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Exercise changes in plasma tryptophan fractions and relationship with prolactin
H G Fischer1, W Hollmann, K De Meirleir
1Institute of Cardiology and Sports Medicine, German Sports University, Cologne.
International Journal of Sports Medicine
|October 1, 1991
Summary
Exercise increases free plasma tryptophan levels, a key amino acid, which correlates with prolactin. This supports the theory that exercise impacts brain function via peripheral amino acid changes.
Area of Science:
- Exercise physiology
- Neuroendocrinology
- Biochemistry
Background:
- The hypothesis suggests plasma tryptophan fractions influence exercise's behavioral and neuroendocrine effects.
- Understanding these mechanisms requires examining tryptophan levels during and after physical activity.
Purpose of the Study:
- To evaluate changes in free and total plasma tryptophan during and after a 1-hour endurance exercise.
- To investigate the functional implications of these changes, particularly their correlation with prolactin.
Main Methods:
- Six male volunteers underwent a 1-hour cycling endurance test below the lactate threshold.
- Plasma free and total tryptophan, prolactin, glycerol, and nonesterified fatty acids (NEFA) were measured.
- High-performance liquid chromatography and radioimmunoassay techniques were employed.
Main Results:
- Total plasma tryptophan showed no significant changes.
- Free plasma tryptophan significantly increased during exercise and peaked post-exercise.
- Prolactin levels demonstrated a strong positive correlation with free plasma tryptophan.
Conclusions:
- Exercise significantly alters free plasma tryptophan, suggesting a role in exercise-induced physiological responses.
- The correlation between free tryptophan and prolactin supports its influence on neuroendocrine pathways.
- Findings reinforce the hypothesis that peripheral amino acid shifts mediate exercise effects on brain systems.