Effects of omega-3 and -6 polyunsaturated fatty acids on ovine follicular cell steroidogenesis, embryo development and molecular markers of fatty acid metabolism

• Published in: Reproduction (Cambridge, England) Vol. 141; no. 1; pp. 105 - 118
• Main Authors: Hughes, Jaime, Kwong, Wing Yee, Li, Dongfang, Salter, Andrew M, Lea, Richard G, Sinclair, Kevin D
• Format: Journal Article
• Language: English
• Published: England BioScientifica 01.01.2011; BioScientifica Ltd; Society for Reproduction and Fertility
• Subjects: Albumin; Animals; Antioxidants; Blastocyst - drug effects; Blastocyst - metabolism; blastocysts; Cell culture; Cells, Cultured; Diets; Embryo Culture Techniques; Embryos; Enzymes; Fatty acids; Fatty Acids - metabolism; Fatty Acids, Omega-3 - pharmacology; Fatty Acids, Omega-6 - pharmacology; Female; Follicular fluid; Follicular Fluid - metabolism; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Granulosa Cells - drug effects; Granulosa Cells - metabolism; Guanylate cyclase; Lipids; Lipoproteins; Lipoproteins (high density); Lipoproteins, HDL - metabolism; Lipoproteins, LDL - metabolism; Ovarian Follicle - drug effects; Ovarian Follicle - metabolism; Phosphoproteins - genetics; Phosphoproteins - metabolism; Polyunsaturated fatty acids; Progesterone; Progesterone - biosynthesis; RNA, Messenger - metabolism; Serum Albumin - metabolism; Sheep; Steroidogenesis; Superoxide dismutase; Theca; Theca Cells - drug effects; Theca Cells - metabolism; Time Factors; Transcription
• DOI: 10.1530/REP-10-0337
• ISSN: 1470-1626

We previously reported increased follicular fluid progesterone (P4) concentrations in ewes fed an n-3 compared to an n-6 polyunsaturated fatty acid (PUFA)-enriched diet, but detected no differential effect of n-3 and n-6 PUFA-enriched high-density lipoproteins (HDL) on granulosa cell (GC) steroidogenesis in vitro. Moreover, net n-6 PUFA-enriched HDL reduced early embryo development, but in the absence of a net uptake of FA. Consequently, we hypothesised that a) effects of n-3 PUFA on ovarian steroidogenesis are mediated by theca rather than GCs and b) during embryo culture lipids are acquired solely from the albumin fraction of serum, so that albumin-delivered n-3 and n-6 PUFA exert a greater differential effect on embryo development than either low-density lipoprotein (LDL)- or HDL-delivered PUFA. Data confirmed that n-3 PUFA increases P4 production solely in theca cells and that this is associated with an increase in STAR transcript expression. Furthermore, LDL- and HDL-delivered n-3 PUFA are equally efficacious in this regard during the first 96 h of culture, but thereafter only HDL-delivered n-3 PUFA induces this effect in partially luteinised theca cells. We also demonstrate that albumin is the sole serum fraction that leads to a net uptake of FA during embryo culture. PUFA-enriched serum and albumin increased the yield of morphologically poorer quality blastocysts with increased transcript expression for the antioxidant enzyme SOD1. Important differential effects of n-3 and n-6 PUFA on ovarian steroidogenesis acting solely on theca cells are identified, but differential effects of PUFA on embryo development are less apparent.