Navegando por Palavras-chave "acute stress"

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    Acute stressor-selective effect on total plasma homocysteine concentration in rats
    (Elsevier B.V., 2004-02-01) Oliveira, A. C. de; Suchecki, D.; Cohen, S.; D'Almeida, V; Universidade Federal de São Paulo (UNIFESP)
    Stress produces several physiological and behavioral alterations that increase cardiovascular morbidity and mortality. Nonetheless, there is a dearth of studies that have evaluated the effects of stress on total plasma homocysteine, an important amino acid associated with cardiovascular disease. We used four distinct acute stressors in rats, i.e., swimming, restrain, novelty and cold exposure, in order to examine whether any acute effect on total plasma homocysteine concentrations would occur. Plasma corticosterone and adrenocorticotropic hormone concentrations were also measured to demonstrate the ability of the chosen manipulations to activate the hypothalamic-pituitary-adrenal (HPA) axis. Three of the four stressors activated the HPA axis and only restrain affected total plasma homocysteine concentrations ( +37%, P=.006) compared with the control group. the complexity of the physiological responses to stress, the peculiarities of stress responses and the intricate regulatory systems involved in homocysteine metabolism must be taken into account in order to clarify the increasing effect of restrain (mainly a psychological stressor) on total plasma homocysteine concentrations in rats and to evaluate its meaning in human pathology. (C) 2003 Elsevier Inc. All rights reserved.
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    Acute stressor-selective effects on homocysteine metabolism and oxidative stress parameters in female rats
    (Elsevier B.V., 2006-10-01) Souza, Femanda G. de; Rodrigues, Mayra D. B.; Tufik, Sergio [UNIFESP]; Nobrega, Jose N.; D'Almeida, Vania; Universidade Federal de São Paulo (UNIFESP); Ctr Addict & Mental Hlth
    Homocysteine levels are affected by diet factors such as vitamin deficiencies, non-diet factors such as genetic disorders, and stress exposure. Hyperhomocysteinemia has been implicated in several disorders, including cardiovascular disease, depression, schizophrenia, Alzheimer's and Parkinson's disease. Since sex differences play a role both in stress responses and in susceptibility to various diseases, the objective of this study was to evaluate possible alterations in homocysteine metabolism including cysteine, folate, and vitamin 136, and oxidative stress markers in female rats exposed to different types of acute stress. Female rats were randomly distributed into eight groups according to stress manipulation (restraint, swimming, cold and control) and estrous cycle (diestrus and estrus). in general no significant differences were seen between rats in estrus and diestrus. Restraint stress was the only type of stress that altered homocysteine concentrations (+33% relative to controls). An increase in levels of thiobarbituric acid reactive substances (TBARS) and a decrease in total glutathione (GSHt) concentration were also observed in animals subjected to restraint and swimming stress, suggesting the possibility of oxidative damage. Thus, both the homocysteine results and the oxidative stress data indicated that restraint stress was the most powerful stress manipulation in female rats, as previously observed in male rats.These findings indicate that hormonal and gonadal differences do not interfere with stress responses related to homocysteine metabolism and suggest that putative gender-related differences in homocysteine responses are probably not involved in the differential prevalence of some diseases in human males and females. (c) 2006 Elsevier Inc. All rights reserved.
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    Differential effects of acute cold and footshock on the sleep of rats
    (Elsevier B.V., 2000-04-07) Palma, B. D.; Suchecki, D.; Tufik, S.; Universidade Federal de São Paulo (UNIFESP)
    Several studies have shown that 1 h of immobilisation stress during the rat's active period results in rebound of paradoxical (PS) and slow wave sleep (SWS). Since the effects of stress on behaviour and physiological parameters vary according to the stimulus, the present study sought to examine the activation of the hypothalamic-pituitary-adrenal (HPA) axis and the sleep pattern of rats submitted to 1 h of footshock, immobilisation or cold, or 18 h of PS deprivation (PSD). Stress sessions began between 0900 and 0930 h. Immediately after the end of the stress session, or at the corresponding time for controls, animals were blood sampled for determination of ACTH and corticosterone (CORT) plasma levels. in Experiment 2, animals were implanted with electrodes for basal and post-stress polysomnographic recording (6 h long). the results showed that all stressors produced an activation of the HPA axis; however, footshock induced the largest ACTH levers, whereas cold resulted in the highest CORT levels. in regard to the sleep data, immobilisation and PSD led to a rebound of SWS (+16.87% and +9.37%, respectively) and PS (+42.45% and +55.25%, respectively). Immobilisation, however, induced an increased number of PS episodes, whereas PSD resulted in longer PS episodes. Cold stress produced an exclusive rebound of SWS (+ 14.23%) and footshock promoted sustained alertness during the animal's resting period ( + 47.18%). These results indicate that different stimuli altered the sleep pattern in a distinct manner; and these alterations might be related to the state of the HPA axis activation. (C) 2000 Published by Elsevier Science B.V. All rights reserved.