DIFFERENTIAL CATCH-UP IN BODY-WEIGHT AND BONE-GROWTH AFTER SHORT-TERMSTARVATION IN RATS

Catch-up or compensatory growth is known as a physiological phenomenon . However, most studies of catch-up growth were based on measurements of body weight, whereas changes in longitudinal bone growth remained l argely undescribed. The present study describes the dynamics of both w eight and longitudinal bone growth using mikro-knemometry, during norm al feeding, severe food restriction (starvation), and refeeding of 14 intact and 28 GH-deficient male rats. Starvation induced rapid weight loss (P < 0.001), and stunted leg growth (P < 0.001). Refeeding led to rapid catch-up in weight of up to 4 times above normal daily weight g ain, both in intact and GH-deficient animals, whereas an equivalent co mpensation of lower leg growth remained undetectable. Intact and GH-de ficient animals show a circaseptan spontaneous variation of growth vel ocity (mini growth spurts). During starvation, mini growth spurts disa ppear, and return to normal after refeeding with no evidence of catch- up. In GH-deficient animals, GH (1 IU/rat, administered twice daily s. c. at 10:00 h and 16:00 h) was capable of augmenting catch-up in weigh t and, to a lesser extent, in leg length increment.