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Browsing by Author "Engleman, Eric A."
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Item The 5-HT7 receptor as a potential target for treating drug and alcohol abuse(2015) Hauser, Sheketha R.; Hedlund, Peter B.; Roberts, Amanda J.; Sari, Youssef; Bell, Richard L.; Engleman, Eric A.; Department of Psychiatry, IU School of MedicineAlcohol and drug abuse take a large toll on society and affected individuals. However, very few effective treatments are currently available to treat alcohol and drug addiction. Basic and clinical research has begun to provide some insights into the underlying neurobiological systems involved in the addiction process. Several neurotransmitter pathways have been implicated and distinct reward neurocircuitry have been proposed—including the mesocorticolimbic dopamine (MCL-DA) system and the extended amygdala. The serotonin (5-HT) neurotransmitter system is of particular interest and multiple 5-HT receptors are thought to play significant roles in alcohol and drug self-administration and the development of drug dependence. Among the 5-HT receptors, the 5-HT7 receptor is currently undergoing characterization as a potential target for the treatment of several psychiatric disorders. Although this receptor has received only limited research regarding addictive behaviors, aspects of its neuroanatomical, biochemical, physiological, pharmacological, and behavioral profiles suggest that it could play a key role in the addiction process. For instance, genomic studies in humans have suggested a link between variants in the gene encoding the 5-HT7 receptor and alcoholism. Recent behavioral testing using high-affinity antagonists in mice and preliminary tests with alcohol-preferring rats suggest that this receptor could mediate alcohol consumption and/or reinforcement and play a role in seeking/craving behavior. Interest in the development of new and more selective pharmacological agents for this receptor will aid in examining the 5-HT7 receptor as a novel target for treating addiction.Item Adolescent alcohol and nicotine exposure alters the adult response to alcohol use(Frontiers Media, 2023-11-22) Hauser, Sheketha R.; Waeiss, Robert A.; Deehan, Gerald A., Jr.; Engleman, Eric A.; Bell, Richard L.; Rodd, Zachary A.; Psychiatry, School of MedicineAdolescence through young adulthood is a unique period of neuronal development and maturation. Numerous agents can alter this process, resulting in long-term neurological and biological consequences. In the clinical literature, it is frequently reported that adolescent alcohol consumption increases the propensity to develop addictions, including alcohol use disorder (AUD), during adulthood. A general limitation of both clinical and human pre-clinical adolescent alcohol research is the high rate of co-using/abusing more than one drug during adolescence, such as co-using/abusing alcohol with nicotine. A primary goal of basic research is elucidating neuroadaptations produced by adolescent alcohol exposure/consumption that promote alcohol and other drug self-administration in adulthood. The long-term goal is to develop pharmacotherapeutics for the prevention or amelioration of these neuroadaptations. This review will focus on studies that have examined the effects of adolescent alcohol and nicotine exposure on adult alcohol consumption, the hypersensitivity of the mesolimbic dopaminergic system, and enhanced responses not only to alcohol but also to nicotine during adulthood. Again, the long-term goal is to identify potential cholinergic agents to prevent or ameliorate the consequences of, peri-adolescent alcohol abuse.Item Adolescent Intermittent Ethanol (AIE) Enhances the Dopaminergic Response to Ethanol within the Mesolimbic Pathway during Adulthood: Alterations in Cholinergic/Dopaminergic Genes Expression in the Nucleus Accumbens Shell(MDPI, 2021-10-29) Hauser, Sheketha R.; Mulholland, Patrick J.; Truitt, William A.; Waeiss, R. Aaron; Engleman, Eric A.; Bell, Richard L.; Rodd, Zachary A.; Psychiatry, School of MedicineA consistent preclinical finding is that exposure to alcohol during adolescence produces a persistent hyperdopaminergic state during adulthood. The current experiments determine that effects of Adolescent Intermittent Ethanol (AIE) on the adult neurochemical response to EtOH administered directly into the mesolimbic dopamine system, alterations in dendritic spine and gene expression within the nucleus accumbens shell (AcbSh), and if treatment with the HDACII inhibitor TSA could normalize the consequences of AIE. Rats were exposed to the AIE (4 g/kg ig; 3 days a week) or water (CON) during adolescence, and all testing occurred during adulthood. CON and AIE rats were microinjected with EtOH directly into the posterior VTA and dopamine and glutamate levels were recorded in the AcbSh. Separate groups of AIE and CON rats were sacrificed during adulthood and Taqman arrays and dendritic spine morphology assessments were performed. The data indicated that exposure to AIE resulted in a significant leftward and upward shift in the dose-response curve for an increase in dopamine in the AcbSh following EtOH microinjection into the posterior VTA. Taqman array indicated that AIE exposure affected the expression of target genes (Chrna7, Impact, Chrna5). The data indicated no alterations in dendritic spine morphology in the AcbSh or any alteration in AIE effects by TSA administration. Binge-like EtOH exposure during adolescence enhances the response to acute ethanol challenge in adulthood, demonstrating that AIE produces a hyperdopaminergic mesolimbic system in both male and female Wistar rats. The neuroadaptations induced by AIE in the AcbSh could be part of the biological basis of the observed negative consequences of adolescent binge-like alcohol exposure on adult drug self-administration behaviors.Item Caenorhabditis elegans as a model system to identify therapeutics for alcohol use disorders(Elsevier, 2019-06) Katner, Simon N.; Bredhold, Kristin E.; Steagall, Kevin B., III; Bell, Richard L.; Neal-Beliveau, Bethany S.; Cheong, Mi C.; Engleman, Eric A.; Psychiatry, School of MedicineAlcohol use disorders (AUDs) cause serious problems in society and few effective treatments are available. Caenorhabditis elegans (C. elegans) is an excellent invertebrate model to study the neurobiological basis of human behavior with a conserved, fully tractable genome, and a short generation time for fast generation of data at a fraction of the cost of other organisms. C. elegans demonstrate movement toward, and concentration-dependent self-exposure to various psychoactive drugs. The discovery of opioid receptors in C. elegans provided the impetus to test the hypothesis that C. elegans may be used as a medications screen to identify new AUD treatments. We tested the effects of naltrexone, an opioid antagonist and effective treatment for AUDs, on EtOH preference in C. elegans. Six-well agar test plates were prepared with EtOH placed in a target zone on one side and water in the opposite target zone of each well. Worms were treated with naltrexone before EtOH preference testing and then placed in the center of each well. Wild-type worms exhibited a concentration-dependent preference for 50, 70 and 95% EtOH. Naltrexone blocked acute EtOH preference, but had no effect on attraction to food or benzaldehyde in wild-type worms. Npr-17 opioid receptor knockout mutants did not display a preference for EtOH. In contrast, npr-17 opioid receptor rescue mutants exhibited significant EtOH preference behavior, which was attenuated by naltrexone. Chronic EtOH exposure induced treatment resistance and compulsive-like behavior. These data indicate that C. elegans can serve as a model system to identify compounds to treat AUDs.Item Caenorhabditis elegans as a Model to Study the Molecular and Genetic Mechanisms of Drug Addiction(Elsevier, 2016) Engleman, Eric A.; Katner, Simon N.; Neal-Beliveau, Bethany S.; Department of Psychiatry, IU School of MedicineDrug addiction takes a massive toll on society. Novel animal models are needed to test new treatments and understand the basic mechanisms underlying addiction. Rodent models have identified the neurocircuitry involved in addictive behavior and indicate that rodents possess some of the same neurobiologic mechanisms that mediate addiction in humans. Recent studies indicate that addiction is mechanistically and phylogenetically ancient and many mechanisms that underlie human addiction are also present in invertebrates. The nematode Caenorhabditis elegans has conserved neurobiologic systems with powerful molecular and genetic tools and a rapid rate of development that enables cost-effective translational discovery. Emerging evidence suggests that C. elegans is an excellent model to identify molecular mechanisms that mediate drug-induced behavior and potential targets for medications development for various addictive compounds. C. elegans emit many behaviors that can be easily quantitated including some that involve interactions with the environment. Ethanol (EtOH) is the best-studied drug-of-abuse in C. elegans and at least 50 different genes/targets have been identified as mediating EtOH's effects and polymorphisms in some orthologs in humans are associated with alcohol use disorders. C. elegans has also been shown to display dopamine and cholinergic system-dependent attraction to nicotine and demonstrate preference for cues previously associated with nicotine. Cocaine and methamphetamine have been found to produce dopamine-dependent reward-like behaviors in C. elegans. These behavioral tests in combination with genetic/molecular manipulations have led to the identification of dozens of target genes/systems in C. elegans that mediate drug effects. The one target/gene identified as essential for drug-induced behavioral responses across all drugs of abuse was the cat-2 gene coding for tyrosine hydroxylase, which is consistent with the role of dopamine neurotransmission in human addiction. Overall, C. elegans can be used to model aspects of drug addiction and identify systems and molecular mechanisms that mediate drug effects. The findings are surprisingly consistent with analogous findings in higher-level organisms. Further, model refinement is warranted to improve model validity and increase utility for medications development.Item Caenorhabditis elegans Show Preference for Stimulants and Potential as a Model Organism for Medications Screening(Frontiers, 2018-08-30) Engleman, Eric A.; Steagall II, Kevin B.; Bredhold, Kristin E.; Breach, Michaela; Kline, Hannah L.; Bell, Richard L.; Katner, Simon N.; Neal-Beliveau, Bethany S.; Psychiatry, School of MedicineThe nematode Caenorhabditis elegans (C. elegans) is a popular invertebrate model organism to study neurobiological disease states. This is due in part to the intricate mapping of all neurons and synapses of the entire animal, the wide availability of mutant strains, and the genetic and molecular tools that can be used to manipulate the genome and gene expression. We have shown that, C. elegans develops a conditioned preference for cues that had previously been paired with either cocaine or methamphetamine exposure that is dependent on dopamine neurotransmission, similar to findings using place conditioning with rats and mice. In the current study, we show C. elegans also display a preference for, and self-exposure to, cocaine and nicotine. This substance of abuse (SOA) preference response can be selectively blocked by pretreatment with naltrexone and is consistent with the recent discovery of an opioid receptor system in C. elegans. In addition, pre-exposure to the smoking cessation treatment varenicline also inhibits self-exposure to nicotine. Exposure to concentrations of treatments that inhibit SOA preference/self-exposure did not induce any significant inhibition of locomotor activity or affect food or benzaldehyde chemotaxis. These data provide predictive validity for the development of high-throughput C. elegans behavioral medication screens. These screens could enable fast and accurate generation of data to identify compounds that may be effective in treating human addiction. The successful development and validation of such models would introduce powerful and novel tools in the search for new pharmacological treatments for substance use disorders, and provide a platform to study the mechanisms that underlie addictions.Item Caffeinated Alcoholic Beverages – An Emerging Trend in Alcohol Abuse(OMICS, 2013-08) Franklin, Kelle M.; Hauser, Sheketha R.; Bell, Richard L.; Engleman, Eric A.; Department of Psychiatry, IU School of MedicineAlcohol use disorders are pervasive in society and their impact affects quality of life, morbidity and mortality, as well as individual productivity. Alcohol has detrimental effects on an individual’s physiology and nervous system, and is associated with disorders of many organ and endocrine systems impacting an individual’s health, behavior, and ability to interact with others. Youth are particularly affected. Unfortunately, adolescent usage also increases the probability for a progression to dependence. Several areas of research indicate that the deleterious effects of alcohol abuse may be exacerbated by mixing caffeine with alcohol. Some behavioral evidence suggests that caffeine increases alcohol drinking and binge drinking episodes, which in turn can foster the development of alcohol dependence. As a relatively new public health concern, the epidemiological focus has been to establish a need for investigating the effects of caffeinated alcohol. While the trend of co-consuming these substances is growing, knowledge of the central mechanisms associated with caffeinated ethanol has been lacking. Research suggests that caffeine and ethanol can have additive or synergistic pharmacological actions and neuroadaptations, with the adenosine and dopamine systems in particular implicated. However, the limited literature on the central effects of caffeinated ethanol provides an impetus to increase our knowledge of the neuroadaptive effects of this combination and their impact on cognition and behavior. Research from our laboratories indicates that an established rodent animal model of alcoholism can be extended to investigate the acute and chronic effects of caffeinated ethanol.Item Co‐administration of ethanol and nicotine heightens sensitivity to ethanol reward within the nucleus accumbens (NAc) shell and increasing NAc shell BDNF is sufficient to enhance ethanol reward in naïve Wistar rats(Wiley, 2019) Waeiss, Robert A.; Knight, Christopher P.; Engleman, Eric A.; Hauser, Sheketha R.; Rodd, Zachary A.; Psychiatry, School of MedicineAlcohol use disorder most commonly presents as a polydrug disorder where greater than 85% are estimated to smoke. EtOH and nicotine (NIC) co‐abuse or exposure results in unique neuroadaptations that are linked to behaviors that promote drug use. The current experiments aimed to identify neuroadaptations within the mesolimbic pathway produced by concurrent EtOH and NIC exposure. The experiments used four overall groups of male Wistar rats consisting of vehicle, EtOH or NIC alone, and EtOH+NIC. Drug exposure through direct infusion into the posterior ventral tegmental area (pVTA) stimulated release of glutamate and dopamine in the nucleus accumbens (NAc) shell, which was quantified through high‐performance liquid chromatography. Additionally, brain‐derived neurotrophic factor (BDNF) protein levels were measured via enzyme‐linked immunosorbent assay (ELISA). A second experiment investigated the effects of drug pretreatment within the pVTA on the reinforcing properties of EtOH within the NAc shell through intracranial self‐administration (ICSA). The concluding experiment evaluated the effect of NAc shell pretreatment with BDNF on EtOH reward utilizing ICSA within that region. The data indicated that only EtOH+NIC administration into the pVTA simultaneously increased glutamate, dopamine, and BDNF in the NAc shell. Moreover, only pVTA pretreatment with EtOH+NIC enhanced the reinforcing properties of EtOH in the NAc shell. BDNF pretreatment in the NAc shell was also sufficient to enhance the reinforcing properties of EtOH in the NAc shell. The collected data suggest that concurrent EtOH+NIC exposure results in a distinct neurochemical response and neuroadaptations within the mesolimbic pathway that alter EtOH reward.Item The Development of a C. Elegans Model of Nicotine Use and Aversion Resistance(2023-05) Omura, Daniel E.; Neal-Beliveau, Bethany S.; Goodlett, Charles R.; Engleman, Eric A.; Grahame, Nicholas J.Nicotine addiction is an extremely costly and widespread issue that affects millions of people globally and current treatments have relatively low long term efficacy rates. This demonstrates the need for a greater understanding of nicotine addiction and its underlying mechanisms. This study created a C. elegans model of compulsive nicotine use. C. elegans, that were pretreated with nicotine (9.7 μM or 120 μM) from larval stage 4 to gravid adulthood, demonstrated reduced aversion to 10% nonanone in the presence of nicotine compared to untreated worms. The pretreatment concentration of 9.7 μM nicotine was chosen for further study due to its ability to induce aversion resistance without significant changes to locomotor speed, food preference, or benzaldehyde preference. This model was then applied to nicotinic acetylcholine (acr-5, acr-15, acr-16) and dopamine (dop-1, dop-2) receptor knockout mutants to determine the roles of these receptors in the development of aversion resistance. For the acr-5, acr-15, and acr-16 mutants, there was an increase in preference following the administration of 10% nonanone, regardless of pretreatment condition, suggesting that the removal of these receptors induces aversion resistance. For the dop-1 receptor mutant, 10-minute timepoint nicotine preference was reduced following preexposure. For the dop-2 receptor mutant, aversion was enhanced at the 5 mM and 50 mM test concentrations following the administration of 10% nonanone, suggesting that the dop-2 receptor is partially responsible for the development of aversion resistance. Additional research should be conducted to determine the underlying mechanisms of this drug induced aversion resistance. With current the lack of highly efficacious nicotine cessation drugs, this model could be used to test novel therapeutic drugs in a rapid high throughput manner.Item The effect of voluntary binge caffeine and ethanol co-exposure on neurobehavioral sensitivity to cocaine in male C57BL/6J mice(2016-05) Fritz, Brandon M.; Boehm, Stephen L., II; Czachowski, Cristine Lynn; Kinzig, Kimberly; Engleman, Eric A.; Grahame, Nicholas J.Recently, the co-consumption of highly caffeinated energy drinks and alcohol has become a public health concern. Consumption of these beverages has been linked to a wide variety negative consequences including alcohol poisoning, driving under the influence, physical harm, and sexual violence. The more protracted consequences of caffeinated alcohol consumption have received very little attention, however. Some evidence suggests that individuals that frequently consume energy drinks mixed with alcohol are more likely to develop an alcohol use disorder. Interestingly, both caffeine and alcohol use alone have been linked to polydrug abuse. It is therefore of interest whether combined caffeine and alcohol consumption may pose an additive risk for substance abuse. Given that both compounds can positively influence dopamine signaling in mesolimbocortical reward circuitry via different mechanisms, this is an important question to address. Psychostimulants, such as cocaine, are of particular interest considering the significant involvement of dopamine in their effects. The current project explored this possibility employing an established mouse model of binge caffeine and alcohol co-consumption. Male C57BL/6J mice underwent 14 days of daily, 2hr limited access to water, alcohol, caffeine, or combined caffeine and alcohol. Water was freely available after these sessions. In Experiment 1, mice underwent an 11-day locomotor sensitization protocol for cocaine initiating on day 15. Locomotor sensitization has been associated with a greater propensity to self-administer psychostimulants in rodents. Mice were subjected to injections of cocaine (5 or 10 mg/kg; i.p.) or saline every other day, with 15 minute activity monitoring until day 25. In Experiment 2, a separate group of mice underwent an identical drinking procedure. A conditioned place preference (CPP) protocol commenced on day 15. CPP assesses the conditioned rewarding effects of cues associated with drugs of abuse. On day 15, mice received saline injections and were immediately placed onto a neutral floor texture (paper) in the place conditioning box for 15 minutes in order to habituate the animals to the apparatus and injection procedure. Starting on day 16, mice received daily alternating systemic injections of cocaine (1 or 5 mg/kg; i.p.) and saline or saline throughout (naïve controls) and were placed onto one of two particular tactile floor cues: a metal floor with holes punched out or a grid floor made of metal rods. Mice were exposed to the other injection/floor pairing on the alternate days. Mice were placed into these activity monitors for 15 minute conditioning sessions. These sessions alternated drug and vehicle over the course of 8 days so that a total of 4 drug and 4 saline injections were given. The first place preference test occurred on day 24 wherein all mice were injected with saline and offered access to both floor textures. On day 25, mice were returned to the conditioning protocol for another 8 days and a second CPP test on day 33. The results of Experiment 1 suggested that prior caffeine consumption, irrespective of the presence of ethanol, enhanced the initial psychomotor stimulating effect of 10 mg/kg cocaine. However, prior fluid consumption history did not influence the capacity to develop locomotor sensitization. The results of Experiment 2 indicate that prior caffeine and/or ethanol consumption had no influence on the development or expression of CPP for 1 mg/kg or 5 mg/kg cocaine. Collectively, these results suggest that a history of caffeine consumption may increase the stimulant response to a moderate dose of cocaine, perhaps indicating cross-sensitization. Although the conditioned rewarding effects of cocaine were not altered by prior caffeine and/or ethanol consumption, an enhanced stimulant response may be indicative of enhanced cocaine abuse potential. This study demonstrates that moderate caffeine consumption may influence an individual’s early interactions with cocaine which may eventually influence the likelihood of later problematic use.