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1 MRC Group in Molecular
Endocrinology, Le Centre Hospitalier de
l'Université Laval, Quebec, Canada
The effects of chronic treatment with hCG (100 I.U.s.c.
every second day) on testicular morphology, LH receptor levels and concentration of steroid intermediates of
the
4 and
5 biosynthetic pathways were studied in
adult rats for periods extending from one to 12 weeks.
Treatment with hCG causes a decrease in testis weight,
a maximal inhibitory effect being observed after two
and four weeks of treatment. At these time intervals,
the loss of testis weight is accompanied by degenerative
changes in most seminiferous tubules and hypertrophy
of Leydig cells. Administration of hCG for one week
leads also to an almost complete loss of LH binding
sites and to a marked stimulation of the levels of testicular steroids of the
4 and
5 pathways, as well as to
an increase in weights of secondary reproductive organs. The initial increment of testicular steroid levels is
followed after two weeks of hCG administration by
an apparent decrease of 17,20-desmolase activity suggested by a reduction in the levels of androst-5-ene-3
,17
-diol, androstenedione, testosterone, and
5
-dihydrotestosterone and an increase in the concentrations of pregnenolone, 17-OH-pregnenolone, progesterone and 17-OH-progesterone. Plasma and pituitary LH levels are maximally reduced at one and four
weeks of treatment, respectively, while plasma and
pituitary FSH levels are only slightly reduced after four
weeks of hCG administration. The effects of hCG on all
of the above-mentioned parameters, except for testicular morphology and testis weight, are completely reversible at the eight and 12 week intervals. This transiency
in the effects of hCG is accompanied by a gradual increase in plasma levels of hCG antibodies. The present
data show that chronic treatment of adult rats with hCG
induces a marked degeneration of the seminiferous
tubules and an inhibition of spermatogenesis that accompanies the well-known loss of testicular LH receptors and inhibition of the steroidogenic pathway.
Key words: hCG, spermatogenesis, steroidogenesis
Submitted on January 21, 1981
Revised on May 27, 1981
Accepted on July 16, 1981
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