The growth of the prostate gland is androgen-dependent.
Testosterone is converted to the most potent dihydrotestosterone
(DHT) by 5α-reductase within the prostate. Androgen interacts
with androgen receptors (AR) to regulate normal growth of the
prostate and has also been implicated in both the progression of
benign prostate hyperplasia and prostate cancer. This study was
conducted to compare the mRNA expression of AR and 5αreductase by the prostate gland from three age categories:
immature, young-mature and old dogs. Quantitative gene
expression was assessed by the real-time PCR and the results
were expressed as a relative mRNA expression of the target
gene. This study revealed that there was no significant difference
in the mRNA expression of the AR gene by the prostate gland of
immature, young and old dogs. In contrast, there is a highly
significant (P<0.001) down-regulation in 5α-reductase gene by
the prostate of young and old dogs as compared with immature
dogs. However, there is no significant difference in mRNA
expression of the 5α-reductase gene by the prostate gland from
young and old dogs. This differential expression of AR and 5αreductase genes, which are involved in the regulation of
androgen effect on prostate gland, might reflect an agedependent growth requirement of the gland for androgens.