| 1. |
- Bakos, J., et al.
(författare)
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Oxytocin levels in the posterior pituitary and in the heart are modified by voluntary wheel running
- 2007
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Ingår i: Regulatory Peptides. - : Elsevier BV. - 1873-1686 .- 0167-0115. ; 139:1-3, s. 96-101
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Tidskriftsartikel (refereegranskat)abstract
- We hypothesized that voluntary wheel running results in increased secretion of oxytocin, a peptide involved in the stress response. An additional hypothesis was that prolonged exercise affects oxytocin levels in the heart, which is in line with the potential role of oxytocin in cardiovascular functions. Voluntary wheel running lasted 3 weeks and daily running distances increased progressively reaching maximum levels about 8 km (Sprague-Dawley rats) and 4 km (Lewis strain). The exercise resulted in significant reduction of epididymal fat, slight increase in glucose transporter GLUT4 mRNA levels and significant enhancement of plasma density. Voluntary exercise failed to influence plasma oxytocin levels either in Lewis or Sprague-Dawley rats, but it resulted in a significant decrease of oxytocin concentrations in the posterior pituitary. Plasma oxytocin concentrations were not modified even if the measurements were made in the dark phase of the day. In voluntary wheel running Sprague-Dawley rats, the content of oxytocin in the right heart atrium was lower than in controls. Thus, the present findings demonstrate that prolonged voluntary wheel running results in a decrease in pituitary oxytocin content without evident changes in hormone concentrations in peripheral blood. However, prolonged exercise used has a significant impact on oxytocin levels in the heart. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Makatsori, A, et al.
(författare)
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Voluntary wheel running modulates glutamate receptor subunit gene expression and stress hormone release in Lewis rats
- 2003
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Ingår i: Psychoneuroendocrinology. - 1873-3360. ; 28:5, s. 702-714
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Tidskriftsartikel (refereegranskat)abstract
- Lewis rats that are known to be addiction-prone, develop compulsive running if they have access to running wheels. The present experiments were aimed 1) to evaluate the activation of stress systems following chronic and acute voluntary wheel running in Lewis rats by measurement of hormone release and gene expression of neuropeptides related to hypothalamic-pituitary-adrenocortical (HPA) axis activity and 2) to test the hypothesis that wheel running as a combined model of addictive behavior and stress exposure is associated with modulation of ionotropic glutamate receptor subunits in the ventral tegmental area. Voluntary running for three weeks but not for one night resulted in a rise in plasma corticosterone and adrenocorticotropic hormone (ACTH) levels (p < 0.05) compared to those in control rats. Principal component analysis revealed the relation between POW gene expression in the intermediate pituitary and running rate. Acute exposure of animals to voluntary wheel running induced a significant decrease in alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor GluR1 subunit mRNA levels (p < 0.01), while repeated voluntary physical activity increased levels of GluR1 mRNA in the ventral tegmentum (P < 0.05). Neither acute nor chronic wheel running influenced N-methyl-D-aspartate (NMDA) receptor subunit NR1 mRNA levels in the ventral tegmental area. Thus, the present study revealed changes in AMPA receptor subunit gene expression in a reward-related brain structure as well as an activation of HPA axis in response to compulsive wheel running in Lewis rats. It may be suggested that hormones of HPA axis and glutamate receptors belong to the factors that substantiate higher vulnerability to addictive behavior. (C) 2003 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Mlynarik, M, et al.
(författare)
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Enriched environment influences adrenocortical response to immune challenge and glutamate receptor gene expression in rat hippocampus
- 2004
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Ingår i: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923 .- 1749-6632. ; 1018, s. 273-280
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Tidskriftsartikel (refereegranskat)abstract
- Housing of animals in an enriched environment (EE) has many positive effects on brain structure and function and can facilitate recovery from various brain injuries. The purpose of this study was to evaluate whether enriched rearing could alter the stress response induced by repeated immune challenge and to investigate the influence of EE and immune challenge on glutamate receptor gene expression in the hippocampus. Male 2-mo-old Wistar rats were kept under standard conditions (SC) or in an EE for 5 weeks. Immune challenge was performed by Escherichia coli lipopolysaccharide (LPS) injected repeatedly (ip) in increasing doses (10, 20, and 40 mug/kg/mL) once daily for five consecutive days. The animals were decapitated 2 h after the last injection. Blood samples, adrenals, and hippocampi were collected. LPS induced an increase in plasma and adrenal levels of corticosterone and a transient decrease in body weight of animals kept under SC, but not in an EE. Enriched housing resulted in an increase in adrenal weights and enhanced gene expression of hippocampal AMPA GluR1 receptor subunit. Concerning the LPS treatment, no effects on adrenal and thymus weights and glutamate receptor mRNA levels in the hippocampus were noticed. Thus, vulnerability to some negative effects of repeated immune challenge may be modified by environmental conditions associated with changes in brain plasticity. The fact that differences in housing conditions change stress response has to be considered in biomedical research.
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| 4. |
- Moncek, F, et al.
(författare)
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Effect of environmental enrichment on stress related systems in rats
- 2004
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Ingår i: Journal of Neuroendocrinology. - : Wiley. - 0953-8194 .- 1365-2826. ; 16:5, s. 423-431
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to test whether environmental enrichment alters the status and responsiveness of pituitary-adrenocortical and sympathetic-adrenomedullary hormones in rats. Previous studies have shown that rats kept in an enriched environment differ from those kept in standard cages in dendritic branching, synaptogenesis, memory function, emotionality and behaviour. In male Wistar rats kept in an enriched environment for 40 days, we studied basal concentrations of hormones, endocrine responses to 5-HT1A challenge and responsiveness and adaptation to repeated handling. Environmental enrichment consisted of large plexiglass cages with 10 rats per cage, which contained variety of objects exchanged three times a week. Rats kept in this enriched environment had higher resting plasma concentrations of corticosterone, larger adrenals and increased corticosterone release to buspirone challenge compared to controls. Lower adrenocorticotropic hormone, corticosterone and adrenaline responses to handling were noticed in rats kept in an enriched environment. Exposure to repeated handling led to a more rapid extinction of corticosterone responses in rats kept in an enriched environment. Thus, environmental enrichment leads to pronounced changes in neuroendocrine regulation, including larger adrenals and increased adrenocortical function, which are so far considered to be indication of chronic stress.
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| 5. |
- Schwendt, M, et al.
(författare)
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Involvement of glutamate neurotransmission in the development of excessive wheel running in Lewis rats
- 2003
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Ingår i: Neurochemical Research. - 1573-6903. ; 28:3-4, s. 653-657
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Tidskriftsartikel (refereegranskat)abstract
- Physical activities such as long-distance running can form a habit and might be related to drug-induced addictive behaviors. We investigated possible modulations of N-methyl-D-aspartate (NMDA) receptor subunits during voluntary wheel running in brain regions implicated in reward and addiction. It was observed that Lewis rats progressively increased their amount of daily running, reaching maximum levels of 4-6 km/day. After 3 weeks of running, mRNA levels coding for NR2A and NR2B subunits were increased in the ventral tegmental area, while only NR2A mRNA levels were found to be elevated in the frontal cortex. Long-term wheel running was also associated with increased binding of specific NMDA receptor antagonist [H-3]CGP39653 in the frontal cortex. Moreover, pharmacological inhibition of glutamate release by repeated administration of phenytoin (20 mg/kg IP for 21 days) significantly suppressed daily running. These results suggest that glutamatergic neurotransmission might be related to neurobiological mechanisms underlying the compulsive character of voluntary wheel running.
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