Browsing by Author "Dagnino Subiabre, Alexies"

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    Chronic stress decreases the expression of sympathetic markers in the pineal gland and increases plasma melatonin concentration in rats
    (WILEY, 2006) Dagnino Subiabre, Alexies; Orellana, Juan A.; Carmona Fontaine, Carlos; Montiel, Juan; Diaz Veliz, Gabriela; Seron Ferre, Maria; Wyneken, Ursula; Concha, Miguel L.; Aboitiz, Francisco
    Chronic stress affects brain areas involved in learning and emotional responses. Although most studies have concentrated on the effect of stress on limbic-related brain structures, in this study we investigated whether chronic stress might induce impairments in diencephalic structures associated with limbic components of the stress response. Specifically, we analyzed the effect of chronic immobilization stress on the expression of sympathetic markers in the rat epithalamic pineal gland by immunohistochemistry and western blot, whereas the plasma melatonin concentration was determined by radioimmunoassay. We found that chronic stress decreased the expression of three sympathetic markers in the pineal gland, tyrosine hydroxylase, the p75 neurotrophin receptor and alpha-tubulin, while the same treatment did not affect the expression of the non-specific sympathetic markers Erk1 and Erk2, and glyceraldehyde-3-phosphate dehydrogenase. Furthermore, these results were correlated with a significant increase in plasma melatonin concentration in stressed rats when compared with control animals. Our findings indicate that stress may impair pineal sympathetic inputs, leading to an abnormal melatonin release that may contribute to environmental maladaptation. In addition, we propose that the pineal gland is a target of glucocorticoid damage during stress.
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    Chronic stress induces dendritic atrophy in the rat medial geniculate nucleus: Effects on auditory conditioning
    (ELSEVIER, 2009) Dagnino Subiabre, Alexies; Munoz Llancao, Pablo; Terreros, Gonzalo; Wyneken, Ursula; Diaz Veliz, Gabriela; Porter, Benjamin; Kilgard, Michael P.; Atzori, Marco; Aboitiz, Francisco
    Chronic stress induces dendritic atrophy in the inferior colliculus (IC, auditory mesencephalon) and impairs auditory avoidance conditioning. The aim of this study was to determine in Golgi preparations and in cued fear conditioning whether stress affects other auditory components, like the thalamic medial geniculate nucleus (MG) or the posterior thalamic nucleus (PO), in Sprague-Dawley rats. Chronic restraint stress produced a significant dendritic atrophy in the MG (stress: 407 +/- 55 mu m; control: 808 +/- 120 mu m; p < 0.01) but did not affect auditory fear conditioning. The last result was in apparent contrast with the fact that stress impairs both the acquisition of auditory avoidance conditioned responses and the dendritic structure in two major nuclei of the auditory system. In order to analyze this disagreement, we investigated whether the stress-related freezing to tone occurring in the fear conditioning protocol corresponded to a conditioned or an unconditioned fear response, using changes in tone instead of light throughout conditioning trials. Chronic stress significantly enhanced visual fear conditioning in stressed animals compared to controls (stress: 58.9 +/- 8.42%, control: 23.31 +/- 8.01%; p < 0.05), but this fear enhancement was related to unconditioned fear. Conversely, chronic stress did not affect the morphology of the PO (subserving both auditory and somatosensory information) or the corresponding auditory and somatosensory unconditioned responses (acoustic startle response and escape behavior). Our results suggest that the auditory conditioned stimulus can be processed in part independently of the IC and MG in the stressed animals, and sent to the amygdala via the PO inducing unconditioned fear. Comparable alterations could be produced in major depression. (C) 2009 Elsevier B.V. All rights reserved.
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    Chronic stress induces upregulation of brain-derived neurotrophic factor (BDNF) rnRNA and integrin alpha 5 expression in the rat pineal gland
    (ELSEVIER SCIENCE BV, 2006) Dagnino Subiabre, Alexies; Zepeda Carreno, Rodrigo; Diaz Veliz, Gabriela; Mora, Sergio; Aboitiz, Francisco
    Chronic stress affects brain areas involved in learning and emotional responses. These alterations have been related with the development of cognitive deficits in major depression. Moreover, stress induces deleterious actions on the epithalamic pineal organ, a gland involved in a wide range of physiological functions. The aim of this study was to investigate whether the stress effects on the pineal gland are related with changes in the expression of neurotrophic factors and cell adhesion molecules. Using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, we analyzed the effect of chronic immobilization stress on the BDNF mRNA and integrin alpha 5 expression in the rat pineal gland. We found that BDNF is produced in situ in the pineal gland. Chronic immobilization stress induced upregulation of BDNF mRNA and integrin alpha 5 expression in the rat pineal gland but did not produce changes in beta-actin mRNA or in GAPDH expression. Stressed animals also evidenced an increase in anxiety-like behavior and acute gastric lesions. These results suggest that BDNF and integrin a5 may have a counteracting effect to the deleterious actions of immobilization stress on functionally stimulated pinealocytes. Furthermore, this study proposes that the pineal gland may be a target of glucocorticoid damage during stress. (c) 2006 Elsevier B.V. All rights reserved.
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    Effect of the Environment on the Dendritic Morphology of the Rat Auditory Cortex
    (2010) Bose, Mitali; Muñoz Llancao, Pablo; Roychowdhury, Swagata; Nichols, Justin A.; Jakkamsetti, Vikram; Porter, Benjamin; Byrapureddy, Rajasekhar; Salgado, Humberto; Kilgard, Michael P.; Aboitiz, Francisco; Dagnino Subiabre, Alexies; Atzori, Marco