[Osteoporosis in monkeys after anti-orthostatic hypokinesia]

Using methods of quantitative histomorphometry, the effect of 15- and 30-day exposure to antiorthostatic hypokinesia (-10 degrees) on spongy bone of iliac crests and proximal metaphysis of tibia of Macaca mulatta was examined. It was found that the exposure caused osteoporosis of bone spongiosa. Osteoporotic changes increased progressively with time of exposure. Osteoporosis developed as a result of stimulated bone resorption, which was indicated by a greater resorption surface and a higher activity of osteoclasts, as well as inhibited bone neoformation, which was indicated by a lower osteoid volume. Comparative analysis of morphological changes in iliac and tibial bones demonstrated that they were distinct and similar in sign. Progressive development of osteoporosis gives evidence that 30-day antiorthostatic hypokinesia is insufficient for primates to get adapted to a new environment.