Plasma concentrations of beta-endorphin in smokers who consume different numbers of cigarettes per day

The harmful effects of smoking on health have been widely documented, altho ugh it is as yet unclear whether tobacco dependence is only psychological i n nature, or both psychological and physical. We studied plasma concentrati ons of beta-endorphin, cortisol, and adrenocorticotropic hormone (ACTH) in healthy persons who consumed different numbers of cigarettes per day, and c ompared the findings with those in a control group of nonsmokers. Beta-endo rphin levels were significantly higher than in controls only in persons who smoked fewer than 10 cigarettes per day. Cortisol levels were significantl y higher in smokers who consumed more than 20 cigarettes per day. There wer e no significant differences between any of the groups in plasma ACTH conce ntrations. (C) 2000 Elsevier Science Inc. All rights reserved.