Vegf 165b Administration Induces Germ Cell Apoptosis in Adult Mouse Testis.

From previous experiments, our laboratory has determined that Vascular Endothelial Growth Factor (VEGF) pro-angiogenic isoforms increase germ cell numbers and anti-angiogenic isoforms reduce the seminiferous cord area and increase the interstitial area in vivo in perinatal male mice. Therefore, our hypothesis was that VEGF pro-angiogenic and anti-angiogenic isoforms altered germ cell apoptosis in testes of adult mice. Adult mice (60-90 days old) expressing LacZ driven by the Kdr promoter (KDR-lacZ) were injected (IP) with recombinant anti-angiogenic isoform VEGF165b (1µg; n=8), PBS Control (1µg; n=8), an antibody which neutralizes anti-angiogenic isoforms of VEGF (AntiVEGFxxxb, 1μg; n=9) or IgG control (1µg; n=8) and blood samples and testes were collected, at 3 or 9 hours following injection. Blood samples were analyzed for testosterone. There were no differences in testosterone among treatments (P > 0.05). Testes were embedded, sectioned and the number of apoptotic cells was quantified on testis sections with a TUNEL assay. At 3 hours, the VEGF165b treatment group tended (P < 0.06) to have increased number of apoptotic germ cells (16.5±4.2) compared to its PBS control (8.0±1.5). At 9 hours after injection, the VEGF165b treatment group had an increased number of TUNEL positive germ cells (20.0±3.0; P < 0.05) compared to PBS Controls (10.1±1.7). Taken together these data indicate that VEGF165b is detrimental to germ cell survival and may initiate the apoptosis pathway. Further experiments are underway to elucidate the VEGF165b mediated mechanisms of apoptosis in germ cells. This research was supported by NIH/NICHD RO1-HD051979. (poster)