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Robison CL, Madore V, Cova N, Drugan RC, Charntikov S. Individual corticosterone response to intermittent swim stress predicts a shift in economic demand for ethanol from pre- stress to post-stress in male rats. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.26.582066. [PMID: 38464299 PMCID: PMC10925097 DOI: 10.1101/2024.02.26.582066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
This study investigated the relationship between stress exposure and subsequent ethanol use, focusing on individual differences among male rats. We combined operant self-administration with behavioral economics to assess how intermittent swim stress affects ethanol consumption. This approach allowed for a nuanced analysis of the transition from regular ethanol intake to stress-induced escalation in economic demand. Results showed a consistent rise in ethanol demand post-stress among subjects, irrespective of exposure to actual swim stress or a sham procedure. This increase may result from a two-week abstinence or an inherent rise in demand over time. Significantly, we identified a direct link between post-stress corticosterone levels and the demand for ethanol, considering baseline levels. This correlation was particularly pronounced when examining the shifts in both corticosterone levels and demand for ethanol post-stress. However, neither post-stress corticosterone levels nor their change over time correlated significantly with changes in ethanol demand following a forced swim test that was administered 24 hours after the intermittent swim stress test. This suggests potential context-specific or stressor-specific effects. Importantly, pre-stress ethanol demand did not significantly predict the corticosterone response to stress, indicating that high ethanol-demand rats do not inherently exhibit heightened stress sensitivity. Our research brings to light the complex interplay between stress and ethanol consumption, highlighting the critical role of individual differences in this relationship. This research introduces a nuanced perspective, underscoring the need for future studies in the realm of stress and substance use to give greater consideration to individual variability.
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Araujo UC, Krahe TE, Ribeiro-Carvalho A, Gomes RAA, Lotufo BM, Moreira MDFR, de Abreu-Villaça Y, Manhães AC, Filgueiras CC. Forced swimming stress increases natatory activity of lead-exposed mice. Toxicol Res 2021; 37:115-124. [PMID: 33489862 DOI: 10.1007/s43188-020-00045-2] [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: 10/02/2019] [Revised: 01/27/2020] [Accepted: 03/26/2020] [Indexed: 12/11/2022] Open
Abstract
Recent evidence points to the relationship between lead toxicity and the function of the hypothalamic-pituitary-adrenal axis, which suggests that lead exposure could influence how an individual cope with stress. Here we test this hypothesis by investigating the behavioral effects of lead exposure in mice during the forced swimming test (FST), a parading in which animals are exposed to a stressful situation and environment. Swiss mice received either 180 ppm or 540 ppm of lead acetate (Pb) in their ad-lib water supply for 60-90 days, starting at postnatal day 30. Control (Ctrl) mice drank tap water. At the end of the exposure period, mice were submitted to a 5-min session of FST or to an open-field session of the same duration. Data from naïve animals showed that corticosterone levels were higher for animals tested in the FST compared to animals tested in the open-field. Blood-lead levels (BLL) in Pb-exposed mice ranged from 14.3 to 106.9 µg/dL. No differences were observed in spontaneous locomotion between Ctrl and Pb-exposed groups in the open-field. However, in the FST, Pb-treated mice displayed higher swimming activity than Ctrl ones and this effect was observed even for animals with BLL higher than 20 µg/dL. Furthermore, significant differences in brain glutathione levels, used as an indicator of led toxicity, were only observed for BLL higher than 40 µg/dL. Overall, these findings suggest that swimming activity in the FST is a good indicator of lead toxicity and confirm our prediction that lead toxicity influences behavioral responses associated to stress.
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Affiliation(s)
- Ulisses C Araujo
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade Do Estado Do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ 20550-170 Brazil
| | - Thomas E Krahe
- Departamento de Psicologia, Pontifícia Universidade Católica Do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Anderson Ribeiro-Carvalho
- Departamento de Ciências, Faculdade de Formação de Professores da, Universidade Do Estado Do Rio de Janeiro, Rua Dr. Francisco Portela 1470-Patronato, São Gonçalo, RJ 24435-005 Brazil
| | - Regina A A Gomes
- Centro de Estudos da Saúde Do Trabalhador E Ecologia Humana, Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Rua Leopoldo Bulhões 1480, Manguinhos, Rio de Janeiro, RJ 21040-210 Brazil
| | - Bruna M Lotufo
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade Do Estado Do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ 20550-170 Brazil
| | - Maria de Fátima R Moreira
- Centro de Estudos da Saúde Do Trabalhador E Ecologia Humana, Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, Rua Leopoldo Bulhões 1480, Manguinhos, Rio de Janeiro, RJ 21040-210 Brazil
| | - Yael de Abreu-Villaça
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade Do Estado Do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ 20550-170 Brazil
| | - Alex C Manhães
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade Do Estado Do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ 20550-170 Brazil
| | - Cláudio C Filgueiras
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade Do Estado Do Rio de Janeiro, Avenida Professor Manuel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ 20550-170 Brazil
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Gashi AI, Gontarev S, Zivkovic V, Gjorgovski I, Azemi A. The Effect of Aerobic Physical Activity in Adrenaline Level in White Laboratory Rats. Med Arch 2020; 74:84-89. [PMID: 32577046 PMCID: PMC7296409 DOI: 10.5455/medarh.2020.74.84-89] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Introduction Physical activity is one important factor in the nervous system of animals, it may affect the structure also the function of the brain. Regular aerobic exercises have a good effect on the whole body and thus improves the sense of well-being. Aim The aim of this experiment was to evaluate the effect of aerobic physical activity in white laboratory rats for 21 days. Methods The experimental animals used were twenty Wistar rats, divided into 2 groups of 10 animals they were subjected to forced swim test for 21 days for 60-90 min swim. The evaluation of levels of Adrenaline was performed on 1st, 7th, 14th day and on the last day of the experiment day 21 using ELISA kit protocol, also body mass was compared between groups. Results Our results showed that inducing aerobic physical activity for 21 days on the rats affects their levels of adrenaline. Comparatively, the control group of rats had significantly higher levels of adrenalin compared with day 21 (p=0.435) but lower compared with day 7 and 14 (p=0.231). There was also a difference in body mass which demonstrates adaptability to the surroundings and better coping with physical stress. Conclusion Regular aerobic activity for 21 days, for 60-90 min swim has a positive impact on adrenaline level also this aerobic exercise protocol could have a positive impact on reducing and maintaining body weight, thus preventing overweight.
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Affiliation(s)
- Arbnore Ibrahimaj Gashi
- University of Prishtina "Hasan Prishtina" Faculty of Medicine, Physiotherapy Department, Prishtina, Kosovo
| | - Seryozha Gontarev
- University "Ss. Cyril and Methodius" Faculty of Physical Education, Sport and Health" Skopje, North Macedonia
| | - Vujica Zivkovic
- University "Ss. Cyril and Methodius" Faculty of Physical Education, Sport and Health" Skopje, North Macedonia
| | - Icko Gjorgovski
- University "Ss. Cyril and Methodius", Faculty of Natural Sciences and Mathematics, Institute of Biology, Skopje, North Macedonia
| | - Arjeta Azemi
- Alma Mater Europaea Campus College of Medical Science "Rezonanca" Prishtina, Kosovo
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Stafford NP, Kazan TN, Donovan CM, Hart EE, Drugan RC, Charntikov S. Individual Vulnerability to Stress Is Associated With Increased Demand for Intravenous Heroin Self-administration in Rats. Front Behav Neurosci 2019; 13:134. [PMID: 31293400 PMCID: PMC6603087 DOI: 10.3389/fnbeh.2019.00134] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 06/05/2019] [Indexed: 12/20/2022] Open
Abstract
Opioid use is a widespread epidemic, and traumatic stress exposure is a critical risk factor in opioid use and relapse. There is a significant gap in our understanding of how stress contributes to heroin use, and there are limited studies investigating individual differences underlying stress reactivity and subsequent stress-induced heroin self-administration. We hypothesized that greater individual vulnerability to stress would predict higher demand for heroin self-administration in a within-subjects rodent model of stress and heroin use comorbidity. Male rats were exposed to inescapable intermittent swim stress (ISS) and individual biological (corticosterone) or behavioral [open field, social exploration, and forced swim tests (FSTs)] measures were assessed before and after the stress episode. Individual demand for self-administered heroin (0.05 mg/kg/infusion; 12-h sessions) was assessed using a behavioral economics approach followed by extinction and reinstatement tests triggered by stress re-exposure, non-contingent cue presentations, and yohimbine (0, 1.0, or 2.5 mg/kg). We found that behavioral, biological, and a combination of behavioral and biological markers sampled prior to and after the stress episode that occurred weeks before the access to heroin self-administration predicted the magnitude of individual demand for heroin. Non-contingent presentation of cues, that were previously associated with heroin, reinstated heroin seeking in extinction. For the first time, we show that individual biological response to an ecologically relevant stressor in combination with associated behavioral markers can be used to predict subsequent economic demand for heroin.
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Affiliation(s)
- Nathaniel P Stafford
- Department of Psychology, University of New Hampshire, Durham, NH, United States
| | - Theodore N Kazan
- Department of Psychology, University of New Hampshire, Durham, NH, United States
| | - Colleen M Donovan
- Department of Psychology, University of New Hampshire, Durham, NH, United States
| | - Erin E Hart
- Department of Psychology, University of New Hampshire, Durham, NH, United States
| | - Robert C Drugan
- Department of Psychology, University of New Hampshire, Durham, NH, United States
| | - Sergios Charntikov
- Department of Psychology, University of New Hampshire, Durham, NH, United States
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5
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Two models of inescapable stress increase tph2 mRNA expression in the anxiety-related dorsomedial part of the dorsal raphe nucleus. Neurobiol Stress 2018. [PMID: 29520369 PMCID: PMC5842308 DOI: 10.1016/j.ynstr.2018.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Expression of TPH2, the rate-limiting enzyme for brain serotonin synthesis, is elevated in the dorsal raphe nucleus (DR) of depressed suicide victims. One hypothesis is that this increase in TPH2 expression is stress-induced. Here, we used an established animal model to address whether exposure to an acute stressor, inescapable tail shock (IS), increases tph2 mRNA and Tph2 protein expression, and if IS sensitizes the DR to a subsequent, heterotypic stressor. In Experiment 1, we measured tph2 mRNA expression 4 h after IS or home cage (HC) control conditions in male rats, using in situ hybridization histochemistry. In Experiment 2, we measured Tph2 protein expression 12 h or 24 h after IS using western blot. In Experiment 3, we measured tph2 mRNA expression following IS on Day 1, and cold swim stress (10 min, 15 °C) on Day 2. Inescapable tail shock was sufficient to increase tph2 mRNA expression 4 h and 28 h later, selectively in the dorsomedial DR (caudal aspect of the dorsal DR, cDRD; an area just rostral to the caudal DR, DRC) and increased Tph2 protein expression in the DRD (rostral and caudal aspects of the dorsal DR combined) 24 h later. Cold swim increased tph2 mRNA expression in the dorsomedial DR (cDRD) 4 h later. These effects were associated with increased immobility during cold swim, elevated plasma corticosterone, and a proinflammatory plasma cytokine milieu (increased interleukin (IL)-6, decreased IL-10). Our data demonstrate that two models of inescapable stress, IS and cold swim, increase tph2 mRNA expression selectively in the anxiety-related dorsomedial DR (cDRD).
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Hamasato EK, Lovelock D, Palermo-Neto J, Deak T. Assessment of social behavior directed toward sick partners and its relation to central cytokine expression in rats. Physiol Behav 2017; 182:128-136. [PMID: 29031549 PMCID: PMC5672824 DOI: 10.1016/j.physbeh.2017.10.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/26/2017] [Accepted: 10/10/2017] [Indexed: 10/18/2022]
Abstract
Acute illness not only reduces the expression of social behavior by sick rodents, but can also lead to avoidance responses when detected by healthy, would-be social partners. When healthy animals interact with a sick partner, an intriguing question arises: does exposure to a sick conspecific elicit an anticipatory immune response that would facilitate defense against future infection? To address this question, healthy adult male Sprague-Dawley rats (N=64) were given a brief social interaction (30min) with a partner that was either sick (250μg/kg injection with lipopolysaccharide [LPS] 3h prior to test) or healthy (sterile saline injection). During this exposure, social behavior directed toward the healthy or sick conspecific was measured. Additionally, the impact of housing condition was assessed, with rats group- or isolate-housed. Immediately after social interaction, brains were harvested for cytokine assessments within socially-relevant brain structures (olfactory bulb, amygdala, hippocampus and PVN). As expected, behavioral results demonstrated that (i) there was a robust suppression of social interaction directed against sick conspecifics; and (ii) isolate-housing generally increased social behavior. Furthermore, examination of central cytokine expression in healthy experimental subjects revealed a modest increase in TNF-α in rats that interacted with a sick social partner, but only in the olfactory bulb. Among the LPS-injected partners, expected increases in IL-1β, IL-6, and TNF-α expression were observed across all brain sites. Moreover, IL-1β and IL-6 expression was exacerbated in LPS-injected partners that interacted with isolate-housed experimental subjects. Together, these data replicate and extend our prior work showing that healthy rats avoid sick conspecifics, and provide preliminary evidence for an anticipatory cytokine response when rats are exposed to a sick partner. These data also provide new evidence to suggest that recent housing history potently modulates cytokine responses evoked by LPS.
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Affiliation(s)
- Eduardo Kenji Hamasato
- Neuroimmunomodulation Research Group, Department of Pathology, School of Veterinary Medicine, University of São Paulo (USP), São Paulo, Brazil; Behavioral Neuroscience Program, Department of Psychology, Binghamton University-SUNY, Binghamton, NY 13902-6000, United States
| | - Dennis Lovelock
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University-SUNY, Binghamton, NY 13902-6000, United States
| | - João Palermo-Neto
- Neuroimmunomodulation Research Group, Department of Pathology, School of Veterinary Medicine, University of São Paulo (USP), São Paulo, Brazil
| | - Terrence Deak
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University-SUNY, Binghamton, NY 13902-6000, United States.
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Ultrasonic vocalizations during intermittent swim stress forecasts resilience in a subsequent juvenile social exploration test of anxiety. Behav Brain Res 2015; 287:196-9. [PMID: 25823762 DOI: 10.1016/j.bbr.2015.03.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 02/09/2015] [Accepted: 03/22/2015] [Indexed: 12/11/2022]
Abstract
Current behavioral paradigms of stress resilience traditionally employ forms of prior manipulation or subsequent testing. Recent work has reported adult rat ultrasonic vocalizations (USVs) emitted during intermittent swim stress (ISS) may serve as a predictor of resilience. ISS-induced USVs predicted resilience on several endpoints of behavioral depression and may be considered a forecast of innate resilience. However, a potential problem for these previous findings is the lack of generalizability to other contexts, because both the stress induction and post-stress testing occur in water. The current study tests the generalizability of USVs as a predictor of stress resilience in a non-water-based post-test, the juvenile social exploration test of anxiety. The results provide further support that USVs emitted during ISS predict resilience to depression- and anxiety-like behaviors. Extensions of this work to examine the neurobiology of innate resilience associated with ISS-induced USVs are discussed with comparisons to extant models of learned resilience.
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Drugan RC, Warner TA, Papallo TA, Castracane LL, Stafford NP. Ultrasonic vocalizations during intermittent swim stress forecasts resilience in subsequent forced swim and spatial learning tests. Behav Brain Res 2014; 259:41-4. [PMID: 24475493 DOI: 10.1016/j.bbr.2013.10.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The examination of stress resilience has substantially increased in recent years. However, current paradigms require multiple behavioral procedures, which themselves may serve as secondary stressors. Therefore, a novel predictor of stress resilience is needed to advance the field. Ultrasonic vocalizations (USVs) have been observed as a behavioral correlate of stress in various rodent species. It was recently reported that rats that emitted ultrasonic vocalizations during intermittent swim stress (ISS) later showed resilience when tested on an instrumental swim escape test. In the current study, we extend this earlier observation on two additional behavioral endpoints. Rats were subjected to ISS, and USVs were recorded. Twenty-four hours later, behavioral performance was evaluated in either the forced swim test or Morris water maze. Rats that emitted ultrasonic vocalizations were resilient to the effects of ISS as indicated by performance similar to controls on both measures. These results extend the original findings that ISS-induced USVs are associated with resilience and are related to subsequent aversively motivated behavior. Such a non-invasive forecast of stress responsivity will allow future work to utilize USVs to examine the neural correlates of initial stress resistance/resilience, thereby eliminating potential confounds of further behavioral testing. Future studies can utilize USVs to target potentially unappreciated neural systems to provide novel pharmacotherapeutic strategies for treatment-resistant depression.
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Warner TA, Stafford NP, Rompala GR, Van Hoogenstyn AJ, Elgert E, Drugan RC. Intermittent swim stress causes Morris water maze performance deficits in a massed-learning trial procedure that are exacerbated by reboxetine. Pharmacol Biochem Behav 2013; 113:12-9. [DOI: 10.1016/j.pbb.2013.09.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/26/2013] [Accepted: 09/28/2013] [Indexed: 01/21/2023]
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Abstract
Various animal models of depression have been used to seek a greater understanding of stress-related disorders. However, there is still a great need for novel research in this area, as many individuals suffering from depression are resistant to current treatment methods. Women have a higher rate of depression, highlighting the need to investigate mechanisms of sex differences. Therefore, we employed a new animal model to assess symptoms of depression, known as intermittent swim stress (ISS). In this model, the animal experiences 100 trials of cold water swim stress. ISS has already been shown to cause signs of behavioral depression in males, but has yet to be assessed in females. Following ISS exposure, we looked at sex differences in the Morris water maze and forced swim test. The results indicated a spatial learning effect only in the hidden platform task between male and female controls, and stressed and control males. A consistent spatial memory effect was only seen for males exposed to ISS. In the forced swim test, both sexes exposed to ISS exhibited greater immobility, and the same males and females also showed attenuated climbing and swimming, respectively. The sex differences could be due to different neural substrates for males and females. The goal of this study was to provide the first behavioral examination of sex differences following ISS exposure, so the stage of estrous cycle was not assessed for the females. This is a necessary future direction for subsequent experiments. The current article highlights the importance of sex differences in response to stress.
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Affiliation(s)
- Timothy A Warner
- Department of Psychology, University of New Hampshire , Durham, NH 03824 , USA
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11
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Prior cold water swim stress alters immobility in the forced swim test and associated activation of serotonergic neurons in the rat dorsal raphe nucleus. Neuroscience 2013; 253:221-34. [PMID: 23999122 DOI: 10.1016/j.neuroscience.2013.08.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 07/30/2013] [Accepted: 08/21/2013] [Indexed: 11/24/2022]
Abstract
Prior adverse experience alters behavioral responses to subsequent stressors. For example, exposure to a brief swim increases immobility in a subsequent swim test 24h later. In order to determine if qualitative differences (e.g. 19°C versus 25°C) in an initial stressor (15-min swim) impact behavioral, physiological, and associated neural responses in a 5-min, 25°C swim test 24h later, rats were surgically implanted with biotelemetry devices 1 week prior to experimentation then randomly assigned to one of six conditions (Day 1 (15 min)/Day 2 (5 min)): (1) home cage (HC)/HC, (2) HC/25°C swim, (3) 19°C swim/HC, (4) 19°C swim/25°C swim, (5) 25°C swim/HC, (6) 25°C swim/25°C swim. Core body temperature (Tb) was measured on Days 1 and 2 using biotelemetry; behavior was measured on Day 2. Rats were transcardially perfused with fixative 2h following the onset of the swim on Day 2 for analysis of c-Fos expression in midbrain serotonergic neurons. Cold water (19°C) swim on Day 1 reduced Tb, compared to both 25°C swim and HC groups on Day 1, and, relative to rats exposed to HC conditions on Day 1, reduced the hypothermic response to the 25°C swim on Day 2. The 19°C swim on Day 1, relative to HC exposure on Day 1, increased immobility during the 5-min swim on Day 2. Also, 19°C swim, relative to HC conditions, on Day 1 reduced swim (25°C)-induced increases in c-Fos expression in serotonergic neurons within the dorsal and interfascicular parts of the dorsal raphe nucleus. These results suggest that exposure to a 5-min 19°C cold water swim, but not exposure to a 5-min 25°C swim alters physiological, behavioral and serotonergic responses to a subsequent stressor.
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12
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Drugan RC, Christianson JP, Warner TA, Kent S. Resilience in shock and swim stress models of depression. Front Behav Neurosci 2013; 7:14. [PMID: 23450843 PMCID: PMC3584259 DOI: 10.3389/fnbeh.2013.00014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 02/12/2013] [Indexed: 11/13/2022] Open
Abstract
Experimental models of depression often entail exposing a rodent to a stressor and subsequently characterizing changes in learning and anhedonia, which may reflect symptoms of human depression. Importantly, not all people, and not all laboratory rats, exposed to stressors develop depressed behavior; these “resilient” individuals are the focus of our review. Herein we describe research from the “learned helplessness” and “intermittent swim stress” (ISS) models of depression in which rats that were allowed to control the offset of the aversive stimulus with a behavioral response, and in a subset of rats that were not allowed to control the stressor that appeared to be behaviorally and neurochemically similar to rats that were either naive to stress or had controllability over the stressor. For example, rats exposed to inescapable tailshock, but do not develop learned helplessness, exhibit altered sensitivity to the behavioral effects of GABAA receptor antagonists and reduced in vitro benzodiazepine receptor ligand binding. This pattern suggested that resilience might involve activation of an endogenous benzodiazepine-like compound, possibly an allostatic modulator of the GABAA receptor like allopregnanolone. From the ISS model, we have observed in resilient rats protection from stressor-induced glucocorticoid increases and immune activation. In order to identify the neural mediators of these correlates of resilience, non-invasive measures are needed to predict the resilient or vulnerable phenotype prior to analysis of neural endpoints. To this end, we found that ultrasonic vocalizations (USVs) appear to predict the resilient phenotype in the ISS paradigm. We propose that combining non-invasive predictive measures, such as USVs with biological endpoint measures, will facilitate future research into the neural correlates of resilience.
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Affiliation(s)
- Robert C Drugan
- Department of Psychology, University of New Hampshire Durham, NH, USA
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13
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Eren S, Drugan RC, Hazi A, Flannery G, Kent S. Coping in an intermittent swim stress paradigm compromises natural killer cell activity in rats. Behav Brain Res 2012; 227:291-4. [PMID: 22085883 DOI: 10.1016/j.bbr.2011.10.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 10/26/2011] [Accepted: 10/31/2011] [Indexed: 11/25/2022]
Abstract
The effects of intermittent swim stress and stressor controllability on natural killer cell activity (NKCA) was examined. Significant decreases in splenic NKCA were observed immediately post-stress, but only when the stress was controllable. Although decreased NKCA was also observed in yoked rats subjected to the same stressor, it failed to attain statistical significance. Previous results suggest these effects are not due to corticosterone. The results suggest a cost of coping on the acute, in vitro immune measure of NKCA.
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Affiliation(s)
- Senem Eren
- School of Psychological Science, La Trobe University, Bundoora, VIC 3086, Australia.
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Warner TA, Drugan RC. Morris water maze performance deficit produced by intermittent swim stress is partially mediated by norepinephrine. Pharmacol Biochem Behav 2011; 101:24-34. [PMID: 22119910 DOI: 10.1016/j.pbb.2011.11.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 10/18/2011] [Accepted: 11/12/2011] [Indexed: 10/15/2022]
Abstract
Intermittent swim stress (ISS) exposes a rat to cold water and the effects of the procedure produce detrimental results on activity measures 24h later. The ISS model can be used with the Morris water maze (MWM) to investigate the impact of stress on a spatial learning and memory task, known to involve the hippocampus. We investigated if the ISS model produced performance deficits in the MWM (experiments 1 and 2). We also investigated the role of norepinephrine by using an alpha-2 adrenergic agonist (i.e., clonidine) to exacerbate ISS-induced deficits (experiment 3), and using antidepressants (i.e., desipramine and reboxetine) that enhance the synaptic availability of norepinephrine to reduce ISS-induced deficits (experiments 4 and 5). Results indicated a main effect for stress in all experiments, with the exception of experiment 2, as ISS did induce performance deficits in the MWM. Clonidine enhanced ISS-induced deficits only in the learning trials, while desipramine and reboxetine reduced ISS-induced deficits in the learning trials. Additionally, only reboxetine reduced memory deficits in the MWM. These findings provide evidence that norepinephrine may act as a partial mediator of ISS-induced deficits in MWM performance.
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Affiliation(s)
- Timothy A Warner
- Department of Psychology, University of New Hampshire, Durham, NH, USA.
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Stiller AL, Drugan RC, Hazi A, Kent SP. Stress resilience and vulnerability: the association with rearing conditions, endocrine function, immunology, and anxious behavior. Psychoneuroendocrinology 2011; 36:1383-95. [PMID: 21530089 DOI: 10.1016/j.psyneuen.2011.03.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 03/21/2011] [Accepted: 03/21/2011] [Indexed: 01/28/2023]
Abstract
BACKGROUND The current study explored the underlying behavioral, endocrine, and immune markers of vulnerability to stress-induced depression, and the impact of rearing environments on adult functioning. METHOD Adult Sprague-Dawley rats (n=195) were reared in either Maternal Separation (MS), Early Weaning and Isolation (EWI), or Non-Handled (NH) conditions. Anxiety behavior was assessed using the emergence test at mean postnatal day (PND) 60. Stress-induced depressive behavior was measured at mean PND 86 using an intermittent cold water swim stress and swim escape test (SET) paradigm. Immediately following the SET, and in a sample of naïve controls (N=31), trunk blood was collected to assay for serum corticosterone (CORT) and spleens were removed for determination of Concanavalin A (Con-A) stimulated T-cell proliferation. RESULTS Stress vulnerable rats (top tertile of SET swim time) were characterised by increased anxiety-like behavior, greater post-stress CORT concentrations, and a significantly higher Con-A induced T-cell proliferative response compared to stress resilient rats (bottom tertile of SET swim time). The EWI rearing condition was a contributing factor in predicting total swim escape time, however MS was not. MS offspring did have double the basal level of CORT than NH offspring, suggestive of a hyperfunctioning HPA axis. CONCLUSION The swim stress animal model enabled observation of stress vulnerability and resilience; results point towards the existence of distinct behavioral, endocrine, and immunological profiles of the vulnerable and resilient animal, which may have important implications for mental health and stress research.
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Affiliation(s)
- Anna L Stiller
- School of Psychological Science, La Trobe University, Bundoora, Victoria 3086, Australia
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16
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Kiselycznyk C, Svenningsson P, Delpire E, Holmes A. Genetic, pharmacological and lesion analyses reveal a selective role for corticohippocampal GLUN2B in a novel repeated swim stress paradigm. Neuroscience 2011; 193:259-68. [PMID: 21704131 DOI: 10.1016/j.neuroscience.2011.06.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2011] [Revised: 06/02/2011] [Accepted: 06/03/2011] [Indexed: 12/16/2022]
Abstract
Glutamate and N-methyl-d-aspartate receptor (NMDAR) dysfunction is strongly implicated in the pathophysiology of mood and anxiety disorders. Treatment with NMDAR antagonists has antidepressant efficacy in treatment-resistant depressives. In preclinical rodent models, NMDAR antagonist administration reduces anxiety- and stress-related behaviors in concert with increases in prefrontal cortical (PFC) dendritic spinogenesis and synaptic proteins. While these effects have been attributed to actions at the NMDAR GluN2B subunit, the precise role of cortical GluN2B in mediating emotional behaviors and stress-responsivity is not fully understood. Here, we employed a novel mutant model in which the GluN2B subunit is postnatally deleted in principal neurons in the cortex and the dorsal CA1 subregion of the hippocampus. GluN2BKO mice were phenotyped on a battery of tests for anxiety-related (light/dark exploration, stress-induced hyperthermia) and antidepressant-sensitive (sucrose preference, novelty-induced hypophagia, single-trial forced swim) behaviors. A novel repeated inescapable forced swim paradigm (riFS) was developed to assess behavioral responses to repeated stress in the GluN2BKO mice. For comparison, non-mutant C57BL/6J mice were tested for single-trial forced swim behavior after systemic Ro 25-6981 treatment and for riFS behavior after lesions of the ventromedial prefrontal cortex. riFS-induced alterations in corticolimbic GluN2B expression were also examined in C57BL/6J mice. We found that GluN2BKO mice reduced "despair-like" behavior in the riFS procedure, as compared to GluN2BFLOX controls. By contrast, GluN2BKO mice showed minimal alterations on anxiety-like or antidepressant-sensitive assays, including the single-trial forced swim test. In C57BL/6J mice, induction of "despair-like" responses in the riFS test was attenuated by vmPFC lesions, and was associated with changes in limbic GluN2B expression. Collectively, these data suggest that cortical GluN2B plays a major role in modulating adaptive responses to stress. Current findings provide further support for GluN2B as a key mechanism underlying stress responsivity, and a novel pharmacotherapeutic target for stress-related neuropsychiatric disorders.
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Affiliation(s)
- C Kiselycznyk
- Laboratory for Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Rockville, MD 20852-9411, USA.
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Efficacy of chronic antidepressant treatments in a new model of extreme anxiety in rats. DEPRESSION RESEARCH AND TREATMENT 2011; 2011:531435. [PMID: 21808731 PMCID: PMC3144710 DOI: 10.1155/2011/531435] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 05/31/2011] [Accepted: 06/03/2011] [Indexed: 11/23/2022]
Abstract
Animal models of anxious disorders found in humans, such as panic disorder and posttraumatic stress disorder, usually include spontaneous and conditioned fear that triggers escape and avoidance behaviors. The development of a panic disorder model with a learned component should increase knowledge of mechanisms involved in anxiety disorders. In our ethological model of extreme anxiety in the rat, forced apnea was combined with cold water vaporization in an inescapable situation. Based on the reactions of vehicle controls, behaviors involved in paroxysmic fear were passive (freezing) and active (jumping) reactions. Our results show that subchronic fluoxetine (5 mg/kg, IP, 21 days) and imipramine (10 mg/kg, IP, 14 days) administration alleviated freezing and jumping behaviors, whereas acute fluoxetine (1 mg/kg, IP) provoked opposite effects. Acute low dose of diazepam (1 mg/kg, IP) was not effective, whereas the higher dose of 3 mg/kg, IP, and clonazepam (1 mg/kg, IP) only had an effect on jumping. Paroxysmic fear generated in this experimental condition may therefore mimic the symptomatology observed in patients with anxiety disorders.
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18
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Drugan RC, Macomber H, Warner TA. Intermittent and continuous swim stress-induced behavioral depression: sensitivity to norepinephrine- and serotonin-selective antidepressants. Psychopharmacology (Berl) 2010; 212:85-91. [PMID: 20623107 DOI: 10.1007/s00213-010-1935-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 06/19/2010] [Indexed: 11/29/2022]
Abstract
RATIONALE Intermittent swim stress (ISS) produces deficits in swim escape learning and increases immobility in the forced swim test (FST). A previous attempt to reverse this immobility with the selective serotonin reuptake inhibitor (SSRI), fluoxetine (FLX), was unsuccessful, but the sensitivity of this immobility to other types of antidepressants is unknown. OBJECTIVES In experiment 1, we evaluate the ability of the norepinephrine (NE) selective reuptake inhibitor (NSRI), desipramine (DES), to reverse the ISS-induced immobility in the FST compared to confined controls (CC), while in experiment 2, we test the efficacy of either the SSRI or NSRI to reverse the immobility produced by either ISS or continuous swim (CS)/FST. METHODS Rats were exposed to their respective behavioral pretreatment (ISS, CS/FST, or CC) and were then injected with an antidepressant or saline solution 23.5, 5, and 1 h prior to the FST. RESULTS In experiment 1, DES reduced immobility and increased the climbing behavior in the ISS group without altering these behaviors in the CC, while in experiment 2, the CS/FST-induced immobility was reduced by both antidepressants (i.e., FLX and DES), while the ISS-induced immobility was only affected by DES. CONCLUSIONS These results suggest that the ISS-induced immobility is mediated through the NE system and may represent a model for atypical depression.
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Affiliation(s)
- Robert C Drugan
- Department of Psychology, University of New Hampshire, Durham, 03824-3567, USA.
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Choi JY, Choi YJ, dela Peña IC, Yoon SY, Lee GS, Shin CY, Ryu JH, Yu GY, Cheong JH. Vitamin C supplementation alleviates electroshock stress but not restraint stress in ICR mice. Food Sci Biotechnol 2010. [DOI: 10.1007/s10068-010-0019-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Christianson JP, Rabbett S, Lyckland J, Drugan RC. The immobility produced by intermittent swim stress is not mediated by serotonin. Pharmacol Biochem Behav 2008; 89:412-23. [PMID: 18295323 DOI: 10.1016/j.pbb.2008.01.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 01/11/2008] [Accepted: 01/21/2008] [Indexed: 11/29/2022]
Abstract
Exposure to uncontrollable stressors such as intermittent swim stress (ISS) produces a behavioral syndrome that resembles behavioral depression including immobility in a Forced Swim Test (FST) and escape learning deficits. The results of previous studies suggest that stress causes a temporary sensitization of the brain serotonin (5-HT) system that is necessary and sufficient for producing behavioral depression. If this hypothesis is true in the ISS paradigm, then enhancing or inhibiting 5-HT transmission during stress should exacerbate or block the development of behavioral depression, respectively. The selective 5-HT uptake inhibitor fluoxetine (FLX) was administered prior to ISS or confinement; 24 h later the FST was used to detect behavioral immobility. ISS, but not FLX, significantly increased immobility in the FST. The purported 5-HT uptake enhancer tianeptine (TPT) was administered in place of FLX. Again ISS increased immobility in the FST, but TPT had no effect. These results suggested that 5-HT is not a critical mediator of ISS induced behavioral depression. However, some authors have raised concern that TPT does not act directly on 5-HT. Therefore, the 5-HT synthesis inhibitor, para-chlorophenylaline (PCPA) was administered to deplete central 5-HT before stress. PCPA did not alter immobility in the FST. Finally, a sub-chronic regimen of FLX given after ISS, but before the FST, was without effect on reversing the ISS-induced immobility. Taken together, these experiments indicate that ISS produces a significant behavioral depression manifested as increased immobility but offer no support of the hypothesis that 5-HT is a critical mediator of these effects.
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Affiliation(s)
- John P Christianson
- Department of Psychology, Conant Hall, University of New Hampshire, Durham, NH, USA.
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21
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King CD, Devine DP, Vierck CJ, Mauderli A, Yezierski RP. Opioid modulation of reflex versus operant responses following stress in the rat. Neuroscience 2007; 147:174-82. [PMID: 17521823 DOI: 10.1016/j.neuroscience.2007.04.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 03/29/2007] [Accepted: 04/04/2007] [Indexed: 02/02/2023]
Abstract
In pre-clinical models intended to evaluate nociceptive processing, acute stress suppresses reflex responses to thermal stimulation, an effect previously described as stress-induced "analgesia." Suggestions that endogenous opioids mediate this effect are based on demonstrations that stress-induced hyporeflexia is enhanced by high dose morphine (>5 mg/kg) and is reversed by naloxone. However, reflexes and pain sensations can be modulated differentially. Therefore, in the present study direct comparisons were made of opioid agonist and antagonist actions, independently and in combination with acute restraint stress in Long Evans rats, on reflex lick-guard (L/G) and operant escape responses to nociceptive thermal stimulation (44.5 degrees C). A high dose of morphine (>8 mg/kg) was required to reduce reflex responding, but a moderate dose of morphine (1 mg/kg) significantly reduced escape responding. The same moderate dose (and also 5 mg/kg) of morphine significantly enhanced reflex responding. Naloxone (3 mg/kg) significantly enhanced escape responding but did not affect L/G responding. Restraint stress significantly suppressed L/G reflexes (hyporeflexia) but enhanced escape responses (hyperalgesia). Stress-induced hyperalgesia was significantly reduced by morphine and enhanced by naloxone. In contrast, stress-induced hyporeflexia was blocked by both naloxone and 1 mg/kg of morphine. Thus, stress-induced hyperalgesia was opposed by endogenous opioid release and by administration of morphine. Stress-induced hyporeflexia was dependent upon endogenous opioid release but was counteracted by a moderate dose of morphine. These data demonstrate a differential modulation of reflex and operant outcome measures by stress and by separate or combined opioid antagonism or administration of morphine.
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MESH Headings
- Acute Disease
- Adaptation, Physiological/drug effects
- Analgesics, Opioid/administration & dosage
- Animals
- Conditioning, Operant/drug effects
- Conditioning, Operant/physiology
- Disease Models, Animal
- Displacement, Psychological
- Dose-Response Relationship, Drug
- Escape Reaction/drug effects
- Escape Reaction/physiology
- Female
- Morphine/administration & dosage
- Naloxone/administration & dosage
- Narcotic Antagonists/administration & dosage
- Opioid Peptides/agonists
- Opioid Peptides/antagonists & inhibitors
- Opioid Peptides/metabolism
- Rats
- Rats, Long-Evans
- Reaction Time/drug effects
- Reaction Time/physiology
- Reflex/drug effects
- Reflex/physiology
- Reflex, Abnormal/drug effects
- Reflex, Abnormal/physiology
- Restraint, Physical
- Stress, Psychological/complications
- Stress, Psychological/metabolism
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Affiliation(s)
- C D King
- Department of Orthodontics, College of Dentistry, Medicine, University of Florida, Gainesville, FL 32610, USA
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Drugan RC, Wiedholz LM, Holt A, Kent S, Christianson JP. Environmental and immune stressors enhance alcohol-induced motor ataxia in rat. Pharmacol Biochem Behav 2007; 86:125-31. [PMID: 17270258 DOI: 10.1016/j.pbb.2006.12.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 12/15/2006] [Accepted: 12/15/2006] [Indexed: 09/30/2022]
Abstract
Infection is now accepted as a stressor, consequently we sought to compare the short- and longer-term consequences of several environmental stressors versus an endotoxin challenge on alcohol-induced motor ataxia. The present set of studies examined the impact of intermittent electric shock (SHOCK), intermittent cold water swim (ICWS), or lipopolysaccharide (LPS) administration on the motor ataxic effects of an intraperitoneal (i.p.) injection of alcohol (ETOH). In Experiment 1 SHOCK, but not ICWS, enhanced the motor ataxic effects of ethanol at both 2 and 24 h post-stress. In Experiment 2 administration of LPS did not affect the motor ataxic effects of ETOH 4 h later, but enhanced the ataxic potency of ETOH 24 h later. The results indicate that certain environmental and immune stressors have the potential to alter the long-term behavioral reactivity to alcohol. These examples of stress-induced enhancement of the motor ataxic effects of ETOH may have important implications for the development of alcohol dependence.
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Affiliation(s)
- Robert C Drugan
- Department of Psychology, University of New Hampshire, Durham, NH 03824, USA.
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23
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Levay EA, Govic A, Hazi A, Flannery G, Christianson J, Drugan RC, Kent S. Endocrine and immunological correlates of behaviorally identified swim stress resilient and vulnerable rats. Brain Behav Immun 2006; 20:488-97. [PMID: 16309884 DOI: 10.1016/j.bbi.2005.10.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 10/04/2005] [Accepted: 10/12/2005] [Indexed: 10/25/2022] Open
Abstract
Animal models of stress-induced depression have identified a bimodal reactivity to stress, namely 'resilience' and 'vulnerability.' Possible corresponding differences in endocrine and immunological responses between these groups have not been delineated. Male Sprague-Dawley rats were divided into three groups: stress (n=25), confined controls (n=7), and home cage controls (n=7). Stress rats were exposed to 80, 5-s inescapable cold water swim trials (15 degrees C). Twenty-four hours later, the stress rats were tested on an instrumental swim escape test (SET) but now they had access to an omnidirectional lever that terminated the stress. Immediately after the SET, trunk blood was collected to assay for serum corticosterone (CORT), and spleens were removed and natural killer cell activity (NKCA) and concanavalin A (CON-A) induced lymphocyte proliferation determined. Subjects in the stress treatment group were divided into distinct 'resilient' and 'vulnerable' categories by a median split for average escape latencies across the last 25 trials of the SET. Stress rats secreted more CORT than controls and vulnerable rats secreted greater levels than resilient rats. NKCA was greatest in control rats, and was decreased in the stress rats although the resilient and the vulnerable groups did not differ. Conversely, CON-A-induced lymphocyte proliferation was greatest in stress rats, vulnerable rats exhibiting more proliferation than resilient rats, but both were greater than both control groups. Stress animals were hypothermic throughout the swim stress procedures but exhibited a stress-induced fever following the initial swim trials. The observed differences may have important predictive and theoretical utility for vulnerable and resilient profiles.
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Affiliation(s)
- Elizabeth A Levay
- School of Psychological Science, La Trobe University, Bundoora, Vic., Australia
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Filgueiras CC, Abreu-Villaça Y, Krahe TE, Manhães AC. Unilateral hemispherectomy at adulthood asymmetrically affects immobile behavior of male Swiss mice. Behav Brain Res 2006; 172:33-8. [PMID: 16697475 DOI: 10.1016/j.bbr.2006.04.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 04/10/2006] [Accepted: 04/12/2006] [Indexed: 12/21/2022]
Abstract
In order to test the hypothesis that behavioral coping with stressful situations is asymmetrically modulated by the hemispheres, we used the unilateral hemispherectomy procedure to assess the relative importance of each hemisphere in the determination of the immobility time during the forced swimming test. Under anesthesia, adult Swiss male mice were submitted to unilateral (right or left) hemispherectomy or sham surgery. Fifteen days after surgery, the immobile and turning behaviors of each mouse were measured during a 5-min forced swimming testing session. In general, while turning activity decreased significantly as the test progressed, an increase in immobility was observed. The unilateral hemispherectomy asymmetrically affected the immobility time in the forced swimming test. Particularly, the increase in immobility time of right-hemispherectomized mice was greater than that observed for sham-operated ones. In contrast, there were no differences in turning activity between the groups. The higher immobility time in males that had their right hemisphere removed supports the hypothesis that the two hemispheres contribute differentially to the behavioral response to stress.
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Affiliation(s)
- Cláudio C Filgueiras
- Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcântara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Avenida Prof. Manuel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ 20 550 170, Brazil.
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