AbstractAstronauts are often on a voluntarily reduced energy intake during space missions, possibly caused by a metabolic or emotional stress response with involvement of the central serotonergic system (SES).We investigated 24h urinary excretion (24h-E) of serotonin (5-HT) and 5-hydroxyindol acidic acid as indicators of the SES in healthy males under two different normocaloric conditions: normal physical activity (NPA) and head-down-tilt (HDT). HDT or NPA were randomly arranged with a recovery period of 6 months in between.24h-E of hormones varied widely among individuals. Values were higher in HDT compared to NPA. Assuming that the 24h-E values are, beside being indicators for alterations in the number and metabolism of platelets, Also indicators of central SES, HDT condition seems to activate central SES in a higher degree compared to NPA. Therefore, changes in central SES might be involved in the mechanisms associated with space flight or microgravity, including possible maladaptations such as voluntary undernutrition.
Increased urinary excretion rates of serotonin and metabolites during bedrest
Acta Astronautica ; 56 , 9-12 ; 801-808
2005-01-01
8 pages
Article (Journal)
Electronic Resource
English
Increased urinary excretion rates of serotonin and metabolites during bedrest
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