G. Ortoft et al., GROWTH-HORMONE ADMINISTRATION CAN IMPROVE GROWTH IN GLUCOCORTICOID-INJECTED RATS WITHOUT AFFECTING THE LYMPHOCYTOPENIC EFFECT OF THE GLUCOCORTICOID, Growth hormone & IGF research, 8(3), 1998, pp. 251-264
Long-term glucocorticoid therapy as it is found in children with kidne
y transplants results in retarded longitudinal growth. The aim of the
present study was to evaluate if growth hormone could improve longitud
inal growth in glucocorticoid-injected experimental animals without af
fecting the immune-suppressive effect of the glucocorticoid. 117 femal
e Wistar rats were injected from the ages of 2-5 months with either sa
line, growth hormone (5 mg/kg/day), or glucocorticoid (methylprednisol
one 1,3,6 or 9 mg/kg/day), alone or in combination with growth hormone
(5 mg/kg/day). Body weight, nose-tail length and length of the lower
extremity were measured continuously during the study. After death, fe
moral and tibial lengths, growth at the proximal, epiphyseal growth pl
ate, muscle mass and immunological parameters were examined. Glucocort
icoid administration dose-dependently decreased weight gain and growth
(nose-tail length, growth of the lower extremity), lengths of femur a
nd tibia, growth at the proximal, epiphyseal growth plate and muscle m
ass. Glucocorticoid administration decreased spleen and thymus weight
as well as the white blood cell count (WBC count), mainly due to a dec
rease in lymphocyte number. For all glucocorticoid doses examined, gro
wth hormone increased weight gain and growth (nose-tail length, growth
of the lower extremity), lengths of femur and tibia, and muscle mass.
The effects of growth hormone were, however, dose-dependently decreas
ed by glucocorticoid administration. Growth hormone injection alone in
creased the WBC count due to an increase in the number of lymphocytes
and monocytes. When the two hormones were administered concomitantly,
growth hormone did not, however, reverse the lymphocytopenic effect in
duced by glucocorticoid administration. In conclusion, growth hormone
can increase longitudinal growth and increase muscle mass in glucocort
icoid-injected rats, if a glucocorticoid preparation of a short half-l
ife is used. Growth hormone does not reverse the lymphocytopenic effec
t of glucocorticoid injections. (C) 1998 Churchill Livingstone.