Abstract
The kynurenine pathway (KP) is gaining attention in several clinical fields. Recent studies show that physical exercise offers a therapeutic way to improve ratios of neurotoxic to neuroprotective KP metabolites. Antioxidant supplementation can blunt beneficial responses to physical exercise. We here studied the effects of endurance training in the form of sprint interval training (SIT; three sessions of 4–6 × 30 s cycling sprints per week for three weeks) in elderly (~65 years) men exposed to either placebo (n = 9) or the antioxidants vitamin C (1 g/day) and E (235 mg/day) (n = 11). Blood samples and muscle biopsies were taken under resting conditions in association with the first (untrained state) and last (trained state) SIT sessions. In the placebo group, the blood plasma level of the neurotoxic quinolinic acid was lower (~30%) and the neuroprotective kynurenic acid to quinolinic acid ratio was higher (~50%) in the trained than in the untrained state. Moreover, muscle biopsies showed a training-induced increase in kynurenine aminotransferase (KAT) III in the placebo group. All these training effects were absent in the vitamin-treated group. In conclusion, KP metabolism was shifted towards neuroprotection after three weeks of SIT in elderly men and this shift was blocked by antioxidant treatment.
Highlights
The results show a statistically significant reduction of the neurotoxic quinolinic acid in the trained state in the placebo group, whereas this kynurenine pathway (KP) metabolite was not affected by training in the vitamin-treated group (Figure 2)
The KYNA/QUIN ratio was ~50% higher in the trained than in the untrained state, whereas it was not affected in the vitamin-treated group (Figure 3B)
sprint interval training (SIT), with a total of less than 30 min of high-intensity exercise, in recreationa derly men and this shift was blocked by antioxidant treatment with vitamin C
Summary
Biological ageing involves a progressive decline of cellular function, is a high-risk factor for morbidity, and places individuals at higher risk of diseases [1,2]. Within an increasingly ageing population, actions towards health promotion are critical to improve the quality of life for older individuals and to mitigate escalating health care costs. The kynurenine pathway (KP) is a unique pathway implicated in a high number of pathologies associated with ageing, including those affecting bone, skeletal muscle, cardiovascular, and mental health [3,4,5]. Changes in KP metabolites both in the 4.0/).
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