Effects of sex steroids on regulation of the levels of C1 peptide of rat prostatic steroid-binding protein mRNA evaluated by in-situ hybridization.
Prostatic steroid-binding protein (PBP) is the most abundant protein synthesized in the rat ventral prostate. The protein is under strict androgenic control and is made of two subunits containing the polypeptides C1, C2 and C3. Using an 35S-labelled cDNA probe, we have used quantitative in-situ hybridization to assess the regulation of polypeptide C1 mRNA levels by sex steroids in the adult male rat. Densitometric quantification of autoradiographic hybridization signals revealed that a significant decrease in C1 mRNA levels could be detected 5 h after castration. Levels of C1 mRNA decreased by 50% 2.5 days after castration, while undetectable levels were reached within 7 days. Administration of the potent androgen 5 alpha-dihydrotestosterone to castrated rats caused a progressive increase in C1 mRNA levels which became significant 5 h after the first injection, while prolonged treatment, for 3 and 7 days, caused 50 and 100% reversals respectively of the effect of castration on C1 mRNA levels. Similar results were obtained by dot-blot hybridization using the same 32P-labelled cDNA probe, thus confirming the specificity and quantification achieved by in-situ hybridization. Administration of oestradiol-17 beta to orchiectomized adult rats for 14 days had no effect on steady-state C1 mRNA levels. Progesterone, on the other hand, at the dose used (2 mg twice daily) caused a marked increase in C1 mRNA levels, measured by in-situ hybridization, which was completely reversed by concomitant administration of the pure antiandrogen flutamide. The present data clearly demonstrate that the expression of PBP C1 peptide mRNA is under strict androgenic control and is a very sensitive and specific parameter of androgenic activity. They also indicate that quantitative in-situ hybridization is a powerful, sensitive and most efficient tool to study the regulation of gene expression while, in addition, providing precise information about the site of mRNA localization as well as information about the histology of the tissue, particularly the heterogeneous nature of the acinar response to androgenic stimulation and deprivation.
Pelletier
G
G
MRC Group in Molecular Endocrinology, Laval University Medical Center, Quebec, Canada.
Labrie
C
C
Simard
J
J
Duval
M
M
Martinoli
M G
MG
Zhao
H
H
Labrie
F
F
D000727:Androgen-Binding Protein / Q000235:genetics*; D000818:Animals; D013196:Dihydrotestosterone / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D012739:Gonadal Steroid Hormones / Q000494:pharmacology*; D008297:Male; D009693:Nucleic Acid Hybridization; D009919:Orchiectomy; D011374:Progesterone / Q000494:pharmacology; D011467:Prostate / Q000166:cytology; D060789:Prostatein; D012313:RNA / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D060765:Secretoglobins; D014598:Uteroglobin; D060788:Mammaglobin B
D000727:Androgen-Binding Protein; D013196:Dihydrotestosterone; D004958:Estradiol; D012739:Gonadal Steroid Hormones; D011374:Progesterone; D060789:Prostatein; D012313:RNA; D060765:Secretoglobins; D014598:Uteroglobin; C511484:Scgb1d2 protein, rat; C511483:Scgb1d4 protein, rat; C556468:Scgb2a1 protein, rat; D060788:Mammaglobin B