Development of HFD‐Fed/Low‐Dose STZ‐Treated Female Sprague‐Dawley Rat Model to Investigate Diabetic Bone Fragility at Different Organization Levels

Abstract

Type 2 diabetes (T2D) adversely affects the normal functioning, intrinsic material properties, and structural integrity of many tissues, and bone fragility is one of them. To simulate human T2D and to investigate diabetic bone fragility, many rodent diabetic models have been developed. Still, an outbred genetically normal nonobese diabetic rat model is not available that can better simulate the disease characteristics of nonobese T2D patients, who have a high prevalence in Asia. In this study, we used a combination treatment of high-fat diet (4 weeks, 58% kcal as fat) and low-dose streptozotocin (STZ; 35 mg/kg i.p. at the end of the fourth week) to develop T2D in female Sprague-Dawley (SD) rats. After 8 weeks of the establishment of the T2D model, the femoral bones were excised after euthanizing rats (animal age approximately 21 to 22 weeks; n = 10 with T2D, n = 10 without diabetes). The bone microstructure (μCT), mechanical, and material properties (three-point bending, cyclic reference point indentation, nanoindentation), mean mineral crystallite size (XRD), bone composition (mineral-to-matrix ratio, nonenzymatic cross-link ratio [NE-xLR], Fourier transform-infrared microspectroscopy), and total fluorescent advanced glycation end products were analyzed. We found that diabetic bone had reduced whole-bone strength and compromised structural properties (μCT). The NE-xLRs were elevated in the T2D group, and strongly and negatively correlated with postyield displacement, which suggests bone fragility was caused by a lack of glycation control. Along with that, the decreased mineral-to-matrix ratio and modulus, increased indentation distance increase, and wider mineral crystallite size in the T2D group were evidence that the diabetic bone composition and material properties had changed, and bone became weaker with a tendency to easily fracture. Altogether, this model simulates the natural history and metabolic characteristics of late-stage T2D (insulin resistance and as disease progress develops, hypoinsulinemia) for nonobese young (and/or adolescent) T2D patients (Asians) and provides potential evidence of diabetic bone fragility at various organization levels.

Can fingernail quality predict bone damage in Type 2 diabetes mellitus? a pilot study

“…In contrast, the previous study published from our institution reported lower BV/TV in individuals with T2DM and fragility fractures [14]. It is also possible that our study finding of lower BV/TV in diabetes is related to the distinct phenotypes of Asians [30,[34][35][36][37][38].…”

“…cortical bone quality making the bone weaker and prone to fragility fractures. The presence of T2DM reduces whole bone strength, compromises structural properties (μCT), and increases AGEs [30]. In another study on individuals with T2DM and known fragility fracture, we have shown that diabetes adversely affects the trabecular bone quality at multiple organization levels.…”

Diosmin, a citrus fruit-derived phlebotonic bioflavonoid protects rats from chronic kidney disease-induced loss of bone mass and strength without deteriorating the renal function

“…The yield point was determined with a 0.2% offset method. 55 2.9.2 Bone mechanical properties by nanoindentation. The cross-section of femur mid-diaphysis was cut with a low-speed diamond blade saw (IsoMet; Buehler, Lake Bluff, IL, USA), and then embedded in epoxy for 2 h for proper cure.…”

“…The load sequence include a loading time of 10 s, an unloading segment, and a hold for 10 s. The resultant, load-displacement curves were analyzed to determine the reduced modulus (Er) and hardness (H) by the method of Oliver and Pharr. 55,56…”

“…Load-displacement data was collected, which was further normalized in stress-strain using bending equation as described in a previous study. 55 From the load-displacement plots, we calculated maximum load, maximum displacement, stiffness, and total energy to fracture. Parameters calculated from stress-strain plots include elastic limit, yield strength, Young modulus, modulus of resilience, modulus of toughness, ultimate strength, fracture point stress, and fracture strain.…”