Administration of glucocorticoids is associated with decreased nitrogen balance. The
main aim of the present study was to elucidate whether this could be counteracted
by subcutaneous infusions of rhGH (360 µg/d), rhIGF-1 (500 µg/d) or insulin (39 µg/d).
During a study period of 8 days one out of 10 groups of rats received dexamethasone
(dex, 26 µg/d) alone, whereas 7 groups were given one or more of the three peptides
in combination with dex. One group was given saline alone and one was food restricted
to match the average food intake among dex groups.
Food restriction and saline alone produced relative nitrogen balances, retained N/ingested
N (× 100) of 44 (SE 3) and 36% (SE 4), respectively. This was decreased (p < 0.001)
to 7% (SE 3) with dex alone. However, if either insulin/rhGH/rhIGF-I, rhIGF-I alone
or insulin/rhIGF-I were given together with dex, the relative nitrogen balances increased
significantly (p < 0.03) up to 16,22 and 24% (SE 3), respectively. Insulin or rhGH
alone were without effect as was rhGH combined with either rhIGF-I or insulin. Although
the relative nitrogen balances associated with insulin/rhIGF-I and rhIGF-I alone were
not found to be significantly different, the former infusion regimen produced a significantly
(p < 0.02) lower plasma urea. It is concluded that in the rat, rhIGF-I has a potential
to counteract the decrease in nitrogen balance induced by potent glucocorticoids,
whereas rhGH as administered in this experiment does not have this effect.
Key words
Insulin - Recombinant Human Growth Hormone - Recombinant Human Insulin-Like Growth
Factor-I - Dexamethasone - Catabolism - Nitrogen Balance, Rat
