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Updated: Sep 15, 2026
Intracavernosal Pressure Recording to Evaluate Erectile Function in Rodents
Published on: June 6, 2018
Diabetes induced erectile dysfunction and apoptosis in penile crura are recovered by insulin treatment in rats
Masaki Yamanaka1, Masato Shirai, Hiroaki Shiina
1Department of Urology, Veterans Affairs Medical Center, University of California at San Francisco, 4150 Clement Street, San Francisco, CA 94121, USA.
Purpose:
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 diabetes induced erectile dysfunction. To test this hypothesis the intracavernous pressure of diabetic and insulin treated rats was measured to assess erectile function. Molecular and immunohistochemical analyses for apoptosis were then performed in rat crura to assess their role in diabetes induced erectile dysfunction and insulin treatment.
Materials And Methods:
A total of 70, 6-month-old male Sprague-Dawley rats were divided into 2 groups, including a diabetic (50) and a healthy control (20) group. The diabetic group received intraperitoneal injection of streptozotocin (STZ) (Sigma-Aldrich Co., St. Louis, Missouri) to induce diabetes. Subcutaneous injection of insulin was administered daily to 9 diabetic rats 4 and 8 weeks after STZ injections for 4 and 8 weeks, respectively. Functional studies were performed in 9 diabetic rats each 4, 8 and 12 weeks after STZ injections, in 6 age matched control rats and in insulin treated rats at the termination of therapy. After the completion of functional study the penile crura were collected from rats for molecular and immunohistochemical studies.
Results:
Mean intracavernous pressure of diabetic rats was significantly lower than in control rats and the decrease in intracavernous pressure was significantly recovered by insulin treatment. Gene expressions of pro-apoptotic and anti-apoptotic factors were present in control, diabetic and insulin treated rat crura. However, anti-apoptotic protein expression was lacking in diabetic rat crura and pro-apoptotic protein expression was lost in insulin treated rat crura. The apoptotic index of diabetic rat crura was significantly higher than that of control rat crura and this index was significantly decreased in insulin treated rat crura.
Conclusions:
There was a significant correlation between the decrease and recovery in intracavernous pressure, and protein expression of apoptotic factors in diabetic and insulin treated rat crura. To our knowledge this is the first report demonstrating that the relief of diabetes associated erectile dysfunction by insulin treatment is due to alterations in the protein expression of apoptotic factors in rat crura.
Insights
Insulin treatment improved erectile function in diabetic rats by restoring the balance of apoptotic factors in penile tissues. This study highlights the role of apoptosis in diabetes-related erectile dysfunction and its reversal with insulin therapy.
Area of Science:
- Urology
- Endocrinology
- Cell Biology
Background:
- Diabetes mellitus is a leading cause of erectile dysfunction (ED).
- The role of apoptosis and its regulators in diabetes-induced ED is not fully understood.
- Apoptosis involves a balance between pro-apoptotic (e.g., Bak, Bax) and anti-apoptotic (e.g., Bcl-2, Bcl-x) factors.
Purpose of the Study:
- To investigate the involvement of apoptotic factors in the etiology of diabetes-induced ED.
- To determine if insulin treatment can reverse these apoptotic changes and improve erectile function.
- To test the hypothesis that apoptosis is a downstream event in diabetes-related ED.
Main Methods:
- Seventy male Sprague-Dawley rats were divided into diabetic (streptozotocin-induced) and control groups.
- Diabetic rats received insulin treatment.
- Intracavernous pressure was measured to assess erectile function.
- Molecular and immunohistochemical analyses of penile crura were performed to evaluate apoptosis.
Main Results:
- Diabetic rats exhibited significantly lower intracavernous pressure compared to controls.
- Insulin treatment significantly recovered intracavernous pressure in diabetic rats.
- Diabetic rat crura showed a lack of anti-apoptotic protein expression and increased apoptotic index.
- Insulin-treated rat crura showed restored pro-apoptotic protein expression and a decreased apoptotic index.
Conclusions:
- Diabetes-induced erectile dysfunction is associated with altered expression of apoptotic factors in rat penile tissues.
- Insulin treatment alleviates diabetes-associated ED by modulating the protein expression of these apoptotic factors.
- This study provides the first evidence for the role of apoptotic factor alterations in diabetes-related ED and their reversal by insulin.
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