Independence of salt intake from the hormones regulating calcium homeostasis

Tordoff, Michael G.; Hughes, Rebecca L.; Pilchak, Diane M.

doi:10.1152/ajpregu.1993.264.3.r500

Cited by 8 publications

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“…One involves circulating PTH and 1,25(OH) 2 D concentrations: High concentrations of these hormones can induce high intracellular calcium concentrations in adipose tissue, and these, in turn, stimulate lipogenesis (i.e., obesity) (51,53,55). However, rats fed vitamin D-deficient diets have normal body weights, unless they are also calcium deficient (44), and chronic infusions of PTH or 1,25(OH) 2 D do not increase body weight (36). Moreover, here and in the study by Papakonstantinou et al (27), there was no clear relation between circulating concentrations of 1,25(OH) 2 D (or PTH in this study) and body weight of rats given diets differing in calcium content (27).…”

Section: Discussionmentioning

confidence: 99%

No effect of dietary calcium on body weight of lean and obese mice and rats

Zhang

Tordoff

2004

American Journal of Physiology-Regulatory, Integrative and Comp

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Zhang, Qinmin, and Michael G. Tordoff. No effect of dietary calcium on body weight of lean and obese mice and rats. Am J Physiol Regul Integr Comp Physiol 286: R669-R677, 2004. First published December 18, 2003 10.1152/ajpregu.00655.2003.-Recent epidemiological and animal studies have led to the hypothesis that low dietary calcium intakes contribute to obesity. Here, we evaluated whether calcium influenced the body weight of normal-weight and obese rodents. All experiments involved female C57BL/6J mice or SpragueDawley rats fed normal-or high-energy-density diets (3.8 or 4.7 kcal/g). Calcium intake was manipulated by allowing mice to drink sweetened 30 mM CaCl2 solution or feeding mice and rats diets differing in calcium content (0.2%, 0.6%, or 1.8% Ca 2ϩ ). Blood samples were taken from rats to confirm that the diets had their intended effects on metabolism. There were no effects of the calcium manipulations on energy intake, body weight, or carcass fat content and no simple relation between calciotropic hormones and body weight. One experiment found a significant decrease in body weight gain of lean and obese rats fed the 1.8% Ca 2ϩ diet, but we suspect that this was due to forced consumption of the unpalatable diet, reducing growth. These studies provide little support for the hypothesis that dietary calcium contributes to the etiology or maintenance of obesity.1,25-dihydroxyvitamin D3; parathyroid hormone; appetite; palatability; food intake THERE HAS BEEN CONSIDERABLE recent interest in the hypothesis that body fat stores are modulated by calcium intake (50, 55). Several epidemiological studies have found inverse correlations between calcium intakes and body weight (7, 10, 13, 17, 22-24, 30, 55). There are also reports that body weight is reduced during clinical trials involving calcium supplementation (10,15,29,55). A measure of the enthusiasm for this hypothesis is the number of reviews written about it (28,35,(48)(49)(50)52).Experimental support for an inverse relation between calcium intake and body weight has been derived from animal studies. There are several reports of reduced body weight gain in rats fed high-calcium diets relative to controls fed moderate levels of calcium (6,26,34,38,54). However, interest has been piqued recently by three studies showing that high dietary calcium reduces the obesity produced by feeding high-energy diets. Two studies (33, 55) involved groups of male aP2-agouti mice fed high-sucrose, high-lard diets that differed in the amount and source of calcium (i.e., 0.4% Ca 2ϩ from CaCO 3 , 1.2% Ca 2ϩ from CaCO 3 , 1.2% Ca 2ϩ from nonfat dry milk, or 2.4% Ca 2ϩ from nonfat dry milk). In one of these studies (33), food intakes of some groups were yoked to those of mice fed the 0.4% Ca 2ϩ diet. In both experiments, the high-calcium diets significantly reduced weight gain and fat pad mass, increased core body temperature, inhibited adipocyte fatty acid synthase expression, stimulated lipolysis, and reduced fasting plasma insulin and glucose concentrations. The third study (27...

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Section: Discussionmentioning

confidence: 99%

No effect of dietary calcium on body weight of lean and obese mice and rats

Zhang

Tordoff

2004

American Journal of Physiology-Regulatory, Integrative and Comp

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The importance of calcium in the control of salt intake

Tordoff

1996

Neuroscience & Biobehavioral Reviews

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Forty mouse strain survey of voluntary calcium intake, blood calcium, and bone mineral content

Tordoff

Bachmanov

Reed

2007

Physiology & Behavior

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We measured voluntary calcium intake, blood calcium, and bone mineral content of male and female mice from 40 inbred strains. Calcium intakes were assessed using 48-h two-bottle tests with a choice between water and one of the following: water, 7.5, 25, and 75 mM CaCl 2 , then 7.5, 25, and 75 mM calcium lactate (CaLa). Intakes were affected by strain, sex, anion, and concentration. In 11 strains females consumed more calcium than did males and in the remaining 29 strains there were no sex differences. Nine strains drank more CaLa than CaCl 2 whereas only one strain (JF1/Ms) drank more CaCl 2 than CaLa. Some strains had consistently high calcium intakes and preferred all calcium solutions relative to water (e.g., PWK/PhJ, BTBR T + tf/J, JF1/Ms). Others had consistently low calcium intakes and avoided all calcium solutions relative to water (e.g., KK/H1J, C57BL/10J, CE/ J, C58/J). After behavioral tests, blood was sampled and assayed for pH, ionized calcium concentration, and plasma total calcium concentration. Bone mineral density and content were assessed by DEXA. There were no significant correlations between any of these physiological measures and calcium intake. However, strains of mice that had the highest calcium intakes generally fell at the extremes of the physiological distributions. We conclude that the avidity for calcium is determined by different genetic architecture and thus different physiological mechanisms in different strains. KeywordsCalcium appetite; Ionized calcium; Bone mineral density; Calcium lactate; Inbred strain; Mouse phenome Adequate calcium intake is essential for many physiological processes but the controls of calcium intake are not well understood [reviews [45,54]]. Blood ionized calcium may regulate calcium intake [30,51,54], perhaps by acting on calcium receptors in the brain [e.g., [32]]. Circulating levels of parathyroid hormone, calcitonin, and 1,25-dihydroxyvitamin D influence calcium intake [e.g., [12,30,43,51,61]] but it is unclear whether these effects are due to the direct action of the hormones on the brain or to their indirect actions on blood calcium levels. The most-studied control of calcium intake involves orosensory acceptance. Calcium deficiency lowers the behavioral and electrophysiological detection thresholds for calcium [25]. It also increases the avidity for concentrations of calcium that are disliked in the replete state: calcium deficiency increases calcium intakes in preference tests [14,25], the rate of shamingestion of calcium [34], the frequency of hedonically positive facial expressions during calcium consumption [33], and the response to oral calcium of sweet-best units in the nucleus of the solitary tract [35]. Ingestion or infusion of calcium can also condition preferences for arbitrary flavors [13,23,24,55]. Taken together, these findings argue that the oral modulation of calcium acceptance plays an important role in governing calcium consumption. Animals consume calcium solutions even when calcium is available in adequate amounts in the d...

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Independence of salt intake from the hormones regulating calcium homeostasis

Cited by 8 publications

References 0 publications

No effect of dietary calcium on body weight of lean and obese mice and rats

No effect of dietary calcium on body weight of lean and obese mice and rats

The importance of calcium in the control of salt intake

Forty mouse strain survey of voluntary calcium intake, blood calcium, and bone mineral content

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