Bone structural, biomechanical, and histomorphometric characteristics of the hindlimb skeleton in the marsh rice rat (Oryzomys palustris)

Abstract

The rice rat (Oryzomys palustris) is a nonconventional laboratory rodent species used to model some human bone disorders. However, no studies have been conducted to characterize the postcranial skeleton. Therefore, we aimed to investigate age‐ and gender‐related features of the hindlimb skeleton of this species. We used femurs and tibiae from 94 rats of both genders aged 4–28 weeks. Bone mineral content (BMC), volumetric bone mineral density (vBMD), and biomechanical properties were determined in femurs. In addition, bone histomorphometry of tibiae was conducted to assess bone cell activities and bone turnover over time. Bone length, total metaphysis BMC and vBMD, mid‐diaphyseal BMC and vBMD, cortical thickness, and cortical area progressively augmented with age. Whereas the increase in these parameters plateaued at age 16–22 weeks in female rats, they continued to rise to age 28 weeks in male rats. Furthermore, bone strength parameters increased with age, with few differences between genders. We also observed a rapid decrease in longitudinal growth between age 4 and 16 weeks. Whereas young rats had a greater bone formation rate and bone turnover, older rice rats had greater bone volume and trabecular thickness, with no differences between genders. (a) Sexual dimorphism in the rice rat becomes grossly evident at age 16 weeks; (b) the age‐related increases in bone mass, structural cortical parameters, and in some biomechanical property parameters plateau at an older age in male than in female rats; and (c) bone growth and remodeling significantly decreased with age irrespective of the gender.

Femoral Structure and Biomechanical Characteristics in Sanfilippo Syndrome Type-B Mice

“…Force and displacement were recorded temporally using TestStar II Software version 4.0 at a sampling rate of 205 Hz. Biomechanical properties from the 3-point bend were derived ( Figure 9 ) using methods previously described (N/mm), ultimate load (N), work to fracture (Nmm), elastic modulus (Mpa), and ultimate stress (Mpa) [ 37 ].…”

“…All pQCT, biomechanical, and histomorphometry variables were analyzed within each age group (three months, six months, and twelve months) using two-way ANOVA, considering independent variables, sex (male and female), and genotype (MPS IIIB and normal phenotype) using GraphPad Prism (version 10.0.2; Boston, MA, USA). For radiological data (pQCT), anomalies were excluded by removing samples with values two standard deviations from the mean for each respective experimental group [37]. All figures were created with BioRender.com under an academic license.…”