Androgens in Health and Disease.pdf - E Library

Chapter 20/Androgens as Anabolic Agents 397
density (HDL) and low-density (LDL) lipoprotein levels, blood counts (hematocrit
[Hct] and hemoglobin [HGB]), PSA levels, and genetic factors, including polymorphisms
in exon 1 of the androgen-receptor gene (i.e., lengths of the polyglutamine :
CAG and polyglycine : GGC trinucleotide tracts). The same two-variable model of TE
dose and age explained 77% and 70% of the variance in change in lean body mass (by
DEXA) and thigh muscle volume (MRI), respectively, during testosterone administration.
The length of CAG and GGC tracts were only weak predictors of change in LBM
and muscle volume in this small sample. These analyses indicate that the anabolic
response of healthy young men to exogenous testosterone administration is largely
predicted by the testosterone dose. Further studies are needed in a larger sample of men
to elucidate the genetic basis of natural variation in androgen responsiveness.
TESTOSTERONE EFFECTS ON FAT METABOLISM
Percent body fat is higher in hypogonadal men (15). Induction of androgen deficiency
in healthy men by administration of a GnRH agonist leads to an increase in fat mass (18).
Some studies of young hypogonadal men have reported a decrease in fat mass with
testosterone-replacement therapy (8,10) whereas others (6,13) found no change. In contrast,
long-term studies of testosterone supplementation of older men have consistently
demonstrated a decrease in fat mass (11). Epidemiologic studies (16,17) have shown that
serum testosterone levels are lower in middle-aged men with visceral obesity than agematched
controls. Serum testosterone levels correlate inversely with visceral fat mass
and directly with plasma HDL levels. Testosterone replacement in middle-aged men
with visceral obesity improves insulin sensitivity and decreases blood glucose and blood
pressure (80,81). Testosterone is an important determinant of regional fat distribution
and metabolism in men (80,82). Therefore, it has been hypothesized that testosterone
supplementation might be beneficial in HIV-infected men with fat-redistribution syndromes;
this hypothesis is being tested in ongoing studies in HIV-infected men with
HIV-associated visceral obesity.
THE ABUSE OF ANDROGENIC STEROIDS
BY ATHLETES AND RECREATIONAL BODYBUILDERS
Use of Andogenic Steroids by Athletes
and Recreational Bodybuilders Is Widespread
The historical aspects of the use of androgenic/anabolic steroids have been extensively
reviewed (1–4). Although their use is most common among weight lifters and
heavy throwers, almost all types of athlete whose event requires explosive strength or
power, including football players, swimmers, and track and field athletes, have been
known to use steroids (1–4). Their use has spread to high school athletes and to amateur
bodybuilders. Disqualification of highly celebrated athletes like Ben Johnson and some
members of the Chinese swim team has focused considerable media attention on this
issue. The recreational bodybuilders and occupational users, including policemen and
prison wardens, are the other groups with high prevalence of androgenic steroid use (1–
4,83–85). Pope et al. (86) have pointed out that because of the pressures exerted by
extraordinary dimensions assumed by our superheroes and figures, body dysmorphia
has become a significant clinical problem for young men. In his recent book, Adonis