The effect of fructan-enriched diet on bone turnover parameters in ovariectomized rats under calcium restriction

Introduction. Osteoporosis, the “quiet epidemic”, is one of the most serious threats to public health. It is known that estrogen plays a significant role in the regulation of bone turnover, and its loss at menopause causes osteoporosis. Added to this, insufficient calcium intake accelerates bone mass loss, increasing the risk of fractures. Objective. The study aimed to answer the question whether a fructan-enriched diet could be helpful in preventing from disturbances in bone turnover caused by calcium restriction combined with ovariectomy-induced estrogen deficiency. The differences related to the kind of fructan and “matrix effect” of fructan action (form of addition) were also evaluated. Materials and method. The study was conducted using sham-operated (control groups) or ovariectomized (OVX) rats fed a calcium restricted diet. The treatment diets contained one of three fructan sources – Jerusalem artichoke, yacon and Beneo Orafti Synergy1 – added alone or as an ingredient of strawberry sorbet, all in the amount providing 8% fructans. Analyses of biological material included: serum Ca, Mg and P concentrations, alkaline phosphatase activity (ALP), osteocalcin (OC) and C-telopeptide degradation products from type I collagen (CTX). Densitometric parameters of femora were also assayed. Results. Among markers of bone turnover, the ALP activity depended both on the kind of fructan and the form of addition. The highest value was shown in the OVX group fed a low-calcium diet, whereas administration of diet enriched with Jerusalem artichoke led to an almost 50% decrease in the value of this parameter. Dietary fructans also lowered the OC level. Feeding rats with diet containing sorbet enriched in yacon or Jerusalem artichoke resulted in a decrease of CTX, compared to the diet containing yacon alone or fructan formulation in both forms No significant differences were observed in densitometric parameters between treatment groups. Conclusions. The obtained findings suggest that fructan administration with a calcium-restricted diet might exert a positive effect on bone turnover parameters. Regarding the form of their addition, it is possible that other constituents of sorbets contributed to the fructan action. It remains open whether this impact would be significant over a longer period of time

Nesfatin-1 prevents negative changes in bone in conditions of developing osteopenia

Objective. The aim of the study was to determine the effect of nesfatin-1 on bone properties in female rats in the conditions of developing osteopenia induced by ovariectomy (OVX). Materials and method. The experiment was performed on 21 female Wistar rats assigned to 3 groups receiving intraperitoneally physiological saline (SHO, OVX-PhS) and nesfatin-1 in dose 2 μg/kg BW of (OVX-NES) once a day for 8 wks. At the end of the experiment, the rats were scanned using the DXA method to determine the body composition, tBMC, and tBMD. The isolated femora and tibia were tested with the DXA method for BMD and BMC, and with the pQCT method for separate analysis of the cortical and trabecular bone tissue. The bone strength parameters were also determined. The immunohistochemical method was used for determination of nesfatin-1 localization in growth cartilage. Bone metabolism markers (osteocalcin, bALP, and NTx) were identified using an ELISA kit. Results. OVX exerts a negative effect on bone tissue. The nesfatin-1 administration influenced positively the DXA parameters of tibia. TvBMD and TbvBMD measured by pQCT in metaphysis of bones were significantly higher in the OVX-NES group than in OVX-PhS. No differences were found in the values of bone strength parameters between SHO and OVX-NES females. Extra- and intracellular immunohistochemical reaction for nesfatin-1 was observed in all zones of growth cartilage, with the strongest reaction detected in the calcifying zone. Nesfatin-1 administration caused a significant increase in the osteocalcin and bALP concentration in relation to the OVX-PhS animals. Conclusion. The results of the experiment indicate that nesfatin-1 exerts a protective effect on bone tissue properties and can be used in the prevention of osteoporosis

Bone losses in obese, ovariectomized rats appear to be independent from sclerostin-induced inhibition of the Wnt/β-catenin pathway

Introduction. Overweight and obesity, as well as a gonadal function, are pivotal factors influencing bone tissue metabolism. Materials and method. The aim of the study was to determine the effect of dietary induced obesity (DIO) on bone tissue metabolism in sham-operated (SHO) or ovariectomized (OVX) adult female Wistar rats. Additionally, the influence of DIO in SHO or OVX on the concentration of sclerostin in the blood serum was analyzed. After SHO or OVX, the rats were placed in groups (n=8) and either received a standard diet (11.5 MJ/kg) (SHO-CON; OVX-CON) or a high-energy diet (17.6 MJ/kg) (SHO-FAT; OVX-FAT). The experiment lasted for 90 days and allowed for the establishment of osteopenia in OVX females and obesity in the rats that had received the high-energy diet. Results. The results of the study demonstrate that obesity or/and ovariectomy increases the resorption of femora and tibiae, hence decreasing the densitometric and mechanical parameters affecting the bone structure in adult females rats. The strongest osteodegenerative effect was seen in the OVX-FAT females. Interestingly, the degree of bone tissue degradation caused exclusively by ovariectomy was similar to that found in the obese sham-operated rats. Conclusions. Bone losses invoked by DIO seem to be independent from the Wnt/β-catenin pathway inhibition induced by sclerostin. While further study is necessary, the obtained results suggest that the usage of sclerostin anti-body in the treatment of osteoporosis can be ineffective, and in obese patients the undertaking of such therapy should be reassessed

Could fructan sources in strawberry matrix be more effective as a tool for improvement of bone structure than these compounds added to diet alone? - Study on osteopenic rat model

Introduction. Osteoporosis, a disease associated with ovarian hormone deficiency following menopause, is the most common cause of age-related bone loss. Although an optimal intake of Ca is vital – both bone accretion during growth and maintenance in adult life – a great percentage of the population consumes far below the recommended amounts of this mineral. On the other hand, there are evidences that fructans enhance not only Ca absorption, but bone calcium as well. Objective. In the knowledge that estrogen deficiency and insufficient Ca in the diet during postmenopause cause serious problems with resultant osteoporosis, the aim of this study is to assess the effects of a diet enriched in fructan-containing sources alone, or in the “strawberry matrix”, on the structure of bone in OVX rats under calcium hypoalimentation. Materials and method. Experimental animals were female Wistar rats, sham-operated or ovariectomized. The treatment with Ca-restricted diets also contained one of the sources of fructan (Jerusalem artichoke, yacon, Beneo Orafti Synergy1), in the amount providing 8% of fructans. Femur architecture of rats was assessed by tomography and Ca content by the AAS method. Results. Ovariectomy led to a significant decrease in femoral Ca content, total mineral content and bone density of rats. This study shows that a diet containing inulin-type fructan (especially as a component of strawberry product) improved bone quality (i.e. increase in Ca content in femur, total density in middle part of bone, as well as decrease of endosteal circumference) in OVX rats under calcium hypoalimentation. Conclusions. These findings suggest that a fructan-enriched diet could be potentially useful for postmenopausal osteoporosis. It is important to determine an optimal dietary level of fructan with the long-term goal of developing a dietary strategy in osteoporosis prevention