Endothelial nitric oxide synthase (eNOS) and soluble guanylyl cyclase (sGC) expression in the ovarian artery during the estrous cycle in overfed or underfed sheep treated with arginine (Arg). (LB324)

Abstract

The aim of this study was to determine if Arg supplementation to control, overfed, and underfed ewes impacts protein and mRNA expression of eNOS and sGC in the ovarian artery. Ewes were categorized by weight and randomly assigned to one of three different nutrition groups: control (C; 2.14 Mcal/kg; n=37), overfed (O; 2xC Mcal/kg; n=37), and underfed (U; 60% of C Mcal/kg; n=37) beginning 60 days prior to Arg treatment and were randomly assigned to one of two treatments; Arg (L‐Arg‐HCl; 155 µmol Arg/kg BW) or saline (~10 ml) i.v. beginning on day 0 of the first estrous cycle until tissue collection at the late‐luteal phase of the first estrous cycle, or early or mid‐luteal phases of the second estrous cycle. Ovarian vascular pedicle was fixed and imaged, and RNA was extracted from the ovarian artery (OA). Compared to saline controls, Arg increased mRNA expression of eNOS nearly 300‐fold and sGC approximately 150‐fold in OA for O group during the mid‐luteal phase (P<0.0001; n=5 for each group). Arg (n=3) increased eNOS 7‐fold (P<0.06) compared to saline (n=7) in U during the early luteal phase. No other Arg effects were observed in either other diet groups or on other luteal phases. eNOS protein was localized in blood vessel endothelium of the ovarian pedicle, whereas sGC‐beta protein was expressed in both vascular smooth muscle and endothelium of blood vessels. During the early or mid‐luteal phase when the corpus luteum is actively growing or fully functional, Arg can dramatically influence the NO system in OA by increasing mRNA expression of eNOS and sGC in U or O, and suggests that Arg supplementation may alter vascular function and blood flow to the ovary in compromised animals.Supported by USDA‐AFRI grant 2011‐67016‐30174, and Hatch Projects ND01754 and ND01748 to ATGB and DAR.