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1 Department of Molecular
Endocrinology, Le Centre Hospitalier de
l'Université Laval, Quebec, Canada
2 Centre de Recherches Roussel-UCLAF,
Romainville, France
Acute or chronic treatment of adult male rats
with LHRH or its agonists leads to a loss of testicular LH and prolactin receptors accompanied
by decreased testis, seminal vesicle, and ventral prostate weight. The inhibition of testosterone formation is due to a blockage of the
steroidogenic pathway at the level of 17-hydroxylase and 17,20-desmolase activities. The
testicular desensitization is accompanied by a
decreased pituitary responsiveness to LHRH.
Although the inhibitory effects at the testicular
level could be explained by endogenous LH
release induced by the LHRH agonist with
secondary testicular desensitization, the LH-releasing peptides also exert direct inhibitory
effects on gonadotropin receptors at the testicular level. Moreover, LHRH and its agonists
bind to a specific LHRH receptor in interstitial
cells. Chronic treatment with LHRH agonists
leads to marked degenerative changes in the
seminiferous tubules, almost all tubules showing signs of histologic damage after four weeks
of treatment. Single administration of an LHRH
agonist by the intranasal route in normal adult
men causes a transient inhibition of plasma
testosterone levels with a temporary loss of
diurnal cyclicity, whereas preliminary data obtained in patients with cancer of the prostate
show inhibition of both testosterone and dihydrotestosterone plasma levels. Such data suggest the potential use of LHRH agonists in
male contraception and for the treatment of
cancer of the prostate.
Key words: LHRH agonists, LH receptor, prolactin receptor, LHRH receptor, desensitization, spermatogenesis, intranasal, blockage of steroidogenesis
Submitted on March 17, 1980
Revised on May 18, 1980
Accepted on June 11, 1980
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