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Rezqaoui A, Ibouzine-Dine L, Elhamzaoui A, Brouzi MYE, Dimaoui A, Hessni AE, Mesfioui A. Potential Role of Oxidative Stress in the Effects of Chronic Administration of Iron on Affective and Cognitive Behavior on Male Wistar Rat. Biol Trace Elem Res 2023; 201:4812-4826. [PMID: 36683122 DOI: 10.1007/s12011-023-03560-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/05/2023] [Indexed: 01/24/2023]
Abstract
In this work, we studied the impact of chronic iron exposure, in the form of iron sulfate (FeSo4), on affective and cognitive disorders and oxidative stress in the male Wistar rat. The treatment was carried out for 8 weeks, the rats received an intraperitoneal injection of iron at different doses: 0.25, 0.5, and 1 mg/kg. Affective and cognitive disorders are assessed in open field test (OFT), elevated plus maze (EPM), forced swimming test (FST), Morris water maze (MWM), and Y-maze. The hippocampus and prefrontal cortex of each animal were taken for biochemical examination. Our results show that iron exerts anxiogenic and depressogenic effects, which were observed first at the dose of 0.5 mg/kg and continued in a dose-dependent manner up to the maximum tested dose of 1 mg/kg. According to results from the MWM and Y-maze tests, continuous exposure to iron induces cognitive disorders that are defined by the disturbance of working memory and influences spatial learning performance causing a deficit of spatial memory retention. We noted that chronic exposure to iron can be associated with the appearance of a state of oxidative stress in the hippocampus and the prefrontal cortex demonstrated by an increase in lipid peroxidation, an increase in nitric oxide, and also by disturbances in the antioxidant defense systems following a determination of the concentrations of catalase. In conclusion, we can deduce from this work that chronic iron exposure can be related to the induction of cognitive and affective disorders and oxidative stress.
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Affiliation(s)
- Ayoub Rezqaoui
- Laboratory of Biology and Health, Department of Biology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco.
| | - Laila Ibouzine-Dine
- Laboratory of Biology and Health, Department of Biology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco
| | - Abdelghafour Elhamzaoui
- Laboratory of Biology and Health, Department of Biology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco
| | - Mohamed Yassine El Brouzi
- Laboratory of Biology and Health, Department of Biology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco
| | - Amal Dimaoui
- Laboratory of Biology and Health, Department of Biology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco
| | - Aboubaker El Hessni
- Laboratory of Biology and Health, Department of Biology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco
| | - Abdelhalem Mesfioui
- Laboratory of Biology and Health, Department of Biology, Faculty of Sciences, Ibn Tofail University, Kenitra, Morocco
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Rbaa M, Mequedade M, Berkiks I, Lakhrissi Y, Mague J, El Hessni A, Hadda TB, Warad I, Lakhrissi B, Zarrouk A. Toxicological and Pharmacological Studies of a Crystal Structure Derivative of 8-Hydroxyquinoline. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2022. [DOI: 10.1007/s13369-021-06007-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Sze Y, Brunton PJ. Effects of prenatal stress on neuroactive steroid responses to acute stress in adult male and female rats. J Neuroendocrinol 2021; 33:e12916. [PMID: 33270955 PMCID: PMC7900968 DOI: 10.1111/jne.12916] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/23/2020] [Accepted: 10/24/2020] [Indexed: 12/20/2022]
Abstract
Acute swim stress results in the robust production of several neuroactive steroids, which act as mediators of the stress response. These steroids include glucocorticoids, and positive GABAA receptor modulatory steroids such as allopregnanolone and tetrahydrocorticosterone (THDOC), which potentiate inhibitory GABA signalling, thereby playing a role in the negative control of the hypothalamic-pituitary-adrenal (HPA) axis. Prenatally stressed (PNS) offspring exhibit increased vulnerability to stress-related disorders and frequently display exaggerated HPA axis responses to stressors during adulthood, which may be a result of reduced neuroactive steroid production and consequently inhibitory signalling. Here, we investigated whether exposure of rats to prenatal social stress from gestational day 16-20 altered neuroactive steroid production under non-stress conditions and in response to an acute stressor (swim stress) in adulthood. Using liquid chromatography-mass spectrometry, nine neuroactive steroids were quantified (corticosterone, deoxycorticosterone [DOC], dihydrodeoxycorticosterone, THDOC, progesterone, dihydroprogesterone, allopregnanolone, pregnenolone, testosterone) in plasma and in five brain regions (frontal cortex, hypothalamus, amygdala, hippocampus, brainstem) of male and female control and PNS rats. There was no difference in the neuroactive steroid profile between control and PNS rats under basal conditions. The increase in circulating corticosterone induced by acute swim stress was similar in control and PNS offspring. However, greater stress-induced corticosterone and DOC concentrations were observed in the brainstem of male PNS offspring, whereas DOC concentrations were lower in the hippocampus of PNS females compared to controls, following acute stress. Although PNS rats did not show deficits in allopregnanolone responses to acute stress, there were modest deficits in the production of THDOC in the brainstem, amygdala, and frontal cortex of PNS males and in the frontal cortex of PNS females. The data suggest that neuroactive steroid modulation of GABAergic signalling following stress exposure may be affected in a sex- and region-specific manner in PNS offspring.
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Affiliation(s)
- Ying Sze
- Centre for Discovery Brain SciencesUniversity of EdinburghEdinburghUK
- The Roslin InstituteUniversity of EdinburghEdinburghUK
| | - Paula J. Brunton
- Centre for Discovery Brain SciencesUniversity of EdinburghEdinburghUK
- The Roslin InstituteUniversity of EdinburghEdinburghUK
- Zhejiang University‐University of Edinburgh Joint InstituteHainingChina
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Nakajima S. Taste Aversion Learning Based on Swimming and Lithium Chloride Injection in Rats: Implications From Cross‐familiarization Tests and Stimulus Selectivity
1. JAPANESE PSYCHOLOGICAL RESEARCH 2020. [DOI: 10.1111/jpr.12281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Béland-Millar A, Larcher J, Courtemanche J, Yuan T, Messier C. Effects of Systemic Metabolic Fuels on Glucose and Lactate Levels in the Brain Extracellular Compartment of the Mouse. Front Neurosci 2017; 11:7. [PMID: 28154523 PMCID: PMC5243849 DOI: 10.3389/fnins.2017.00007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 01/04/2017] [Indexed: 01/11/2023] Open
Abstract
Classic neuroenergetic research has emphasized the role of glucose, its transport and its metabolism in sustaining normal neural function leading to the textbook statement that it is the necessary and sole metabolic fuel of the mammalian brain. New evidence, including the Astrocyte-to-Neuron Lactate Shuttle hypothesis, suggests that the brain can use other metabolic substrates. To further study that possibility, we examined the effect of intraperitoneally administered metabolic fuels (glucose, fructose, lactate, pyruvate, ß-hydroxybutyrate, and galactose), and insulin, on blood, and extracellular brain levels of glucose and lactate in the adult male CD1 mouse. Primary motor cortex extracellular levels of glucose and lactate were monitored in freely moving mice with the use of electrochemical electrodes. Blood concentration of these same metabolites were obtained by tail vein sampling and measured with glucose and lactate meters. Blood and extracellular fluctuations of glucose and lactate were monitored for a 2-h period. We found that the systemic injections of glucose, fructose, lactate, pyruvate, and ß-hydroxybutyrate increased blood lactate levels. Apart for a small transitory rise in brain extracellular lactate levels, the main effect of the systemic injection of glucose, fructose, lactate, pyruvate, and ß-hydroxybutyrate was an increase in brain extracellular glucose levels. Systemic galactose injections produced a small rise in blood glucose and lactate but almost no change in brain extracellular lactate and glucose. Systemic insulin injections led to a decrease in blood glucose and a small rise in blood lactate; however brain extracellular glucose and lactate monotonically decreased at the same rate. Our results support the concept that the brain is able to use alternative fuels and the current experiments suggest some of the mechanisms involved.
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Affiliation(s)
| | - Jeremy Larcher
- School of Psychology, University of Ottawa Ottawa, ON, Canada
| | | | - Tina Yuan
- School of Psychology, University of Ottawa Ottawa, ON, Canada
| | - Claude Messier
- School of Psychology, University of Ottawa Ottawa, ON, Canada
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Aburawi S, Al-Tubuly R, Alghzewi E, Gorash Z. Effects of calcium channel blockers on antidepressant action of Alprazolam and Imipramine. Libyan J Med 2016. [DOI: 10.3402/ljm.v2i4.4727] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- S.M. Aburawi
- Dept of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, El-Fateh University, Libya
| | - R.A. Al-Tubuly
- Dept of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, El-Fateh University, Libya
| | - E.A. Alghzewi
- Dept of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, El-Fateh University, Libya
| | - Z.M. Gorash
- Dept of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, El-Fateh University, Libya
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Al-Tubuly R, Aburawi S, Alghzewi E, Gorash Z, Errwami S. The Effect of Sympathetic Antagonists on the Antidepressant Action of Alprazolam. Libyan J Med 2016. [DOI: 10.3402/ljm.v3i2.4763] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- R.A. Al-Tubuly
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, AlFateh University, Tripoli, Libya
| | - S.M. Aburawi
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, AlFateh University, Tripoli, Libya
| | - E.A. Alghzewi
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, AlFateh University, Tripoli, Libya
| | - Z.M. Gorash
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, AlFateh University, Tripoli, Libya
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Western High-Fat Diet Consumption during Adolescence Increases Susceptibility to Traumatic Stress while Selectively Disrupting Hippocampal and Ventricular Volumes. eNeuro 2016; 3:eN-NWR-0125-16. [PMID: 27844058 PMCID: PMC5099604 DOI: 10.1523/eneuro.0125-16.2016] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 09/23/2016] [Accepted: 10/26/2016] [Indexed: 11/29/2022] Open
Abstract
Psychological trauma and obesity co-occur frequently and have been identified as major risk factors for psychiatric disorders. Surprisingly, preclinical studies examining how obesity disrupts the ability of the brain to cope with psychological trauma are lacking. The objective of this study was to determine whether an obesogenic Western-like high-fat diet (WD) predisposes rats to post-traumatic stress responsivity. Adolescent Lewis rats (postnatal day 28) were fed ad libitum for 8 weeks with either the experimental WD diet (41.4% kcal from fat) or the control diet (16.5% kcal from fat). We modeled psychological trauma by exposing young adult rats to a cat odor threat. The elevated plus maze and the open field test revealed increased psychological trauma-induced anxiety-like behaviors in the rats that consumed the WD when compared with control animals 1 week after undergoing traumatic stress (p < 0.05). Magnetic resonance imaging showed significant hippocampal atrophy (20% reduction) and lateral ventricular enlargement (50% increase) in the animals fed the WD when compared with controls. These volumetric abnormalities were associated with behavioral indices of anxiety, increased leptin and FK506-binding protein 51 (FKBP51) levels, and reduced hippocampal blood vessel density. We found asymmetric structural vulnerabilities to the WD, particularly the ventral and left hippocampus and lateral ventricle. This study highlights how WD consumption during adolescence impacts key substrates implicated in post-traumatic stress disorder. Understanding how consumption of a WD affects the developmental trajectories of the stress neurocircuitry is critical, as stress susceptibility imposes a marked vulnerability to neuropsychiatric disorders.
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Prior running, but not swimming, hinders running-based taste aversion learning in rats. LEARNING AND MOTIVATION 2015. [DOI: 10.1016/j.lmot.2015.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Abstract
SUMMARYWe developed a novel small rat-like robot calledWasedaRat No.4(WR-4) to interact with real rats. WR-4 can perform both rearing (rising up on its hind limbs) and rotating (body bending during movement) actions faster than live mature rats. After robot–rat interaction involving rearing and body grooming (body cuddling and head curling) actions of WR-4, real rats showed more activity and greater interest in the robot. Similar results evident from rat–rat interaction suggest that a rat-like robot is able to interact with rats in the same way as real rats. Furthermore, lower variances between the rat subjects in robot–rat interaction reveals that a rat-like robot can more effectively impact rat's behavior in a controllable, predictable way.
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Nyuyki KD, Maloumby R, Reber SO, Neumann ID. Comparison of corticosterone responses to acute stressors: chronic jugular vein versus trunk blood samples in mice. Stress 2012; 15:618-26. [PMID: 22251167 DOI: 10.3109/10253890.2012.655348] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A commonly used method for obtaining blood samples from mice is decapitation. However, there is an obvious need for repeated blood sampling in mice under stress-free conditions. Here, we describe a simple technique to repeatedly collect blood samples from conscious, freely moving mice through a chronically implanted jugular vein catheter. Furthermore, we compare plasma corticosterone (CORT) concentrations in samples obtained through the catheter 1 day after surgery with samples taken from trunk blood obtained under basal or acute stress conditions. CORT concentrations in repeated 100-μl venous blood samples were found to be similar to trunk blood samples both under basal conditions and after stressor exposure collected at identical time points (at 5, 15, and 60 min). Using both techniques, we demonstrate a progressive increase in CORT levels until 15 min after termination of stressor exposure and a decrease towards baseline values 60 min later. Anxiety-related behavior, as assessed on the elevated plus maze 3-4 days after surgery, did not differ between catheterized and non-catheterized mice. Our results provide evidence for application of jugular vein catheterization as a technique for repeated blood sampling in conscious laboratory mice. Use of this technique will greatly reduce the number of animals required for experiments involving endocrine endpoints.
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Affiliation(s)
- Kewir D Nyuyki
- Department of Behavioral and Molecular Neurobiology, University of Regensburg, 93040 Regensburg, Germany
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Zouhairi N, Ba-M'hamed S, Bennis M. Maternal prenatal stress in rats influences c-fos expression in the spinal cord of the offspring. Acta Histochem 2012; 114:525-33. [PMID: 22000863 DOI: 10.1016/j.acthis.2011.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 09/20/2011] [Accepted: 09/22/2011] [Indexed: 11/17/2022]
Abstract
Previous studies in humans have reported a link between maternal stress and disturbed infant physiological behavior. The objective of our study was to examine in experimental rats how maternal prenatal stress induced by a forced swim test affects offspring afferent spinal responses mediated by stimulation of vaginocervical receptors. The activation of spinal cord neurons showing c-fos expression was examined following vaginocervical mechanical stimulation in adult rats, which were the offspring of dams exposed to gestational stress from E10 until delivery. Vaginocervical stimulation of both prenatal-stressed and non-prenatal-stressed rats induced an increase in immunoreactive protein in the spinal cord ranging from T12 to S1 segmental levels. However, a significantly higher (40%) increase in the expression of Fos-immunoreactive neurons was observed in vaginocervical stimulated prenatally stressed rats than in non-stimulated prenatally stressed ones. This increase was higher in L5-S1 levels than in T12-L4. When the regional distribution was examined, results showed that up to 80% of activated neurons were located in the dorsal horn in both non-stimulated prenatally stressed and stimulated prenatally stressed groups, with a significantly higher density in the latter. Our results demonstrate that maternal prenatal stress can have consequences on vaginocervical responses conveyed to the spinal cord. The increase in Fos labeled neurons in T12-S1 in prenatally stressed rats induced by vaginocervical stimulation suggests the hypersensitivity of the genital tract associated with activation of spinal circuits spanning multiple segments.
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Affiliation(s)
- Nadia Zouhairi
- Laboratoire de Pharmacologie, Neurobiologie et Comportement, Unité associée au CNRST, Université Cadi Ayyad, Faculté des Sciences Semlalia, Marrakech, Morocco
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Cacace S, Plescia F, Barberi I, Cannizzaro C. Acetaldehyde oral self-administration: evidence from the operant-conflict paradigm. Alcohol Clin Exp Res 2012; 36:1278-87. [PMID: 22324727 DOI: 10.1111/j.1530-0277.2011.01725.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 11/21/2011] [Indexed: 11/29/2022]
Abstract
BACKGROUND Acetaldehyde (ACD), ethanol's first metabolite, has been reported to interact with the dopaminergic reward system, and with the neural circuits involved in stress response. Rats self-administer ACD directly into cerebral ventricles, and multiple intracerebroventricular infusions of ACD produce conditioned place preference. Self-administration has been largely employed to assess the reinforcing and addictive properties of most drugs of abuse. In particular, operant conditioning is a valid model to investigate drug-seeking and drug-taking behavior in rats. METHODS This study was aimed at the evaluation of (i) the motivational properties of oral ACD in the induction and maintenance of an operant-drinking behavior; (ii) ACD effect in a conflict situation employing the punishment-based Geller-Seifter procedure; and (iii) the onset of a relapse drinking behavior, following ACD deprivation. The lever-pressing procedure in a sound-attenuated operant-conditioning chamber was scheduled into 3 different periods: (i) training-rewarded responses with a fixed ratio 1; (ii) conflict-rewarded responses periodically associated with a 0.2 mA foot-shock; and (iii) relapse-rewarded lever presses following 1-week ACD abstinence. RESULTS Our results show that oral self-administrated ACD induced: a higher rate of punished responses in Geller-Seifter procedures; and the establishment of a relapse behavior following ACD deprivation. CONCLUSIONS In conclusion, our results indicate that ACD is able to induce an operant-drinking behavior, which is also maintained besides the conflict procedure and enhanced by the deprivation effect, supporting the hypothesis that ACD itself possesses motivational properties, such as alcohol and other substances of abuse.
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Affiliation(s)
- Silvana Cacace
- Department of Science for Health Promotion G. D'Alessandro, Section of Pharmacology, University of Palermo, Palermo, Italy
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Hellemans KG, Sliwowska J, Verma P, Weinberg J. Prenatal alcohol exposure: fetal programming and later life vulnerability to stress, depression and anxiety disorders. Neurosci Biobehav Rev 2010; 34:791-807. [PMID: 19545588 PMCID: PMC5518679 DOI: 10.1016/j.neubiorev.2009.06.004] [Citation(s) in RCA: 238] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Revised: 06/01/2009] [Accepted: 06/11/2009] [Indexed: 01/21/2023]
Abstract
Children with fetal alcohol spectrum disorder (FASD) exhibit cognitive, neuropsychological and behavioral problems, and numerous secondary disabilities including depression and anxiety disorders. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is common in depression/anxiety, reflected primarily in increased HPA tone or activity. Prenatal alcohol exposure (PAE) increases HPA tone and results in HPA dysregulation throughout life, paralleling many of the HPA changes in depression/anxiety. We review data demonstrating altered HPA function and increased depression/anxiety in FASD. In the context of the stress-diathesis model, we discuss the hypothesis that fetal programming of the HPA axis by PAE alters neuroadaptive mechanisms that mediate the stress response, thus sensitizing the organism to stressors encountered later in life, and mediating, at least partly, the increased vulnerability to depression/anxiety disorders. Furthermore, we present evidence demonstrating sex-specific alterations in both hormonal and behavioral responsiveness to tasks measuring depressive- and anxiety-like behaviors in PAE offspring. Overall, the research suggests that the stress-diathesis model provides a powerful approach for elucidating mechanisms underlying the increased vulnerability to mental illness among individuals with FASD, and developing appropriate treatments for these individuals. Dr. Seymour Levine's seminal work on the long-term consequences of early life experiences formed a framework for the development of the research described in this review.
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Affiliation(s)
- Kim G.C. Hellemans
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3
- Department of Psychology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
| | - Joanne Sliwowska
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3
| | - Pamela Verma
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3
| | - Joanne Weinberg
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3
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Abstract
OBJECTIVE Given the lack of reliable murine model of binge-like eating, we tried to induce this pathological behavior in mice. METHOD We used an experimental protocol mimicking the etiological factors involved in the development of binge eating in humans, that is, food restriction, refeeding (R-R) in presence of high palatable food, and stress (S). RESULTS Mice subjected to at least three cycles of R-R plus S (forced swimming stress), showed a binge-like behavior evident as early as 4 h, persisting 24 h after stress application and not associated to depressive-like behavior. However, after the third R-R/S cycle, food intakes of mice returned to normal levels. DISCUSSION (i) at least three cycles of R-R plus S are required to promote abnormal eating in mice, (ii) this is not associated to depressive-like behaviors, and (iii) the enhanced pathological behavior showed a transient nature not persisting after the third R-R/S cycle.
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Affiliation(s)
- Daniele Consoli
- Department of Experimental and Clinical Pharmacology, Medical School, University of Catania, Catania, Italy.
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Al-Tubuly R, Aburawi S, Alghzewi E, Gorash Z, Errwami S. The effect of sympathetic antagonists on the antidepressant action of alprazolam. Libyan J Med 2008; 3:78-83. [PMID: 21499463 PMCID: PMC3074285 DOI: 10.4176/080101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Alprazolam is an anti-anxiety drug shown to be effective in the treatment of depression. In this study, the effect of sympathetic receptor antagonists on alprazolam-induced antidepressant action was studied using a mouse model of forced swimming behavioral despair. The interaction of three sympathetic receptor antagonists with benzodiazepines, which may impact the clinical use of alprazolam, was also studied. Behavioral despair was examined in six groups of albino mice. Drugs were administered intraperitoneally. The control group received only a single dose of 1% Tween 80. The second group received a single dose of alprazolam, and the third group received an antagonist followed by alprazolam. The fourth group was treated with imipramine, and the fifth group received an antagonist followed by imipramine. The sixth group was treated with a single dose of an antagonist alone (atenolol, a β1-selective adrenoceptor antagonist; propranolol, a non selective β-adrenoceptor antagonist; and prazocin, an α1-adrenoceptor antagonist). Results confirmed the antidepressant action of alprazolam and imipramine. Prazocin treatment alone produced depression, but it significantly potentiated the antidepressant actions of imipramine and alprazolam. Atenolol alone produced an antidepressant effect and potentiated the antidepressant action of alprazolam. Propranolol treatment alone produced depression, and antagonized the effects of alprazolam and imipramine, even producing depression in combined treatments.In conclusion, our results reveal that alprazolam may produce antidepressant effects through the release of noradrenaline, which stimulates β2 receptors to produce an antidepressant action. Imipramine may act by activating β2 receptors by blocking or down-regulating β1 receptors.
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Affiliation(s)
- Ra Al-Tubuly
- Department of Pharmacology and Clinical Pharmacy, Faculty of Pharmacy, AlFateh University, Tripoli, Libya
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Aburawi S, Al-Tubuly R, Alghzewi E, Gorash Z. Effects of calcium channel blockers on antidepressant action of Alprazolam and Imipramine. Libyan J Med 2007; 2:169-75. [PMID: 21503240 PMCID: PMC3078248 DOI: 10.4176/070909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Alprazolam is effective as an anxiolytic and in the adjunct treatment of depression. In this study, the effects of calcium channel antagonists on the antidepressant action of alprazolam and imipramine were investigated. A forced swimming maze was used to study behavioral despair in albino mice. Mice were divided into nine groups (n = 7 per group). One group received a single dose of 1% Tween 80; two groups each received a single dose of the antidepressant alone (alprazolam or imipramine); two groups each received a single dose of the calcium channel blocker (nifedipine or verapamil); four groups each received a single dose of the calcium channel blocker followed by a single dose of the antidepressant (with same doses used for either in the previous four groups). Drug administration was performed concurrently on the nine groups. Our data confirmed the antidepressant action of alprazolam and imipramine. Both nifedipine and verapamil produced a significant antidepressant effect (delay the onset of immobility) when administered separately. Verapamil augmented the antidepressant effects of alprazolam and imipramine (additive antidepressant effect). This may be due to the possibility that verapamil might have antidepressant-like effect through different mechanism. Nifedipine and imipramine combined led to a delay in the onset of immobility greater than their single use but less than the sum of their independent administration. This may be due to the fact that nifedipine on its own might act as an antidepressant but blocks one imipramine mechanism that depends on L-type calcium channel activation. Combining nifedipine with alprazolam produced additional antidepressant effects, which indicates that they exert antidepressant effects through different mechanisms.
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Andrade S, Silveira SL, Gomez R, Barros HMT, Ribeiro MFM. Gender differences of acute and chronic administration of dehydroepiandrosterone in rats submitted to the forced swimming test. Prog Neuropsychopharmacol Biol Psychiatry 2007; 31:613-21. [PMID: 17223242 DOI: 10.1016/j.pnpbp.2006.12.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 11/21/2006] [Accepted: 12/06/2006] [Indexed: 11/19/2022]
Abstract
Previous pre-clinical and clinical studies investigating the antidepressant potential of DHEA revealed conflicting results. In this study, the effects of exogenous DHEA on performance in the forced swimming test (FST) were examined in male and female Wistar rats in different phases of the estrous cycle. Furthermore, the effects of treatment and of the FST, on corticosterone and DHEA serum levels were investigated. Acute administration of DHEA (2 mg/kg) significantly increased freezing only in proestrus female rats. Similarly, the chronic administration of DHEA (2 mg/kg) increased freezing duration and decreased climbing behavior but only in females in diestrus II compared to those given vehicle. These results demonstrate that chronically administered DHEA induces a depressant-like effect, and this effect is sex dependent. There was no direct correlation between corticosterone levels or the corticosterone/DHEA ratio and the behaviors studied. After the FST, serum DHEA and corticosterone levels were increased, with females showing higher DHEA levels than males. Nevertheless, corticosterone levels were unaltered with chronic procedure; an effect that was independent of sex and treatment. These findings are relevant for research examining alternative treatment for depression and may elucidate the gender differences involved in stress-related diseases.
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Affiliation(s)
- S Andrade
- Department of Physiology, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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21
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Tejedor-Real P, Sahagún M, Biguet NF, Mallet J. Neonatal handling prevents the effects of phencyclidine in an animal model of negative symptoms of schizophrenia. Biol Psychiatry 2007; 61:865-72. [PMID: 17125743 DOI: 10.1016/j.biopsych.2006.08.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Revised: 06/23/2006] [Accepted: 08/10/2006] [Indexed: 10/23/2022]
Abstract
BACKGROUND Environmental factors during the neonatal period have long-lasting effects on the brain. Neonatal handling, an early mild stress, enhances the ability to cope with stress in adult rats. In humans, inappropriate stress responses increase the risk of schizophrenia in genetically predisposed individuals. We studied the effect of neonatal handling on the phencyclidine (PCP)-induced immobility time of rats in the forced swimming test (FST, an animal model of negative symptoms of schizophrenia) and on plasma adrenocorticotropic hormone (ACTH) as a measure of hypothalamic-pituitary-adrenal axis (HPA) reactivity. METHODS Pups were removed from their mothers 15 min/21 days after birth. Postnatal day 65: animals were submitted to restraint stress. Postnatal day 75: after PCP treatment (5 mg/kg/5 days) animals were submitted to the FST. RESULTS Neonatal handling reduced HPA reactivity to passive stress (restraint) but not to active coping stress (forced swimming). Immobilization time was significantly lower in saline- and PCP-treated, handled animals than in non-handled ones. Handling prevented the ACTH increase induced by PCP that was observed in the non-handled rats after FST. CONCLUSIONS First, neonatal handling protects animals from acquiring the schizophrenic-like behavior provoked by sub-chronic PCP treatment, which was associated with a reduced HPA activity. Second, the beneficial properties of handling in stress responses seem to depend on the type of stress.
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Calil CM, Marcondes FK. The comparison of immobility time in experimental rat swimming models. Life Sci 2006; 79:1712-9. [PMID: 16814809 DOI: 10.1016/j.lfs.2006.06.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 05/26/2006] [Accepted: 06/02/2006] [Indexed: 01/22/2023]
Abstract
Rat swimming models have been used in studies about stress and depression. However, there is no consensus about interpreting immobility (helplessness or adaptation) in the literature. In the present study, immobility time, glucose and glycogen mobilization, corticosterone and the effect of desipramine and diazepam were investigated in two different models: swimming stress and the forced swimming test. Immobility time was lower in swimming stress than in the forced swimming test. Both swimming models increased corticosterone levels in comparison with control animal levels. Moreover, swimming stress induced higher corticosterone levels than the forced swimming test did [F(2,14)=59.52; p<0.001]. Liver glycogen content values differed from one another (swimming stress<forced swimming test<control), [F(2,17)=32.08; p<0.001]. The glycogen content values in the gastrocnemius [F(2,16)=11.35; p=0.026] and soleus [F(2,16)=8.68; p=0.006] muscles were lower during swimming stress in comparison with the forced swimming test and control. The immobility time was recorded and measured in another group treated with desipramine and diazepam in two protocols: a single session of forced swimming test or swimming stress and two sessions (pre- and retest) of forced swimming model or swimming stress. Desipramine decreased the immobility time in the forced swimming test in both the single [F(2,25)=20.63; p<0.0001] and retest [F(2,37)=7.28; p=0.002] swimming session, without changes in the swimming stress model. Diazepam increased the immobility time in the swimming stress but not in the forced swimming test during the single [F(2,26)=11.24; p=0.0003] and retest sessions [F(2,38)=4.17; p=0.02]. It was concluded that swimming stress and the forced swimming test induced different behavior, hormonal and metabolic responses and represented different situations to the animal.
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Affiliation(s)
- Caroline Morini Calil
- Department of Physiological Sciences, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil
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Neumann ID, Torner L, Toschi N, Veenema AH. Oxytocin actions within the supraoptic and paraventricular nuclei: differential effects on peripheral and intranuclear vasopressin release. Am J Physiol Regul Integr Comp Physiol 2006; 291:R29-36. [PMID: 16424083 DOI: 10.1152/ajpregu.00763.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In response to forced swimming (FS), AVP is released somato-dendritically within the supraoptic nucleus (SON) and paraventricular nucleus (PVN), but not from neurohypophyseal terminals into blood. Together with AVP, oxytocin (OXT) is released within the SON and PVN. Here, we studied the role of intra-SON and intra-PVN OXT in the regulation of local AVP release and into the blood in male rats. Within the SON, bilateral retrodialysis of an OXT receptor antagonist (OXT-A) increased local AVP release in response to FS [60 s, 21°C, vehicle twofold, not significant (ns); OXT-A: 15-fold increase, P < 0.05] without significantly affecting basal AVP release. In addition, local OXT-A elevated plasma AVP secretion under basal conditions (twofold increase, P < 0.05) without further elevation after FS. Within the PVN, exposure to FS elevated local AVP release, reaching significance only in the OXT-A group (vehicle: 1.4-fold, ns; OXT-A: 1.6-fold increase, P = 0.050). Bilateral OXT-A into the PVN did not affect peripheral AVP secretion either under basal or stress conditions. Basal ACTH concentrations tended to be elevated by local OXT-A within the PVN (1.7-fold increase, P = 0.076). In contrast, the swim-induced ACTH secretion was attenuated after retrodialysis of OXT-A within both the SON (at 5 min) and PVN (at 15 min) ( P < 0.05 both) compared with vehicle. The results demonstrate a receptor-mediated effect of OXT within the SON and PVN on local and neurohypophyseal AVP release, which depends upon the activity conditions. Further, while exerting an inhibitory effect on hypothalamo-pituitary-adrenal axis activity under basal conditions, hypothalamic OXT is essential for an adequate acute ACTH response.
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Affiliation(s)
- Inga D Neumann
- Institute of Zoology, Department of Behavioural Neuroendocrinology, University of Regensburg, Resenburg, Germany.
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Masaki T, Nakajima S. Taste aversion learning induced by delayed swimming activity. Behav Processes 2005; 67:357-62. [PMID: 15518986 DOI: 10.1016/j.beproc.2004.06.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Accepted: 06/22/2004] [Indexed: 11/26/2022]
Abstract
The experiment reported here demonstrated that forced swimming endows rats with aversion to a taste solution consumed 30 min before the swimming. The experimental rats were allowed to drink 0.2% sodium saccharin solution, which was followed by a 30-min empty interval, and then a 20-min swimming opportunity in water. Compared with the control rats, which were returned to their home cages after drinking the saccharin, the experimental rats drank a small amount of saccharin solution both in the later sessions of one-bottle training and in the subsequent two-bottle choice (saccharin versus tap water) testing. The delayed swimming procedure was as effective as an immediate swimming procedure, extending the generality of the swimming-induced taste aversion, which we recently discovered with the immediate swimming procedure.
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Affiliation(s)
- Takahisa Masaki
- Department of Integrated Psychological Science, Kwansei Gakuin University, Nishinomiya 662-8501, Japan
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25
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Ebner K, Bosch OJ, Krömer SA, Singewald N, Neumann ID. Release of oxytocin in the rat central amygdala modulates stress-coping behavior and the release of excitatory amino acids. Neuropsychopharmacology 2005; 30:223-30. [PMID: 15536493 DOI: 10.1038/sj.npp.1300607] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Previous experiments have indicated that the release of oxytocin (OXT) occurs in various hypothalamic and extrahypothalamic brain areas. In the present study, we investigated in male rats whether swim stress triggers the release of OXT in the central amygdala (CeA), a key area in processing emotions and stress responses. Further, we examined the physiological significance of OXT released within the CeA for behavioral responses during forced swimming as well as effects on the local release of selected amino acids including glutamate, aspartate, arginine, taurine, and GABA, which are thought to modulate processing of emotions. Exposure to a 10-min forced swimming session caused a significant increase in OXT release (200%, p<0.01) within, but not outside, the CeA as monitored by microdialysis. Administration of the OXT receptor antagonist des-Gly-NH2d(CH2)5(Tyr(Me)2Thr4)OVT via inverse microdialysis into the amygdala before and during exposure to swimming reduced the floating time by 55% (p<0.05) and increased the swimming time by 29% (p<0.05) indicative of a more active stress-coping strategy. Simultaneously, local administration of the OXT receptor antagonist caused a significant increase in the stress-induced release of the excitatory amino acids glutamate and aspartate, whereas the basal release of these amino acids remained unchanged. Taken together, these findings demonstrate a significant activation of the oxytocinergic system in the CeA in response to swim stress. Furthermore, our data indicate that OXT receptor-mediated mechanisms within the amygdala are involved in the generation of passive stress-coping strategies, which might be mediated at least in part via its inhibitory influence on the local release of excitatory amino acids during stress.
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Affiliation(s)
- Karl Ebner
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria.
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26
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Masaki T, Nakajima S. Further evidence for conditioned taste aversion induced by forced swimming. Physiol Behav 2004; 84:9-15. [PMID: 15642601 DOI: 10.1016/j.physbeh.2004.09.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Accepted: 09/02/2004] [Indexed: 11/23/2022]
Abstract
A series of experiments with rats reported that aversion to a taste solution can be established by forced swimming in a water pool. Experiment 1 demonstrated that correlation of taste and swimming is a critical factor for this phenomenon, indicating associative (i.e., Pavlovian) nature of this learning. Experiment 2 showed that this learning obeys the Pavlovian law of strength, by displaying a positive relationship between the duration of water immersion in training and the taste aversion observed in subsequent testing. Experiment 3 revealed that swimming rather than being wet is the critical agent, because a water shower did not endow rats with taste aversion. Experiment 4 found that taste aversion was a positive function of water level of the pools in training (0, 12 or 32 cm). These results, taken together, suggest that energy expenditure caused by physical exercise might be involved in the development of taste aversion.
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Affiliation(s)
- Takahisa Masaki
- Psychology Section, Department of Integrated Psychological Science, Kwansei Gakuin University, Nishinomiya, 662-8501, Japan
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27
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Masaki T, Nakajima S. Swimming-induced taste aversion and its prevention by a prior history of swimming. LEARNING AND MOTIVATION 2004. [DOI: 10.1016/j.lmot.2004.04.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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28
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Nakajima S, Masaki T. Taste aversion learning induced by forced swimming in rats. Physiol Behav 2004; 80:623-8. [PMID: 14984795 DOI: 10.1016/j.physbeh.2003.11.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2003] [Revised: 09/16/2003] [Accepted: 11/07/2003] [Indexed: 10/26/2022]
Abstract
Two experiments demonstrated that forced swimming endowed rats with aversion to the taste solution consumed before the swimming. In Experiment 1, the rats given a trial of taste-swimming sequence drank less of the taste solution in a later test than did the rats given a taste-alone trial. The rats given a trial of taste-poisoning-swimming sequence, however, drank more of the taste solution in the testing than did the rats given a trial of taste-poisoning sequence. These results suggest that some effects of swimming (e.g., energy expenditure caused by physical exercise) induce conditioned taste aversion although they attenuate taste aversion conditioned by poisoning. The attenuation of poison-induced taste aversion by swimming has been reported in the literature, but the swimming-induced taste aversion is novel. Experiment 2, accordingly, was planned to confirm this phenomenon with a differential conditioning procedure, where one of two taste solutions was paired with swimming while the other was not. After a few repetitions of these two types of trials, the rats' intakes of these two solutions were differentiated to show that swimming has the ability to cause taste aversion.
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Affiliation(s)
- Sadahiko Nakajima
- Department of Integrated Psychological Science, Kwansei Gakuin University, Nishinomiya, Hyogo 662-8501, Japan.
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29
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Sampaio-Barros MM, Farias-Silva E, Grassi-Kassisse DM, Spadari-Bratfisch RC. Effect of swimming session duration and repetition on metabolic markers in rats. Stress 2003; 6:127-32. [PMID: 12775332 DOI: 10.1080/1025389031000110169] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The aim of this study was to investigate the profile of metabolites in male rats subjected to 50-60 min of swimming on three protocols: group A, a single 50 min swimming session; group B, one session a day for three days (5 min on day 1, 15 min on day 2 and 30 min on day 3); and group C, one session a day for 5 days, with increasing duration from 5 min on day 1, 15, 30, 45 and 60 min on consecutive days. The interval between sessions was 24 h. Measurements were made after the last swimming session. Controls did not swim. The glycogen content of liver and gastrocnemius and soleus muscle was depleted in the three groups that swam, but blood glucose concentration was significantly increased only in group B. Serum lactate concentrations were greater than the controls in groups A and B. There were significant increases in serum free fatty acid concentrations in all groups that swam. The increases in plasma free fatty acids may have resulted from lipolysis stimulated by endogenous catecholamines in groups A and C, since basal lipolysis measured in vitro was unchanged by swimming. The large increase in basal lipolysis in group B may have contributed to the rise in plasma free fatty acids. Adipocytes from rats in groups A and B were supersensitive to epinephrine, whereas those from group C were not. We conclude that the metabolic alterations were less pronounced after the last of five swimming sessions over 5 days than after a single session, even though session duration and the contribution of the physical component were similar. Glucose mobilization, but probably not utilization, was similar in the three groups that swam. The mechanisms of lipid mobilization from adipose tissue differed, depending on the stress paradigm. The metabolic changes in groups A and B indicated that three daily swimming sessions were insufficient to cause adaptation. The results contrast with previous findings for foot-shock stress, which leads to sensitization rather than adaptation in response to repeated stimuli.
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Affiliation(s)
- M M Sampaio-Barros
- Laboratório de Estudo do Estress, Departamento de Fisiologia e Biofísica, Instituto de Biologia, Universidade Estadual de Campinas, SP, Brazil
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30
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Neumann ID. Involvement of the brain oxytocin system in stress coping: interactions with the hypothalamo-pituitary-adrenal axis. PROGRESS IN BRAIN RESEARCH 2002; 139:147-62. [PMID: 12436933 DOI: 10.1016/s0079-6123(02)39014-9] [Citation(s) in RCA: 263] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
In response to various ethologically relevant stressors, oxytocin is released not only from neurohypophysial terminals into the blood, but also within distinct brain regions, for example the hypothalamic supraoptic and paraventricular nuclei, the septum and the amygdala in dependence on the quality and intensity of the stressor. Thus, oxytocin secretory activity may accompany the response of the hypothalamo-pituitary-adrenal (HPA) axis to a given stressor. In the present chapter, I try to summarize our efforts to reveal the physiological significance of intracerebrally released oxytocin in rats with respect to the regulation of the HPA axis under basal and stress conditions as well as with respect to behavioural stress responses. The effects of oxytocin appear to depend on the brain region studied and the state of activity of the animal (basal versus stress). In order to reveal interactions between the oxytocin system and the HPA axis, preliminary results are presented pointing towards a differential action of glucocorticoids on intracerebral and peripheral oxytocin release.
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Affiliation(s)
- Inga D Neumann
- Institute of Zoology, University of Regensburg, 93040 Regensburg, Germany.
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Wigger A, Neumann ID. Endogenous opioid regulation of stress-induced oxytocin release within the hypothalamic paraventricular nucleus is reversed in late pregnancy: a microdialysis study. Neuroscience 2002; 112:121-9. [PMID: 12044477 DOI: 10.1016/s0306-4522(02)00068-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Oxytocin secretion into blood in response to swim stress is differentially regulated by endogenous opioids in virgin and pregnant rats. Here, the influence of endogenous opioids on oxytocin release within the hypothalamic paraventricular and supraoptic nuclei was investigated using microdialysis in virgin and pregnant (day 19-21) rats. Rats fitted with a U-shaped microdialysis probe 3 days before testing were injected with naloxone (5 mg/kg body weight, s.c.) or vehicle (sterile saline) and, 3 min later, were forced to swim (10 min at 19 degrees C). Within the paraventricular nucleus, basal and stimulated oxytocin release did not significantly differ between vehicle-treated virgin and pregnant rats. After naloxone, local oxytocin release in response to swimming was lowered in virgin rats (P<0.01), whereas it was further increased in pregnant rats (P<0.01). Within the supraoptic nucleus, basal oxytocin release was significantly lower in pregnant compared to virgin rats (P<0.01). Forced swimming induced a similar rise in intranuclear oxytocin release in both vehicle-treated virgin and pregnant rats, but peak levels were still higher in the virgin controls. In contrast to the paraventricular nucleus, naloxone did not alter swim-induced oxytocin release within the supraoptic nucleus either in virgin or pregnant rats. Vasopressin release in the paraventricular nucleus was also increased by forced swimming but there was no effect of pregnancy or naloxone on it. In summary, in pregnancy, basal and stress-induced oxytocin release within the paraventricular nucleus was not changed, whereas it was blunted within the supraoptic nucleus. Further, within the paraventricular nucleus the excitatory effect of endogenous opioids on local oxytocin release seen in virgins was switched into an inhibitory action in pregnancy. In contrast, endogenous opioids were evidently not involved in the regulation of swim-induced oxytocin release within the supraoptic nucleus either in virgin or pregnant rats. Thus, pregnancy-related neuroendocrine plasticity also includes site-specific functional alterations in opioid receptor-mediated actions in the hypothalamus.
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Affiliation(s)
- A Wigger
- Max Planck Institute of Psychiatry, Kraepelinstrasse 2, 80804 Munich, Germany
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Sillaber I, Rammes G, Zimmermann S, Mahal B, Zieglgänsberger W, Wurst W, Holsboer F, Spanagel R. Enhanced and delayed stress-induced alcohol drinking in mice lacking functional CRH1 receptors. Science 2002; 296:931-3. [PMID: 11988580 DOI: 10.1126/science.1069836] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
There is a relation between stress and alcohol drinking. We show that the corticotropin-releasing hormone (CRH) system that mediates endocrine and behavioral responses to stress plays a role in the control of long-term alcohol drinking. In mice lacking a functional CRH1 receptor, stress leads to enhanced and progressively increasing alcohol intake. The effect of repeated stress on alcohol drinking behavior appeared with a delay and persisted throughout life. It was associated with an up-regulation of the N-methyl-d-aspartate receptor subunit NR2B. Alterations in the CRH1 receptor gene and adaptional changes in NR2B subunits may constitute a genetic risk factor for stress-induced alcohol drinking and alcoholism.
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Affiliation(s)
- Inge Sillaber
- Max Planck Institute of Psychiatry, Kraepelinstrasse 2-10, 80804 Munich, Germany.
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Torner L, Toschi N, Nava G, Clapp C, Neumann ID. Increased hypothalamic expression of prolactin in lactation: involvement in behavioural and neuroendocrine stress responses. Eur J Neurosci 2002; 15:1381-9. [PMID: 11994132 DOI: 10.1046/j.1460-9568.2002.01965.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Prolactin (PRL) has recently been shown to exert an anxiolytic effect in male and virgin female rats, as well as an inhibitory tone on hypothalamic-pituitary-adrenal (HPA) axis activity. Reduced emotional and neuroendocrine stress responses have been described in lactation, a time of high blood PRL levels. Here we tested brain PRL-receptor (PRL-R)-mediated effects on anxiety, maternal behaviour, HPA axis and oxytocin stress responses in lactating rats. Chronic intracerebroventricular (i.c.v.) infusion of antisense oligonucleotides against the long form of the PRL-R (AS; osmotic minipump, 0.5 microg/0.5 microL/h) in order to downregulate brain PRL-R expression increased the anxiety-related behaviour on the elevated plus maze (P < 0.01) compared with mixed bases- and vehicle-treated rats. Also, PRL-R AS treatment impaired maternal behaviour (P < 0.05), whereas physiological parameters of lactation (weight gain of the litter, number of milk ejection reflexes during a 20-min suckling period) were not affected. PRL-R AS treatment further evoked an increase (P < 0.05) in the stress-induced adrenocorticotropin release, demonstrating an inhibitory role of PRL on HPA axis responses in lactation. Inhibition of stress responses of the oxytocin system by brain PRL was evidenced by higher stress-induced (P < 0.05) plasma oxytocin concentration in PRL-R AS-treated lactating rats and, in contrast, decreased stress-induced oxytocin release (P < 0.01) in chronic i.c.v. ovine PRL-treated (1 microg/0.5 microL/h) virgin rats. Finally, an increased expression of the hypothalamic PRL gene was seen by RT-PCR in pregnancy and lactation, suggesting an activated state of the brain PRL system during the peripartum period. In summary, activation of the brain PRL system in the peripartum period significantly contributes to emotional and neuroendocrine adaptations, including downregulation of the responsiveness of the HPA axis and oxytocin systems to stressors seen at this time.
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MESH Headings
- Adrenocorticotropic Hormone/metabolism
- Animals
- Animals, Newborn
- Anxiety/chemically induced
- Anxiety/metabolism
- Anxiety/physiopathology
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Down-Regulation/drug effects
- Down-Regulation/physiology
- Female
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/physiology
- Hypothalamo-Hypophyseal System/drug effects
- Hypothalamo-Hypophyseal System/metabolism
- Lactation/metabolism
- Male
- Maternal Behavior/drug effects
- Maternal Behavior/physiology
- Oligonucleotides, Antisense/pharmacology
- Oxytocin/blood
- Oxytocin/metabolism
- Pregnancy
- Prolactin/genetics
- Prolactin/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Receptors, Prolactin/antagonists & inhibitors
- Receptors, Prolactin/metabolism
- Stress, Physiological/metabolism
- Stress, Physiological/physiopathology
- Up-Regulation/drug effects
- Up-Regulation/physiology
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Affiliation(s)
- Luz Torner
- Institute of Zoology, University of Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany.
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Anxiolytic and anti-stress effects of brain prolactin: improved efficacy of antisense targeting of the prolactin receptor by molecular modeling. J Neurosci 2001. [PMID: 11312305 DOI: 10.1523/jneurosci.21-09-03207.2001] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We provide the first evidence that prolactin is a neuromodulator of behavioral and neuroendocrine stress coping in the rat. In virgin female and male rats, intracerebral infusion of ovine prolactin (oPRL) into the lateral cerebral ventricle (intracerebroventricular) exerted an anxiolytic effect on the elevated plus-maze in a dose-dependent manner (0.1 and 1.0 microg/5 microl; p < 0.01). In contrast, downregulation of the expression of the long form of brain prolactin receptors by chronic intracerebroventricular infusion of an antisense oligodeoxynucleotide (ODN) (osmotic minipump, 0.5 microg. 0.5 microl(-1). hr(-1); 5 d) increased anxiety-related behavior on the plus-maze compared with mixed bases-treated and vehicle-treated rats (p < 0.01), again demonstrating an anxiolytic effect of PRL acting at brain level. Furthermore, in jugular vein-catheterized female rats, the stress-induced increase of corticotropin secretion was decreased after chronic intracerebroventricular infusion of oPRL (osmotic minipump, 1.0 microg. 0.5 microl(-1). hr(-1); p < 0.05) and, in contrast, was further elevated by antisense targeting of the brain prolactin receptors (p < 0.01). This provides evidence for a receptor-mediated attenuation of the responsiveness of the hypothalamo-pituitary-adrenal (HPA) axis by prolactin. The antisense ODN sequence was selected on the basis of secondary structure molecular modeling of the target mRNA to improve antisense ODN-mRNA hybridization. Receptor autoradiography confirmed the expected improvement in the efficacy of downregulation of prolactin receptor expression [empirically designed antisense, 30%; p > 0.05, not significant; adjustment of target position after mRNA modeling, 72%; p < 0.05). Taken together, prolactin acting at brain level has to be considered as a novel regulator of both emotionality and HPA axis reactivity.
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Neumann ID, Krömer SA, Toschi N, Ebner K. Brain oxytocin inhibits the (re)activity of the hypothalamo-pituitary-adrenal axis in male rats: involvement of hypothalamic and limbic brain regions. REGULATORY PEPTIDES 2000; 96:31-8. [PMID: 11102649 DOI: 10.1016/s0167-0115(00)00197-x] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In response to various stressors, oxytocin is released not only into blood, but also within hypothalamic and extrahypothalamic limbic brain regions. Here, we describe the involvement of intracerebrally released oxytocin in the regulation of the activity of the hypothalamo-pituitary-adrenal (HPA) axis by infusion of the oxytocin receptor antagonist (des Gly-NH(2) d(CH(2))(5) [Tyr(Me)(2), Thr(4)] OVT; pH 7.4; Dr. M. Manning, Toledo, OH, USA) either into the lateral cerebral ventricle (icv[0.75 microg/5 microl,]) or via retrodialysis (10 microg/ml, 3.3 microl/min, 15 min) into the hypothalamic paraventricular nuclei (PVN), the medio-lateral septum or the amygdala. Male Wistar rats fitted with a chronic jugular vein catheter and an icv guide cannula or a microdialysis probe targeting the respective brain region 4 days prior to the experiment were blood sampled under basal as well as stressful conditions. Rats were exposed to the elevated platform (emotional stressor) and/or to forced swimming (combined physical and emotional stressor). Blockade of the receptor-mediated action of endogenous oxytocin within the PVN resulted in an enhanced basal secretion of ACTH whereas, in response to forced swimming, ACTH secretion was rather reduced, indicating a tonic inhibitory effect of OXT on basal HPA axis activity, but a potentiating action under conditions of stress. Within the medio-lateral septum, antagonist treatment did not alter basal ACTH secretion, but significantly disinhibited ACTH secretion in response to the elevated platform, but not to forced swimming. Within the amygdala, no significant effects either on basal or stress-induced HPA axis activity could be found. The results indicate a differential involvement of brain oxytocin in the regulation of the HPA axis activity which depends both on the site of intracerebral oxytocin release and the stressor the animals are exposed to.
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Affiliation(s)
- I D Neumann
- Max Planck Institute of Psychiatry, Kraepelinstr. 2, D80804, Munich, Germany.
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Keck ME, Engelmann M, Müller MB, Henniger MS, Hermann B, Rupprecht R, Neumann ID, Toschi N, Landgraf R, Post A. Repetitive transcranial magnetic stimulation induces active coping strategies and attenuates the neuroendocrine stress response in rats. J Psychiatr Res 2000; 34:265-76. [PMID: 11104838 DOI: 10.1016/s0022-3956(00)00028-5] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effects of repetitive transcranial magnetic stimulation (rTMS) on various brain functions were investigated in adult male Wistar rats. The stimulation parameters were adjusted according to the results of accurate computer-assisted, magnetic resonance imaging-based reconstructions of the current density distributions induced by rTMS in the rat and human brain, ensuring comparable stimulation patterns in both cases. The animals were subjected to daily rTMS-treatment (three trains of 20 Hz; 2.5 s) for 8 weeks from the age of 4 weeks on. In the forced swim test these rats showed a more active stress coping strategy than the control rats. This was accompanied by a significantly attenuated stress-induced elevation of plasma ACTH concentrations. Pituitary changes accounting for the attenuation were ruled out by the corticotropin-releasing hormone test. Baseline concentrations of ACTH and corticosterone were indistinguishable in the two groups. No changes were found in the anxiety-related behavior of the rats on the elevated plus-maze or in behavior during the social interaction test. Accordingly, the binding characteristics of the benzodiazepine agonist [(3)H]flunitrazepam at the benzodiazepine/gamma-aminobutyric acid type A receptor complex were similar in the rTMS and control groups. In summary, chronic rTMS treatment of frontal brain regions in rats resulted in a change in coping strategy that was accompanied by an attenuated neuroendocrine response to stress, thus revealing parallels to the effects of antidepressant drug treatment.
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Affiliation(s)
- M E Keck
- Max Planck Institute of Psychiatry, Kraepelinstr. 2-10, 80804, Munich, Germany.
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Keck ME, Hatzinger M, Wotjak CT, Landgraf R, Holsboer F, Neumann ID. Ageing alters intrahypothalamic release patterns of vasopressin and oxytocin in rats. Eur J Neurosci 2000; 12:1487-94. [PMID: 10762376 DOI: 10.1046/j.1460-9568.2000.00030.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ageing process has been shown to have a profound impact on the hypothalamo-neurohypophysial system (HNS) and the hypothalamo-pituitary-adrenocortical (HPA) axis in humans as well as in rodents. Therefore, in this study, the intracerebral and peripheral release patterns of both vasopressin and oxytocin have been studied in aged male Wistar rats under basal conditions and in response to ethologically relevant stressors, using intracerebral microdialysis and chronic blood sampling techniques, respectively. Approximately a twofold higher basal release of arginine vasopressin (AVP) within the hypothalamic paraventricular nucleus (PVN), but not within the supraoptic nucleus (SON), was found in aged rats, whereas basal oxytocin (OXT) release did not differ in comparison with young rats. With increasing age the rise in intra-PVN release of both AVP and OXT was blunted in response to forced swimming. In contrast, the intra-SON release of AVP was unrelated to age. Simultaneously recorded basal secretion of both AVP and OXT from the neurohypophysis into blood was increased in aged rats, with a blunted OXT response to swim stress. Opposed to that, plasma AVP levels remained unchanged in both groups. Basal plasma levels of corticotropin (ACTH) and corticosterone were elevated in aged rats, whereas stress-elicited ACTH and corticosterone responses were indistinguishable. These results indicate age-related changes in the HNS and HPA axis with an enhanced basal activity opposed to a blunted response to stressors with increasing age. The increased basal release of AVP within the PVN suggests a role of intracerebral AVP in age-associated alterations of HPA axis regulation.
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Affiliation(s)
- M E Keck
- Max Planck Institute of Psychiatry, Kraepelinstr. 2-10, D-80804 Munich, Germany.
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Neumann ID, Torner L, Wigger A. Brain oxytocin: differential inhibition of neuroendocrine stress responses and anxiety-related behaviour in virgin, pregnant and lactating rats. Neuroscience 2000; 95:567-75. [PMID: 10658637 DOI: 10.1016/s0306-4522(99)00433-9] [Citation(s) in RCA: 271] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The involvement of brain oxytocin in the attenuated responsiveness of the hypothalamo-pituitary-adrenal axis and the oxytocin systems to external stressors found in pregnant and lactating rats has been studied, including both neuroendocrine and behavioural aspects. Intracerebroventricular infusion of an oxytocin receptor antagonist (0.75 microg/5 microl), but not of vehicle, elevated basal corticotropin and corticosterone secretion into blood of virgin female, but not of late pregnant or lactating rats. Oxytocin antagonist treatment further elevated the stress-induced (exposure to the elevated plus-maze or forced swimming) secretion of both corticotropin and corticosterone, but only in virgin and not in pregnant or lactating rats. Thus, corticotropin and corticosterone plasma concentrations remained attenuated in antagonist-treated pregnant and lactating animals. In contrast, infusion of the oxytocin antagonist significantly elevated the stress-induced secretion of oxytocin into blood in pregnant and lactating, but not in virgin, animals, indicating an autoinhibitory influence of intracerebral oxytocin on neurohypophysial oxytocin secretion induced by non-reproduction-related stimuli. Treatment with oxytocin antagonist 10 min prior to behavioural testing on the elevated plus-maze significantly reduced the anxiety-related behaviour in both pregnant and lactating rats, without exerting similar effects in virgin female rats. The results demonstrate a tonic inhibitory effect of endogenous oxytocin on corticotropin and, consequently, corticosterone secretion in virgin female rats, an effect which is absent in the peripartum period. In contrast, an anxiolytic action of endogenous oxytocin was detectable exclusively in pregnant and lactating rats. Therefore, we conclude that the actions of intracerebral oxytocin include independent effects on the responses of the hypothalamo-pituitary-adrenal axis and oxytocin systems to stressors and the anxiety-related behaviour which are modulated by the reproductive state of the animals.
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Affiliation(s)
- I D Neumann
- Max Planck Institute of Psychiatry, Munich, Germany.
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Neumann ID, Wigger A, Torner L, Holsboer F, Landgraf R. Brain oxytocin inhibits basal and stress-induced activity of the hypothalamo-pituitary-adrenal axis in male and female rats: partial action within the paraventricular nucleus. J Neuroendocrinol 2000; 12:235-43. [PMID: 10718919 DOI: 10.1046/j.1365-2826.2000.00442.x] [Citation(s) in RCA: 308] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Oxytocin is a classic reproductive neuropeptide in the female mammal, but its functions in the brain of the male have been less well studied. As stress induces intracerebral oxytocin release independently of gender, we postulated that central oxytocin may play a role in the control of stress responses. In both male and virgin female rats, oxytocin receptor blockade in the brain by intracerebral infusion of a selective oxytocin antagonist (des Gly-NH2 d(CH2)5 [Tyr(Me)2, Thr4] OVT; 0.75 microgram/5 microliter increased the activity of the hypothalamo-pituitary-adrenal (HPA) axis as indicated by a significantly enhanced basal and stress-induced (exposure to the elevated plus-maze, forced swimming) secretion of corticotropin (ACTH) and corticosterone into blood. The anxiety-related behaviour on the plus-maze was not altered by the antagonist in either males or females. Infusion of the oxytocin antagonist into the hypothalamic paraventricular nucleus by reversed microdialysis resulted in a significant increase in basal release of ACTH in both male and virgin female rats. These results demonstrate a novel, gender-independent physiological function of endogenous brain oxytocin in the regulation of neuroendocrine stress responses. Under basal conditions, the inhibition of the HPA axis occurs, at least in part, within the paraventricular nucleus.
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Affiliation(s)
- I D Neumann
- Max Planck Institute of Psychiatry, Munich, Germany.
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Wigger A, Lörscher P, Oehler I, Keck ME, Naruo T, Neumann ID. Nonresponsiveness of the rat hypothalamo-pituitary-adrenocortical axis to parturition-related events: inhibitory action of endogenous opioids. Endocrinology 1999; 140:2843-9. [PMID: 10342876 DOI: 10.1210/endo.140.6.6784] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
During the last 2 days of pregnancy in rats, basal corticosterone secretion is enhanced, although the response of the hypothalamo-pituitary-adrenocortical (HPA) axis to emotional and physical stressors is blunted, independent of the action of endogenous opioids. In this study, alterations in the reactivity of the HPA axis, which may accompany parturition-related stimuli, and the involvement of endogenous opioids were examined in chronically catheterized rats. In vehicle-treated controls (n = 9), ACTH and corticosterone secretion decreased in preparation for birth (P < 0.01) and further declined immediately after delivery of the second pup (P < 0.01), remaining low for 150 min. In contrast, in animals injected with the opiate antagonist naloxone (5 mg ml(-1) kg(-1), i.v., n = 6) after delivery of the second pup, ACTH and corticosterone release were enhanced within 20 min (ACTH, 5.0-fold; corticosterone, 2.3-fold; P < 0.01 vs. controls) and returned to control levels after 90 min. In confirmation of previous reports, oxytocin secretion into blood was elevated in control rats after the onset of parturition (P < 0.01) and was further enhanced in the naloxone group (1.4-fold, P < 0.01 vs. control). Plasma lactate concentration was increased, 30 min after the onset of delivery (1.9-fold, P < 0.01), independent of the treatment. The data indicate that parturition-related events do not trigger HPA axis hormone release because of an effective inhibition by endogenous opioids. This nonresponsiveness of the HPA axis is likely to protect the pups' well-being during birth.
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Affiliation(s)
- A Wigger
- Max Planck Institute of Psychiatry, Munich, Germany
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Wigger A, Neumann ID. Periodic maternal deprivation induces gender-dependent alterations in behavioral and neuroendocrine responses to emotional stress in adult rats. Physiol Behav 1999; 66:293-302. [PMID: 10336157 DOI: 10.1016/s0031-9384(98)00300-x] [Citation(s) in RCA: 352] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
There is evidence that stressful events during the neonatal "stress hyporesponsive period" may influence both emotional behavior and the maturation of the hypothalamic-pituitary-adrenal (HPA) axis in rats. We tested whether periodic maternal deprivation (180 min daily on postnatal days 3-10, PMD) caused chronic changes in emotional behavior and HPA axis activity in either male or female adult rats, or both. In addition, HPA secretory responses to human/rat corticotropin-releasing factor (CRH, 50 ng/kg i.v.) were determined in the adult males. In the elevated plus-maze test, adult (4-5 months of age) PMD-treated animals of both sexes displayed increased anxiety-related behavior compared to control rats. This was indicated by a reduction in the number of entries (male: 70% reduction, p < 0.01; female: 31% reduction, p < 0.01) and amount of time spent on the open arms (male: 86% reduction, p < 0.01; female: 40% reduction, NS). Neuroendocrine parameters were also altered in PMD-treated rats in a gender-dependent manner. Whereas basal plasma adrenocorticotropin (ACTH) and corticosterone levels did not differ significantly between PMD and control groups of either sex, the ACTH response to elevated plus-maze exposure, a predominantly emotional stressor, was higher in male (p < 0.01), but not female, PMD animals than in the respective controls. In contrast, PMD had no effect on behavioral (duration of struggling) or HPA axis responses to forced swimming (90 s, 19 degrees C), a complex and predominantly physical stressor, in either male or female rats. In response to CRH stimulation, PMD-treated males did not show differences in the ACTH secretion compared to controls, indicating alterations in HPA axis regulation at a suprapituitary level. Thus, PMD caused long-term changes in the emotional behavior of adult rats of both sexes, although to a differing degree in males and females, whereas it appeared to cause predominantly alterations in the HPA axis response in males, depending on the characteristics of the stressor used.
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Affiliation(s)
- A Wigger
- Max Planck Institute of Psychiatry, Munich, Germany
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Barros HM, Ferigolo M. Ethopharmacology of imipramine in the forced-swimming test: gender differences. Neurosci Biobehav Rev 1999; 23:279-86. [PMID: 9884121 DOI: 10.1016/s0149-7634(98)00029-3] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Most of the pre-clinical tests used to assay the efficacy of prospective new agents are done with male experimental animals. In this case, a large part of the population is disregarded as is the interaction of the new agent's effects with female hormonal fluctuations. The present study reviews the technical procedures characteristic for the forced-swimming test and the behavioral outcome induced by the testing procedure in males. It also compares the anti-immobility effects of the classic antidepressant imipramine (IMI) in male and female rats using a detailed behavioral scoring. Female rats had vaginal smears done before the beginning of the behavioral testing and were administered with three doses 24 h, 5 h and 1 h before the retest, as were male rats. Tests were videotape-recorded for analysis of the frequency and duration of the behaviors during forced-swimming. Male rats spend around 50% of the time immobile during the retest. There was a significant, dose-dependent decrease in immobility duration and a decrease in head-shakes of male rats treated with IMI. Both active behaviors of climbing and swimming were equally enhanced by the tricyclic antidepressant, climbing behavior comprising 75% of the mobile behaviors. Females showed much lower immobility duration and head-shake frequency during the forced-swimming than males and spent longer periods in mobile behaviors. Imipramine only decreases immobility frequency and head-shakes of females, and increases the escape-type behavior of climbing, decreasing swimming in the middle of the tank. This effect is more noticeable during estrus and proestrus. These results demonstrate the main behavioral differences between males and females in the forced-swimming test. It also elucidates that the effects of imipramine are measurable in males using the duration of the behaviors, while the frequencies of behaviors are modified in females treated with imipramine.
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Affiliation(s)
- H M Barros
- Division of Pharmacology, Federal Faculty of Medical Sciences of Porto Alegre, RS, Brazil
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Zuri I, Gottreich A, Terkel J. Social stress in neighboring and encountering blind mole-rats (Spalax ehrenbergi). Physiol Behav 1998; 64:611-20. [PMID: 9817571 DOI: 10.1016/s0031-9384(98)00085-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Blind mole-rats (Spalax ehrenbergi) are solitary aggressive subterranean rodents. They inhabit individual territories, comprised of branched tunnels. Each such tunnel system is completely separate from that of any neighboring mole-rat. Although intraspecific encounters between neighbors are infrequent, when they do occur, they may result in the injury or death of one or both animals. Avoidance of encounters may be due to the awareness of a neighbor's whereabouts through scent-marking and/or seismic (vibratory) communication. The present study was intended to examine whether encounters between individual mole-rats result in physiological stress. Two experimental conditions were designed to simulate natural situations: a brief encounter between two neighboring mole-rats, taking place either once or several times and long-term residency of neighbors whose only contact was either vibratory or vibratory plus odor communication. Blood samples were taken before, during, and after encounters in the first experiment and at set intervals in the second. The blood variables measured were blood glucose levels (BGL) and neutrophil/lymphocyte ratio (N/L). Blood glucose levels and neutrophil/lymphocyte ratio ratios increased in both members of encountering pairs. Long-term residency with a neighbor resulted in the establishment of a dominant-subordinate relationship through vibratory communication only, with increased neutrophil/lymphocyte ratio ratio in the subordinate males. However, long-term residency of males exposed to both vibrations and odors of neighboring males resulted in the death of both individuals. It seems that brief direct encounters and long-term neighboring conditions without physical contact are sufficient to cause severe stress to mole-rats. It is possible that in the wild, in some situations in which neighboring mole-rats cannot avoid constant exposure to each other's vibratory and odor signals, the consequent extensive stress may result in death.
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Affiliation(s)
- I Zuri
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Israel.
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Neumann ID, Johnstone HA, Hatzinger M, Liebsch G, Shipston M, Russell JA, Landgraf R, Douglas AJ. Attenuated neuroendocrine responses to emotional and physical stressors in pregnant rats involve adenohypophysial changes. J Physiol 1998; 508 ( Pt 1):289-300. [PMID: 9490853 PMCID: PMC2230858 DOI: 10.1111/j.1469-7793.1998.289br.x] [Citation(s) in RCA: 281] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
1. The responsiveness of the rat hypothalamo-pituitary-adrenal (HPA) axis and hypothalamo-neurohypophysial system (HNS) to emotional (elevated plus-maze) and physical (forced swimming) stressors and to administration of synthetic corticotrophin-releasing hormone (CRH) was investigated during pregnancy and lactation. In addition to pregnancy-related adaptations at the adenohypophysial level, behavioural responses accompanying the neuroendocrine changes were studied. 2. Whereas basal (a.m.) plasma corticosterone, but not corticotrophin (adrenocorticotrophic hormone; ACTH), levels were increased on the last day (i.e. on day 22) of pregnancy, the stress-induced rise in both plasma hormone concentrations was increasingly attenuated with the progression of pregnancy beginning on day 15 and reaching a minimum on day 21 compared with virgin control rats. A similar attenuation of responses to both emotional and physical stressors was found in lactating rats. 3. Although the basal plasma oxytocin concentration was elevated in late pregnancy, the stress-induced rise in oxytocin secretion was slightly lower in day 21 pregnant rats. In contrast to vasopressin, oxytocin secretion was increased by forced swimming in virgin and early pregnant rats indicating a differential stress response of these neurohypophysial hormones. 4. The blunted HPA response to stressful stimuli is partly due to alterations at the level of corticotrophs in the adenohypophysis, as ACTH secretion in response to CRH in vivo (40 ng kg-1, i.v.) was reduced with the progression of pregnancy and during lactation. In vitro measurement of cAMP levels in pituitary segments demonstrated reduced basal levels of cAMP and a lower increase after CRH stimulation (10 nM, 10 min) in day 21 pregnant compared with virgin rats, further indicating reduced corticotroph responsiveness to CRH in pregnancy. 5. The reduced pituitary response to CRH in late pregnancy is likely to be a consequence of a reduction in CRH receptor binding as revealed by receptor autoradiography. [125I] CRH binding in the anterior pituitary was significantly reduced in day 11, 17 and 22 pregnant rats compared with virgin controls. 6. Anxiety-related behaviour of the animals as revealed by the time on and entries into the open arms of the elevated plus-maze was different between virgin and pregnant rats with decreased number of entries indicating increased anxiety with the progression of pregnancy (except on pregnancy day 18). The emotional behaviour, however, was not correlated with the neuroendocrine responses. 7. The results indicate that the reduced response of the HPA axis to stressors described previously during lactation is already manifested around day 15 of pregnancy in the rat and involves physiological adaptations at the adenohypophysial level. However, alterations in stressor perception at higher brain levels with the progression of pregnancy may also be involved.
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Affiliation(s)
- I D Neumann
- Max Planck Institute of Psychiatry, Munich, Germany.
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Brewer GJ. Effects of acidosis on the distribution of processing of the beta-amyloid precursor protein in cultured hippocampal neurons. MOLECULAR AND CHEMICAL NEUROPATHOLOGY 1997; 31:171-86. [PMID: 9376023 DOI: 10.1007/bf02815241] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Reported increases in brain lactate production in Alzheimer disease led us to test the hypothesis that lactic acid acidosis alters the processing of the beta-amyloid precursor protein, beta PP, in neurons. To test this proposition, embryonic rat hippocampal neurons were first cultures for 4 d in serum-free B27/neurobasal medium. Lactic acid at 0.5 and 1 mg/mL (pH 7.1 and, 6.9, respectively) caused a dose-dependent increase in cellular beta-amyloid immunoreactivity detected with antibody 4G8. Acidosis did not affect secretion of beta PP or its derivatives into the medium. The cytoplasmic production of beta PP was slightly reduced by acidosis without a differential effect on maturation or proteolytic processing. In the substrate-bound material, which was insoluble in nonionic detergent, acidosis caused increases in an N-terminal 75-kDa band, a C-terminal 72-kDa band, and potentially amyloidogenic bands at 35 and 38 kDa. Processing to the 4-kDa amyloid beta protein was not observed in these early pure rat neuronal cultures. These results suggest that mild acidosis id sufficient to alter neuronal processing to the amyloid precursor protein into potentially amyloidogenic forms and increase certain beta PP fragments bound to the substrate. If a similar process occurs in the presence of other cell types in the aging brain, acidosis may stimulate an extracellular deposition of amyloid and contribute to the pathogenesis of Alzheimer disease.
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Affiliation(s)
- G J Brewer
- Department of Medical Microbiology and Immunology, Southern Illinois University School of Medicine, Springfield 62794-1220, USA.
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Santín LJ, Begega A, Rubio S, Arias JL. Behaviour laterality in male rats: influence of practice and stress. Physiol Behav 1996; 60:161-4. [PMID: 8804657 DOI: 10.1016/0031-9384(95)02258-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
During recent decades, the existence of cerebral and behavioural asymmetries has been manifested in many different animal species. In this work, the asymmetric spatial preference recorded in the water T-maze has been analysed. Fifty-five male rats were tested in this maze for 8 consecutive days. Spatial preference, the number of times each arm was chosen, and the percentages of animals that showed right, left, or no spatial preference were calculated. The results show the evolution of this asymmetric behaviour. Most of the animals tested preferred the right arm (populational laterality). Recently, the influence of factors such as stress and practice in the process of acquiring this behaviour has been investigated. We used 40 male rats divided into two groups with two different stress levels: water temperature at 21 degrees C and 14 degrees C. Our results, based on these two criteria, hypothesize that both variables, stress and practice, are involved in the acquisition of spatial preference behaviour.
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Affiliation(s)
- L J Santín
- Laboratory of Psychobiology, Faculty of Psychology, Oviedo University, Spain
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Abel EL. Circannual changes in the duration of the immobility response of rats in the forced swim test. Physiol Behav 1995; 58:591-3. [PMID: 8587969 DOI: 10.1016/0031-9384(95)00098-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Separate groups of male rats were tested in the forced swim test on the third Tuesday of each mo for 14 mo. A distinct pattern was observable in their immobility response such that animals were most immobile during the winter months (Dec-Mar) and least immobile during the summer months (June-Sept). Bicarbonate-carbon dioxide levels were significantly correlated with immobility times (r = 0.48), as were glucose (r = 0.34) and phosphorus (r = -0.33) levels, whereas corticosterone and testosterone levels were not significantly correlated with immobility. These results indicate that there is a circannual rhythm in the floating behavior of rats in the forced swim test.
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Affiliation(s)
- E L Abel
- Department of Obstetrics and Gynecology, C.S. Mott Center for Human Growth and Development, Wayne State University, Detroit, MI, USA
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48
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Abstract
Rats were immersed for 15 min in a forced swim test in cylinders filled with water to a depth of 20 or 35 cm. The following day, they were reimmersed for a 5-min test period at one of these two depths. Water immersion, regardless of water depth, resulted in increased serum lactate and corticosterone levels, reduced serum carbon dioxide and potassium levels, a metabolic acidosis, and an increase in the phosphorus/potassium ratio. Testing at the greater water depth resulted in lower immobility times, higher lactate and lower carbon dioxide levels, a greater metabolic acidosis, and a higher phosphorus/potassium ratio than testing at the shallower depth. Water depth did not significantly affect corticosterone or potassium responses. None of the interactions between day 1 and day 2 depth was significant. The correlation between immobility time and corticosterone was very low, whereas the correlation with lactate, carbon dioxide, anion gap, and the phosphorus/potassium ratio were high. The inference from these results is water depth at time of testing affects the rat's behavioral and physiological reactions in the forced swim test and prior exposure to water at any depth does not.
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Affiliation(s)
- E L Abel
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48202
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