Wednesday, August 4, 2004
10:30 AM–12:30 PM
(659) CELLULAR EXPRESSION OF VASCULAR ENDOTHELIAL GROWTH FACTOR RECEPTOR-2 (VEGFR-2) INDICATES POTENTIAL NON-ANGIOGENIC ROLES FOR VEGFR-2 IN SPERMATOGENESIS AND OVULATION IN VEGFR-2 LACZ MICE.
Clopton, Debra 1, Bott, Rebecca1, McFee, Ryann1, Cupp, Andrea1, 1 University of Nebraska - Lincoln, Lincoln, Nebraska
ABSTRACT- Angiogenic and non-angiogenic roles of VEGF and its receptor (VEGFR-2) have been described by our laboratory during testis morphogenesis. We have also identified non-angiogenic roles for VEGF and VEGFR-2 during follicle progression. Transgenic mice expressing lacZ driven by the VEGFR-2 promoter were collected at different ages and after hormone treatments to determine cellular localization of VEGFR-2. VEGFR-2 was expressed in primordial germ cells in the male at embryonic day 17 (E17) and in spermatogonia at postnatal day 4 (P4). VEGFR-2 was present in many stages of germ cells at P20-P30 with elevated expression levels in spermatogonia and in sperm at P60. To determine the effects of hCG on VEGFR-2 in male germ cells, adult male mice were injected with 50 IU of hCG and testes collected for histology at 12, 24 and 48 hr after injection (n = 12/trt). Testes were also collected from 6 males not injected with hCG. Preliminary results indicate reduced VEGFR-2 at 24 and 48 hr suggesting hCG regulated genes may alter germ cell expression of VEGFR-2. In the female, VEGFR-2 was not observed in thecal cells, granulose cells or oocytes of the embryonic or early postnatal ovary. By P30, faint expression was present in both granulosa cells and oocytes of primary, secondary and some tertiary follicles. To determine VEGFR-2 expression prior to ovulation, adult female mice were superovulated and ovaries collected at 3, 6 and 9 hr after hCG treatment (n = 3/trt). Preliminary results indicate VEGFR-2 increased in theca cells of both secondary and tertiary follicles after 3, 6 and 9 hr. By 9 hr, VEGFR-2 was present in granulosa cells suggesting VEGFR-2 may be involved in granulosa cell differentiation prior to ovulation. No oocytes from tertiary follicles expressed VEGFR-2 in response to superovulation. These results indicate VEGFR-2 and VEGF may be critical to germ and sperm cell maturation in spermatogenesis and differentiation of theca and granulosa cells prior to ovulation.
KEY WORDS: OVARY, GRANULOSA DIFFERENTIATION, TESTIS, GERM CELL