Calorie restriction aggravated cortical and trabecular bone architecture in ovariectomy-induced estrogen-deficient rats

Moderate caloric restriction improved body composition and maintains bone quality of rats under hypoestrogenism

BACKGROUND

Hypoestrogenism state is associated with weight and adiposity gain, generally impairing bone properties. Caloric restriction (CR) is the main intervention to promote weight loss, however, a chronic severe restriction can lead to bone loss and malnutrition.

OBJECTIVE

To analyse whether 12 weeks of moderate CR could reduce body mass and adiposity without worsening the bone health of ovariectomized (OVX) rats.

METHODS

CR and OVX-CR animals were subject daily to receive a 20 % less amount of food based on the last week's consumption of C and OVX groups. Body mass and food intake were recorded weekly, and spontaneous physical activity (SPA) biweekly. The adipose tissue of subcutaneous (SAT), peritoneal (PTAT), and perigonadal (PGAT) portions was collected to record its mass, and the right femur was collected to determine bone volume (BV), density (BD), mineral density (BMD), and percentage of mineral material (MM).

RESULTS

Ovariectomy increased body mass and food intake (p < 0.001), SAT, PTAT, and PGAT mass (p < 0.01), decreased BV (p < 0.05), BD and BMD (p < 0.01) and MM (p < 0.05), but not affected SPA (p = 0.16). CR decreased body mass, SAT, PTAT, and PGAT mass (p < 0.01) and BMD and MM (p < 0.05), but did not affect BV (p = 0.90), BD (p = 0.24), and SPA (p = 0.25). Therefore, post-hoc data did not demonstrate significant differences in these bone parameters between the OVX and OVX-RC groups (p > 0.05).

CONCLUSION

12 weeks of 20 % of CR is enough to prevent weight and fat gain in the hypoestrogenism state without causing additional worsening in bone properties.

Refeeding partially reverses impaired fracture callus in undernourished rats

Background

Adequate nutritional intake plays a crucial role in maximizing skeletal acquisition. The specific effects of a general food restriction and refeeding on fracture healing are yet to be fully understood. The aim of this study was to assess the impact of general food restriction and refeeding on fracture repair.

Methods

Fifty-four male Wistar Hannover rats were randomly assigned into three groups: (1) Sham: Sham rats with femoral fracture; (2) FRes: Food-restricted rats with fracture, (3) Fres+Ref: Fres rats with refeeding. Following weaning, the FRes and Fres+Ref groups received 50% of the food amount provided to the Shams. In the sixth week of the experiment, all animals underwent a mid-right femur bone fracture, which was subsequently surgically stabilized. Following the fracture, the Fres+Ref group was refed, while the other groups maintained their pre-fracture diet. Bone calluses were analyzed on the fifth-day post-fracture by gene expression and on the sixth-week post-fracture using dual-energy X-ray absorptiometry, morphometry, histomorphometry, immunohistochemistry, computed microtomography, and torsion mechanical testing. Statistical significance was determined at a probability level of less than 0.05, and comparisons were made using the ANOVA test.

Results

Food restriction resulted in significant phenotypic changes in bone calluses when compared to sham rats characterized by deterioration in microstructure (i.e., BV, BV/TV, Tb.N, and Conn.D) reduced collagen deposition, bone mineral density, and mechanical strength (i.e., torque at failure, energy, and stiffness). Moreover, a higher rate of immature bone indicated a decrease in bone callus quality. Refeeding stimulated bone callus collagen formation, reduced local resorption, and effectively restored the microstructural (i.e., SMI, BCa.BV/TV, Tb.Sp, Tb.N, and Conn.D) and mechanical changes (i.e., torque at failure, energy, and angular displacement at failure) caused by food restriction. Despite these positive effects, the density of the bone callus, collagen deposition, and OPG expression remained lower when compared to the shams. Gene expression analysis didn't evidence any significant differences among the groups.

Conclusions

Food restriction had detrimental effects on osseous healing, which was partially improved by refeeding. Based on these findings, new research can be developed to create targeted nutritional strategies to treat and improve fracture healing.

The Effects of Different Dietary Patterns on Bone Health

Bone metabolism is a process in which osteoclasts continuously clear old bone and osteoblasts form osteoid and mineralization within basic multicellular units, which are in a dynamic balance. The process of bone metabolism is affected by many factors, including diet. Reasonable dietary patterns play a vital role in the prevention and treatment of bone-related diseases. In recent years, dietary patterns have changed dramatically. With the continuous improvement in the quality of life, high amounts of sugar, fat and protein have become a part of people's daily diets. However, people have gradually realized the importance of a healthy diet, intermittent fasting, calorie restriction, a vegetarian diet, and moderate exercise. Although these dietary patterns have traditionally been considered healthy, their true impact on bone health are still unclear. Studies have found that caloric restriction and a vegetarian diet can reduce bone mass, the negative impact of a high-sugar and high-fat dietary (HSFD) pattern on bone health is far greater than the positive impact of the mechanical load, and the relationship between a high-protein diet (HPD) and bone health remains controversial. Calcium, vitamin D, and dairy products play an important role in preventing bone loss. In this article, we further explore the relationship between different dietary patterns and bone health, and provide a reference for how to choose the appropriate dietary pattern in the future and for how to prevent bone loss caused by long-term poor dietary patterns in children, adolescents, and the elderly. In addition, this review provides dietary references for the clinical treatment of bone-related diseases and suggests that health policy makers should consider dietary measures to prevent and treat bone loss.

Associations between special diet and incidence risk of osteoporosis: a Mendelian randomization study

Introduction

Osteoporosis is a prevalent challenge in clinical orthopedics, affecting a significant percentage of individuals aged 50 and above. The goal of this study was to comprehensively understand the relationships between a specialized dietary regimen and the risk of developing osteoporosis.

Methods

This study employed extensive genome-wide association study (GWAS) summary statistics derived from the UK Biobank. It encompassed 8 kinds of special diets and 7 datasets pertaining to osteoporosis and associated symptoms. The principal analytical approach employed was the inverse-variance weighted method. Additionally, sensitivity analysis was employed to elucidate the diverse multiplicity patterns observed in the final model.

Results

Our results showed that there is significant evidence that a gluten-free diet is associated with osteoporosis [odds ratio (OR): 1.080, 95% confidence interval (CI): 1.048-1.112, p = 4.23E-07)]. Furthermore, there exists a suggestive link between the three distinct dietary approaches and osteoporosis [(OR: 0.949, 95%CI: 0.929-0.970, p = 3.00E-06) for comprehensive consumption; (OR: 1.053, 95%CI: 1.018-1.089, p = 2.23E-03) for abstaining from wheat consumption; (OR: 1.036, 95%CI: 1.005-1.068, p = 1.97E-02) for abstaining from sugar consumption]. No additional correlation between the special dietary regimens and osteoporosis has been observed.

Conclusion

Our research has uncovered a notable correlation between a gluten-free diet and the occurrence of osteoporosis. Furthermore, it exerts a promoting influence on the onset of osteoporosis, which stands in direct contradiction to the therapeutic principles for Celiac Disease's complications. As such, a novel association among these three elements is postulated.

Changes in bone mass associated with obesity and weight loss in humans: Applicability of animal models

The implications of obesity and weight loss for human bone health are not well understood. Although the bone changes associated with weight loss are similar in humans and rodents, that is not the case for obesity. In humans, obesity is generally associated with increased bone mass, an outcome which is exacerbated by advanced age and menopause. In rodents, by contrast, bone mass decreases in proportion to severity and duration of obesity, and is influenced by sex, age and mechanical load. Despite these discrepancies, rodents are frequently used to model the situation in humans. In this review, we summarise the existing knowledge of the effects of obesity and weight loss on bone mass in humans and rodents, focusing on the translatability of findings from animal models. We then describe how animal models should be used to broaden the understanding of the relationship between obesity, weight loss, and skeletal health in humans. Specifically, we highlight the aspects of study design that should be considered to optimise translatability of the rodent models of obesity and weight loss. Notably, the sex, age, and nutritional status of the animals should ideally match those of interest in humans. With these caveats in mind, and depending on the research question asked, our review underscores that animal models can provide valuable information for obesity and weight-management research.

Effects of Biliopancreatic Diversion on Bone Turnover Markers and Association with Hormonal Factors in Patients with Severe Obesity

BACKGROUND

This study evaluated early and medium-term changes in bone turnover markers, and their associations with weight loss, total bone mineral density (BMD), and hormonal changes after biliopancreatic diversion (BPD).

METHODS

Ancillary study from a one-year prospective cohort of 16 individuals assessed before, 3 days, 3 and 12 months after BPD. Bone turnover markers (C-terminal telopeptide (CTX), intact osteocalcin (OC), sclerostin, and osteoprotegerin (OPG)) and several hormones were measured at each visit. Total BMD by DXA was assessed at baseline, 3 and 12 months after BPD. Three participants were lost to follow-up.

RESULTS

CTX increased significantly at 3 days (+ 66%), 3 months (+ 219%), and 12 months (+ 295%). OC decreased at 3 days (- 19%) then increased at 3 months (+ 69%) and 12 months (+ 164%). Change in sclerostin was only significant between 3 days and 3 months (+ 13%), while change in OPG was significant between baseline and 3 days (+ 48%) and baseline and 12 months (+ 45%). CTX increase correlated negatively with weight loss at 3 (r = - 0.63, p = 0.009) and 12 months (r = - 0.58, p = 0.039), and total BMD decrease (r = - 0.67, p = 0.033) at 12 months. Change in insulin and adiponectin correlated with changes in bone turnover markers independently of weight loss.

CONCLUSION

BPD causes an earlier and greater increase in bone resorption over bone formation markers and a decrease in total BMD. Sclerostin did not increase as expected following extensive weight loss. Changes in insulin and adiponectin seem to play a role in the activation of bone remodeling after BPD.

Bone callus formation is highly disrupted by dietary restriction in growing rats sustaining a femoral fracture1

PURPOSE

To evaluate the effects of food restriction on fracture healing in growing rats.

METHODS

Sixty-eight male Wistar rats were assigned to two groups: (1) Control and (2) Dietary restriction. After weaning the dietary restricted animals were fed ad libitum for 42 days with 50% of the standard chow ingested by the control group. Subsequently, the animals underwent bone fracture at the diaphysis of the right femur, followed by surgical stabilization of bone fragments. On days 14 and 28 post-fracture, the rats were euthanized, and the fractured femurs were dissected, the callus was analyzed by dual-energy X-ray absorptiometry, micro-computed tomography, histomorphometry, mechanical tests, and gene expression.

RESULTS

Dietary restriction decreased body mass gain and resulted in several phenotypic changes at the bone callus (a delay in cell proliferation and differentiation, lower rate of newly formed bone and collagen deposition, reductions in bone callus density and size, decrease in tridimensional callus volume, deterioration in microstructure, and reduction in bone callus strength), together with the downregulated expression of osteoblast-related genes.

CONCLUSION

Dietary restriction had detrimental effects on osseous healing, with a healing delay and a lower quality of bone callus formation.

Progenitor recruitment and adipogenic lipolysis contribute to the anabolic actions of parathyroid hormone on the skeleton

Intermittent administration of parathyroid hormone (PTH) stimulates bone formation in vivo and also suppresses the volume of bone marrow adipose tissue (BMAT). In contrast, a calorie-restricted (CR) diet causes bone loss and induces BMAT in both mice and humans. We used the CR model to test whether PTH would reduce BMAT in mice by both altering cell fate and inducing lipolysis of marrow adipocytes. Eight-week-old mice were placed on a control (Ctrl) diet or CR diet. At 12 wk, CR and Ctrl mice were injected daily with PTH (CR/PTH or Ctrl/PTH) or vehicle for 4 wk. Two other cohorts were CR and simultaneously injected (CR + PTH or CR + Veh) for 4 wk. CR mice had low bone mass and increased BMAT in the proximal tibias. PTH significantly increased bone mass in all cohorts despite calorie restrictions. Adipocyte density and size were markedly increased with restriction of calories. PTH reduced adipocyte numbers in CR + PTH mice, whereas adipocyte size was reduced in CR/PTH-treated mice. In contrast, osteoblast number was increased 3-8-fold with PTH treatment. In vitro, bone marrow stromal cells differentiated into adipocytes and, treated with PTH, exhibited increased production of glycerol and fatty acids. Moreover, in cocultures of bone marrow adipocyte and osteoblast progenitors, PTH stimulated the transfer of fatty acids to osteoblasts. In summary, PTH administration to CR mice increased bone mass by shifting lineage allocation toward osteogenesis and inducing lipolysis of mature marrow adipocytes. The effects of PTH on bone marrow adiposity could enhance its anabolic actions by providing both more cells and more fuel for osteoblasts during bone formation.-Maridas, D. E., Rendina-Ruedy, E., Helderman, R. C., DeMambro, V. E., Brooks, D., Guntur, A. R., Lanske, B., Bouxsein, M. L., Rosen, C. J. Progenitor recruitment and adipogenic lipolysis contribute to the anabolic actions of parathyroid hormone on the skeleton.

Soy protein improves tibial whole-bone and tissue-level biomechanical properties in ovariectomized and ovary-intact, low-fit female rats

BACKGROUND

Osteoporosis and related fractures, decreased physical activity, and metabolic dysfunction are serious health concerns for postmenopausal women. Soy protein might counter the negative effects of menopause on bone and metabolic health due to the additive or synergistic effects of its bioactive components.

OBJECTIVE

To evaluate the effects of ovariectomy (OVX) and a soy-protein diet (SOY) on bone outcomes in female, low-capacity running (LCR) rats selectively bred for low aerobic fitness as a model of menopause.

METHODS

At 27 weeks of age, LCR rats (N = 40) underwent OVX or sham (SHAM) surgery and were randomized to one of two isocaloric and isonitrogenous plant-protein-based dietary treatments: 1) soy-protein (SOY; soybean meal); or, 2) control (CON, corn-gluten meal), resulting in four treatment groups. During the 30-week dietary intervention, animals were provided ad libitum access to food and water; body weight and food intake were measured weekly. At completion of the 30-week intervention, body composition was measured using EchoMRI; animals were fasted overnight, euthanized, and blood and hindlimbs collected. Plasma markers of bone formation (osteocalcin, OC; N-terminal propeptide of type I procollagen, P1NP) and resorption (tartrate-resistant acid phosphatase, TRAP5b; C-terminal telopeptide of type I collagen, CTx) were measured using ELISA. Tibial trabecular microarchitecture and cortical geometry were evaluated using μCT; and torsional loading to failure was used to assess cortical biomechanical properties. Advanced glycation end-product (AGE) content of the femur was measured using a fluorimetric assay, and was expressed relative to collagen content measured by a colorimetric OH-proline assay. Two-factor ANOVA or ANOVCA was used to test for significant main and interactive effects of ovarian status (OV STAT: OVX vs. SHAM) and DIET (SOY vs. CON); final body weight was included as a covariate for body-weight-dependent cortical geometry and biomechanical properties.

RESULTS

OVX had significantly greater CTx than SHAM; SOY did not affect bone turnover markers. OVX adversely affected trabecular microarchitecture as evidenced by reduced BV/TV, trabecular thickness (Tb.Th), trabecular number (Tb.N), and connectivity density (Conn.D), and by increased trabecular separation (Tb.Sp) and structural model index (SMI). SOY increased BV/TV only in ovary-intact animals. There was no effect of OVX or SOY on tibial cortical geometry. In SHAM and OVX rats, SOY significantly improved whole-bone strength and stiffness; SOY also increased tissue-level stiffness and tended to increase tissue-level strength (p = 0.067). There was no effect of OVX or SOY on AGE content.

CONCLUSION

Soy protein improved cortical bone biomechanical properties in female low-fit rats, regardless of ovarian hormone status.

Soy isoflavone supplementation improves longitudinal bone growth and bone quality in growing female rats

OBJECTIVES

The aim of this study was to investigate the effects of soy isoflavone on tibia length, bone mineral density (BMD), and structural parameters in growing female rats.

METHODS

Three-week-old female Sprague-Dawley rats were randomly assigned to four experimental groups: control (CON: distilled water gavage); low-dose isoflavone (low-IF: 10 mg/kg body weight [BW]/d gavage); high-dose isoflavone (high-IF: 50 mg/kg BW/d gavage); and 17 β-estradiol (E2: subcutaneous injection of 10 μg). All animals received a soy-free diet and vaginal opening was monitored daily. After an 8-wk treatment period, bone-related parameters (alkaline phosphatase [ALP], osteocalcin [OC], N-terminal telopeptide [NTx], bone length, failure load, stiffness, BMD, and structural parameters) were analyzed.

RESULTS

Serum ALP levels of the high-IF group were higher than those of the CON group (P < 0.05); however, serum OC levels of the high-IF group were lower than those of the CON, low-IF, and E2 groups (P < 0.05). The tibias and femurs of the low-IF group were longer than those of the CON and high-IF groups (P < 0.05). Bone volume, trabecular number, and BMD of trabecular bone of the high-IF and E2 groups were higher than those of the CON and low-IF groups (P < 0.05). The trabecular thickness of the high-IF group was higher than that of the CON and low-IF groups (P < 0.05). The failure load of the high-IF group was higher than those of the CON group (P < 0.05). Age and body weight at vaginal opening of the E2 group were significantly lower than those of the CON, low-IF, and high-IF groups (P < 0.05).

CONCLUSIONS

This study suggests that 8 wk of low-dose supplementation with soy isoflavone stimulates longitudinal bone growth. Additionally, high-dose supplementation with soy isoflavone may improve bone quality (BMD and structural parameters) in growing female rats.

Bone Mineral Density and Cognitive Decline in Elderly Women: Results from the InCHIANTI Study

Osteoporosis and cognitive impairment, which are highly prevalent conditions in elderly populations, share several risk factors. This study aims at evaluating the association of bone mineral density (BMD) with prevalent and incident cognitive impairment after a 3-year follow-up. We studied 655 community-dwelling women aged 65+ participating in the InCHIANTI study, who had been followed for 3 years. Total, trabecular, and cortical BMD were estimated by peripheral quantitative computed tomography using standard transverse scans at 4 and 38 % of the tibial length. Cognitive performance was evaluated using the Mini-Mental State Examination and the Trail Making Tests (TMT) A and B; a MMSE score <24 was adopted to define cognitive impairment. The TMT A-B score was calculated as the difference between TMT-A and TMT-B times (ΔTMT). The association of cognitive performance after 3 years with baseline indices of BMD was assessed by logistic and linear regression analyses. Cortical, but not trabecular, BMD was independently associated with incident cognitive impairment (OR 0.93, 95 % CI 0.88-0.98; P = 0.012), worsening cognitive performance (OR 0.96, 95 % CI 0.92-0.98; P = 0.039), and worsening performance in ΔTMT (OR 0.96, 95 % CI 0.92-0.99; P = 0.047). Increasing cortical BMD tertiles was associated with decreasing probability of incident cognitive impairment (P for linear trend =0.001), worsening cognitive performance (P = 0.013), and a worsening performance below the median value (P for linear trend <0.0001). In older women, low BMD might represent an independent and early marker of subsequent cognitive impairment. Physicians should assess and monitor cognitive performance in the routine management of elderly women with osteoporosis.