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Updated: Oct 5, 2026
Intracavernosal Pressure Recording to Evaluate Erectile Function in Rodents
Published on: June 6, 2018
Decreased trabecular smooth muscle and caveolin-1 expression in the penile tissue of aged rats
M E Bakircioglu1, K D Sievert, L Nunes
1Knuppe Molecular Urology Laboratory, Department of Urology, University of California-San Francisco, San Francisco, California 94115-3465, USA.
Purpose:
Because decreased trabecular smooth muscle content is reportedly associated with vasculogenic impotence in men, we performed a rodent study to investigate the effect of aging on trabecular smooth muscle content and caveolin-1 protein expression in penile smooth muscle cells.
Materials And Methods:
In 6 young (age 3 months) and 6 old (age 24 months) rats erectile function was evaluated by cavernous nerve stimulation. At sacrifice penile tissue samples were collected for Western blot analysis, Masson's trichrome staining, caveolin-1 immunostaining and electron microscopy. The percent of smooth muscle in the trabecular tissue was assessed by computer assisted image analysis.
Results:
In the aged rats mean intracavernous pressure plus or minus standard deviation was decreased (70 +/- 8.8 versus 107 +/- 12.3 cm. water) and the latency period was increased (7.8 +/- 1.2 versus 4.5 +/- 0.5 seconds) significantly compared to values in the young rats (p <0.001). The mean ratio of trabecular smooth muscle-to-connective tissue was also significantly altered in old versus young rats (27% +/- 2.9% versus 42.1% +/- 5.1%, p <0.001). Immunostaining for caveolin-1 was noted in each group in the sarcolemma of smooth muscle cells and endothelium of trabecular sinusoids but the staining pattern was less intense and the percent of smooth muscle positive for caveolin-1 was decreased in aged versus young rats (17.9% +/- 2.5% versus 27.5% +/- 3.6%, p <0.001). Moreover, young trabecular smooth muscle cells had more caveolae in the sarcolemma on electron microscopy and a higher expression of caveolin-1 protein on Western blot analysis. In contrast, higher endothelial nitric oxide synthase protein expression was noted in the penile tissue of old rats.
Conclusions:
In these aged rats the decreased ratio of trabecular smooth muscle-to-collagen and the reduced expression of caveolin-1 may contribute to erectile dysfunction.
Insights
Aging impairs erectile function by reducing penile smooth muscle and caveolin-1 expression. This study in aged rats reveals a lower smooth muscle ratio and decreased caveolin-1, potentially contributing to erectile dysfunction.
Area of Science:
- Urology
- Gerontology
- Cell Biology
Background:
- Decreased trabecular smooth muscle content is linked to vasculogenic impotence.
- Understanding the aging process's impact on penile tissue is crucial for addressing erectile dysfunction.
Purpose of the Study:
- To investigate the effect of aging on trabecular smooth muscle content in rat penile tissue.
- To examine the impact of aging on caveolin-1 protein expression in penile smooth muscle cells.
Main Methods:
- Evaluated erectile function in young (3 months) and old (24 months) rats via cavernous nerve stimulation.
- Analyzed penile tissue using Western blot, Masson's trichrome staining, caveolin-1 immunostaining, and electron microscopy.
- Quantified smooth muscle percentage in trabecular tissue using computer-assisted image analysis.
Main Results:
- Aged rats exhibited significantly reduced intracavernous pressure and increased latency compared to young rats (p <0.001).
- The ratio of trabecular smooth muscle to connective tissue was significantly lower in aged rats (27% vs. 42.1%, p <0.001).
- Aged rats showed decreased caveolin-1 expression and fewer caveolae in smooth muscle cells, alongside increased endothelial nitric oxide synthase expression.
Conclusions:
- Reduced trabecular smooth muscle-to-collagen ratio in aged rats may contribute to erectile dysfunction.
- Decreased caveolin-1 expression in penile smooth muscle cells of aged rats is associated with impaired erectile function.
