Resumo

PAULI, J. Rodrigo et al. Influence of physical training on hypothalamo-pituitary-adrenal axis parameters of rates administered with dexametasone. Rev. Port. Cien. Desp. [online]. 2005, vol.5, n.2, pp.142-152. ISSN 1645-0523.

The aim of present study was to investigate the influence of acute and chronic physical exercise on the hypothalamo-pituitary-adrenal axis in Wistar rats administered with dexamethasone. Young Wistar rats were divided into four groups: sedentary control (CS), sedentary dexamethasone (DxS), trained control (CT) and trained dexamethasone (DxT). Training protocol consisted of swimming 1h/day, 5 days/week, during 10 weeks, supporting a load of 5% of their body weight. Dexamethasone was administered 5 times for week (2µg/day in 150µl 0,9% NaCl). Before sacrifying the rats each received a subcutaneous insulin to calculate the maximum decreased in blood glucose. Venous blood samples were obtained at the end of the experimental period to determine serum glucose and ACTH. Gastrocnemius, adrenal and adipose epididimal tissues’ samples were used to determine weight, glycogen and ascorbic acid concentration, respectively. Data suggests that chronic exposure to dexamethasone was associated with decreased insulin sensitivity. The dexametasona treatment decreased ACTH release in response to acute exercise, showing marked differences in the functioning of the CRH-ACTH-adrenal axis between groups of rats. In conclusion, exercise can override the dexamethasone negative feedback of hypothalamo-pituitary-adrenal axis activation in rats.

Palavras-chave : physical training; dexamethasone; insulin resistance; hypothalamo-pituitary-adrenal axis.

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