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Abstract:
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Androgens are essential for the maintenance of normal spermatogenesis in
the rat. We assessed the sites, developmental pattern, and hormonal
control of androgen receptors (AR) in the rat testis. Adult male rats were
studied after 1) no treatment; 2) ethane dimethane sulfonate (EDS), which
eradicates Leydig cells and endogenous testosterone (T); 3) EDS plus T
replacement beginning at the time of EDS administration; or 4)
methoxyacetic acid, which leads to the loss of specific germ cell types.
Testes were also obtained from normal immature rats (aged 5, 14, 16, 21,
28, 31, 35, 38, and 45 days). After microwave antigen retrieval,
immunohistochemistry was performed using a rabbit polyclonal antibody
(Novocastra) raised against a peptide unique to the N-terminal region of
the AR and detection with biotinylated swine antirabbit immunoglobulin G,
avidin-biotin complex/alkaline phosphatase, and nitroblue tetrazolium salt
(NBT)/5 bromo-4-chloro-3-indolylphosphate (BCIP) substrate. In adults,
nuclear immunostaining of Sertoli cells (SC) increased progressively in
intensity from stages II through VII of the spermatogenic cycle, and then
declined precipitously during stage VIII to become barely detectable in
stages IX-XIII. Prominent AR immunostaining was also evident in
peritubular myoid cells, arterioles, and interstitial cells; staining in
these cells did not vary with the stage of the cycle of the adjacent
tubules. EDS caused a severe loss of AR immunostaining in all cell types.
Replacement of T in EDS-treated animals resulted in a pattern of AR
immunostaining comparable to that in controls, although staining intensity
was reduced. Methoxyacetic acid administration did not affect the pattern
of AR staining. In immature rats, peritubular myoid cell immunostaining
was prominent from day 5; SC staining was detectable on day 5, increased
in intensity with age, and became stage dependent between days 21-35. The
following conclusions were reached. 1) Immunohistochemically detectable AR
expression in SC occurs predominantly in stages II-VII of the
spermatogenic cycle, with highest levels at stage VII. 2) AR
immunostaining is also prominent in peritubular myoid cells, arterioles,
and Leydig cells (but not in germ cells), but is unrelated to the stage of
adjacent tubules. 3) Endogenous T and/or its metabolites control the
expression of AR in the testis. 4) AR immunostaining is detectable by day
5 of age and becomes stage specific in SC between days 21-35. |