Effects of mental stress on insulin-mediated glucose metabolism and energyexpenditure in lean and obese women

The effects of the sympathetic activation elicited by a mental stress on in sulin sensitivity and energy expenditure ((V) over dot O-2 were studied in 11 lean and 8 obese women during a hyperinsulinemic-euglycemic clamp. Six l ean women were restudied under nonselective beta-adrenergic blockade with p ropranolol to determine the role of beta-adrenoceptors in the metabolic res ponse to mental stress. In lean women, mental stress increased (V) over dot O-2 by 20%, whole body glucose utilization ([ 6,6-H-2(2)]glucose) by 34%, and cardiac index (thoracic bioimpedance) by 25%, whereas systemic vascular resistance decreased by 24%. In obese women, mental stress increased energ y expenditure as in lean subjects, but it neither stimulated glucose uptake nor decreased systemic vascular resistance. In the six lean women who were restudied under propranolol, the rise in (V) over dot O-2, glucose uptake, and cardiac output and the decrease in systemic vascular resistance during mental stress were all abolished. It is concluded that 1) in lean subjects , mental stress stimulates glucose uptake and energy expenditure and produc es vasodilation; activation of beta-adrenoceptors is involved in these resp onses; and 2) in obese patients, the effects of mental stress on glucose up take and systemic vascular resistance, but not on energy expenditure, are b lunted.