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Engeln M, Ahmed SH. The multiple faces of footshock punishment in animal research on addiction. Neurobiol Learn Mem 2024; 213:107955. [PMID: 38944108 DOI: 10.1016/j.nlm.2024.107955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 06/05/2024] [Accepted: 06/20/2024] [Indexed: 07/01/2024]
Abstract
Continued drug use despite negative consequences is a hallmark of addiction commonly modelled in rodents using punished drug intake. Over the years, addiction research highlighted two subpopulations of punishment sensitive and resistant animals. While helpful to interrogate the neurobiology of drug-related behaviors, these procedures carry some weaknesses that need to be recognized and eventually defused. Mainly focusing on footshock-related work, we will first discuss the criteria used to define punishment-resistant animals and how their relative arbitrariness may impact our findings. With the overarching goal of improving our interpretation of the punishment-resistant phenotype, we will evaluate how tailored punishment protocols may better apprehend resistance to punishment, and how testing the robustness of punishment resistance could yield new results and strengthen interpretations. Second, we will question whether and to what extent punishment sensitivity, as currently defined, is reflective of abstinence and suggest that punishment resistance is, in fact, a prerequisite to model abstinence from addiction. Again, we will examine how challenging the robustness of the punishment-sensitive phenotype may help to better characterize it. Finally, we will evaluate whether diminished relapse-like behavior after repeated punishment-induced abstinence could not only contribute to better understand the mechanisms of abstinence, but also uniquely model progressive recovery (i.e., after repeated failed attempts at recovery) which is the norm in people with addiction. Altogether, by questioning the strengths and weaknesses of our models, we would like to open discussions on the different ways we interpret punishment sensitivity and resistance and the aspects that remain to be explored.
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Affiliation(s)
- Michel Engeln
- Univ. Bordeaux, CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France.
| | - Serge H Ahmed
- Univ. Bordeaux, CNRS, INCIA, UMR 5287, F-33000 Bordeaux, France.
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Maddern XJ, Walker LC, Anversa RG, Lawrence AJ, Campbell EJ. Understanding sex differences and the translational value of models of persistent substance use despite negative consequences. Neurobiol Learn Mem 2024; 213:107944. [PMID: 38825163 DOI: 10.1016/j.nlm.2024.107944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 05/14/2024] [Accepted: 05/27/2024] [Indexed: 06/04/2024]
Abstract
Persistent substance use despite negative consequences is a key facet of substance use disorder. The last decade has seen the preclinical field adopt the use of punishment to model adverse consequences associated with substance use. This has largely involved the pairing of drug use with either electric foot shock or quinine, a bitter tastant. Whilst at face value, these punishers may model aspects of the physical and psychological consequences of substance use, such models are yet to assist the development of approved medications for treatment. This review discusses progress made with animal models of punishment to understand the behavioral consequences of persistent substance use despite negative consequences. We highlight the importance of examining sex differences, especially when the behavioral response to punishment changes following drug exposure. Finally, we critique the translational value these models provide for the substance use disorder field.
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Affiliation(s)
- Xavier J Maddern
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia
| | - Leigh C Walker
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia
| | - Roberta G Anversa
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia
| | - Andrew J Lawrence
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, VIC, 3010, Australia
| | - Erin J Campbell
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW, Australia; Brain Neuromodulation Research Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.
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Arnold ME, Schank JR. Sex differences in neuronal activation in the cortex and midbrain during quinine-adulterated alcohol intake. Alcohol Alcohol 2024; 59:agae031. [PMID: 38742547 PMCID: PMC11091839 DOI: 10.1093/alcalc/agae031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/10/2024] [Accepted: 04/23/2024] [Indexed: 05/16/2024] Open
Abstract
AIMS Continued alcohol consumption despite negative consequences is a core symptom of alcohol use disorder. This is modeled in mice by pairing negative stimuli with alcohol, such as adulterating alcohol solution with quinine. Mice consuming alcohol under these conditions are considered to be engaging in aversion-resistant intake. Previously, we have observed sex differences in this behavior, with females more readily expressing aversion-resistant consumption. We also identified three brain regions that exhibited sex differences in neuronal activation during quinine-alcohol drinking: ventromedial prefrontal cortex (vmPFC), posterior insular cortex (PIC), and ventral tegmental area (VTA). Specifically, male mice showed increased activation in vmPFC and PIC, while females exhibited increased activation in VTA. In this study, we aimed to identify what specific type of neurons are activated in these regions during quinine-alcohol drinking. METHOD We assessed quinine-adulterated alcohol intake using the two-bottle choice procedure. We also utilized RNAscope in situ hybridization in the three brain regions that previously exhibited a sex difference to examine colocalization of Fos, glutamate, GABA, and dopamine. RESULT Females showed increased aversion-resistant alcohol consumption compared to males. We also found that males had higher colocalization of glutamate and Fos in vmPFC and PIC, while females had greater dopamine and Fos colocalization in the VTA. CONCLUSIONS Collectively, these experiments suggest that glutamatergic output from the vmPFC and PIC may have a role in suppressing, and dopaminergic activity in the VTA may promote, aversion-resistant alcohol consumption. Future experiments will examine neuronal circuits that contribute to sex differences in aversion resistant consumption.
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Affiliation(s)
- Miranda E Arnold
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, 501 D. W. Brooks Drive, Athens, GA 30602, United States
| | - Jesse R Schank
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, 501 D. W. Brooks Drive, Athens, GA 30602, United States
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Castle ME, Flanigan ME. The role of brain serotonin signaling in excessive alcohol consumption and withdrawal: A call for more research in females. Neurobiol Stress 2024; 30:100618. [PMID: 38433994 PMCID: PMC10907856 DOI: 10.1016/j.ynstr.2024.100618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 02/01/2024] [Accepted: 02/14/2024] [Indexed: 03/05/2024] Open
Abstract
Alcohol Use Disorder (AUD) is a leading cause of death and disability worldwide, but current treatments are insufficient in fully addressing the symptoms that often lead to relapses in alcohol consumption. The brain's serotonin system has been implicated in AUD for decades and is a major regulator of stress-related behaviors associated with increased alcohol consumption. This review will discuss the current literature on the association between neurobiological adaptations in serotonin systems and AUD in humans as well as the effectiveness of serotonin receptor manipulations on alcohol-related behaviors like consumption and withdrawal. We will further discuss how these findings in humans relate to findings in animal models, including a comparison of systemic pharmacological manipulations modulating alcohol consumption. We next provide a detailed overview of brain region-specific roles for serotonin and serotonin receptor signaling in alcohol-related behaviors in preclinical animal models, highlighting the complexity of forming a cohesive model of serotonin function in AUD and providing possible avenues for more effective therapeutic intervention. Throughout the review, we discuss what is known about sex differences in the sequelae of AUD and the role of serotonin in these sequelae. We stress a critical need for additional studies in women and female animals so that we may build a clearer path to elucidating sex-specific serotonergic mechanisms and develop better treatments.
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Affiliation(s)
- Megan E. Castle
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, 27599, USA
| | - Meghan E. Flanigan
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, 27599, USA
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Toivainen S, Xu L, Gobbo F, Della Valle A, Coppola A, Heilig M, Domi E. Different mechanisms underlie compulsive alcohol self-administration in male and female rats. Biol Sex Differ 2024; 15:17. [PMID: 38368341 PMCID: PMC10874042 DOI: 10.1186/s13293-024-00592-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 02/09/2024] [Indexed: 02/19/2024] Open
Abstract
BACKGROUND Sex is an important factor in the progression and treatment of alcohol addiction, and therapeutic approaches may have to be tailored to potential sex differences. This highlights the importance of understanding sex differences in behaviors that reflect key elements of clinical alcohol addiction, such as continued use despite negative consequences ("compulsive use"). Studies in experimental animals can help provide an understanding of the role sex plays to influence these behaviors. METHODS Large populations of genetically heterogeneous male and female Wistar rats were tested in an established model of compulsive alcohol self-administration, operationalized as alcohol responding despite contingent foot shock punishment. We also tested baseline (fixed ratio, unpunished) operant alcohol self-administration, motivation to self-administer alcohol (progressive ratio), and temporal discounting for alcohol reward. In search of predictors of compulsivity, animals were screened for novelty-induced place preference, anxiety-like behavior, pain sensitivity and corticosterone levels. The estrous cycle was monitored throughout the study. RESULTS Unpunished self-administration of alcohol did not differ between males and females when alcohol intake was corrected for body weight. Overall, females showed higher levels of compulsive responding for alcohol. Compulsive response rates showed bimodal distributions in male but not in female rats when intermediate shock intensities were used (0.2 and 0.25 mA); at higher shock intensities, responding was uniformly suppressed in both males and females. We also found less steep discounting in females when alcohol was devalued by delaying its delivery. Males exhibited a stronger motivation to obtain alcohol under unpunished conditions, while females showed higher corticosterone levels at baseline. Factor analysis showed that an underlying dimension related to stress and pain predicted compulsivity in females, while compulsivity in males was predicted by a reward factor. We did not find differences in alcohol-related behaviors throughout the various stages of the estrous cycle. CONCLUSIONS Our results suggest that mechanisms promoting compulsivity, a key feature of alcohol addiction, likely differ between males and females. This underscores the importance of considering sex as a biological variable in both preclinical and clinical research, and has potential treatment implications in alcohol addiction.
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Affiliation(s)
- Sanne Toivainen
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, S-581 85, Linköping, Sweden
| | - Li Xu
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, S-581 85, Linköping, Sweden
| | - Francesco Gobbo
- Centre for Discovery Brain Sciences, University of Edinburgh, 1 George Square, Edinburgh, EH8 9JZ, UK
| | - Andrea Della Valle
- School of Pharmacy, Center for Neuroscience, University of Camerino, 62032, Camerino, Italy
| | - Andrea Coppola
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, S-581 85, Linköping, Sweden
| | - Markus Heilig
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, S-581 85, Linköping, Sweden
| | - Esi Domi
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, S-581 85, Linköping, Sweden.
- School of Pharmacy, Center for Neuroscience, University of Camerino, 62032, Camerino, Italy.
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Sneddon EA, Masters BM, Shi H, Radke AK. Removal of the ovaries suppresses ethanol drinking and promotes aversion-resistance in C57BL/6J female mice. Psychopharmacology (Berl) 2023; 240:2607-2616. [PMID: 37653347 PMCID: PMC11170684 DOI: 10.1007/s00213-023-06456-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 08/23/2023] [Indexed: 09/02/2023]
Abstract
RATIONALE Female rodents consume more ethanol (EtOH) than males and exhibit greater aversion-resistant drinking in some paradigms. Ovarian hormones promote EtOH drinking but the contribution of ovarian hormones to aversion-resistant drinking has not been assessed. OBJECTIVES We aimed to investigate the role of ovarian hormones to aversion-resistant drinking in female mice in a drinking in the dark (DID) task. METHODS Female C57BL/6 J mice first underwent an ovariectomy (OVX, n = 16) or sham (SHAM, n = 16) surgery. Four weeks following surgery, mice underwent a DID paradigm where they were given access to water and 15% EtOH 3 h into the dark cycle for up to 4 h across 15 drinking sessions. To assess frontloading behavior, bottles were weighed at 30 min, 2 h, and 4 h. Aversion-resistance was tested by adding escalating concentrations of quinine (0, 100, 250, and 500 µM) to the 15% EtOH bottle on sessions 16 - 19. RESULTS Removal of the ovaries reduced EtOH consumption in OVX subjects. When assessing aversion-resistant EtOH drinking, mice with ovarian hormones (SHAM) reduced consumption of 250 and 500 µM quinine in EtOH, while OVX subjects exhibited aversion-resistance at all quinine concentrations. OVX mice had greater frontloading for quinine + EtOH at higher concentrations of quinine. CONCLUSIONS These results indicate that circulating ovarian hormones may be protective against the development of aversion-resistant EtOH drinking and call for further investigation of the role of ovarian hormones in models of addictive behavior.
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Affiliation(s)
- Elizabeth A Sneddon
- Department of Psychology and Center for Neuroscience and Behavior, Miami University, 90 N Patterson Ave, Oxford, OH, 45056, USA
| | - Brianna M Masters
- Department of Psychology and Center for Neuroscience and Behavior, Miami University, 90 N Patterson Ave, Oxford, OH, 45056, USA
| | - Haifei Shi
- Department of Psychology and Center for Neuroscience and Behavior, Miami University, 90 N Patterson Ave, Oxford, OH, 45056, USA
- Department of Biology, Miami University, Oxford, OH, USA
| | - Anna K Radke
- Department of Psychology and Center for Neuroscience and Behavior, Miami University, 90 N Patterson Ave, Oxford, OH, 45056, USA.
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Arnold ME, Decker Ramirez EB, Beugelsdyk LA, Siano Kuzolitz MV, Jiang Q, Schank JR. Estradiol mediates sex differences in aversion-resistant alcohol intake. Front Neurosci 2023; 17:1282230. [PMID: 38027489 PMCID: PMC10651753 DOI: 10.3389/fnins.2023.1282230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Alcohol consumption despite negative consequences is a core symptom of alcohol use disorder. This can be modeled in mice by pairing aversive stimuli with alcohol consumption, such as adding the bitter tastant quinine to the alcohol solution. If an animal continues to drink alcohol despite such negative stimuli, this is typically considered aversion-resistant, or inflexible, drinking behavior. Previous studies in our lab have found that females are more aversion-resistant than males in that they tolerate higher concentrations of quinine before they suppress their alcohol intake. Interestingly, we did not observe any differences in intake across the estrous cycle. In regards to neuronal activation patterns during quinine-alcohol intake, we have found that male mice show higher levels of activation in the ventromedial prefrontal cortex and posterior insular cortex, while females show higher levels of activation in the ventral tegmental area. Methods In the experiments presented here, we conducted ovariectomies to further examine the role of circulating sex hormones in aversion-resistant alcohol intake and neuronal activation patterns. Furthermore, we used hormonal addback of estradiol or progesterone to determine which ovarian sex hormone mediates aversion-resistant consumption. Results We found that ovariectomy reduced quinine-adulterated alcohol intake, demonstrating that circulating sex hormones play a role in this behavior. We also observed reduced neuronal activation in the VTA of ovariectomized mice compared to sham females, and that estradiol supplementation reversed the effect of ovariectomy on quinine-alcohol intake. Discussion Taken together with our prior data, these findings suggest that circulating estradiol contributes to the expression of aversion-resistant alcohol intake and neuronal activity in the VTA. However, since this behavior is not affected by the estrous cycle, we believe this is due to a threshold level of this hormone, as opposed to fluctuations that occur across the estrous cycle.
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Affiliation(s)
| | | | | | | | | | - Jesse R. Schank
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
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Arnold ME, Schank JR. Aversion-associated drug and alcohol seeking in females. Front Neuroendocrinol 2023; 71:101095. [PMID: 37558185 DOI: 10.1016/j.yfrne.2023.101095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/27/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023]
Abstract
Compulsive drug intake is characterized by the continuation of use regardless of negative consequences. This is modeled preclinically using procedures where a negative stimulus is delivered contingently with consumption of the reinforcer. In humans, women and men exhibit different drug taking behavior as it pertains to overall use, withdrawal symptoms, and rate of dependence. In substance use research, females have often been excluded from many studies due to concerns that circulating sex hormones may affect drug seeking behavior. However, the more recent inclusion of females in preclinical studies has identified interesting sex differences in aversion-resistant intake of drugs and alcohol. This review will serve to summarize key findings in aversion-related intake of alcohol, psychostimulants, and opioids in females by examining studies that have included female subjects. Further discussion will examine the effect of intake model, neuroanatomical pathways, and sex hormones in the expression of aversion-resistant drug and alcohol consumption.
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Affiliation(s)
- Miranda E Arnold
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Jesse R Schank
- Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
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