Effect of acute and chronic psychogenic stress on corticoadrenal and pituitary-thyroid hormones in male rats

The effects of acute and chronic stress on serum corticosterone and pituitary-thyroid hormones were studied in male Wistar rats. Acute noise activated both the pituitary-adrenal and pituitary-thyroid axes. Chronic noise did not modify the basal serum levels of either corticosterone or pituitary-thyroid hormones. A decreased corticosterone response to noise was observed in chronically stressed rats, but the pituitary-thyroid response was the same in control and chronically stressed rats, suggesting that the mechanisms which control the responsiveness of both axes to a repeated stimulus are dissociated.