Additive effects of dietary protein and energy deficiencies on diaphysis and bone tissue of rat femurs as determined by bending tests

Abstract

The present study was designed to study the effects of diets moderately restricted in protein and/or carbohydrate derived calories on morphometric parameters (geometric properties) and mechanical performance of both diaphysis (structural properties) and cortical bone tissue (material properties) from growing rat femurs, as determined by bending tests at low strain rates. Male rats aged 30 days were divided in four groups, namely NN = normal protein and energy, NPLE = normal protein and low energy, LP = low protein and normal energy, and LPLE = low protein and low energy. Each group was fed on a corresponding diet for 20 days. Both body weight and femoral length were greater in NN and lower in LL than in LE and LP groups. Geometrical and structural variables (with the exception of wall/lumen ratio) grossly paralleled changes in body weight, while material properties showed independent and less significant changes. Therefore, the assayed levels of restriction of either plastic or energetic nutrients seemed to alter bone biomechanics proportionally to the way it affected bone growth.