Seasonal and diurnal melatonin production in exercising sled dogs

Dunlap, Kriya L.; Reynolds, Arleigh J.; Tosini, Gianluca; Kerr, Wendell W.; Duffy, Lawrence K.

doi:10.1016/j.cbpa.2007.02.015

Cited by 19 publications

(19 citation statements)

References 19 publications

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“…Thus, urinary 6-sulfatoxymelatonin excretion may be not useful to evaluate melatonin changes in exercise. Working with sled dogs, a dog strain that can be considered elite athletes, Dunlap et al [43] reported a reduction in melatonin levels after exercise in both winter and summer seasons in dogs raised in Alaska, but only a reduction in winter in sled dogs raised in New York. These data also account for seasonal variations in exercisedependent melatonin changes.…”

Section: Influence Of Physical Exercise On Melatonin Levelsmentioning

confidence: 99%

Exercise and melatonin in humans: reciprocal benefits

Escames

Öztürk

Baño-Otálora

et al. 2011

Journal of Pineal Research

116

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: The aim of this review is to update the reader as to the association between physical exercise and melatonin, and to clarify how the melatonin rhythm may be affected by different types of exercise. Exercise may act as a zeitgeber, although the effects of exercise on the human circadian system are only now being explored. Depending on the time of the day, on the intensity of light, and on the proximity of the exercise to the onset or decline of the circadian production of melatonin, the consequence of exercise on the melatonin rhythm varies. Moreover, especially strenuous exercise per se induces an increased oxidative stress that in turn may affect melatonin levels in the peripheral circulation because indole is rapidly used to combat free radical damage. On the other hand, melatonin also may influence physical performance, and thus, there are mutually interactions between exercise and melatonin production which may be beneficial.

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Section: Influence Of Physical Exercise On Melatonin Levelsmentioning

confidence: 99%

Exercise and melatonin in humans: reciprocal benefits

Escames

Öztürk

Baño-Otálora

et al. 2011

Journal of Pineal Research

116

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“…Acute exercise promotes noradrenergic stimulation of the pineal gland, which increases the production of melatonin (Reiter, 1991). Season and timing of exercise strongly influence the magnitude of its production, since nocturnal exercise increases plasma melatonin more than morning or evening exercises (Dunlap, Reynolds, Tosini, Kerr, & Duffy, 2007;Hardeland et al, 2009). Melatonin also reduces the expression of pro-inflammatory enzymes such as inducible nitric oxide synthase and the cytokines interleukin-2, tumour necrosis factor-a, interferon g, and granulocyte-macrophage colony-stimulating factor (Rodríguez et al, 2007b).…”

Section: Introductionmentioning

confidence: 99%

Antioxidant defence and inflammatory response in professional road cyclists during a 4-day competition

Serrano

Venegas

Escames

et al. 2010

Journal of Sports Sciences

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Cycling competitions represent an important physical overload even for well-trained individuals. In six professional cyclists, we studied the adaptive oxidative and anti-inflammatory response to a 4-day road cycling competition and its relationship with melatonin, an antioxidant and anti-inflammatory stress hormone. Blood and urine samples were collected before and after the competition. Plasma lipid peroxidation, cytokines (interleukin-1beta, interleukin-6, and tumour necrosis factor-alpha), creatine kinase and other metabolic markers, melatonin, erythrocyte glutathione, and glutathione peroxidase and reductase activities were measured. Urinary excretion of 6-sulphatoxymelatonin was analysed. Lipid peroxidation increased after the competition, but the erythrocyte glutathione pool remained unchanged. Changes in both glutathione peroxidase and reductase activities probably account for the recycling of glutathione after exercise. Interleukin-6 (216%) and tumour necrosis factor-alpha (159%) but not interleukin-1beta increased after exercise. A parallel increase in plasma melatonin concentrations was detected, whereas metabolic markers, including creatine kinase, showed minor modifications. Thus, professional cyclists display an adaptative response to the physical overloads in the competitions for which they are trained. Consequently, they seem to be able to regulate efficiently the intracellular oxidative stress, and prevent an exaggerated pro-inflammatory cytokines induction. A modulator role of melatonin in these adaptive responses is also supported.

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“…The exercise in this study was not as strenuous as previously described, but a similar decrease in concentration of T4 and fT4 as in strenuous exercise was seen [15]. Variables that could account for the decreases are multiple and could include exercise-induced alterations in distribution or metabolism of hormones [34], altered protein binding of thyroid hormones due to exposure to cold temperatures [35], changed melatonin production which is related to light and exercise [36,37] and diurnal fluctuation [38]. The contribution of the latter is considered to be minimal in this study, due to the similar collection times.…”

Section: Discussionmentioning

confidence: 78%

Exercise induced hypercoagulability, increased von Willebrand factor and decreased thyroid hormone concentrations in sled dogs

et al. 2014

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BackgroundSled dogs performing endurance races have been reported to have a high incidence of gastric erosions or ulcerations and an increased risk of gastro intestinal bleeding leading to death in some cases. In addition, these dogs also become hypothyroid during training and exercise. Canine hypothyroidism has been shown to correlate with decreased von Willebrand factor antigen and potentially increased bleeding tendency. Whether increased gastro intestinal bleeding risk is exacerbated due to changes in the hemostatic balance is unknown. The aim of this study was to investigate the hemostatic balance in sled dogs before and after exercise and in addition evaluate any correlation to thyroid status. Twenty sled dogs have been assessed in untrained and trained condition and immediately after exercise. The first sample was collected in the autumn following a resting period, and subsequently the dogs were exposed to increased intensity of training. After four months the peak of physical condition was reached and a 68 km long sled pulling exercise was performed. Samples were collected before and immediately after the exercise. Evaluated parameters were: plasma thromboelastographic (TEG) R, SP, α and MA, activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen, von Willebrand factor (vWf), D-dimer, platelet number, thyroid hormones, hematocrit and C-reactive protein (CRP).ResultsExercise induced an overall hypercoagulable state characterized by significant decreases of TEG R and SP and an increase of α, increased concentrations of plasma vWf and decreased aPTT. In addition, a proinflammatory status was seen by a significant increase of serum CRP concentrations. Thyroid status was confirmed to be hypothyroid as training and exercise induced significant decrease of thyroxin (T4), free thyroxin (fT4) and thyroxin stimulating hormone (TSH) concentrations. Fibrinogen decreased significantly and PT increased. The training-induced changes showed correlation between T4, fT4 and aPTT and correlation between TSH and fibrinogen. Exercise-induced changes showed correlation between T4 and PT.ConclusionsExercise was associated with a hypercoagulable state and an increase of vWf concentration in this group of sled dogs. Decreased thyroid hormone concentrations after training and exercise were confirmed, but were associated with increased and not decreased vWf in this group of sled dogs.

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Seasonal and diurnal melatonin production in exercising sled dogs

Cited by 19 publications

References 19 publications

Exercise and melatonin in humans: reciprocal benefits

Exercise and melatonin in humans: reciprocal benefits

Antioxidant defence and inflammatory response in professional road cyclists during a 4-day competition

Exercise induced hypercoagulability, increased von Willebrand factor and decreased thyroid hormone concentrations in sled dogs

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