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Sedhom S, Hammond N, Thanos KZ, Blum K, Elman I, Bowirrat A, Dennen CA, Thanos PK. Potential Link Between Exercise and N-Methyl-D-Aspartate Glutamate Receptors in Alcohol Use Disorder: Implications for Therapeutic Strategies. Psychol Res Behav Manag 2024; 17:2363-2376. [PMID: 38895648 PMCID: PMC11185169 DOI: 10.2147/prbm.s462403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 05/16/2024] [Indexed: 06/21/2024] Open
Abstract
Alcohol use disorder (AUD) is a significant risk factor, accounting for approximately 13% of all deaths in the US. AUD not only destroys families but also causes economic losses due to reduced productivity, absenteeism, and healthcare expenses. Statistics revealing the sustained number of individuals affected by AUD over the years underscore the need for further understanding of the underlying pathophysiology to advance novel therapeutic strategies. Previous research has implicated the limbic brain regions N-methyl-D-aspartate glutamate receptors (NMDAR) in the emotional and behavioral effects of AUD. Given that aerobic exercise can modulate NMDAR activity and sensitivity to alcohol, this review presents a summary of clinical and basic science studies on NMDAR levels induced by alcohol consumption, as well as acute and protracted withdrawal, highlighting the potential role of aerobic exercise as an adjunctive therapy for AUD. Based on our findings, the utility of exercise in the modulation of reward-linked receptors and AUD may be mediated by its effects on NMDA signaling. These data support further consideration of the potential of aerobic exercise as a promising adjunctive therapy for AUD.
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Affiliation(s)
- Susan Sedhom
- Behavioral Neuropharmacology and Neuroimaging Laboratory on Addictions (BNNLA), Research Institute on Addictions, Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Nikki Hammond
- Behavioral Neuropharmacology and Neuroimaging Laboratory on Addictions (BNNLA), Research Institute on Addictions, Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Kyriaki Z Thanos
- Behavioral Neuropharmacology and Neuroimaging Laboratory on Addictions (BNNLA), Research Institute on Addictions, Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Kenneth Blum
- Division of Addiction Research & Education, Center for Sports, Exercise & Global Mental Health, Western University Health Sciences, Pomona, CA, USA
- Department of Molecular Biology and Adelson School of Medicine, Ariel University, Ariel, Israel
| | - Igor Elman
- Department of Psychiatry, Harvard School of Medicine, Cambridge Health Alliance, Cambridge, MA, USA
| | - Abdalla Bowirrat
- Department of Molecular Biology and Adelson School of Medicine, Ariel University, Ariel, Israel
| | | | - Panayotis K Thanos
- Behavioral Neuropharmacology and Neuroimaging Laboratory on Addictions (BNNLA), Research Institute on Addictions, Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
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2
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Strohm AO, Majewska AK. Physical exercise regulates microglia in health and disease. Front Neurosci 2024; 18:1420322. [PMID: 38911597 PMCID: PMC11192042 DOI: 10.3389/fnins.2024.1420322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Accepted: 05/20/2024] [Indexed: 06/25/2024] Open
Abstract
There is a well-established link between physical activity and brain health. As such, the effectiveness of physical exercise as a therapeutic strategy has been explored in a variety of neurological contexts. To determine the extent to which physical exercise could be most beneficial under different circumstances, studies are needed to uncover the underlying mechanisms behind the benefits of physical activity. Interest has grown in understanding how physical activity can regulate microglia, the resident immune cells of the central nervous system. Microglia are key mediators of neuroinflammatory processes and play a role in maintaining brain homeostasis in healthy and pathological settings. Here, we explore the evidence suggesting that physical activity has the potential to regulate microglia activity in various animal models. We emphasize key areas where future research could contribute to uncovering the therapeutic benefits of engaging in physical exercise.
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Affiliation(s)
- Alexandra O. Strohm
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, NY, United States
| | - Ania K. Majewska
- Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, United States
- Del Monte Institute for Neuroscience, University of Rochester Medical Center, Rochester, NY, United States
- Center for Visual Science, University of Rochester Medical Center, Rochester, NY, United States
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3
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Perez EC, Gehm KH, Lobo VG, Olvera M, Leasure JL. Adulthood effects of developmental exercise in rats. Dev Psychobiol 2024; 66:e22444. [PMID: 38131238 DOI: 10.1002/dev.22444] [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: 03/06/2023] [Revised: 10/11/2023] [Accepted: 11/06/2023] [Indexed: 12/23/2023]
Abstract
Exercise is known to promote efficient function of stress circuitry. The developing brain is malleable and thus exercise during adolescence could potentially exert lasting beneficial effects on the stress response that would be detectable in adulthood. The current study determined whether adolescent wheel running was associated with reduced stress response in adulthood, 6 weeks after cessation of exercise. Male and female adolescent rats voluntarily ran for 6 weeks and then were sedentary for 6 weeks prior to 10 days of chronic restraint stress in adulthood. Fecal corticosterone levels were measured during stress, and escape from the restraint tube was assessed on the final day as a proxy for depressive-like behavior. Anxiety-like behavior was measured 24 h later with the elevated plus maze and locomotor behaviors with the open field. Brain and body measurements were taken immediately following behavioral testing. Developmental exercise and adulthood stress both exerted independent effects on physiological and behavioral outcomes in adulthood. Exercise history increased the odds ratio of escape from restraint stress in males, but did not influence other stress-induced behaviors. In summary, exercise early in life exerted lasting effects, but did not substantially alter the adulthood response to restraint stress.
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Affiliation(s)
- Emma C Perez
- Department of Psychology, University of Houston, Houston, Texas, USA
| | - Kevin H Gehm
- Department of Psychology, University of Houston, Houston, Texas, USA
| | - Valeria Gaume Lobo
- Department of Biology & Biochemistry, University of Houston, Houston, Texas, USA
| | - Marcelle Olvera
- Department of Psychology, University of Houston, Houston, Texas, USA
| | - J Leigh Leasure
- Department of Psychology, University of Houston, Houston, Texas, USA
- Department of Biology & Biochemistry, University of Houston, Houston, Texas, USA
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4
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Macht VA, Vetreno RP, Crews FT. Cholinergic and Neuroimmune Signaling Interact to Impact Adult Hippocampal Neurogenesis and Alcohol Pathology Across Development. Front Pharmacol 2022; 13:849997. [PMID: 35308225 PMCID: PMC8926387 DOI: 10.3389/fphar.2022.849997] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 02/14/2022] [Indexed: 01/21/2023] Open
Abstract
Alcohol (ethanol) use and misuse is a costly societal issue that can affect an individual across the lifespan. Alcohol use and misuse typically initiates during adolescence and generally continues into adulthood. Not only is alcohol the most widely abused drug by adolescents, but it is also one of the most widely abused drugs in the world. In fact, high rates of maternal drinking make developmental ethanol exposure the most preventable cause of neurological deficits in the Western world. Preclinical studies have determined that one of the most consistent effects of ethanol is its disruption of hippocampal neurogenesis. However, the severity, persistence, and reversibility of ethanol’s effects on hippocampal neurogenesis are dependent on developmental stage of exposure and age at assessment. Complicating the neurodevelopmental effects of ethanol is the concurrent development and maturation of neuromodulatory systems which regulate neurogenesis, particularly the cholinergic system. Cholinergic signaling in the hippocampus directly regulates hippocampal neurogenesis through muscarinic and nicotinic receptor actions and indirectly regulates neurogenesis by providing anti-inflammatory regulatory control over the hippocampal environmental milieu. Therefore, this review aims to evaluate how shifting maturational patterns of the cholinergic system and its regulation of neuroimmune signaling impact ethanol’s effects on adult neurogenesis. For example, perinatal ethanol exposure decreases basal forebrain cholinergic neuron populations, resulting in long-term developmental disruptions to the hippocampus that persist into adulthood. Exaggerated neuroimmune responses and disruptions in adult hippocampal neurogenesis are evident after environmental, developmental, and pharmacological challenges, suggesting that perinatal ethanol exposure induces neurogenic deficits in adulthood that can be unmasked under conditions that strain neural and immune function. Similarly, adolescent ethanol exposure persistently decreases basal forebrain cholinergic neuron populations, increases hippocampal neuroimmune gene expression, and decreases hippocampal neurogenesis in adulthood. The effects of neither perinatal nor adolescent ethanol are mitigated by abstinence whereas adult ethanol exposure-induced reductions in hippocampal neurogenesis are restored following abstinence, suggesting that ethanol-induced alterations in neurogenesis and reversibility are dependent upon the developmental period. Thus, the focus of this review is an examination of how ethanol exposure across critical developmental periods disrupts maturation of cholinergic and neuroinflammatory systems to differentially affect hippocampal neurogenesis in adulthood.
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Affiliation(s)
- Victoria A Macht
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Ryan P Vetreno
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.,Department of Psychiatry, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Fulton T Crews
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.,Department of Psychiatry, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States.,Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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5
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Nawarawong NN, Thompson KR, Guerin SP, Anasooya Shaji C, Peng H, Nixon K. Reactive, Adult Neurogenesis From Increased Neural Progenitor Cell Proliferation Following Alcohol Dependence in Female Rats. Front Neurosci 2021; 15:689601. [PMID: 34594180 PMCID: PMC8477003 DOI: 10.3389/fnins.2021.689601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 08/16/2021] [Indexed: 11/25/2022] Open
Abstract
Hippocampal neurodegeneration is a consequence of excessive alcohol drinking in alcohol use disorders (AUDs), however, recent studies suggest that females may be more susceptible to alcohol-induced brain damage. Adult hippocampal neurogenesis is now well accepted to contribute to hippocampal integrity and is known to be affected by alcohol in humans as well as in animal models of AUDs. In male rats, a reactive increase in adult hippocampal neurogenesis has been observed during abstinence from alcohol dependence, a phenomenon that may underlie recovery of hippocampal structure and function. It is unknown whether reactive neurogenesis occurs in females. Therefore, adult female rats were exposed to a 4-day binge model of alcohol dependence followed by 7 or 14 days of abstinence. Immunohistochemistry (IHC) was used to assess neural progenitor cell (NPC) proliferation (BrdU and Ki67), the percentage of increased NPC activation (Sox2+/Ki67+), the number of immature neurons (NeuroD1), and ectopic dentate gyrus granule cells (Prox1). On day seven of abstinence, ethanol-treated females showed a significant increase in BrdU+ and Ki67+ cells in the subgranular zone of the dentate gyrus (SGZ), as well as greater activation of NPCs (Sox2+/Ki67+) into active cycling. At day 14 of abstinence, there was a significant increase in the number of immature neurons (NeuroD1+) though no evidence of ectopic neurogenesis according to either NeuroD1 or Prox1 immunoreactivity. Altogether, these data suggest that alcohol dependence produces similar reactive increases in NPC proliferation and adult neurogenesis. Thus, reactive, adult neurogenesis may be a means of recovery for the hippocampus after alcohol dependence in females.
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Affiliation(s)
- Natalie N Nawarawong
- College of Pharmacy, The University of Texas at Austin, Austin, TX, United States
| | - K Ryan Thompson
- College of Pharmacy, The University of Texas at Austin, Austin, TX, United States
| | - Steven P Guerin
- College of Pharmacy, The University of Texas at Austin, Austin, TX, United States
| | | | - Hui Peng
- Division of Pharmacology & Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, United States
| | - Kimberly Nixon
- College of Pharmacy, The University of Texas at Austin, Austin, TX, United States
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6
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Pinheiro-da-Silva J, Agues-Barbosa T, Luchiari AC. Embryonic Exposure to Ethanol Increases Anxiety-Like Behavior in Fry Zebrafish. Alcohol Alcohol 2021; 55:581-590. [PMID: 32886092 DOI: 10.1093/alcalc/agaa087] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/16/2020] [Accepted: 07/31/2020] [Indexed: 12/18/2022] Open
Abstract
AIMS Fetal alcohol spectrum disorder (FASD) is an umbrella term to describe the effects of ethanol (Eth) exposure during embryonic development, including several conditions from malformation to cognitive deficits. Zebrafish (Danio rerio) are a translational model popularly applied in brain disorders and drug screening studies due to its genetic and physiology homology to humans added to its transparent eggs and fast development. In this study, we investigated how early ethanol exposure affects zebrafish behavior during the initial growth phase. METHODS Fish eggs were exposed to 0.0 (control), 0.25 and 0.5% ethanol at 24 h post-fertilization. Later, fry zebrafish (10 days old) were tested in a novel tank task and an inhibitory avoidance protocol to inquire about morphology and behavioral alterations. RESULTS Analysis of variance showed that ethanol doses of 0.25 and 0.5% do not cause morphological malformations and did not impair associative learning but increased anxiety-like behavior responses and lower exploratory behavior when compared to the control. CONCLUSION Our results demonstrate that one can detect behavioral abnormalities in the zebrafish induced by embryonic ethanol as early as 10 days post-fertilization and that alcohol increases anxious behavior during young development in zebrafish.
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Affiliation(s)
| | - Thais Agues-Barbosa
- Department of Physiology and Behavior, Universidade Federal do Rio Grande do Norte, Rio Grande do Norte, Brazil
| | - Ana Carolina Luchiari
- Department of Physiology and Behavior, Universidade Federal do Rio Grande do Norte, Rio Grande do Norte, Brazil
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7
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Nawarawong NN, Nickell CG, Hopkins DM, Pauly JR, Nixon K. Functional Activation of Newborn Neurons Following Alcohol-Induced Reactive Neurogenesis. Brain Sci 2021; 11:499. [PMID: 33921189 PMCID: PMC8071556 DOI: 10.3390/brainsci11040499] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/10/2021] [Accepted: 04/11/2021] [Indexed: 02/07/2023] Open
Abstract
Abstinence after alcohol dependence leads to structural and functional recovery in many regions of the brain, especially the hippocampus. Significant increases in neural stem cell (NSC) proliferation and subsequent "reactive neurogenesis" coincides with structural recovery in hippocampal dentate gyrus (DG). However, whether these reactively born neurons are integrated appropriately into neural circuits remains unknown. Therefore, adult male rats were exposed to a binge model of alcohol dependence. On day 7 of abstinence, the peak of reactive NSC proliferation, rats were injected with bromodeoxyuridine (BrdU) to label dividing cells. After six weeks, rats underwent Morris Water Maze (MWM) training then were sacrificed ninety minutes after the final training session. Using fluorescent immunohistochemistry for c-Fos (neuronal activation), BrdU, and Neuronal Nuclei (NeuN), we investigated whether neurons born during reactive neurogenesis were incorporated into a newly learned MWM neuronal ensemble. Prior alcohol exposure increased the number of BrdU+ cells and newborn neurons (BrdU+/NeuN+ cells) in the DG versus controls. However, prior ethanol exposure had no significant impact on MWM-induced c-Fos expression. Despite increased BrdU+ neurons, no difference in the number of activated newborn neurons (BrdU+/c-Fos+/NeuN+) was observed. These data suggest that neurons born during alcohol-induced reactive neurogenesis are functionally integrated into hippocampal circuitry.
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Affiliation(s)
| | - Chelsea G. Nickell
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA; (C.G.N.); (D.M.H.); (J.R.P.)
| | - Deann M. Hopkins
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA; (C.G.N.); (D.M.H.); (J.R.P.)
| | - James R. Pauly
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA; (C.G.N.); (D.M.H.); (J.R.P.)
| | - Kimberly Nixon
- College of Pharmacy, The University of Texas at Austin, Austin, TX 78712, USA;
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY 40536, USA; (C.G.N.); (D.M.H.); (J.R.P.)
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8
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Nickell CG, Thompson KR, Pauly JR, Nixon K. Recovery of Hippocampal-Dependent Learning Despite Blunting Reactive Adult Neurogenesis After Alcohol Dependence. Brain Plast 2020; 6:83-101. [PMID: 33680848 PMCID: PMC7903006 DOI: 10.3233/bpl-200108] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Background: The excessive alcohol drinking that occurs in alcohol use disorder (AUD) causes neurodegeneration in regions such as the hippocampus, though recovery may occur after a period of abstinence. Mechanisms of recovery are not clear, though reactive neurogenesis has been observed in the hippocampal dentate gyrus following alcohol dependence and correlates to recovery of granule cell number. Objective: We investigated the role of neurons born during reactive neurogenesis in the recovery of hippocampal learning behavior after 4-day binge alcohol exposure, a model of an AUD. We hypothesized that reducing reactive neurogenesis would impair functional recovery. Methods: Adult male rats were subjected to 4-day binge alcohol exposure and two approaches were tested to blunt reactive adult neurogenesis, acute doses of alcohol or the chemotherapy drug, temozolomide (TMZ). Results: Acute 5 g/kg doses of EtOH gavaged T6 and T7 days post binge did not inhibit significantly the number of Bromodeoxyuridine-positive (BrdU+) proliferating cells in EtOH animals receiving 5 g/kg EtOH versus controls. A single cycle of TMZ inhibited reactive proliferation (BrdU+ cells) and neurogenesis (NeuroD+ cells) to that of controls. However, despite this blunting of reactive neurogenesis to basal levels, EtOH-TMZ rats were not impaired in their recovery of acquisition of the Morris water maze (MWM), learning similarly to all other groups 35 days after 4-day binge exposure. Conclusions: These studies show that TMZ is effective in decreasing reactive proliferation/neurogenesis following 4-day binge EtOH exposure, and baseline levels of adult neurogenesis are sufficient to allow recovery of hippocampal function.
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Affiliation(s)
- Chelsea G Nickell
- University of Kentucky, Department of Pharmaceutical Sciences, Lexington, KY, USA
| | - K Ryan Thompson
- The University of Texas at Austin, College of Pharmacy, Austin, TX, USA
| | - James R Pauly
- University of Kentucky, Department of Pharmaceutical Sciences, Lexington, KY, USA
| | - Kimberly Nixon
- University of Kentucky, Department of Pharmaceutical Sciences, Lexington, KY, USA.,The University of Texas at Austin, College of Pharmacy, Austin, TX, USA
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9
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West RK, Rodgers SP, Leasure JL. Neural Perturbations Associated With Recurrent Binge Alcohol in Male and Female Rats. Alcohol Clin Exp Res 2020; 45:365-374. [PMID: 33295022 DOI: 10.1111/acer.14529] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 12/01/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND Binge drinking, characterized by brief periods of high intoxication interspersed with periods of abstinence, appears to be particularly damaging to the brain. Binge drinking is increasing among American women, yet few preclinical studies have assessed sex differences in the neurobehavioral effects of binge alcohol. METHODS Adult Long-Evans rats were administered 4 g/kg ethanol (EtOH; or an isocaloric control dose) via intragastric gavage once-weekly. Brains were collected after 3 or 8 binge doses, and immunohistochemistry for mature neurons (NeuN), microglia (Iba1), neurogenesis (DCX), and reactive astrogliosis (vimentin) performed. Stereology was used to quantify target cell populations in the hippocampus and medial prefrontal cortex (mPFC). In a separate cohort of animals, cognition (spatial navigation and reversal learning), affect (tickling-evoked ultrasonic vocalizations), and task-induced c-fos activation were assessed after 3 or 8 binge doses. RESULTS Blood EtOH concentration did not differ significantly between females (175 ± 3.6 mg/dl) and males (180 ± 3.7 mg/dl) and did not change significantly over time, indicating that tolerance did not develop. After 3 or 8 binge doses, the number of granule neurons in the hippocampal dentate gyrus of both sexes was significantly reduced in comparison with controls, although there was no binge effect on newly generated neurons. Moreover, 8 (but not 3) binge doses significantly increased the total number of microglia and the number of partially activated microglia in the hippocampus and mPFC in both sexes. There was no detectable reactive astrogliosis (vimentin) in either region at any timepoint. There was no effect of binge alcohol on behavior outcomes in either sex, but binged rats showed increased cellular activation in the mPFC following reversal learning. CONCLUSIONS Our data indicate that recurrent binge alcohol results in similar neural damage and neuroimmune activation in alcohol-vulnerable corticolimbic brain regions in males and females.
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Affiliation(s)
- Rebecca K West
- Department of Psychology, University of Houston, Houston, Texas
| | | | - J Leigh Leasure
- Department of Psychology, University of Houston, Houston, Texas.,Department of Biology & Biochemistry, University of Houston, Houston, Texas
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10
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Marshall SA, McClain JA, Wooden JI, Nixon K. Microglia Dystrophy Following Binge-Like Alcohol Exposure in Adolescent and Adult Male Rats. Front Neuroanat 2020; 14:52. [PMID: 32903737 PMCID: PMC7439004 DOI: 10.3389/fnana.2020.00052] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/20/2020] [Indexed: 12/13/2022] Open
Abstract
Microglia are dynamic cells that have roles in neuronal plasticity as well as in recovery responses following neuronal injury. Although many hypothesize that hyperactivation of microglia contributes to alcohol-induced neuropathology, in other neurodegenerative conditions disruption of normal microglial processes also contributes to neuronal loss, particularly as microglia become dystrophic or dysfunctional. Based on the observation of a striking, abnormal morphology in microglia during binge-like ethanol exposure, the present study investigated the impact of excessive ethanol exposure on microglia number and dystrophic morphology in a model of alcohol dependence that includes neurodegeneration in both adult and adolescent rats. Following 2- and 4-day binge ethanol exposure, the number of microglia was decreased in the hippocampus and the perirhinal and entorhinal cortices of both adult and adolescent rats. Furthermore, a significant number of microglia with a dystrophic morphology were observed in ethanol-exposed tissue, accompanied by a significant decrease in brain-derived neurotrophic factor (BDNF) expression in the hippocampus. Together these findings suggest another means by which microglia may contribute to alcohol-induced neurodegeneration, specifically dystrophic microglia and/or loss of microglia may disrupt homeostatic and recovery mechanisms. These results demonstrate that microglia also degenerate with excessive alcohol exposure, which has important implications for understanding the role of microglia-and specifically their contributions to plasticity and neuronal survival-in neurodegenerative disease.
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Affiliation(s)
- S Alex Marshall
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, United States
| | - Justin A McClain
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, United States
| | - Jessica I Wooden
- Division of Pharmacology & Toxicology, College of Pharmacy, The University of Texas, Austin, TX, United States
| | - Kimberly Nixon
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, United States.,Division of Pharmacology & Toxicology, College of Pharmacy, The University of Texas, Austin, TX, United States
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11
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Mira RG, Lira M, Tapia-Rojas C, Rebolledo DL, Quintanilla RA, Cerpa W. Effect of Alcohol on Hippocampal-Dependent Plasticity and Behavior: Role of Glutamatergic Synaptic Transmission. Front Behav Neurosci 2020; 13:288. [PMID: 32038190 PMCID: PMC6993074 DOI: 10.3389/fnbeh.2019.00288] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/18/2019] [Indexed: 12/19/2022] Open
Abstract
Problematic alcohol drinking and alcohol dependence are an increasing health problem worldwide. Alcohol abuse is responsible for approximately 5% of the total deaths in the world, but addictive consumption of it has a substantial impact on neurological and memory disabilities throughout the population. One of the better-studied brain areas involved in cognitive functions is the hippocampus, which is also an essential brain region targeted by ethanol. Accumulated evidence in several rodent models has shown that ethanol treatment produces cognitive impairment in hippocampal-dependent tasks. These adverse effects may be related to the fact that ethanol impairs the cellular and synaptic plasticity mechanisms, including adverse changes in neuronal morphology, spine architecture, neuronal communication, and finally an increase in neuronal death. There is evidence that the damage that occurs in the different brain structures is varied according to the stage of development during which the subjects are exposed to ethanol, and even much earlier exposure to it would cause damage in the adult stage. Studies on the cellular and cognitive deficiencies produced by alcohol in the brain are needed in order to search for new strategies to reduce alcohol neuronal toxicity and to understand its consequences on memory and cognitive performance with emphasis on the crucial stages of development, including prenatal events to adulthood.
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Affiliation(s)
- Rodrigo G Mira
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Laboratory of Neurobiology of Aging, Universidad San Sebastián, Santiago, Chile
| | - Matias Lira
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Cheril Tapia-Rojas
- Laboratory of Neurobiology of Aging, Universidad San Sebastián, Santiago, Chile.,Laboratory of Neurodegenerative Diseases, Universidad Autónoma de Chile, Providencia, Chile
| | - Daniela L Rebolledo
- Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.,Escuela de Obstetricia y Puericultura and Centro Integrativo de Biología y Química Aplicada (CIBQA), Facultad de Salud, Universidad Bernardo O Higgins, Santiago, Chile
| | - Rodrigo A Quintanilla
- Laboratory of Neurobiology of Aging, Universidad San Sebastián, Santiago, Chile.,Laboratory of Neurodegenerative Diseases, Universidad Autónoma de Chile, Providencia, Chile
| | - Waldo Cerpa
- Laboratorio de Función y Patología Neuronal, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Laboratory of Neurobiology of Aging, Universidad San Sebastián, Santiago, Chile.,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile
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12
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Abstract
There are vast literatures on the neural effects of alcohol and the neural effects of exercise. Simply put, exercise is associated with brain health, alcohol is not, and the mechanisms by which exercise benefits the brain directly counteract the mechanisms by which alcohol damages it. Although a degree of brain recovery naturally occurs upon cessation of alcohol consumption, effective treatments for alcohol-induced brain damage are badly needed, and exercise is an excellent candidate from a mechanistic standpoint. In this chapter, we cover the small but growing literature on the interactive neural effects of alcohol and exercise, and the capacity of exercise to repair alcohol-induced brain damage. Increasingly, exercise is being used as a component of treatment for alcohol use disorders (AUD), not because it reverses alcohol-induced brain damage, but because it represents a rewarding, alcohol-free activity that could reduce alcohol cravings and improve comorbid conditions such as anxiety and depression. It is important to bear in mind, however, that multiple studies attest to a counterintuitive positive relationship between alcohol intake and exercise. We therefore conclude with cautionary notes regarding the use of exercise to repair the brain after alcohol damage.
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