significant differences in locomotor sensitization between HLS and LLS lines by the fourth generation. Twenty-two percent of the observed line difference(s) were attributable to genes (h2=.22). However, there were no significant differences in conditioned place preference between lines despite significant line differences in ethanol-stimulated locomotion following repeated exposures. The results of this work have several implications. First, that changes in ethanol sensitivity following repeated exposures are in part genetically regulated highlights the relevance of studies aimed at determining how genes regulate susceptibility to ethanol-induced behavioral and neural adaptations. Additionally, the lack of line differences in ethanol-induced CPP, and the observation that CPP and ethanol sensitization are dissociable, suggests that 1) different genes regulate these two behaviors and 2) the utility of locomotor sensitization as a model of alterations in ethanol’s positive motivational effects is, at best, still unclear. Together these studies provide evidence that genes are capable of regulating alterations in ethanol-induced locomotor behavior but provide little support for ethanol-induced locomotor sensitization as a model for increases in ethanol’s positive subjective effects in mice.

Browsing by Author "Chester, Julia A."

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