Effect of rhGH and rhIGF-I treatment on protein utilization in elderly women.
To assess the effect of recombinant human growth hormone (rhGH) and recombinant human insulin-like growth factor I (rhIGF-I) on protein utilization, 14 women, age 66-82 yr, were invited to participate in studies of nitrogen balance (n = 14), whole body protein turnover (n = 14), and muscle protein synthesis (n = 8). They were studied both 1 wk before and during the last week of a 1-mo regimen, to which they had been randomly assigned, of either 0.025 mg rhGH/kg once daily or rhIGF-I at 0.015 (low), 0.03 (mid), or 0.06 (high) mg/kg twice daily. Nitrogen balance increased significantly after 1 wk of treatment in all groups (P < 0.05). After 1 mo, the magnitude of this effect had diminished by 50% in the rhGH group but remained elevated throughout the treatment period with all doses of rhIGF-I. Both protein synthesis and breakdown, measured by a primed constant infusion of [15N]glycine, were significantly increased with rhGH (9% and 8%, respectively), low-dose rhIGF-I (4.5% and 4%), and high-dose rhIGF-I (18% and 17%). Net synthesis was significantly increased with rhGH (48%) and high- and mid-dose rhIGF-I (27% and 196%, respectively). Muscle protein synthesis as measured by incorporation of [1-13C]leucine increased significantly with rhGH (50%) and the mid (67%) and high (57%) doses of rhIGF-I. These data show that whole body and muscle protein synthesis are responsive to growth factor stimulation in elderly women.
Butterfield
G E
GE
Geriatric Research, Education, and Clinical Center, Veterans Affairs Health Care System, Palo Alto 94304, California, USA.
Thompson
J
J
Rennie
M J
MJ
Marcus
R
R
Hintz
R L
RL
Hoffman
A R
AR
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D005260:Female; D019382:Human Growth Hormone / Q000494:pharmacology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009124:Muscle Proteins / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins
D009124:Muscle Proteins; D011506:Proteins; D011994:Recombinant Proteins; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D009584:Nitrogen