[Age-related characteristics of osteopenia in rats caused by deficient support loads on hind limbs].

Progress of osteopenia in 40-, 100-, and 220-d old rats who had been suspended by tails to release support loading on their hind limbs for 30 days was compared. Deficient support loading was shown to inhibit the longitudinal growth of tibia and produce osteopenia of the proximal metaphysis spongiosis in all groups of rats. Humerus of the rats whose front limbs were still partially loaded, suffered same changes as tibia though much less pronounced. Inhibition of bone growth in length and osteopenia in bone spongiosis reached maximum dimensions in 220-d old rats as a result of summation of kindred changes due to the load deprivation, and aging. Established was a correlation between suppression of the functional activity of STH-cells in adenohypophysis and progress of bone atrophy during suspension. Functional activity of thyroid calcitonin-producing cells was also reduced with the maximum decline in the 40-d old rats.