Reproduction Abstracts

Lysophosphatidic acid (LPA) is a bioactive lipid mediator that exerts a wide range of biological actions. LPA acting specifically through LPA receptor 1 (LPAR1) seems to be essential for the development of fibrosis in several organs. We determined whether the LPA–LPARs signalling system correlates to equine endometrial fibrosis (endometrosis). A total of 24 uteri from diestrus (n=6 for each category: I, II A, II B, and III according to Kenney and Doig classification) and 20 uteri from oestrus (n=5 for each four endometrosis category) were used for this experiment. The level of LPA and expression of four types of LPAR (1–4) were investigated in the endometrial tissue in the course of endometrosis. Additionally, the effect of LPA (10⁻⁹ M) on secretion of connective tissue growth factor (CTGF) and prostaglandin E₂ (PGE₂) from endometrial tissue at different stages of endometrosis was determined. The LPAR1–4 mRNA transcription was not correlated with endometrosis development. In diestrus, LPA up-regulated CTGF secretion in category III compared to the control (P<0.05). In diestrus, LPA up-regulated endometrial PGE₂ secretion in all categories, while in oestrus it up-regulated PGE₂ secretion only in category I endometrium (P<0.05). There is no strong positive linking between LPA level and LPAR1–4 expression in endometrosis, but LPA up-regulated endometrial CTGF secretion in severe stage of fibrosis in diestrus. Moreover, the endometrial LPA level and LPA-stimulated PGE₂ secretion was impaired in estrus in the course of endometrosis what may disturb homeostasis essential in physiological processes occurring in endometrium. Supported by grant MAESTRO of National Research Center (2011/02/A/NZ5/00338).