Submission Number: TOM-4-4-19

Abstract Number: 264

ATRIAL NATRIURETIC PEPTIDE SYSTEM IN THE BOVINE CORPUS LUTEUM.

TJ Acosta* 1, B Berisha 2, K Miwata 1, S Kobayashi 1, T Ozawa 1, K Hayashi 1, D Schams* 2 and A Miyamoto* 1

Obihiro University of Agriculture & Veterinary Medicine, Obihiro, Japan 1
TU-Munich, Freising-Weihenstephan, Germany 2

Abstract:
Recent findings suggest that vasoactive peptides including atrial natriuretic peptide (ANP) regulate the ovarian function. Thus, to obtain further information that ANP may take part in the functional regulation of the corpus luteum (CL), we investigated 1) changes in the ANP concentration in the ovarian venous plasma (OVP) as well as jugular venous plasma (JVP) during the early luteal stage, 2) the intraluteal release of ANP and the expression of mRNA for ANP type C receptor (ANP-CR), 3) the interaction between ANP and prostaglandin (PG) F2, and 4) the effects of ANP on the local release of progesterone (P) within the bovine CL.

The ANP concentrations in OVP was significantly higher than that of JVP (63.7 pg/ml vs. 46.8 pg/ml) during Days 3-5 of the estrous cycle. The semi-quantitative reverse transcription-polymerase chain reaction analysis revealed the expression of ANP-CR mRNA in the CL, but it did not change during the estrous cycle. Additionally, endothelial cells isolated from developing CL expressed the ANP-CR mRNA. In the study of in vitro microdialysis system, ANP was detected in the perfusate. The concentration in the early CL (Days 3-5: 13.4 pg/ml) was higher than that of the mid (Days 8-12: 4.3 pg/ml) and the late CL (Days 15-18: 3.0 pg/ml). The infusion of ANP (10-7 M) increased the release of PGF2 in the early and late CL, but showed no effect on the PGE2 release at any of the stages. The infusion of PGF2 in turn stimulated the release of ANP in the CL of all stages. However, the ANP infusion did not affect the P release in the early CL.

The results suggest that in addition to its vascular control, ANP may support the PGF2 production in the bovine developing CL in which angiogenesis is active. Supported by Grant-in-Aid for Scientific Research and the Japan-Germany joint research project of JSPS.

Keywords: ANP, PGF2, Corpus Luteum, Cow

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This abstract is being presented at: 8:00 AM in session:
Corpus Luteum II