Effects of short‐term training on insulin sensitivity and skeletal muscle glucose metabolism in Standardbred horses

Stewart-Hunt, L.; Geor, Raymond J.; McCutcheon, L. J.

doi:10.1111/j.2042-3306.2006.tb05544.x

Cited by 61 publications

(59 citation statements)

References 40 publications

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“…insulin sensitivity have been characterized, have shown no increase in whole body insulin sensitivity measured by hyperinsulinemic euglycemic clamp after a single bout of exercise (42). In contrast, exercise training increased insulin-stimulated glucose uptake in some (49,50), but not all (11), studies in the horse, which is more consistent with the increase in insulin sensitivity induced by training in humans and rodents (45). Pratt et al (42) hypothesized that the lack of response to acute exercise reflected the relatively small increase in glycogen synthase activity and slow glycogen replenishment in muscle after exercise in horses compared with humans and rodents.…”

Section: Discussionmentioning

confidence: 99%

Acute exercise increases insulin sensitivity in adult sheep: a new preclinical model

McConell

Kaur

Falcão-Tebas

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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In healthy humans and rodents, chronic and acute exercise improves subsequent insulin sensitivity of skeletal muscle. A large animal species with similar metabolic responses to exercise would permit longitudinal studies, including repeated biopsies of muscle and other tissues not possible in rodents, and enable study of interactions with insulin-resistant physiological states not feasible in humans. Therefore, we examined whether acute exercise increases insulin sensitivity in adult sheep. Insulin sensitivity was measured by hyperinsulinemic euglycemic clamp (HEC) in mature female sheep (n ϭ 7). Sheep were familiarized to treadmill walking and then performed an acute exercise bout (30 min, 8% slope, up to 4.4 km/h). A second HEC was conducted ϳ18 h after the acute exercise. Musculus semimembranosus biopsies were obtained before and after each HEC. Glucose infusion rate during the HEC increased 40% (P ϭ 0.003) and insulin sensitivity (glucose infusion rate/plasma insulin concentration) increased 32% (P ϭ 0.028) after acute exercise. Activation of proximal insulin signaling in skeletal muscle after the HEC, measured as Ser 473 phosphorylation of Akt, increased approximately five-fold in response to insulin (P Ͻ 0.001) and was unaltered by acute exercise performed 18 h earlier. PGC1␣ and GLUT4 protein, glycogen content and citrate synthase activity in skeletal muscle did not change in response to insulin or exercise. In conclusion, improved insulin sensitivity and unchanged proximal insulin signaling on the day after acute exercise in sheep are consistent with responses in humans and rodents, suggesting that the sheep is an appropriate large-animal model in which to study responses to exercise. exercise; insulin sensitivity; muscle; sheep REGULAR EXERCISE TRAINING increases insulin-stimulated whole body and skeletal muscle glucose uptake in humans, in healthy individuals as well as in those who have Type 2 diabetes (T2D) or are obese or aged (reviewed by Refs. 14, 31, 45). Increased expression of hexokinase 2, some insulin signaling proteins and GLUT4, and greater insulin-induced vasodilation are implicated as mechanisms for enhanced insulin-stimulated glucose uptake after training (14,31,45). Exercise training probably acts mainly at distal sites to increase glucose uptake, with the balance of evidence, suggesting that proximal insulin signaling is not upregulated (14, 38). Importantly, a single bout of exercise also increases the insulin sensitivity of glucose uptake during the following 4 -48 h in healthy humans (34,46,52,54,55). Similar effects have been demonstrated in rodents, where an acute exercise bout increases in vitro insulin-stimulated glucose uptake in mouse muscle 85 min after exercise (18) and in rat muscle collected 3-16 h after a single bout of exercise (8,15,19,43,44). Available evidence from studies in humans and rodents suggests that acute exercise, like exercise training, increases insulin sensitivity without changes in proximal insulin signaling (reviewed in Ref. 31).A large animal model with...

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Section: Discussionmentioning

confidence: 99%

Acute exercise increases insulin sensitivity in adult sheep: a new preclinical model

McConell

Kaur

Falcão-Tebas

et al. 2015

American Journal of Physiology-Regulatory, Integrative and Comp

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“…12 Additionally, exercise training in obese subjects may improve SI through mechanisms involving weight reduction. 13 Previous studies 14,15 in horses support a role of short-term (7-day) exercise training for increasing SI, although sustained effects lasting > 1 day after the last exercise session are inconsistent. Additionally, in obese, insulin-resistant ponies, decreased adiposity through controlled feed intake increases SI to a similar degree as exercise training alone.…”

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confidence: 99%

Effects of exercise training on adiposity, insulin sensitivity, and plasma hormone and lipid concentrations in overweight or obese, insulin-resistant horses

Carter

McCutcheon²,

Valle³

et al. 2010

ajvr

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“…Other studies confirmed the increased GLUT4 content of horse muscles after 6 weeks of training. Stewart-Hunt et al (2006) reported a twofold increase in whole-body sensitivity to insulin, a 10-fold increase in GLUT4 content, increases in glycogen synthase and hexokinase activity, as well as a 9% increase in muscle aerobic endurance. What is more, these have persisted later on during the period of physical inactivity (Pratt et al 2006;Stewart-Hunt et al 2006;Schmidt & Hickey 2009).…”

Section: Prevention and Treatment Of Ir In Horsesmentioning

confidence: 99%

“…This mechanism is not completely understood, but it is ascribed to the increased number of GLUT4 (the main glucose-transporting protein in muscle) and to the higher activity of insulin-signalling proteins (hexokinase) and glycogen synthase as a result of training. This increases the availability of glucose and insulin to muscle tissues, thus increasing the insulin sensitivity of skeletal muscles (Pratt et al 2006;Stewart-Hunt et al 2006;Schmidt & Hickey 2009).…”

Section: Prevention and Treatment Of Ir In Horsesmentioning

confidence: 99%

Insulin resistance in the horse: a review

Kaczmarek

Janicki

Głowska

2015

Journal of Applied Animal Research

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Insulin resistance (IR) is a state in which the tissues show a reduced sensitivity to insulin despite its normal or even increased concentration in blood. IR causes inability of peripheral tissues to respond to the hormone and to increase the glucose uptake from blood nor to raise the metabolism rate. The tissues resistance to insulin may refer to the prereceptor malfunctions, which reduce the concentration of insulin or decrease the number of insulin receptors; however, in most cases changes in signal transduction after insulin binding to the receptor are observed. The development of IR is determined by a number of genetic and environmental factors. One of the most relevant causes is obesity, which develops into a growing problem among the horse population all over the world. The accumulation of lipids in the tissues (lipotoxicity) and a mild inflammation caused by the release of proinflammatory adipokines and cytokines from the fat tissue are a common denominator that links obesity with IR. Both IR and obesity seem to cause metabolism malfunctions in horses and are the key components of equine metabolic syndrome; moreover, both may be the reason for endocrinological laminitis. The methods of prevention and treatment of IR include feeding the animals with low glycemic index food and increasing physical activity as well as pharmacological treatment, where levothyroxine sodium and metformin are of the highest importance. ARTICLE HISTORY

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Effects of short‐term training on insulin sensitivity and skeletal muscle glucose metabolism in Standardbred horses

Abstract: Insulin resistance in equids has been associated with obesity and predisposition to laminitis. Regular physical activity may mitigate risk of these conditions via enhancement of insulin sensitivity and/or control of bodyweight.

Cited by 61 publications

References 40 publications

Acute exercise increases insulin sensitivity in adult sheep: a new preclinical model

Acute exercise increases insulin sensitivity in adult sheep: a new preclinical model

Effects of exercise training on adiposity, insulin sensitivity, and plasma hormone and lipid concentrations in overweight or obese, insulin-resistant horses

Insulin resistance in the horse: a review

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