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Effects of castration and testosterone administration on angiotensin II receptor mRNA expression and

Ryuto Nakazawa1, Masami Tanaka, Takeshi Takahashi

  • 1Department of Urology, St. Marianna University, Kawasaki, Japan.

Endocrine Journal
|January 24, 2007
PubMed

Insights

Castration increases angiotensin II receptor type 2 (AT2 receptor) mRNA and caspase-3 in rat bladders, effects reversed by testosterone. Bladder AT2 receptor and apoptosis are androgen-dependent.

Area of Science:

  • Urology
  • Endocrinology
  • Molecular Biology

Background:

  • Androgen levels significantly influence various physiological processes.
  • The role of androgens in regulating urinary bladder function and molecular pathways remains incompletely understood.
  • Angiotensin II receptors and apoptosis-related proteins are implicated in bladder pathophysiology.

Purpose of the Study:

  • To investigate the impact of castration and subsequent androgen (testosterone) administration on angiotensin II receptor (AT1 and AT2) mRNA expression in rat bladders.
  • To examine the effects of altered androgen levels on the expression of key apoptosis-related proteins (caspase-3, Bcl-2, Bax, MAP kinase phosphatase-1) in the rat urinary bladder.
  • To elucidate the relationship between androgen status and AT2 receptor expression and apoptosis in the urinary bladder.

Main Methods:

  • Utilized a rat model with three groups: control (sham operation), castration, and castration plus testosterone administration.
  • Quantified mRNA expression of angiotensin converting enzyme (ACE), AT1 receptor, and AT2 receptor using real-time PCR.
  • Determined the protein expression levels of apoptosis-related factors (caspase-3, Bcl-2, Bax, MAP kinase phosphatase-1) via Western blotting.

Main Results:

  • Castration led to a significant increase in AT2 receptor mRNA and caspase-3 protein expression in rat bladders.
  • Testosterone administration reversed these increases, returning AT2 receptor and caspase-3 levels to control levels.
  • Bcl-2 and Bax protein expression remained unchanged, while MAP kinase phosphatase-1 expression increased post-castration but was reduced with testosterone treatment.

Conclusions:

  • Urinary bladder expression of AT2 receptor mRNA and caspase-3 protein is significantly influenced by the androgen environment and is androgen-dependent.
  • Changes in androgen levels affect the expression of specific apoptosis-related proteins in the rat urinary bladder.
  • This study provides the first evidence clarifying the direct relationship between AT2 receptor and androgen regulation within the urinary bladder.

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