PARENT SESSION
OVARY - B

Tuesday, August 3, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(451) SUPPRESSION OF CORPUS LUTEUM DEVELOPMENT AT EARLY STAGE OF FORMATION BY ANTIBODY AGAINST VASCULAR ENDOTHELIAL GROWTH FACTOR IN THE COW.

Kamada, Daichi¹, Matsui, Motozumi¹, Shibanuma, Takumi¹, Yamamoto, Dai¹, Schams, Dieter ², Miyamoto, Akio¹, ¹ Department of Agricultural and Life Science, Obihiro, Japan² Institute of Physiology, Freising, Germany

ABSTRACT- The corpus luteum (CL) acquires intensive vascular network and progesterone (P) synthesis ability in the course of formation. Vascular endothelial growth factor (VEGF) has been shown to contribute these processes. The impact of VEGF in the onset of luteal angiogenesis has been demonstrated by specific VEGF neutralization in primate (Fraser et al. Endocrinology 141: 995-1000, 2000). The objective of the present study was to investigate the effect of treatment with VEGF antibody during early stage of luteal formation in the cow. Holstein cows were given prostaglandin (PG) F ₂ in the mid luteal phase of the pretreatment cycle to induce luteolysis, and 2 days after PGF ₂ injection, GnRH was injected (Day = 0) to induce ovulation. Using ultrasound guided needle, the antibody against bovine VEGF for treatment animals (n = 4), or rabbit IgG for control animals (n = 4), was injected into the site of ovulation commenced on Day 1 (just after ovulation), and was continued 3 times per day for 7 days. Cows were examined every day by transrectal color Doppler ultrasonography to determine the blood flow area and the CL volume by Day 8. Luteal biopsies were collected from all cows on Day 8, and mRNA expression for VEGF receptors (flt-1 and flk-1) were quantified by real-time PCR. Blood samples were collected at each observation to determine plasma P concentration. The CL size was markedly suppressed by VEGF antibody treatment, which resulted in ∼ 65% of those in control group (P < 0.05). Plasma P concentration was also suppressed by the VEGF antibody treatment (P < 0.05). However, blood flow area of luteal basal area was not different as compared to control group. Expression of mRNA for VEGF receptors were markedly suppressed by the VEGF antibody treatment on Day 8 (P < 0.05). These results indicate that CL development and function are suppressed by the intra-ovarian injection of VEGF antibody during the early stage of formation. Moreover, the data suggest that a suppression of VEGF action downregulates VEGF receptors expression. It is concluded that CL development at the early stage of formation is primarily driven by VEGF, and VEGF-mediated angiogenesis is an essential component of luteal function in the cow. Supported by JSPS and the 21 ^st century COE program (A-1).

KEY WORDS: VEGF, Cow, Corpus Luteum, Angiogenesis