EMBARGOED
FOR RELEASE UNTIL
August 8, 2007
APS Contact
Donna Krupa
Office:
(301) 634-7253
Cell: (703) 967-2751
dkrupa@the-aps.org
Testosterone Replacement
Therapy: How Safe For Aging Men?
Austin, TX – For decades, older women have taken
hormone replacements to replenish estrogen and progesterone levels lost to
aging. More recently, testosterone (the most important male hormone)
supplements have been used by aging men to improve their muscle mass, bone
strength, libido and quality of life. In 2002, the number of elderly
American men taking testosterone replacement therapy was nearly 819,000, and
the number is growing. The increased use has occurred despite the fact that
the cardiovascular effects of chronic testosterone treatment in aging males
are largely unknown, and the safety of testosterone replacement has not been
evaluated.
A team of researchers has been using an animal model to
investigate potential links between testosterone supplements and
cardiovascular and renal disease. The team, comprised of Radu Iliescu, Licy
L. Yanes, Julio C. Sartori-Valinotti, and Jane F. Reckelhoff, is affiliated
with the University of Mississippi Medical Center’s Department of Physiology
and Biophysics, Jackson, MS. Their most recent study and an overview of data
from other human and animal studies is part of the upcoming conference, Sex
and Gender in Cardiovascular-Renal Physiology and Pathophysiology.
The meeting, sponsored by The American Physiological Society (APS;
www.The-APS.org), is being held August 9-12, 2007 at the Hyatt
Regency Austin on Town Lake, Austin, TX.
Latest Study
The team is presenting its work entitled, “Testosterone
Supplements Promote Renal Injury and Exacerbate Hypertension in Aging
Spontaneously Hypertensive Rats (SHR),” in which spontaneously hypertensive
rats were used as a model for genetic hypertension.
Three groups of rats were used: intact, gonadectomized
(at eight months of age), and testosterone-supplemented rats. Testosterone
supplements were administered chronically via pellets and rats were
monitored until 13 months of age. Blood pressure was measured at the end of
the experiment via indwelling arterial catheters inserted into conscious,
freely moving rats. Urine was collected for two hours and urinary protein
excretion was determined.
The researchers found that blood pressure was
significantly higher in testosterone-supplemented male SHR as compared with
intact rats, whereas castration did not alter blood pressure levels.
Testosterone supplemented SHR excreted more urinary protein than intact
rats, and castration reduced proteinuria (urinary protein).
The results suggest that testosterone supplementation
of aging male SHR promotes renal injury and thereby exacerbates
hypertension. The results also show that removal of endogenous androgens
later in life (eight months) prevents the development of hypertensive renal
injury without altering existing hypertension levels.
The Big Picture
The study is part of the researchers’ ongoing project
to investigate the effects of testosterone-supplementation in animal models
of disease that mimic the characteristics of the human male population that
currently receive testosterone supplements. They are currently testing the
hypotheses that the natural decrease in testosterone brought on by aging may
affect the progression of pre-existing cardiovascular/renal disease.
# # #
The
American Physiological Society (APS) has been an integral part of the
scientific discovery process since it was established in 1887. Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease.
***
NOTE TO EDITORS: The APS meeting is being held
at the Hyatt Regency Austin on Town Lake, Austin, TX, August 9-12, 2007.
Members of the media are invited to attend the sessions. To schedule an
interview with Dr. Iliescu, please contact Donna Krupa at
301.634.7209 (direct dial), 703.967.2751 (cell) or
DKrupa@the-APS.org.
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