Ovariectomy Alters Concentrations of Mitogens in Platelets and Platelet-Induced Proliferation of Arterial Smooth Muscle

Experiments were designed to determine how ovariectomy modulates mitogenic factors in platelets and how these factors affect proliferation of coronary arterial smooth muscle. Platelet-derived growth factors (PDGFAB and PDGFBB), transforming growth factors (TGF 1 and 2), and vascular endothelial growth factor (VEGF165) were quantified in platelet lysates and platelet -poor plasma (PPP) from adult gonadally intact and ovariectomized (OVX) female pigs by ELISA. Proliferation of cultured coronary arterial smooth muscle cells (SMCs) from both groups of pigs was determined in response to autologous or heterologous platelet lysates. Platelet concentrations of PDGFBB, but not PDGFAB, TGF 1, and TGF 2, increased with ovariectomy. VEGF165 was not detected in platelets from either group. Proliferation of SMCs from OVX females was significantly greater upon exposure to autologous or heterologous platelet lysates than proliferation of SMCs from intact females. These results indicate that ovariectomy increases concentrations of PDGFBB in platelets. Higher levels of PDGFBB in platelets in synergy with other platelet-derived products could contribute to increased proliferative arterial response to injury following ovariectomy.