Swim-trained rats have greater bone mass, density, strength, and dynamics

“…The rat model of exercise has been used extensively to study the physiological effects of physical activity using such exercise modalities as swimming (24,32), running (20,29,41,49,52), jumping (57), tower climbing (43), rising to an erect bipedal stance (11,64), and weight lifting (62). The effects of exercise on bone have been widely characterized in the rat.…”

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confidence: 99%

Short-term voluntary exercise in the rat causes bone modeling without initiating a physiological stress response

Rosa¹,

Firth²,

Blair³

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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research has revealed a neuroendocrine connection between the skeleton and metabolism. Exercise alters both bone modeling and energy balance and may be useful in further developing our understanding of this complex interplay. However, research in this field requires an animal model of exercise that does not cause a physiological stress response in the exercised subjects. In this study, we develop a model of short-term voluntary exercise in the female rat that causes bone modeling without causing stress. Rats were randomly assigned to one of three age-matched groups: control, tower climbing, and squat exercise (rising to an erect bipedal stance). Exercise for 21 days resulted in bone modeling as assessed by peripheral quantitative computed tomography. Fecal corticosterone output was used to assess physiological stress at three time points during the study (preexercise, early exercise, and late in the exercise period). There were no differences in fecal corticosterone levels between groups or time points. This model of voluntary exercise in the rat will be useful for future studies of the influence of exercise on the relationship between skeletal and metabolic health and may be appropriate for investigation of the developmental origins of those effects. computed tomography; corticosterone; exercise; metabolism; stress RECENT ADVANCES IN OUR UNDERSTANDING of the dynamic relationship between body structure and metabolism have revealed a neuroendocrine connection between bone remodeling and energy balance, with both bone and fat acting as endocrine organs (14). The osteoblast-specific protein osteocalcin regulates glucose handling through effects on insulin secretion and sensitivity (33). This action is in turn mediated by the adipokine leptin, which inhibits insulin secretion through direct effects on pancreatic ␤-cells (18) and through inhibition of osteocalcin activity (25). The interplay between bone and metabolism has recently been further elucidated by the discovery that the Forkhead family transcription factor FoxO1, a key regulator of insulin handling in multiple tissues, also acts within the osteoblast to control osteocalcin expression and bioactivity (46).Exercise stimulates modeling of the musculoskeletal system (19, 55, 65), alters metabolism (40), and enhances brain function (17), and thus exercise provides an excellent means of exploring the neuroendocrine connection between bone, fat, and energy balance. The rat model of exercise has been used extensively to study the physiological effects of physical activity using such exercise modalities as swimming (24, 32), running (20,29,41,49,52), jumping (57), tower climbing (43), rising to an erect bipedal stance (11, 64), and weight lifting (62). The effects of exercise on bone have been widely characterized in the rat. Ovariectomized rats undergo changes in bone structure that are nearly identical to those seen in human osteoporosis (28,42), and these animals have proven useful for the study of exercise interventions in osteoporosis treatment (36).In examini...

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“…The present microarray study also provided relevant information for further investigations into the intestinal nutrient and electrolyte transport during nonimpact exercise. gene ontology; microarray; nonimpact exercise; real-time polymerase chain reaction; Ussing chamber ENDURANCE WEIGHT-BEARING or impact exercise with moderate intensity such as running is known to benefit calcium metabolism by increasing bone formation rate, bone mineral density (BMD), and bone strength and by decreasing urinary calcium excretion, thereby inducing positive calcium balance in trained animals (22,26). These beneficial effects of endurance running are contributed, in part, by the enhanced intestinal calcium absorption (58).…”

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confidence: 99%

Endurance swimming stimulates transepithelial calcium transport and alters the expression of genes related to calcium absorption in the intestine of rats

Teerapornpuntakit¹,

Dorkkam²,

Wongdee³

et al. 2009

American Journal of Physiology-Endocrinology and Metabolism

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Teerapornpuntakit J, Dorkkam N, Wongdee K, Krishnamra N, Charoenphandhu N. Endurance swimming stimulates transepithelial calcium transport and alters the expression of genes related to calcium absorption in the intestine of rats. Am J Physiol Endocrinol Metab 296: E775-E786, 2009. First published January 27, 2009 doi:10.1152/ajpendo.90904.2008.-Endurance impact exercise, e.g., running, is known to enhance the intestinal calcium absorption. However, nonimpact exercise, e.g., swimming, is more appropriate for osteoporotic patients with cardiovascular diseases or disorders of bone and joint, but the effect of swimming on the intestinal calcium transport was unknown. This study, therefore, aimed to investigate the transepithelial calcium transport and the expression of related genes in the intestine of rats trained to swim nonstop 1 h/day, 5 days/wk for 2 wk. We found that endurance swimming stimulated calcium transport in the duodenum, proximal jejunum, and cecum, while decreasing that in the proximal colon. Swimming affected neither the transepithelial potential difference nor resistance. As demonstrated by real-time PCR, the small intestine, especially the duodenum, responded to swimming by upregulating a number of genes related to the transcellular calcium transport, i.e., TRPV5, TRPV6, calbindin-D 9k, PMCA1b, and NCX1, and the paracellular calcium transport, i.e., ZO-1, ZO-2, ZO-3, cingulin, occludin, and claudins, as well as nuclear receptor of 1,25(OH)2D3. In contrast, swimming downregulated those genes in the colon. Microarray analysis showed that swimming also altered the expression of duodenal genes related to the transport of several ions and nutrients, e.g., Na ϩ , K ϩ , Cl Ϫ , glucose, and amino acids. In conclusion, endurance swimming enhanced intestinal calcium absorption, in part, by upregulating the calcium transporter genes. The present microarray study also provided relevant information for further investigations into the intestinal nutrient and electrolyte transport during nonimpact exercise. gene ontology; microarray; nonimpact exercise; real-time polymerase chain reaction; Ussing chamber ENDURANCE WEIGHT-BEARING or impact exercise with moderate intensity such as running is known to benefit calcium metabolism by increasing bone formation rate, bone mineral density (BMD), and bone strength and by decreasing urinary calcium excretion, thereby inducing positive calcium balance in trained animals (22,26). These beneficial effects of endurance running are contributed, in part, by the enhanced intestinal calcium absorption (58). However, little is known regarding the mechanism by which exercise affects the intestinal calcium transport.In contrast to running, swimming is an unloaded nonimpact exercise that is suitable for several groups of patients, such as cardiovascular, postmenopausal, osteoporotic patients, and patients, who need to prevent high blood pressure or impact that can cause bone and joint injuries (17,38,43,49). Although the effect of swimming on bone metabolism may not be as obvious as...

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Swim-trained rats have greater bone mass, density, strength, and dynamics

Cited by 96 publications

References 27 publications

Modelo de suspensão pela cauda e seu efeito em algumas propriedades mecânicas do osso do rato

Modelo de suspensão pela cauda e seu efeito em algumas propriedades mecânicas do osso do rato

Short-term voluntary exercise in the rat causes bone modeling without initiating a physiological stress response

Endurance swimming stimulates transepithelial calcium transport and alters the expression of genes related to calcium absorption in the intestine of rats

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