Opioid peptide modulation of circulatory and endocrine response to mental stress in humans.

Healthy subjects were classified according to their percent increase in systolic blood pressure (SBP) after mental arithmetic test (MAT) as low (delta SBP 9.3-15.1%, n = 15) and high (delta SBP 35.1-45.4%, n = 15) responders. During MAT, low responders showed significantly (p < 0.01) increased plasma levels of beta-endorphin, cortisol, catecholamines, and atrial natriuretic factor (ANF) and decreased levels of endothelin-1, whereas high responders showed increased (p < 0.01) levels of Metenkephalin, dynorphin B, and catecholamines. Pretreatment with naloxone hydrochloride enhanced (p < 0.01) SBP, heart rate, noradrenaline, cortisol, and endothelin-1 levels, and reduced (p < 0.01) ANF in low responders in response to MAT, whereas it decreased (p < 0.01) hemodynamic parameters, noradrenaline, and endothelin-1 in high responders. The individual differences in hemodynamic and endocrine responses to MAT may depend on a different activation of the endogenous opioid system.