Caveolin-1 and heme-oxygenase-1 as tissue markers of the protective effect of sildenafil on pathologic penile remodeling in spontaneous hypertensive rats (SHR)

Mazza, O⁽¹⁾; Becher, E⁽¹⁾; Sacca, P⁽²⁾; Vazquez, E⁽²⁾; Grosman, H⁽³⁾; Toblli, J⁽⁴⁾

⁽¹⁾Div. Urology, Hospital de Clinicas “José de San Martín”. University of Buenos Aires. ⁽²⁾Dept. Biologic Chemistry, School of Sciences, University of Buenos Aires. ⁽³⁾Dept. Clinical Biochemistry, School of Pharmacy and Biochemistry, University of Buenos Aires. ⁽⁴⁾Laboratory of Experimental Medicine, Hospital Alemán, Buenos Aires, Argentina.

Introduction and Objectives: Caveolae are specialized plasma membrane invaginations on the surface of most cells and are involved in endocytosis. Caveolin is a family of integral membrane proteins associated with caveolae and trans-Golgi network derived vesicles. Caveolin-1 (Cav-1) is present in corporal smooth muscle. In electron microscopy studies it was observed a dramatic decrease in caveolae in older rats, meaning that aging and other pathologies which also affects trabecular smooth muscle/ collagen ratio might show a reduced expression of Cav-1 as well, which could be used as a marker of erectile dysfunction. Furthermore, the localization of heme degradation enzymes on caveolae presents a novel evidence that caveolin-1 interacts and modulates heme oxygenase1 (HO-1) activity. Recently, we showed that Cav-1 and HO-1 were both significantly higher in control WKY versus SHR but we couldn’t establish a positive effect of sildenafil using western blots. (J Sex Med 2006;3 Suppl 5:409). In this study, we performed immunostaining techniques to determine more precisely the expression of Caveolin-1 and HO-1 and its modification with sildenafil.
Materials and Methods: Twelve-week-old SHR (n=16) and control Wistar-Kyoto (WKY) (n=16) male rats were divided into four groups: 1) SHR (n=8); 2) SHR with sildenafil (n=8); 3) WKY (n=8); and 4) WKY with sildenafil. Daily dose of sildenafil citrate was of 10 mg/Kg administered in drinking water. After 12 weeks of treatment, the animals were sacrificed and proteins expressions were analyzed with immunostaining techniques using antibodies anti-caveolin 1 and anti-HO-1.
Results: Mean protein values on immunostaining were: Group1: Cav-1:4.84, HO-1:5.20; Group2: Cav-1:8.19, HO-1:7.84; Group3: Cav-1:13.6, HO-1:11.9; Group4: Cav-1:14.3, HO-1:12.4 (see table). The differences were statistically significant between SHR and SHR with sildenafil on both Cav-1 (p=0.0001) and HO-1 (p=0.0011). The values were not significantly modified on the control animals.
Conclusions: Using immunostaining techniques we showed not only that Cav-1 and HO-1 were both significantly higher in WKY versus SHR, but also that sildenafil treatment caused a significant increase of both proteins expression on SHR showing its ability to interfere on the morphologic changes in cavernous space smooth muscle caused by hypertension.

Tabla: Caveolin-1 and Heme Oxygenase-1 in cavernous smooth muscle. Positive staining area (%)