Related Experiment Video
Updated: Sep 15, 2026
Preparation of Acute Hippocampal Slices from Rats and Transgenic Mice for the Study of Synaptic Alterations during Aging and Amyloid Pathology
Published on: March 23, 2011
Loss of anti-apoptotic genes in aging rat crura
Masaki Yamanaka1, Masato Shirai, Hiroaki Shiina
1Department of Urology, Veterans Affairs Medical Center and University of California at San Francisco, San Francisco, California 94121, USA.
Purpose:
Erectile dysfunction is a common problem in aging men. The molecular mechanisms associated with aging erectile dysfunction are not completely understood. We hypothesized that apoptosis is a downstream event in erectile dysfunction, and pro-apoptotic (Bak and Bax) and anti-apoptotic (Bcl-2 and Bcl-x) factors are involved in the etiology of aging erectile dysfunction. To test this hypothesis intracavernous pressure in aging rats was measured to assess erectile function. Gene and protein expression of pro-apoptotic and anti-apoptotic factors was then analyzed in aging rat crura to assess its role in aging erectile dysfunction.
Materials And Methods:
A total of 25 male Sprague-Dawley rats divided into 5 groups of 5 each based on age (6, 12, 18, 24 and 28 months old, respectively) were used in functional and apoptotic studies. In addition, 5, 3-month-old male Sprague-Dawley rats were used in the apoptotic study. The rats were anesthetized with pentobarbital. Erectile function was assessed by measuring intracavernous pressure after electrostimulation of the cavernous nerves. After completion of the functional study the penile crura were immediately harvested for histochemical and molecular studies. Gene expression of pro-apoptotic (Bak and Bax) and anti-apoptotic (Bcl-2 and Bcl-x) factors were then analyzed by reverse transcription-polymerase chain reaction. Protein expressions of these apoptotic factors were also analyzed by immunohistochemistry using specific antibodies.
Results:
Mean intracavernous pressure plus or minus SD in 18, 24 and 28-month-old rats was significantly lower than in 6-month-old rats (101.6 +/- 24.8, 77.7 +/- 24.5 and 45.7 +/- 7.3 versus 136.7 +/- 11.4 cm. water, respectively; p <0.05). The reduction in intracavernous pressure was an age dependent phenomenon. Gene and protein expression of the pro-apoptotic genes Bak and Bax was detected in the crura of all age groups but there was no significant difference in young and old rat crura. The anti-apoptotic Bcl-2 and Bcl-x genes were expressed in 3, 6 and 12-month-old crura, whereas this expression was lost at 18, 24 and 28 months. Anti-apoptotic Bcl-2 and Bcl-x proteins were also expressed in young rat crura, whereas this expression was lost in old rat crura.
Conclusions:
The decline in intracavernous pressure correlated significantly with a loss of anti-apoptotic genes in aging rat crura. To our knowledge this is the first report to show the loss of anti-apoptotic factors in aging rat crura and suggest their role in the pathogenesis of aging erectile dysfunction.
Insights
Aging erectile dysfunction is linked to a loss of anti-apoptotic factors in rat penile tissue. This study reveals that reduced Bcl-2 and Bcl-x gene and protein expression correlates with decreased erectile function in older rats.
Area of Science:
- Urology
- Molecular Biology
- Gerontology
Background:
- Erectile dysfunction (ED) is a prevalent condition in aging men, with underlying molecular mechanisms not fully elucidated.
- Apoptosis, or programmed cell death, is increasingly recognized as a potential contributor to age-related pathologies.
Purpose of the Study:
- To investigate the role of apoptosis and the balance of pro-apoptotic (Bak, Bax) and anti-apoptotic (Bcl-2, Bcl-x) factors in the pathogenesis of aging erectile dysfunction.
- To correlate changes in these apoptotic factors with functional measures of erectile capacity in aging rats.
Main Methods:
- Erectile function was assessed in Sprague-Dawley rats aged 6 to 28 months by measuring intracavernous pressure (ICP) following cavernous nerve electrostimulation.
- Gene expression of Bak, Bax, Bcl-2, and Bcl-x was analyzed using reverse transcription-polymerase chain reaction (RT-PCR).
- Protein expression of these apoptotic factors was evaluated through immunohistochemistry in penile crura.
Main Results:
- A significant, age-dependent decrease in ICP was observed in rats aged 18, 24, and 28 months compared to 6-month-old rats.
- While pro-apoptotic factors (Bak, Bax) were present in all age groups, their expression did not significantly differ between young and old rats.
- Expression of anti-apoptotic factors (Bcl-2, Bcl-x) at both gene and protein levels was detected in young rats but was lost in aging rats (18 months and older).
Conclusions:
- The decline in erectile function in aging rats is significantly correlated with the loss of anti-apoptotic factors (Bcl-2, Bcl-x) in the penile crura.
- This study provides the first evidence suggesting a critical role for the downregulation of anti-apoptotic factors in the pathogenesis of age-related erectile dysfunction.
