Document Detail


Exercise Increases Tryptophan Availability to the Brain in Older Men Aged 57-70 Years.
MedLine Citation:
PMID:  22051569     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
PURPOSE:: Many aspects of serotonergic activity, both central and peripheral in origin, undergo significant changes with human aging. These alterations might predispose elderly people to develop mood disorders. Since previous work showed that increasing the peripheral availability of tryptophan (TRP) to the brain holds antidepressant properties, this study evaluated whether TRP availability to the brain is increased during prolonged exercise in older men. METHODS:: Nineteen males aged 64±3 yrs completed a treadmill exercise bout at a heart rate eliciting ∼68%VO2peak for 60 min. Fasting blood was collected at rest, after 30- and 60 min of exercise, and at 90 min (postexercise). Branched-chain amino acids (BCAA), total and free TRP, prolactin, ammonia, non-esterified fatty acids (NEFA), glucose and lactate were measured. RESULTS:: Changes in free TRP:BCAA ratio and prolactin were used as peripheral proxies of central serotonin synthesis rate and activity. The free TRP:BCAA ratio observed at baseline was increased by 102% after 1 h of exercise (p<.0001) and remained elevated postexercise (78% above baseline, p<.001). The free TRP portion in serum increased from 2,8±0,7 to 5,7±1,8 μmol·L after 1 h of exercise (p<.001), and was strongly correlated with plasma NEFA contents (r(17)=.887 p<.0001, all timepoints). Serum prolactin was significantly elevated after 1 h of exercise (8.6±2.4 μg·L, p<.001), and was positively correlated with free TRP:BCAA ratio (r(16)=.48, p<.05, all timepoints). CONCLUSION:: These results concur with previous observations in younger men and unveil that significant elevations in tryptophan availability to the brain are encountered during sustained exercise in older men. These results provide support to the hypothesis that increases in serotonin synthesis and activity might be involved in the antidepressant effect of exercise in the elderly.
Authors:
Michel O Melancon; Dominique Lorrain; Isabelle J Dionne
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-11-2
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  -     ISSN:  1530-0315     ISO Abbreviation:  -     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-11-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1Research Center on Aging, University Institute of Geriatrics of Sherbrooke, Sherbrooke, Quebec, CANADA; 2Department of Kinanthropology, Faculty of Physical and Sport Education, and 3Department of Psychology, Faculty of Human Sciences, University of Sherbrooke, Sherbrooke, Quebec, CANADA.
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