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Kuhn BN, Cannella N, Crow AD, Roberts AT, Lunerti V, Allen C, Nall RW, Hardiman G, Woods LCS, Chung D, Ciccocioppo R, Kalivas PW. Novelty-induced locomotor behavior predicts heroin addiction vulnerability in male, but not female, rats. Psychopharmacology (Berl) 2022; 239:3605-3620. [PMID: 36112154 PMCID: PMC9632364 DOI: 10.1007/s00213-022-06235-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/02/2022] [Indexed: 11/28/2022]
Abstract
RATIONALE The ongoing rise in opioid use disorder (OUD) has made it imperative to better model the individual variation within the human population that contributes to OUD vulnerability. Using animal models that capture such variation can be a useful tool. Individual variation in novelty-induced locomotion is predictive of substance use disorder (SUD) propensity. In this model, rats are characterized as high-responders (HR) or low-responders (LR) using a median split based on distance travelled during a locomotor test, and HR rats are generally found to exhibit a more SUD vulnerable behavioral phenotype. OBJECTIVES The HR/LR model has commonly been used to assess behaviors in male rats using psychostimulants, with limited knowledge of the predictive efficacy of this model in females or the use of an opioid as the reward. In the current study, we assessed several behaviors across the different phases of drug addiction (heroin taking, refraining, and seeking) in over 500 male and female heterogeneous stock rats run at two geographically separate locations. Rats were characterized as HRs or LRs within each sex for analysis. RESULTS Overall, females exhibit a more OUD vulnerable phenotype relative to males. Additionally, the HR/LR model was predictive of OUD-like behaviors in male, but not female rats. Furthermore, phenotypes did not differ in anxiety-related behaviors, reacquisition of heroin-taking, or punished heroin-taking behavior in either sex. CONCLUSIONS These results emphasize the importance of assessing females in models of individual variation in SUD and highlight limitations in using the HR/LR model to assess OUD propensity.
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Affiliation(s)
- Brittany N Kuhn
- Department of Neuroscience, Medical University of South Carolina, 173 Ashley Avenue, BSB 403-MSC 510, Charleston, SC, 29425, USA.
| | | | - Ayteria D Crow
- Department of Neuroscience, Medical University of South Carolina, 173 Ashley Avenue, BSB 403-MSC 510, Charleston, SC, 29425, USA
| | - Analyse T Roberts
- Department of Neuroscience, Medical University of South Carolina, 173 Ashley Avenue, BSB 403-MSC 510, Charleston, SC, 29425, USA
| | | | - Carter Allen
- Department of Biomedical Informatics, The Ohio State University, Columbus, OH, USA
| | - Rusty W Nall
- Department of Psychology, Jacksonville State University, Jacksonville, AL, USA
| | - Gary Hardiman
- School of Biological Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | | | - Dongjun Chung
- Department of Biomedical Informatics, The Ohio State University, Columbus, OH, USA
| | | | - Peter W Kalivas
- Department of Neuroscience, Medical University of South Carolina, 173 Ashley Avenue, BSB 403-MSC 510, Charleston, SC, 29425, USA
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Glover ME, Unroe KA, Moughnyeh MM, McCoy C, Kerman IA, Clinton SM. Structural and metabolic activity differences in serotonergic cell groups in a rat model of individual differences of emotionality and stress reactivity. Neurosci Lett 2022; 784:136752. [PMID: 35753615 DOI: 10.1016/j.neulet.2022.136752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/17/2022] [Accepted: 06/21/2022] [Indexed: 11/27/2022]
Abstract
Serotonin regulates a diverse set of functions, including emotional behavior, cognition, sociability, appetite, and sleep. Serotonin is also a key trophic factor that shapes neurodevelopmental processes. Genetic and environmental factors that drive individual differences in the serotonergic system have the capacity to impact brain structure and behavior, and likely contribute to pathophysiological processes involved in neuropsychiatric disorders. Using adult rats selectively bred for low novelty exploration (Low Responders, LR), we previously demonstrated pronounced increases in the levels of their anxiety- and depression- relevant behaviors as compared to the selectively bred High Novelty Responder (HR) rats. These behavioral differences were accompanied by alterations in the expression of genes that regulate serotonin synthesis in the brainstem, and its signaling in the forebrain. The present study extends these observations with a focus on the organization and the metabolism of brainstem serotonin cell groups that provide serotonergic innervation of the hippocampus and other limbic regions of male HR/LR rats. Using design-based stereology, we found the median raphe (MnR) in adult male LR rats contains increased number of serotonergic neurons as compared to the HRs. This is preceded by an increase in the metabolic activity of the caudal dorsal raphe (DRC) and the intrafascicular DR (DRI) during early postnatal development. These findings suggest that structural and functional differences in the raphe-limbic projections shape behavioral inhibition throughout the lifespan.
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Affiliation(s)
| | - Keaton A Unroe
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA; Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA, USA
| | | | - Chelsea McCoy
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA
| | - Ilan A Kerman
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA; Behavioral Health Service Line, Veterans Affairs Pittsburgh Health System, Pittsburgh, PA 15240, USA
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Schmidt MV, Robinson OJ, Sandi C. EJN stress, brain and behaviour special issue. Eur J Neurosci 2022; 55:2053-2057. [PMID: 35569819 DOI: 10.1111/ejn.15718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 05/13/2022] [Accepted: 05/13/2022] [Indexed: 12/01/2022]
Affiliation(s)
- Mathias V Schmidt
- Research Group Neurobiology of Stress Resilience, Max Planck Institute of Psychiatry, Munich, Germany
| | - Oliver J Robinson
- Neuroscience and Mental Health Group, Institute of Cognitive Neuroscience, University College London, London, UK
| | - Carmen Sandi
- Brain Mind Institute, Ecole Polytechnique Federal de Lausanne (EPFL), Lausanne, Switzerland
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Reinhart CJ, McIntyre DC, Pellis SM, Kolb BE. Prefrontal neuronal morphology in kindling-prone (FAST) and kindling-resistant (SLOW) rats. Synapse 2021; 75:e22217. [PMID: 34120374 DOI: 10.1002/syn.22217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 06/10/2021] [Indexed: 11/10/2022]
Abstract
The epileptogenic-prone (FAST) and epileptogenic-resistant (SLOW) rat strains have become a valuable tool for investigating neural plasticity. The strains were generated by breeding the rats that required the fewest amygdala stimulations to elicit a stage-5 convulsive seizure (FAST) and rats requiring the most stimulations (SLOW). Previous studies have shown differences in behavior and amygdala physiology in the two strains. This study examined the dendritic morphology of pyramidal neurons in the brains of adult male and female rats of the two strains. The brains were stained with the Golgi-Cox method and the length and branching from layer III pyramidal cells were measured in parietal cortex (Zilles Par1), medial frontal cortex (Zilles Cg3), and orbitofrontal cortex (Zilles AID) in these two strains of rats. We observed significantly longer dendrites in Cg3 in the FAST group but longer dendrites in the SLOW group in AID and Par1. There was also a sex difference (M > F) in Par1 in both strains. These morphological differences can provide insights into the neurobiological basis of the behavioral differences and suggest that localized changes in the amygdala do not occur independently of changes in other brain regions, and especially prefrontal cortex.
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Affiliation(s)
- Christine J Reinhart
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Dan C McIntyre
- Institute for Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Sergio M Pellis
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Bryan E Kolb
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
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