Platelet-derived growth factor (PDGF) and PDGF receptors in rat corpus cavernosum: changes in expression after transient in vivo hypoxia

Platelet-derived growth factor (PDGF) overactivity has been implicated in a therosclerosis and several fibrotic conditions including lung and kidney fi brosis, liver cirrhosis and myelofibrosis. Low oxygen tension (hypoxia) is a known stimulus for transcriptional induction of PDGF ligand and receptor genes in different tissues. We studied the expression and localization of P DGF-A. PDGF-B, and PDGF receptor (PDGFR)-alpha and -beta subunits in adult rat isolated corpus cavernosum (CC) under generalized transient hypoxia (pO (2) 10%) in comparison with normoxic conditions. Semi-quantitative RT-PCR a nalysis of mRNA extracted from rat penis showed higher amounts of PDGF-A, P DGF-B and PDGFR-beta mRNA transcripts in hypoxic versus normoxic animals. T he immunohistochemical analysis showed that the localization of PDGF subuni ts and PDGFR-beta was confined to the cytoplasm of the perivascular smooth muscle cells. endothelium and trabecular fibroblasts. Our findings indicate that transient low oxygen tension induces PDGF overexpression in rat CC, w hich in the long term may lead to an increase of connective tissue producti on. We suggest that a local impairment of the PDGF/PDGFR system may contrib ute to CC fibrosis, which is an established cause of erectile dysfunction i n man.