G. Ortoft et al., GROWTH-HORMONE IS NOT ABLE TO COUNTERACT OSTEOPENIA OF RAT CORTICAL BONE INDUCED BY GLUCOCORTICOID WITH PROTRACTED EFFECT, Bone, 17(6), 1995, pp. 543-548
Osteopenia and inhibited longitudinal growth in childhood are serious
side effects during glucocorticoid therapy, The effects of glucocortic
oids on bone have been confirmed in animal experiments, Long-term gluc
ocorticoid administration to rats results in reduced body weights, red
uced bone growth (length and cross-sectional area), and bone strength,
Glucocorticoid treatment also resulted in a reduced bending stress, i
ndicating reduced bone quality, Growth hormone, on the other hand, inc
reased body weights, bone dimensions, and bone strength, The aim of th
e present study was to evaluate if growth hormone administration would
have an anabolic effect on rat bone when given to animals also receiv
ing a high dosage of glucocorticoid. Five groups of female rats, 3.5 m
onths old, were treated as follows: (1) saline control; (2) glucocorti
coid (prednisolone: Delcortol 5 mg/kg/day); (3) growth hormone (recomb
inant human growth hormone 5 mg/kg/day); (4) glucocorticoid and growth
hormone; and (5) food restriction, consisting of restricted access to
food to reduce their weight gain to match that of the glucocorticoid
injected rats, After 80 days of hormone administration the animals wer
e sacrificed, The right femur was removed and tested biomechanically i
n a three-point bending procedure, The left femur was used for determi
nation of bone dimensions, Biomechanical parameters (ultimate load and
ultimate stiffness) were then normalized to diaphyseal cross-sectiona
l diameters of the femur, giving the values of ultimate bending stress
and Young's modulus, Results: administration of both hormones simulta
neously could not reverse the decrease in body weights, bone length, a
nd diameters, or the decreased bone strength induced by glucocorticoid
administration. In conclusion, growth hormone cannot prevent cortical
osteopenia in female rats induced by a high dose of glucocorticoid wi
th protracted effect.