EFFECTS OF DIFFERENT AEROBIC EXERCISE INTENSITIES ON THE KYNURENINE PATHWAY METABOLITES IN INDIVIDUALS WITH DEPRESSION.

The evidence supporting the efficacy of exercise as a treatment for depression has grown in recent years. Nevertheless, the biological mechanisms through which exercise improve symptoms, as well as the effects of different exercise intensities remain unclear. Recently, the kynurenine pathway (KP) has been identified as a potential contributor to depression, as kynurenine (KYN) is increased in individuals with the disorder. Exercise appears to interfere positively with this pathway. PURPOSE: To investigate the effects of moderate and vigorous-intensity aerobic exercise on KP metabolites in individuals diagnosed with depression. METHODS: Seventeen clinically diagnosed and treating depression adults (F = 11, M = 6; Age: 35.9 ± 1.9 yrs; Body mass: 76.2 ± 3.8 kg; Height: 168.1 ± 2.7 cm; BMI: 26.9 ± 1.3 kg/m2; HAM-D Score: 10.1 ± 1.9) underwent two exercise tests at intensities based on the %Vpeak of a treadmill maximal graded test separated by 7 days: 1) Moderate (MOD) for 30 minutes (55% Vpeak); 2) Vigorous (VIG) until volitional exhaustion (85% Vpeak). Subjects had blood samples collected at baseline (T1), immediately after (T2), and 30 minutes after exercise (T3) and Kynurenine (KYN), Kynurenic Acid (KYNA) and Quinolinic Acid (QA) were measured with ELISA. Intensities were compared using GEE (General Estimating Equations) based on gaussian distribution of the dependent variable and identity link function. Data presented as mean ± SE and significance p ≤ 0.05. The protocol was approved by UNIFESP Ethics Committee (#4.286.307). RESULTS: The analysis indicated significant main effects for KYN (W = 195.82; p < 0.001) and QA (W = 28.090; p < 0.001) but not for KYNA (W = 12.175; p = 0.351). The MOD intensity exercise increased KYN (259.20 ± 35.4 vs 439.46 ± 27.7; p = 0.002) and decreased QA (59.89 ± 2.31 vs 55.01 ± 2.5; p = 0.04) at T2. The VIG intensity also increased KYN (286.17 ± 40.1 vs 467.46 ± 33.3; p = 0.01) and decreased QA (60.41 ± 1.8 vs 54.96 ± 2.9; p < 0.001) at T2. Metabolites concentrations returned to baseline levels at T3. CONCLUSION: In this study both exercise intensities had an impact on the KP metabolites, resulting in increased KYN and decreased neurotoxic QA. However, these impacts appear to be transient with concentrations returning to baseline levels at T3. Furthermore, no differences were observed between intensities. Supported by: Supported by AFIP, CAPES (001 code), and CNPq grants 142402/2020-6 and 313405/2020-4