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Montgomery SE, Li L, Russo SJ, Calipari ES, Nestler EJ, Morel C, Han MH. Mesolimbic Neural Response Dynamics Predict Future Individual Alcohol Drinking in Mice. Biol Psychiatry 2024; 95:951-962. [PMID: 38061466 DOI: 10.1016/j.biopsych.2023.11.019] [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: 03/22/2023] [Revised: 11/11/2023] [Accepted: 11/14/2023] [Indexed: 01/27/2024]
Abstract
BACKGROUND Individual variability in response to rewarding stimuli is a striking but understudied phenomenon. The mesolimbic dopamine system is critical in encoding the reinforcing properties of both natural reward and alcohol; however, how innate or baseline differences in the response dynamics of this circuit define individual behavior and shape future vulnerability to alcohol remain unknown. METHODS Using naturalistic behavioral assays, a voluntary alcohol drinking paradigm, in vivo fiber photometry, in vivo electrophysiology, and chemogenetics, we investigated how differences in mesolimbic neural circuit activity contribute to the individual variability seen in reward processing and, by proxy, alcohol drinking. RESULTS We first characterized heterogeneous behavioral and neural responses to natural reward and defined how these baseline responses predicted future individual alcohol-drinking phenotypes in male mice. We then determined spontaneous ventral tegmental area dopamine neuron firing profiles associated with responses to natural reward that predicted alcohol drinking. Using a dual chemogenetic approach, we mimicked specific mesolimbic dopamine neuron firing activity before or during voluntary alcohol drinking to link unique neurophysiological profiles to individual phenotype. We show that hyperdopaminergic individuals exhibit a lower neuronal response to both natural reward and alcohol that predicts lower levels of alcohol consumption in the future. CONCLUSIONS These findings reveal unique, circuit-specific neural signatures that predict future individual vulnerability or resistance to alcohol and expand the current knowledge base on how some individuals are able to titrate their alcohol consumption whereas others go on to engage in unhealthy alcohol-drinking behaviors.
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Affiliation(s)
- Sarah E Montgomery
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Friedman Brain Institute and the Center for Affective Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Long Li
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Friedman Brain Institute and the Center for Affective Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Scott J Russo
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Friedman Brain Institute and the Center for Affective Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Erin S Calipari
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Friedman Brain Institute and the Center for Affective Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Departments of Pharmacology, Molecular Physiology and Biophysics, and Psychiatry and Behavioral Sciences, Vanderbilt Center for Addiction Research, Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee
| | - Eric J Nestler
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Friedman Brain Institute and the Center for Affective Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Carole Morel
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York.
| | - Ming-Hu Han
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Friedman Brain Institute and the Center for Affective Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Mental Health and Public Health, Faculty of Life and Health Sciences, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.
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Biswas B, Eapen V, Morris MJ, Jones NM. Combined Effect of Maternal Separation and Early-Life Immune Activation on Brain and Behaviour of Rat Offspring. Biomolecules 2024; 14:197. [PMID: 38397434 PMCID: PMC10886936 DOI: 10.3390/biom14020197] [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: 11/17/2023] [Revised: 01/14/2024] [Accepted: 01/22/2024] [Indexed: 02/25/2024] Open
Abstract
Adversity during early life, a critical period for brain development, increases vulnerability and can have a lasting impact on the brain and behaviour of a child. However, the long-term effects of cumulative early-life stressors on brain and behaviour are not well known. We studied a 2-hit rat model of early-life adversity using maternal separation (MS) and immune activation (lipopolysaccharide (LPS)). Rat pups underwent MS for 15 (control) or 180 (MS) minutes per day from postnatal day (P)2-14 and were administered saline or LPS (intraperitoneal) on P3. Open-field (OFT) and object-place recognition tests were performed on rat offspring at P33-35 and P42-50, respectively. The pre-frontal cortex (PFC) and hippocampus were removed at the experimental endpoint (P52-55) for mRNA expression. MS induced anxiety-like behaviour in OFT in male and reduced locomotor activity in both male and female offspring. LPS induced a subtle decline in memory in the object-place recognition test in male offspring. MS increased glial fibrillary acidic protein (GFAP) and brain-derived neurotrophic factor expression in PFC and ionised calcium-binding adapter molecule-1 expression in male hippocampus. MS and LPS resulted in distinct behavioural phenotypes in a sex-specific manner. The combination of MS and LPS had a synergistic effect on the anxiety-like behaviour, locomotor activity, and GFAP mRNA expression outcomes.
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Affiliation(s)
- Bharti Biswas
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW 2052, Australia; (B.B.); (V.E.)
- School of Biomedical Sciences, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW 2052, Australia
| | - Valsamma Eapen
- School of Clinical Medicine, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW 2052, Australia; (B.B.); (V.E.)
| | - Margaret J. Morris
- School of Biomedical Sciences, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW 2052, Australia
| | - Nicole M. Jones
- School of Biomedical Sciences, Faculty of Medicine & Health, UNSW Sydney, Kensington, NSW 2052, Australia
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Löscher W. Of Mice and Men: The Inter-individual Variability of the Brain's Response to Drugs. eNeuro 2024; 11:ENEURO.0518-23.2024. [PMID: 38355298 PMCID: PMC10867552 DOI: 10.1523/eneuro.0518-23.2024] [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: 12/08/2023] [Revised: 01/12/2024] [Accepted: 01/18/2024] [Indexed: 02/16/2024] Open
Abstract
Biological variation is ubiquitous in nature. Despite highly standardized breeding and husbandry under controlled environmental conditions, phenotypic diversity exists in laboratory mice and rats just as it does in humans. The resulting inter-individual variability affects various characteristics of animal disease models, including the responsiveness to drugs. Thus, the common practice of averaging data within an experimental group can lead to misinterpretations in neuroscience and other research fields. In this commentary, the impact of inter-individual variation in drug responsiveness is illustrated by examples from the testing of antiseizure medications in rodent temporal lobe epilepsy models. Individual mice and rats rendered epileptic by treatment according to standardized protocols fall into groups that either do or do not respond to antiseizure medications, thus mimicking the clinical situation in patients with epilepsy. Population responses are not normally distributed, and divergent responding is concealed in averages subjected to parametric statistical tests. Genetic, epigenetic, and environmental factors are believed to contribute to inter-individual variation in drug response but the specific molecular and physiological causes are not well understood. Being aware of inter-individual variability in rodents allows an improved interpretation of both behavioral phenotypes and drug effects in a pharmacological experiment.
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Affiliation(s)
- Wolfgang Löscher
- Translational Neuropharmacology Lab, NIFE, Department of Experimental Otology of the ENT Clinics, Hannover Medical School, Hannover 30625, Germany
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