Negligible Effect of Estrogen Deficiency on Development of Skeletal Changes Induced by Type 1 Diabetes in Experimental Rat Models

Abstract

Although postmenopausal osteoporosis often occurs concurrently with diabetes, little is known about interactions between estrogen deficiency and hyperglycemia in the skeletal system. In the present study, the effects of estrogen deficiency on the development of biochemical, microstructural, and mechanical changes induced by streptozotocin-induced diabetes mellitus (DM) in the rat skeletal system were investigated. The experiments were carried out on nonovariectomized (NOVX) and ovariectomized (OVX) control and diabetic mature female Wistar rats. Serum levels of bone turnover markers (CTX-I and osteocalcin) and 23 cytokines, bone mass and mineralization, histomorphometric parameters, and mechanical properties of cancellous and compact bone were determined. The results were subjected to two-way ANOVA and principal component analysis (PCA). Estrogen deficiency induced osteoporotic changes, with increased bone resorption and formation, and worsening of microstructure (femoral metaphyseal BV/TV decreased by 13.0%) and mechanical properties of cancellous bone (the maximum load in the proximal tibial metaphysis decreased by 34.2%). DM in both the NOVX and OVX rats decreased bone mass, increased bone resorption and decreased bone formation, and worsened cancellous bone microarchitecture (for example, the femoral metaphyseal BV/TV decreased by 17.3% and 18.1%, respectively, in relation to the NOVX controls) and strength (the maximum load in the proximal tibial metaphysis decreased by 35.4% and 48.1%, respectively, in relation to the NOVX controls). Only in the diabetic rats, profound increases in some cytokine levels were noted. In conclusion, the changes induced by DM in female rats were only slightly intensified by estrogen deficiency. Despite similar effects on bone microstructure and strength, the influence of DM on the skeletal system was based on more profound systemic homeostasis changes than those induced by estrogen deficiency.

Effect of Administration of Azithromycin and/or Probiotic Bacteria on Bones of Estrogen-Deficient Rats

“…However, bone loss (decreases in the ratios of bone mass and bone mineral mass to body mass) led to significant decreases in bone strength. The changes in cancellous bone (mechanical properties of the proximal tibial metaphysis and histomorphometric parameters of the femoral epiphysis and metaphysis) were much more significant than those in compact bone (mechanical properties of the tibial diaphysis), consistent with our previous studies [ 67 , 68 ]. Taking into account the abovementioned relations between osteoporosis and changes in the intestinal microbiome, we studied the effects of LR and AZM on the development of skeletal changes in OVX rats.…”

“…The histomorphometric measurements of the longitudinal cross-sections of the distal femoral metaphysis and epiphysis were performed on decalcified preparations that were stained with hematoxylin and eosin, prepared as previously described [ 68 , 71 , 72 ], and the measurements of the transverse cross-sections of the femoral diaphysis were made on undecalcified, unstained slides of the femoral diaphysis, prepared as previously described [ 5 , 68 , 71 , 72 ].…”

“…To determine the mechanical properties of the proximal tibial metaphysis, the epiphysis was removed before the test, and the test was performed as previously described [ 67 , 68 , 87 ]. The support points were the edge of the proximal tibial metaphysis and the location of the fibula attachment to the tibial bone.…”

Silymarin from Milk Thistle Fruits Counteracts Selected Pathological Changes in the Lenses of Type 1 Diabetic Rats

“…In another study performed in the rats with type 2 diabetes, a similar pattern was observed—diabetic groups merged together and separated from the nondiabetic cluster [ 103 ]. Moreover, in a different study on rats with type 1 diabetes and estrogen deficiency, a PCA revealed that the effect of estrogen deficiency was negligible and was clearly dominated by the diabetes effect [ 104 ]. Contrary to ANOVA, which makes it possible to compare every single parameter according to quantitative differences, PCA is a qualitative analysis that provides information on the significance of all the measured parameters on total observed variance, highlighting these which affect this variability the most, even if they are not significant in quantitative comparisons [ 104 , 105 ].…”

“…Moreover, in a different study on rats with type 1 diabetes and estrogen deficiency, a PCA revealed that the effect of estrogen deficiency was negligible and was clearly dominated by the diabetes effect [ 104 ]. Contrary to ANOVA, which makes it possible to compare every single parameter according to quantitative differences, PCA is a qualitative analysis that provides information on the significance of all the measured parameters on total observed variance, highlighting these which affect this variability the most, even if they are not significant in quantitative comparisons [ 104 , 105 ]. In the case of the serum, the most important parameters affecting the total variance and cluster formation were glucose and fructosamine, and then MDA, whose high levels were correlated with groups of rats with type 1 diabetes.…”