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Morphological changes in cavernous tissue in spontaneously hypertensive rats
J E Toblli1, I Stella, F Inserra
1Laboratory of Experimental Medicine, Hospital Alemán, and Instituto de Investigaciones Cardiológicas, Buenos Aires, Argentina. jtoblli@hospitalaleman.com
Insights
Arterial hypertension in rats causes significant morphologic changes in penile cavernous tissue, including smooth muscle proliferation and fibrosis. These changes correlate with elevated blood pressure, suggesting hypertension directly impacts erectile tissue structure.
Area of Science:
- Urology
- Cardiovascular Research
- Pathology
Background:
- Erectile dysfunction (ED) is common in hypertensive patients, but the cause—hypertension itself or its treatment—remains debated.
- Understanding the direct impact of arterial hypertension on erectile tissue is crucial for managing ED in this population.
Purpose of the Study:
- To investigate the morphologic alterations in penile cavernous tissue (CT) in an animal model of arterial hypertension.
- To determine the relationship between systolic blood pressure (SBP) and these structural changes.
Main Methods:
- Male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were studied for 8 months.
- Systolic blood pressure was monitored monthly; penile cavernous tissue was analyzed microscopically for smooth muscle and fibrosis.
- Histological stains (hematoxylin and eosin, Masson's trichrome) and immunohistochemistry (anti-alpha smooth muscle actin) were employed.
Main Results:
- SHR exhibited significantly higher cavernous smooth muscle (CSM) and vascular smooth muscle (VSM) proliferation compared to WKY rats (P < .001).
- Increased cavernous tissue (CT) fibrosis was observed in SHR (P < .001).
- Positive correlations were found between SBP and CSM proliferation (r²=0.9277), VSM proliferation (r²=0.8828), and CT fibrosis (r²=0.7775).
- Neural structures within the CT also showed increased surrounding connective tissue in SHR.
Conclusions:
- Spontaneously hypertensive rats develop significant morphologic changes in their erectile tissue, including vascular and interstitial remodeling.
- These structural alterations in penile cavernous tissue are strongly correlated with elevated blood pressure.
- Hypertension-induced extracellular matrix expansion may impact both the vascular and neural components of the penis.
Abstract:
Erectile dysfunction has an increased prevalence in hypertensive patients and is associated with cardiovascular diseases. For many years the discussion has been polarized on whether in hypertensive patients, it is the arterial hypertension or the antihypertensive therapy that is the cause of male erectile dysfunction. The aim of our study was to determine the morphologic changes in cavernous tissue (CT) in an animal model of arterial hypertension. Male spontaneously hypertensive rats (SHR) (n = 15) and normotensive Wistar-Kyoto (WKY) rats (n = 15) were studied for 8 months. Animals were allowed to drink tap water and fed a standard rat chow ad libitum. Systolic blood pressure (SBP) was measured monthly by the tail/cuff method. At the end of the experiment all the animals were sacrificed for microscopic studies. Cavernous tissue was processed by hematoxylin and eosin, Masson's trichrome, and monoclonal anti-alpha smooth muscle actin. Cavernous smooth muscle (CSM) and vascular smooth muscle (VSM) proliferation and CT fibrosis were evaluated by a semiquantitative score. SHR showed a higher proliferative score in CSM (2.7 +/- 0.28 v 1.1 +/- 0.07; P < .001), as well as in VSM (2.7 +/- 0.25 v 1 +/- 0.05; P < .001), and higher CT fibrosis score (2.8 +/- 0.28 v 0.1 +/- 0.07; P < .001), when compared to WKY rats. Furthermore, SHR showed a positive correlation between SBP and CSM proliferative score (r2 = 0.9277), SBP and VSM proliferative score (r2 = 0.8828), and SBP and CT fibrosis score (r2 = 0.7775). In addition, an increase in the surrounding connective tissue at the perineurium and endoneurium of the amielinic nerves in CT was observed in the SHR group. According to these results we conclude that SHR present morphologic changes in vessels as well as in cavernous spaces of the erectile tissue that have a high positive correlation with high blood pressure. Moreover, the increase in extracellular matrix expansion seems to affect not only the interstitium but also the neural structures of the penis.