The hormonal response to a d-fenfluramine challenge in trained and sedentary men

• Published in: Medicine and science in sports and exercise 1999-04, Vol.31 (4), p.547-553
• Main Authors: STRACHAN, A. T, MAUGHAN, R. J
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Adult; Biological and medical sciences; Fenfluramine - pharmacology; Fundamental and applied biological sciences. Psychology; Humans; Hydrocortisone - blood; Male; Physical Endurance - physiology; Prolactin - blood; Receptors, Serotonin - physiology; Serotonin; Serotonin Uptake Inhibitors - pharmacology; Space life sciences; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
• ISSN: 0195-9131; 1530-0315
• DOI: 10.1097/00005768-199904000-00009

The purpose of the present study was to examine the responsiveness of serotonergic receptors in endurance trained and sedentary men. The serum prolactin and cortisol responses to the oral administration of 30 mg of the serotonin releaser and reuptake inhibitor d-fenfluramine were determined in eight male endurance-trained subjects and seven male sedentary controls. A Friedman's repeated-measures test for both the endurance-trained (P = 0.006) and sedentary (P = 0.018) prolactin results demonstrated a change in the mean prolactin concentration over time, but no difference in prolactin response was observed between the subject groups (P = 0.81). In both subject groups, the serum cortisol concentration remained unchanged. However, the mean serum concentration of cortisol for the endurance-trained subjects at each time point tended to be lower than at the corresponding time point for the sedentary subject group and was significantly lower at 180 min (P = 0.04). The present study suggests that, in contrast to an earlier report of down-regulation of 5-HT1A receptor function in endurance-trained subjects in response to a nonspecific challenge, postsynaptic 5-HT2 function as determined by the d-fenfluramine-evoked alteration in the plasma concentration of prolactin is not altered by endurance training.