Cytoskeletal protein translation and expression in the rat brain are stressor-dependent and region-specific.

Stress is an integral component of life that can sometimes cause a critical overload, depending on the qualitative and quantitative natures of the stressors. The involvement of actin, the predominant component of dendritic integrity, is a plausible candidate factor in stress-induced neuronal cytoskeletal changes. The major aim of this study was to compare the effects of three different stress conditions on the transcription and translation of actin-related cytoskeletal genes in the rat brain. Male Wistar rats were exposed to one or other of the frequently used models of physical stress, i.e. electric foot shock stress (EFSS), forced swimming stress (FSS), or psychosocial stress (PSS) for periods of 3, 7, 14, or 21 days. The relative mRNA and protein expressions of β-actin, cofilin and mitogen-activated protein kinase 1 (MAPK-1) were determined by qRT- PCR and western blotting from hippocampus and frontal cortex samples. Stressor-specific alterations in both β-actin and cofilin expression levels were seen after stress. These alterations were most pronounced in response to EFSS, and exhibited a U-shaped time course. FSS led to a significant β-actin mRNA expression elevation in the hippocampus and the frontal cortex after 3 and 7 days, respectively, without any subsequent change. PSS did not cause any change in β-actin or cofilin mRNA or protein expression in the examined brain regions. EFSS, FSS and PSS had no effect on the expression of MAPK-1 mRNA at any tested time point. These findings indicate a very delicate, stress type-dependent regulation of neuronal cytoskeletal components in the rat hippocampus and frontal cortex

Stress type-dependent alterations of the weights of the adrenal glands and thymus.

<p>Effects of electric foot shock stress (EFSS), forced swimming stress (FSS) and psychosocial stress (PSS) on the weights of the adrenal glands (<b>A</b>) and the thymus (<b>B</b>) of rats, measured every 7 days. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073504#s3" target="_blank">Results</a> are expressed as percentages of the control (unstressed rats). Values for each group are means ± SEM, n = 6–10. *<i>p</i><0.05 and **<i>p</i><0.01: significant differences as compared to the control.</p

Stress type-dependent transcriptional alterations.

<p>Effects of electric foot shock stress (EFSS), forced swimming stress (FSS) and psychosocial stress (PSS) on the expressions of β-actin (<b>A, B</b>), cofilin (<b>C, D</b>) and MAPK-1 (<b>E, F</b>) mRNA in the rat hippocampus and frontal cortex. GAPDH was used as reference gene. Values for each group are means ± SEM, n = 6–10. *<i>p</i><0.05 and **<i>p</i><0.01: significant differences as compared to the control.</p

Stress type-dependent body weight alterations.

<p>Effects of electric foot shock stress (EFSS) (<b>A</b>), forced swimming stress (FSS) (<b>B</b>) and psychosocial stress (PSS) (<b>C</b>) on the overall body weight of rats, measured on days 3, 7, 14 and 21. Values for each group are means ± SEM, n = 6–10. *<i>p</i><0.05 and **<i>p</i><0.01: significant differences as compared to the control.</p

Western blot analysis of β-actin and cofilin after different stressors in hippocampus and frontal cortex.

<p>The specific bands for β-actin and cofilin in rat hippocampus (<b>A, B</b>) and frontal cortex (<b>E, F</b>) appeared at 43 kDa and 19 kDa, respectively. Antibodies used are described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073504#s2" target="_blank">Materials and methods</a>. Semi-quantitative representations of electric foot shock stress (EFSS), forced swimming stress (FSS) and psychosocial stress (PSS) on the levels of β-actin and cofilin protein in the rat hippocampus (<b>C, D</b>) and frontal cortex (<b>G, H</b>). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0073504#s3" target="_blank">Results</a> are expressed as percentages of the control (unstressed rats). GAPDH (38 kDa) was used as reference gene. Values for each group are means ± SEM, n = 6–10. *p<0.05 and **p<0.01: significant differences as compared to the control.</p