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1 Group in Molecular
Endocrinology, Le Centre Hospitalier de
l’Université Laval, Quebec, Canada
Following the recent observation that chronic
treatment with [D-Ala6, des-Gly-NH210]LHRH
ethylamide, a potent LHRH agonist, leads to an
almost complete degeneration of seminiferous
tubules in the rat, the time-course of recovery of spermatogenesis after cessation of
treatment was investigated. Adult rats injected
with the LHRH agonist (100 ng, every second
day) for four weeks were studied four, eight,
and 16 weeks later. Although progressive improvement was noted from four to 16 weeks
after cessation of treatment, about 25% of
tubules still appeared completely degenerated
at the end of the recuperation period. One
month following cessation of treatment, testicular LH and prolactin receptor concentrations, testicular testosterone (T) and dihydrotestosterone (DHT) levels, and ventral
prostate and seminal vesicle weights had returned to normal values. Testis weight, however, which was decreased by 40% one month
after treatment with the LHRH analog, increased more slowly toward normal and was
still at 85% of control value four months after
treatment. Plasma LH and FSH levels, which
were Increased approximately 100% after
treatment with the LHRH analogue, returned to
within normal values between one and two
months following cessation of treatment, respectively. Administration of androgens (T or
DHT) concomitantly with the LHRH agonist only
partially prevented the deleterious effects of
the peptide on spermatogenesis. On the other
hand, administration of the LHRH agonist had
no effect on testicular morphology in hypophysectomized rats. These data show a rapid
return to normal of the hypophyseal testicular elements responsible for androgen formation after desensitization by LHRH agonist treatment in adult rats. These results suggest that
the inhibitory effect of chronic LHRH agonist
administration on spermatogenesis is at least
partially reversible, and that a decrease in
androgen production is probably not the only
factor involved in the inhibition of spermatogenesis by LHRH agonist treatment.
Key words: antifertility, spermatogenesis, LHRH agonist, gonadotropin receptors, steroidogenesis
Submitted on September 10, 1979
Revised on February 13, 1980
Accepted on March 5, 1980
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