Elsevier

Neuroscience

Volume 192, 29 September 2011, Pages 661-674
Neuroscience

Neurodegeneration, Neuroprotection, and Disease-Oriented Neuroscience
Research Paper
Molecular aspects involved in swimming exercise training reducing anhedonia in a rat model of depression

https://doi.org/10.1016/j.neuroscience.2011.05.075Get rights and content

Abstract

Patients suffering from depression frequently display hyperactivity of the hypothalamic–pituitary–adrenal axis (HPA) resulting in elevated cortisol levels. One main symptom of this condition is anhedonia. There is evidence that exercise training can be used as a rehabilitative intervention in the treatment of depressive disorders. In this scenario, the aim of the present study was to assess the effect of an aerobic exercise training protocol on the depressive-like behavior, anhedonia, induced by repeated dexamethasone administration. The study was carried out on adult male Wistar rats randomly divided into four groups: the “control group” (C), “exercise group” (E), “dexamethasone group” (D) and the “dexamethasone plus exercise group” (DE). The exercise training consisted of swimming (1 h/d, 5 d/wk) for 3 weeks, with an overload of 5% of the rat body weight. Every day rats were injected with either dexamethasone (D/DE) or saline solution (C/E). Proper positive controls, using fluoxetine, were run in parallel. Decreased blood corticosterone levels, reduced adrenal cholesterol synthesis and adrenal weight (HPA disruption), reduced preference for sucrose consumption and increased immobility time (depressive-like behavior), marked hippocampal DNA oxidation, increased IL-10 and total brain-derived neurotrophic factor (BDNF; pro-plus mature-forms) and a severe loss of body mass characterized the dexamethasone-treated animals. Besides increasing testosterone blood concentrations, the swim training protected depressive rats from the anhedonic state, following the same profile as fluoxetine, and also from the dexamethasone-induced impaired neurochemistry. The data indicate that physical exercise could be a useful tool in preventing and treating depressive disorders.

Highlights

▶Exercise training rescue dexamethasone-exposed rats from the anhedonic behavior. ▶The exercise antidepressive effect was found at intensity below the anaerobic threshold. ▶The exercise protected depressive rats also from neurochemical alterations.

Section snippets

Animals and reagents

Male Wistar rats of 60 days of life (200–250 g) obtained from the Central Animal House of the Centre for Biological Sciences, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil, were used. The animals were maintained on a 12-h light/dark cycle in a constant temperature (22±1 °C) colony room, with free access to water and protein commercial chow (Nuvital, PR, Brazil). The experimental protocol was approved by the Ethics Committee for Animal Research (PP000420/CEUA) of the

Effect of repeated dexamethasone administration on rat body weight and blood corticosterone levels

Fig. 1A shows that the rat body weight was significantly reduced in the dexamethasone-treated groups, starting 6 days after dexamethasone administration and remaining different until the end of the treatment. Three-way ANOVA for repeated measures analysis showed significant effects for dexamethasone treatment [F=157.43; P<0.001], exercise [F=4.38; P<0.05], and days of life [F=81.81; P<0.001]. Interaction was observed between dexamethasone and days of life [F=22.94; P<0.001], and between the two

Discussion

Associated with both morbidity and mortality, depression is a major public health problem throughout the world and is characterized by lowered mood, loss of capacity to experience pleasure, increased sense of worthlessness, fatigue, and preoccupation with death and suicide (Cassano and Fava, 2002, Nestler et al., 2002, Parker et al., 2003, Moussavi et al., 2007, Chapman and Perry, 2008, Helmich et al., 2010). Emerging evidence suggests that exercise may be as effective as psychotherapy and more

Acknowledgments

This work was supported by grants from Fundação de Apoio à Pesquisa Científica e Tecnológica do Estado de Santa Catarina, Conselho Nacional de Desenvolvimento Científico e Tecnológico, and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior. Latini A and de Bem AF are CNPq fellows.

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