Plasma levels of adrenaline, noradrenaline, dopamine, serotonin, and cortisol in sarcopenia: comparison with non-sarcopenic individuals and the impact of resistance exercise and nutrition interventions.

BACKGROUND: Sarcopenia may disrupt the hypothalamic‒pituitary‒adrenal axis, affecting neurotransmitter and hormone levels. However, the impact of sarcopenia on these markers, particularly in comparison to non-sarcopenic controls, is understudied. Additionally, the effects of resistance exercise and nutritional support on neurotransmitter levels in sarcopenic patients are largely unknown. This study explores these neurochemical changes and their response to therapeutic interventions. METHODS: This post hoc analysis of a randomized controlled trial included 57 sarcopenic and 57 non-sarcopenic participants from the same cohort. Grip strength and body composition were measured. Sarcopenic patients received a 12-week intervention involving resistance exercise and supplementation with branched-chain amino acids, calcium, and vitamin D3. Plasma adrenaline, noradrenaline, dopamine, serotonin, and cortisol were assessed using enzyme-linked immunosorbent assay (ELISA). RESULTS: Sarcopenic individuals had significantly lower levels of serotonin (13.28 vs 19.21  ng/mL, p = 0.002), adrenaline (97.6 vs 110.9  pg/mL, p < 0.001), and noradrenaline (169.2 vs 302.5  pg/mL, p < 0.001), with a trend toward reduced dopamine (246.9 vs 270.6  pg/mL, p = 0.053). Cortisol levels were similar between the groups (48.2 vs 49.5  ng/mL, p = 0.436). Generalized estimating equations adjusted for age and gender, showed sarcopenia was linked to reduced serotonin (β = -5.92, p = 0.002), adrenaline (β = -13.32, p < 0.001), and noradrenaline (β = -132.9, p < 0.001), while the intervention raised noradrenaline levels (β = 27.75, p = 0.001). CONCLUSION: Sarcopenic patients exhibit lower serotonin, adrenaline, and noradrenaline compared to non-sarcopenic controls, with no significant difference in cortisol levels. Resistance exercise and nutritional interventions increased noradrenaline in sarcopenic individuals. Further studies are needed to evaluate the long-term effects on neurotransmitter and hormone levels.