Effect of penile tourniquet on growth factors in rat penile tissue

This study aimed to evaluate the effect of penile tourniquet application on growth factors in rat penile tissues.

Forty Wistar male rats were included in the study. Rats were divided into 4 groups. After anesthetization, perimeatal penile skin and the corpus cavernosum were sampled in the control group (CG). A Mathieu-like flap was designed without a penile tourniquet (PT) to serve as a sham group (SG). In the PT groups, a Mathieu-like flap was created and a 5 mm diameter rubber circular band was applied at the base of the penis. The PT was applied for 10 min in the PT-10 group and for 30 min in the PT-30 group. Penile tissue was sampled 24 h after PT application in the SG and PT groups. Tissues obtained were examined in three sections: the subepithelial vascular plexus (SVP), the corpus cavernosum (CC) and the smooth muscle-like mesenchymal cells in the corpus cavernosum (MC). Acute inflammation was evaluated with hematoxylin-eosin staining. The effect of PT on vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR) and transforming growth factor beta receptor (TGF beta-R) levels was evaluated.

Higher grades of acute inflammation were encountered in the PT-10 and PT-30 groups compared to the CG and SG (p<0.005). However, mean grades of acute inflammation did not show a statistical difference between the PT-10 and PT-30 groups (p>0.05). When the levels of growth factors were compared between the CG and PT-10 group, the PT-10 group showed increased levels of VEGF and TGF beta-R. In the PT-30 group, both VEGF and VEGFR levels were found to be decreased. When acute inflammation grades of tissues were correlated with VEGF and TGF beta-R, higher acute inflammation grades correlated with decreased VEGF and increased TGF beta-R levels (Spearman's correlation, p<0.005). Although alterations in VEGF and TGF beta-R levels were detected in the SVP and CC of penile tissues, altered VEGFR levels were only detected in the MC sections.

PT caused higher grades of acute inflammation which correlated with decreased VEGF levels and increased TGF beta-R levels. Decreased VEGF levels after PT may alter the angiogenesis phase of wound healing and cause poor angiogenesis in penile skin flaps. Increased levels of TGF beta-R can be considered as an acute inflammatory response to PT. These results confirmed that prolonged PT application may result in altered growth factors in penile tissue and may reduce the success rate of repair.