Age-related decreases in insulin-like growth factor-I and transforming growth factor-beta in femoral cortical bone from both men and women: implications for bone loss with aging.
We determined the skeletal content of insulin-like growth factor-I (IGF-I) and transforming growth factor-beta (TGF beta) in human bone as a function of age, using 66 samples of femoral cortical bone obtained from 46 men and 20 women between the ages of 20-64 yr. We found a linear decline in the skeletal content of IGF-I (nanograms per mg protein) with donor age (r = -0.43; P < 0.001) in the total population. The skeletal content of TGF beta also decreased with age (i.e. 1/TGF beta vs. age; r = 0.28; P < 0.02) for the total population. We did not observe any difference in the skeletal growth factor content between male and female donors. IGF-I content, when analyzed by decade divisions of age, showed a reduction between the 20- to 29-yr-old and the 50- to 59-yr-old subjects (P < 0.02). The loss rate of IGF-I was 1.56 ng/mg protein.yr, corresponding to a net loss of 60% of skeletal IGF-I between the ages of 20-60 yr. The loss rate of TGF beta was 0.03 ng/mg protein.yr, corresponding to a net loss of 25% of the skeletal TGF beta between the ages of 20-60 yr.
Nicolas
V
V
Jerry L. Pettis Veterans Hospital, Loma Linda, California 92374.
Prewett
A
A
Bettica
P
P
Mohan
S
S
Finkelman
R D
RD
Baylink
D J
DJ
Farley
J R
JR
D000328:Adult; D000375:Aging / Q000502:physiology*; D005260:Female; D005269:Femur / Q000737:chemistry*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000209:etiology*; D016212:Transforming Growth Factor beta / Q000032:analysis*
D016212:Transforming Growth Factor beta; D007334:Insulin-Like Growth Factor I