ORIGINAL ARTICLE

Hormonal responses during prolonged exercise are influenced by a selective DA/NA reuptake inhibitor

M F Piacentini, R Meeusen, L Buyse, G De Schutter, K De Meirleir

Vrije Universiteit, Brussels, Belgium

Correspondence to:
Correspondence to:
R Meeusen
Vrije Universiteit Brussels, Faculty LK, Department of Human Physiology and Sports Medicine, Pleinlaan 2, B-1050 Brussels, Belgium; rmeeusen{at}vub.ac.be

Objective: A decrease in dopamine activity is thought to lead to a reduction in motivation and arousal and therefore to the "central" component of fatigue. The purpose of the present study was to investigate the effects of a dopamine (DA) noradrenaline (NA) reuptake inhibitor, bupropion (Zyban^TM), on exercise performance and on the hormonal response to exercise.

Methods: Eight healthy well trained male cyclists (Watt_max 397±15 W) participated in the study. Subjects completed one maximal exercise test (to determine maximal power output Watt_max), and two endurance performance tests (time trials) in a double blind randomised cross-over design. Subjects took either placebo capsules (lactose) or 2x300 mg bupropion (BUP). Blood samples were collected for adrenocorticotropin (ACTH), prolactin, cortisol, growth hormone, beta-endorphins, and catecholamines.

Results: Performance was not influenced by BUP (placebo: 89±1 min; BUP 2x300 mg: 89±0.7 min). All hormones increased during exercise in all trials. Cortisol plasma concentrations were significantly higher in the BUP trial at rest, at min 60, and at the end of exercise, while beta-endorphins were higher in the BUP trial at the end of exercise and during recovery, and ACTH at the end of exercise.

Conclusion: From the present results, we can conclude that bupropion had a more marked central noradrenergic effect (compared to dopaminergic) on the hormonal response to exercise, but no effect on the outcome of performance.

Keywords: catecholamines; fatigue; hypothalamic pituitary adrenal axis; neurotransmitters

Abbreviations: ACTH, adrenocorticotropin; ß-E, beta-endorphins; BUP, bupropion; DA, dopamine; GH, growth hormone; NA, noradrenaline; NARI, noradrenaline reuptake inhibitor; PRL, prolactin; RPE, rate of perceived exertion

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