Reproduction Abstracts

Lysophosphatidic acid (LPA) is a simple phospholipid and exerts various biological functions effecting on reproductive processes in rats, pigs, ewes and cow. LPA acts through three subtypes of Edg family G protein-coupled receptors (LPA1-3) and ‘non-Edg family’ LPA receptors (LPA4-6). The aim of the study was to determine LPA: i) concentrations and its receptors mRNA transcription, and ii) effect on P₄ secretion from equine CL during the oestrous cycle and early pregnancy. CLs were obtained in early-, mid-, and late luteal stages of the cycle and at Day 28 of pregnancy (n=6, each stage). In experiment 1. the concentration of LPA extracted from CL tissue was measured using ELISA. Additionally, the expression of LPA receptors (1–4) was determined by qPCR. In experiment 2. the CL explants were cultured for 24 h with LPA (10⁻⁹M) and concentration of P₄ was determined using EIA. The concentration of LPA was up-regulated in the mid CL, and down-regulated in the early and pregnant CL (P<0.05). The mRNAs transcription of LPAR1-4 were up-regulated in the late luteal phase compared to early, mid luteal stage of the cycle and pregnancy (P<0.05). Moreover, LPA stimulated P4 secretion from early and mid CL explants compared to other phases (P<0.05). We showed for the first time the presence of LPA and its receptor expression in equine CL. The results indicate that concentration of LPA and LPAR1-4 mRNA transcription in equine CL is estrous cycle-dependent and LPA affect P₄ secretion during development of CL.

Supported by NRC Grant Maestro 2011/02/A/NZ5/00338.