Sj. Winters et al., Secretion of testosterone and its Delta(4) precursor steroids into spermatic vein blood in men with varicocele-associated infertility, J CLIN END, 84(3), 1999, pp. 997-1001
Insight into the mechanisms by which steroid hormones are released from the
testes was sought by examining the concentrations of progesterone, 17 alph
a-hydroxyprogesterone, and androstenedione as well as testosterone in sperm
atic vein blood every 15 min for 4 h in men with varicocele-associated infe
rtility. Coincident discrete secretory episodes of all four steroids were f
ound, and spermatic vein concentrations of testosterone were highly positiv
ely correlated to the concentrations of progesterone (r = 0.79), 17 alpha-h
ydroxyprogesterone (r = 0.81), and androstenedione (r = 0.82), respectively
. The sum of the four measured steroids per mt plasma was calculated, and t
estosterone was found to account for 70%, 17 alpha-hydroxyprogesterone for
24%, androstenedione for 5%, and progesterone for 1% of the total. In a pre
vious study of the intratesticular steroids in a separate population of men
with varicocele-associated infertility, the sum of these four steroids per
g tissue was similarly calculated. Testosterone accounted for 70% of the f
our measured steroids, 17 alpha-hydroxyprogesterone for 22%, androstenedion
e for 4%, and progesterone for 3% of the total. Thus, the relative concentr
ations of these four steroids are nearly identical in testicular tissue and
spermatic vein plasma. From these data we hypothesize that steroids in the
testicular interstitium are cosecreted into peripheral plasma in response
to stimulation by LH and propose that the mechanism initiating this pulsati
le mode of secretion of testosterone and its precursor steroids may not be
coupled to testosterone biosynthesis.