Anaiysis of Testicular Growth Factors by Quantitative Polymerase Chain Reaction
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Date
1996-02
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Addis Ababa Universty
Abstract
Expression of testicular Interleukin-l a was anaIysed both at the lavel of biological active
peptide and its encoding mRNA, using a sensitive bioassay, Thymocyte proliferation assay, and
Polymerase Chain Reaction. In order to analyse the relative change in the level of IL -1 a mRNA
expression a Quantitative PCR technique was developed involving an intemal standard IL -1 a RNA
construct derived from rat macrophage IL -1 a cDNA preparation.
The IL -1 a mRNA expression during postnatal rat development could be detected by PCR as
early as 20 days, postnatal, and The intensity of amplified cDNA band was found to increase with
increasing days of postnatal age.
By using Quantitative PCR, a relative increase in the level of amplified IL-lacDNA could be
demonstrated starting from day 20, and this increase in the level of amplified cDNA is found to reach
a sustained high level from 30 to 60 postnatal days of rat testicular development. This study shows
that the level of IL -1 a mRNA rises in parallel to the level of IL -1 a peptide during maturity, previously
demonstrated, and suggests that it is controlled at the level of mRNA expression, probably attranscriptionalleve/.
The role of testosterone in the regulation of tiL -1 a was analysed using rats treated with, EDS
with and without testosterone replacement, and androgen receptor blocker, cyproterone acetate. The
result showed that EDS pretreatment resulted in an increase in the level of both IL -1 a bioactivity and
the level of its mRNA. Exogenous testosterone replacement along with EDS treatment significantly
reduced the effect of EDS treatment on the expression of tiL-I a peptide and mRNA. Cyproterone
acetate treatment in contrast resulted in a decrease in the IL -1 a mRNA levels.
This study shows that tiL -1 a expression is developmentally regulated at the level of its mRNA
expression. It also suggests that testosterone regulates testicular IL -1 a expression at the level of
transcription. This finding further strengthens the importance of testicular IL -1 a as a paracrine growth
factor in the regulation of testicular development and function.
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Keywords
Quantitative Polymerase Chain Reaction