title: Effect of exercise intensity on free tryptophan to branched-chain amino acids ratio and plasma prolactin during endurance exercise.
abstract: The potential of exercise-induced changes in peripheral amino acids to alter blood prolactin levels through a serotonergic system modification was investigated in 8 male athletes. In two trials, subjects (N = 8) exercised on a cycle ergometer for 5 hr. The intensity of exercise corresponded to 55% VO2max (T55) or 75% VO2max (T75), respectively. In each trial, each subject received a 25-g energy bar (111 kcal) every 60 min, as well as 300 ml of a 6% carbohydrate solution (90 kcal) every 30 min of exercise duration. Plasma glucose and insulin declined (p < or = .05) in both trials during exercise. Ammonia was augmented (p < or = .05) above the baseline concentration after 120 min in both trials. During the last 2 hr of exercise, plasma free fatty acids were higher (p < or = .05) in T75 than in T55. During this time, the plasma free TRP/BCAA ratio was also augmented (p < or = .05) in T75, while no change was induced in T55. Plasma prolactin did not change in T55, while an increase (p < or = .05) was found in T75. The findings may further support the hypothesis that during endurance exercise changes in peripheral amino acid concentration may influence prolactin response via serotonergic system modifications.
authors.affiliation: Institute of Sports Games, German Sport University, Cologne, Germany.
authors.forename: H K
authors.initials: HK
authors.lastname: Strüder
authors.forename: W
authors.initials: W
authors.lastname: Hollmann
authors.forename: P
authors.initials: P
authors.lastname: Platen
authors.forename: R
authors.initials: R
authors.lastname: Wöstmann
authors.forename: A
authors.initials: A
authors.lastname: Ferrauti
authors.forename: K
authors.initials: K
authors.lastname: Weber
mesh_terms: D000328:Adult; D000597:Amino Acids, Branched-Chain / Q000097:blood*; D000641:Ammonia / Q000097:blood; D001784:Blood Gas Analysis; D001786:Blood Glucose / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006339:Heart Rate; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D011388:Prolactin / Q000097:blood*; D014364:Tryptophan / Q000097:blood*
chemical_list: D000597:Amino Acids, Branched-Chain; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D000641:Ammonia; D014364:Tryptophan; D011388:Prolactin