Bone mass changes in vivo during the entire reproductive cycle in rats feeding different dietary calcium and calcium/phosphorus ratio content

Supplementation of Calcium and Fluoride-Free Water Mitigates Skeletal Fluorosis in Fluoride-Intoxicated Rats

Fluorosis is a public health concern in 25 countries around the globe. The present study is about the mitigation of fluoride (F) toxicity by giving F-free water (FFW) and calcium (Ca). A study was conducted by taking 76 Wistar rats in two phases, phase I (6 months), where rats were randomly divided into four groups: normal-Ca diet (NCD) 0.5%; low-Ca diet (LCD) 0.25%; NCD + 100 ppm F and LCD + 100 ppm F in groups 1, 2, 3 and 4, respectively. F and Ca were given through water and diet respectively. Phase II is the reversal of fluorosis for 3 months, where LCD group 2 was treated with NCD. Groups 3 and 4 were divided into two subgroups each: 3X and 3Y, and 4X and 4Y, respectively. Groups 3X and 4X received FFW with NCD. Group 3Y continued as phase I and 4Y NCD and F. The biochemical expression, gene expression, biomechanical properties and DXA were studied by standard methods. The results revealed that in phase I, bone turnover was significantly increased whereas bone mineral content and biomechanical properties of group 4 were significantly decreased (p ≤ 0.05) as compared with that of all other groups. Trabecular separation and total porosity increased in groups 2 and 4. Expression of osteocalcin, osteonectin and osteopontin genes was significantly downregulated in group 4. Bone turnover in group 4X was normalised. Expressions of osteocalcin, osteonectin and osteopontin were upregulated after providing NCD and FFW. In conclusion, low calcium aggravates skeletal fluorosis which could be mitigated on supplementation of Ca and FFW.

Is bone loss a physiological cost of reproduction in the Great fruit-eating bat Artibeus lituratus?

During mammalian pregnancy and lactation, the maternal demand for calcium is increased to satisfy fetus and newborn skeletal growth. In addition to the dietary intake, females use the calcium contained in their bones to supply this increased demand, leading to a decrease in maternal bone mineral content. In reproductive insectivorous female bats, bone loss has been described as a physiological cost of reproduction, due to the reported increased risk of bone fracture. This physiological cost may be the mechanism underlying the conflict between increasing litter size and maintaining wing skeletal integrity, which would help to explain the small litter size of most bat species. If bone loss is a linking cost between reproduction and survival in bats, and most bat species have small litter sizes, one would expect to find a loss of bone and an increasing probability of bone fracture during pregnancy and lactation in other non-insectivorous bats. In this study, we tested for the existence of this cost in the Great-fruit eating bat, Artibeus lituratus. We analyzed trabecular structure, bone strength and bone mineral content for the humerus bone, hypothesizing that bone loss during reproduction in females would increase the risk of fracture. Our results showed a decrease of 22-31% in bone trabecular area in lactating females, rapidly compensated following weaning. Bone strength did not differ among reproductive and non-reproductive groups and seems to be more influenced by bone organic components rather than mineral contents. Since we observed bone loss during reproduction yet the humerus strength seems to be unaffected, we suggest that bone loss may not represent a physiological cost during reproduction for this frugivorous bat.

Effects of the intake of white wheat bread added with garlic and resistant starch: action on calcium bioavailability and metabolic parameters of growing Wistar rats

Functional bread with resistant starch and garlic improved the metabolism of calcium and lipids and the growth of beneficial gut microbiota.

Calcium economy in human pregnancy and lactation

Pregnancy and lactation are times of additional demand for Ca. Ca is transferred across the placenta for fetal skeletal mineralisation, and supplied to the mammary gland for secretion into breast milk. In theory, these additional maternal requirements could be met through mobilisation of Ca from the skeleton, increased intestinal Ca absorption efficiency, enhanced renal Ca retention or greater dietary Ca intake. The extent to which any or all of these apply, the underpinning biological mechanisms and the possible consequences for maternal and infant bone health in the short and long term are the focus of the present review. The complexities in the methodological aspects of interpreting the literature in this area are highlighted and the inter-individual variation in the response to pregnancy and lactation is reviewed. In summary, human pregnancy and lactation are associated with changes in Ca and bone metabolism that support the transfer of Ca between mother and child. The changes generally appear to be independent of maternal Ca supply in populations where Ca intakes are close to current recommendations. Evidence suggests that the processes are physiological in humans and that they provide sufficient Ca for fetal growth and breast-milk production, without relying on an increase in dietary Ca intake or compromising long-term maternal bone health. Further research is needed to determine the limitations of the maternal response to the Ca demands of pregnancy and lactation, especially among mothers with marginal and low dietary Ca intake, and to define vitamin D adequacy for reproductive women.

Calcium availability influences litter size and sex ratio in white-footed mice (Peromyscus leucopus)

The production of offspring typically requires investment of resources derived from both the environment and maternal somatic reserves. As such, the availability of either of these types of resources has the potential to limit the degree to which resources are allocated to reproduction. Theory and empirical studies have argued that mothers modify reproductive performance relative to exogenous resource availability and maternal condition by adjusting size, number or sex of offspring produced. These relationships have classically been defined relative to availability of energy sources; however, in vertebrates, calcium also plays a critical role in offspring production, as a considerable amount of calcium is required to support the development of offspring skeleton(s). We tested whether the availability of calcium influences reproductive output by providing female white-footed mice with a low-calcium or standard diet from reproductive maturity to senescence. We then compared maternal skeletal condition and reproductive output, based on offspring mass, offspring number and litter sex ratio, between dietary treatments. Mothers on the low-calcium diet exhibited diminished skeletal condition at senescence and produced smaller and strongly female-biased litters. We show that skeletal condition and calcium intake can influence sex ratio and reproductive output following general theoretical models of resource partitioning during reproduction.

[High-fat diets and body composition over two generations. An experimental study]

INTRODUCTION AND OBJECTIVE

Despite recent findings reported on the nutritional factors that induce epigenetic changes, little information is available at early ages. This study analyzed in an experimental model, over two generations, potential changes in body composition and potential expression of epigenetic changes as the result of the intake of isoenergetic diets with different fat levels.

MATERIALS AND METHODS

At weaning, Wistar female rats were divided into two groups that were fed either a control diet (fat=7% w/w) or a high-fat diet (15% w/w). Rats were mated at 70 days (M(1)) and their pups (P(1)) were the first generation; P(1) rats were mated at 70 days (M(2)) and their pups (P(2)) represented the second generation. At weaning, mothers and pups (M(1), M(2) and P(1), P(2)) were measured body weight (W) and composition (% body fat, %BF), and total skeleton bone mineral content (BMC), expressed as %BMC, using chemical and DXA methods respectively.

RESULTS

At weaning, high-fat diet groups M(2) and P(2) showed significant increases in W and %BF (p<0.05); increased %BF values were already found in the M(1) and P(1) groups (p<0.001). By contrast, %BMC significantly decreased in M(2) and P(2) rats (p<0.001).

CONCLUSION

This study demonstrates the need to review certain eating habits to avoid perpetuation of unhealthy patterns generation after generation.

Effect of dietary calcium (Ca) on body composition and Ca metabolism during growth in genetically obese (β) male rats

INTRODUCTION

Obese β rats may be a suitable model to evaluate the association between calcium intake (CaI) and obesity during growth.

OBJECTIVE

The present study comparatively evaluated Ca absorption and retention, and changes in body composition in spontaneously genetically obese (β) male rats fed three different dietary Ca levels: high 0.9% (HCa); normal: 0.5% (NCa); low: 0.2% (LCa).

METHODS

Pregnant rats were fed isocaloric diets which varied in Ca content only. Male pups continued feeding the same maternal diet until postnatal day 60. The percentage of Apparent Ca absorption (CaA %), Ca balance (CaB), body composition, glucose, triglycerides (TGL), and insulin levels were evaluated.

RESULTS

Food consumption and body weight (BW) were higher in Group LCa than in Groups NCa and HCa (p < 0.01); no differences were observed between the latter two groups. Group LCa presented the highest body fat, liver weight, perigonadal and retroperitoneal fat (p < 0.05); conversely, body ashes and total skeleton bone mineral content were significantly lower compared with animals in both the NCa (p < 0.01) and HCa groups (p < 0.01). CaB (mg/day) reached a plateau at the highest CaI (mg/day) value (r = 0.985, p < 0.001). CaA%, serum glucose, insulin, and TGL levels rose as CaI decreased (p < 0.01).

CONCLUSIONS

Although further studies are required, low Ca consumption in this strain of rats could modulate BW inducing changes in several lipid metabolism parameters, which in turn lead to an increase in body fat.

Protein deficiency and nematode infection during pregnancy and lactation reduce maternal bone mineralization and neonatal linear growth in mice

Using a 2 x 2 factorial design, we investigated the combined impact of protein deficiency (PD) and gastrointestinal nematode infection during late pregnancy and lactation on resting metabolic rate (RMR), body composition and bone mineralization, neonatal growth, and the regulatory hormones [corticosterone, leptin, and insulin-like growth factor-1 (IGF-1)] and proinflammatory cytokines [interleukin (IL)-1 beta and IL-6] that may drive these processes. Pregnant CD1 mice, fed either a protein-sufficient (PS; 24%) or protein-deficient (PD; 6%) isocaloric diet, were infected 4 times with either 0 (sham) or 100 Heligmosomoides bakeri larvae beginning on d 14 of pregnancy. Dams were killed on d 20 postpartum and pups on d 2, 7, 14, and 21. Diet and infection had largely independent effects. The PD diet elevated corticosterone and upregulated leptin concentration in maternal serum, which was associated with reduced food intake leading to lower body mass, RMR, and body temperature. Infection reduced food intake but elevated maternal serum IL-1 beta and IL-6 and did not affect corticosterone, leptin, RMR, or body temperature. The PD diet decreased maternal bone area and bone mineral content. Infection lowered maternal bone mineral density, consistent with elevated IL-1 beta and IL-6. The elevated serum IL-1 beta and lower IGF-1 in pups of PD dams and lower serum leptin and IGF-1 in pups of infected dams were both consistent with the lower pup body mass and shorter crown-rump length. This mouse model provides a novel framework to study the impact of diet and nematode infection on bone.

Concurrent nematode infection and pregnancy induce physiological responses that impair linear growth in the murine foetus

This study examined concurrent stresses of nematode infection and pregnancy using pregnant and non-pregnant CD1 mice infected 3 times with 0, 50 or 100 Heligmosomoides bakeri larvae. Physiological, energetic, immunological and skeletal responses were measured in maternal and foetal compartments. Resting metabolic rate (RMR) was elevated by pregnancy, but not by the trickle infection. Energy demands during pregnancy were met through increased food intake and fat utilization whereas mice lowered their body temperature during infection. Both infection and pregnancy increased visceral organ mass and both altered regional bone area and mineralization. During pregnancy, lumbar mineralization was lower but femur area and mineralization were higher. On the other hand, infection lowered maternal femur bone area and this was associated with higher IFN-γ in maternal serum of heavily infected pregnant mice. Infection also reduced foetal crown-rump length which was associated with higher amniotic fluid IL-1β.

Reversal of osteoporotic changes of mineral composition in femurs of diabetic rats by insulin

Insulin plays an important role in bone prevention of diabetic osteoporosis, but little is known about the relation between the bone mineral density (BMD) increase and the change of mineral element content after treated with insulin. To address this problem, male Wistar rats were randomly divided into three groups: normal group (n = 6), streptozotocin-induced diabetic group (n = 5), and streptozotocin-induced diabetic group with insulin treatment (n = 5). The femoral BMD was measured by dual energy X-ray absorptiometry, and the element content was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that the femoral BMD in diabetic group was significantly lower than that in normal group (P < 0.01) but restored by insulin treatment (P < 0.01 vs diabetic group). ICP-AES analysis revealed that the element content of calcium (Ca), phosphorous (P), magnesium (Mg), strontium (Sr), and potassium (K) in diabetic group were remarkably lower than those in normal group (P < 0.01) but only Ca, P, and Mg content were significantly increased compared with diabetic group (P < 0.05) after insulin treatment. However, no significant differences were observed in element zinc (Zn) content among three groups. Our findings suggested that the loss of Ca, P, Mg, Sr, and K content accounted for the lower BMD in streptozotocin-induced diabetes rats, insulin treatment could restore BMD by increasing the content of Ca, P, and Mg.

Effects of pregnancy and lactation on bone mineral density, and their relation to the serum calcium, phosphorus, calcitonin and parathyroid hormone levels in rats

The aim of this study was to evaluate the net changes in bone mineral density (BMD) during the reproductive cycle, and their relation with changes in serum calcium (Ca), phosphorus (P), PTH and calcitonin levels in rats. Twenty-seven female Wistar rats were included in this study. They were divided into three groups as pregnant, lactating and control groups. BMDs of lumbar vertebrates, femoral and tibial bones, and Ca, P, calcitonin and PTH levels were measured at the end of pregnancy, at the end of lactation and in nulliparous controls. In the pregnant group, the BMDs of rats were significantly higher in lumbar vertebrates, femoral and tibia bones than those of the control group (p<0.05). Their PTH and Ca levels were significantly lower than the control group (p<0.05). However, no statistically significant difference was found regarding P and calcitonin levels when compared to those of the control group. In the lactating group, the BMDs were significantly lower in lumbar vertebrates, femoral and tibia bones than those seen in the control and pregnant groups (p<0.05). Ca and PTH levels were significantly higher in lactating rats than in those of pregnant rats (p<0.005). Normal pregnancy increases BMD in rats, whereas lactation decreases it. Change in PTH levels is supposed to contribute to the mineralization and demineralization of the skeleton during pregnancy and lactation, respectively.