Expression of TGF-β-1 mRNA and ultrastructural alterations in pharmacologically induced prolonged penile erection in a canine model

Pupose: Transforming growth factor beta (TGF-beta) is known to induce fibrosis. Our objective was to study the role of TGF-beta as a possible mediator of fibrosis that may follow prolonged penile erection. Materials and Methods: Prolonged penile erection was induced in seven adult male mongrel dogs by intracavernosal injection of papaverine into one of the corpora cavernosa while the other was used as a control. Intracavernosal pressure measurements were carried out prior to administration of papaverine and at the end of the procedure. Penile tissue was collected from anesthetized animals prior to euthanasia for histological and electron microscopic (EM) studies. RT-PCR was carried out for detection of mRNA on same tissue samples. Results: The light microscopy showed stasis of blood in the cavernosal sinusoids. EM studies revealed sporadic endothelial defects, loss of plasma membrane integrity and cytoplasmic condensation. There was expression of TGF-beta 1 mRNA in 66.7% of the experimental group compared with 16.7% of the control group. Conclusions: Pharmacologically induced low flow prolonged penile erection in canine models is associated with histomorphological changes in relatively short periods of time, suggesting that early therapeutic intervention is desirable. The gene expression for TGF-beta 1 may be a mediator of fibrosis; therefore the use of anti-TGF-beta agents presents a possible tool for therapeutic intervention.