Central fatigue and nycthemeral change of serum tryptophan and serotonin in the athletic horse.
Abstract: BACKGROUND: The serotonergic system is associated with numerous brain functions, including the resetting of the mammalian circadian clock. The synthesis and metabolism of 5-HT in the brain increases in response to exercise and is correlated with high levels of blood-borne tryptophan (TRP). The present investigation was aimed at testing the existence of a daily rhythm of TRP and 5-HT in the blood of athletic horses. METHODS: Blood samples from 5 Thoroughbred mares were collected at 4-hour intervals for 48 hours (starting at 08:00 hours on day 1 and finishing at 4:00 on day 2) via an intravenous cannula inserted into the jugular vein. Tryptophan and serotonin concentrations were assessed by HPLC. Data analysis was conducted by one-way repeated measures analysis of variance (ANOVA) and by the single cosinor method. RESULTS: ANOVA showed a highly significant influence of time both on tryptophan and on serotonin, in all horses, on either day, with p values < 0.0001. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. Both parameters studied showed evening acrophases. CONCLUSION: The results showed that serotonin and tryptophan blood levels undergo nycthemeral variation with typical evening acrophases. These results enhance the understanding of the athlete horse's chronoperformance and facilitate the establishment of training programs that take into account the nycthemeral pattern of aminoacids deeply involved in the onset of central fatigue.
Publication Date: 2005-04-28 PubMed ID: 15860131PubMed Central: PMC1112610DOI: 10.1186/1740-3391-3-6Google Scholar: Lookup
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Summary
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This study investigates the daily rhythm of tryptophan (TRP) and serotonin (5-HT) in athletic horses, and its connection to central fatigue. The results revealed a significant time influence on both substances, showing notable increase in the evening (evening acrophases). This can aid in understanding an athlete horse’s “chronoperformance” and help create effective training programs that factor in this daily pattern.
Research Methodology
- To conduct this investigation, blood samples were drawn from 5 Thoroughbred mares at 4-hour intervals over a 48-hour period. This process began at 08:00 hours on day 1 and ended at 4:00 on day 2.
- The sampling was carried out via an intravenous cannula inserted into the jugular vein.
- Tryptophan and serotonin concentrations in the samples were determined using a process called High Performance Liquid Chromatography (HPLC).
- The collected data was analysed using a one-way repeated measures analysis of variance (ANOVA) and a single cosinor method.
Key Findings
- Analysis of Variance (ANOVA) showed a highly significant influence of time on both tryptophan and serotonin levels in all horses, on both days, with p values less than 0.0001, indicating a statistically significant difference.
- The cosinor analysis – a method used to analyse rhythmic variation – identified the periodic parameters and their acrophases (time point of the peak value in a day) during the monitoring period.
- Both tryptophan and serotonin showed evening acrophases, meaning their concentrations peaked in the evening.
Implications and Conclusions
- The results indicate that tryptophan and serotonin levels in the blood of athletic horses follow a daily (nycthemeral) pattern with typical evening peaks. This may be connected to the onset of central fatigue, a phenomenon where the central nervous system reduces the neural drive or motor command to working muscles, causing a decline in performance.
- Understanding these variations can contribute to the knowledge of an athlete horse’s chronoperformance – the performance variation relating to biological rhythms.
- A practical implication of these findings is the potential ability to develop more effective training programs for athletic horses. These programs could take into account the daily pattern of tryptophan and serotonin levels, optimizing the timing of training to align with an athlete horse’s biological rhythm.
Cite This Article
APA
Piccione G, Assenza A, Fazio F, Percipalle M, Caola G.
(2005).
Central fatigue and nycthemeral change of serum tryptophan and serotonin in the athletic horse.
J Circadian Rhythms, 3(1), 6.
https://doi.org/10.1186/1740-3391-3-6 Publication
Researcher Affiliations
- Dipartimento di Morfologia, Biochimica, Fisiologia e Produzioni Animali, Facoltà di Medicina Veterinaria, Università degli Studi di Messina, 98168 Messina, Italy. giuseppe.piccione@unime.it.
References
This article includes 20 references
Citations
This article has been cited 5 times.- Arfuso F, Giannetto C, Giudice E, Fazio F, Panzera M, Piccione G. Peripheral Modulators of the Central Fatigue Development and Their Relationship with Athletic Performance in Jumper Horses.. Animals (Basel) 2021 Mar 8;11(3).
- Riggio G, Mariti C, Sergi V, Diverio S, Gazzano A. Serotonin and Tryptophan Serum Concentrations in Shelter Dogs Showing Different Behavioural Responses to a Potentially Stressful Procedure.. Vet Sci 2020 Dec 24;8(1).
- Torfs SC, Maes AA, Delesalle CJ, Pardon B, Croubels SM, Deprez P. Plasma serotonin in horses undergoing surgery for small intestinal colic.. Can Vet J 2015 Feb;56(2):178-84.
- Alberghina D, Giannetto C, Piccione G. Peripheral serotoninergic response to physical exercise in athletic horses.. J Vet Sci 2010 Dec;11(4):285-9.
- Haritou SJ, Zylstra R, Ralli C, Turner S, Tortonese DJ. Seasonal changes in circadian peripheral plasma concentrations of melatonin, serotonin, dopamine and cortisol in aged horses with Cushing's disease under natural photoperiod.. J Neuroendocrinol 2008 Aug;20(8):988-96.
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