POTENTIALLY PREDICTIVE AND MANIPULATABLE BLOOD-SERUM CORRELATES OF AGING IN THE HEALTHY-HUMAN MALE - PROGRESSIVE DECREASES IN BIOAVAILABLE TESTOSTERONE, DEHYDROEPIANDROSTERONE-SULFATE, AND THE RATIO OF INSULIN-LIKE-GROWTH-FACTOR-1 TO GROWTH-HORMONE
Je. Morley et al., POTENTIALLY PREDICTIVE AND MANIPULATABLE BLOOD-SERUM CORRELATES OF AGING IN THE HEALTHY-HUMAN MALE - PROGRESSIVE DECREASES IN BIOAVAILABLE TESTOSTERONE, DEHYDROEPIANDROSTERONE-SULFATE, AND THE RATIO OF INSULIN-LIKE-GROWTH-FACTOR-1 TO GROWTH-HORMONE, Proceedings of the National Academy of Sciences of the United Statesof America, 94(14), 1997, pp. 7537-7542
A cross sectional survey was made in 56 exceptionally healthy males, r
anging in age from 20 to 84 years. Measurements were made of selected
steroidal components and peptidic hormones in blood serum, and cogniti
ve and physical tests were performed. Of those blood serum variables t
hat gave highly significant negative correlations with age (r > -0.6),
bioavailable testosterone (BT), dehydroepiandrosterone sulfate (DHEAS
), and the ratio of insulin-like growth factor 1 (IGF-1) to growth hor
mone (GH) showed a stepwise pattern of age-related changes most closel
y resembling those of the age steps themselves. Of these, BT correlate
d best with significantly age correlated cognitive and physical measur
es. Because DHEAS correlated well with BT and considerably less well t
han BT with the cognitive and physical measures, it seems likely that
BT and/or substances to which BT gives rise in tissues play a more dir
ect role in whatever processes are rate-limiting in the functions meas
ured and that DHEAS relates more indirectly to these functions. The hi
gh correlation of IGF-1/GH with age, its relatively low correlation wi
th BT, and the patterns of correlations of IGF-1/GH and BT with signif
icantly age-correlated cognitive and physical measures suggest that th
e GH-IGF-1 axis and BT play independent roles in affecting these funct
ions. Serial determinations made after oral ingestion of pregnenolone
and data from the literature suggest there is interdependence of stero
id metabolic systems with those operational in control of interrelatio
ns in the GH-IGF-1 axis. Longitudinal concurrent measurements of serum
levels of BT, DHEAS, and IGF-1/GH together with detailed studies of t
heir correlations with age-correlated functional measures may be usefu
l in detecting early age-related dysregulations and may be helpful in
devising ameliorative approaches.