Endocrine Abstracts

Increased dietary intake of polyunsaturated fatty acids (PUFAs) has been reported to be associated with a decreased incidence of cardiovascular disease. Increased dietary intake of polyunsaturated fatty acids (PUFAs) has been reported to be associated with a decreased incidence of cardiovascular disease. We have recently reported that ovarian steroid synthesis in ewes fed a diet high in n-3 PUFAs is significantly compromised¹. Hence in this study we have assessed the impact of a diet high in n-3 PUFAs on adrenal steroid synthesis. Two groups of Welsh Mountain ewes were fed either a control diet or a diet supplemented with n-3 PUFAs (linseed) for six weeks. Ewes were then culled and adrenal glands removed and tissue either stored at –80°C for the analysis of protein expression or used for isolation of adrenal cells, which were cultured under basal conditions for 24 h in serum-supplemented media. Spent media was then removed and cells re-incubated in the presence or absence of 10⁻⁹ M ACTH for a further 24 h after which spent media was stored at –20°C prior to analysis for cortisol by RIA. The cortisol response to ACTH in PUFA-fed ewes was significantly attenuated [(control: 4756.5±683.9 vs n-3: 687.6±57.3) ng/5×10⁴ cells/24 h; n=8 per group P<0.001)]. When adrenal tissue was assessed for protein expression, steroidogenic acute regulatory protein (StAR) and steroidogenic factor -1 (SF-1) were found to be inhibited compared to the control (P<0.05) whereas expression of steroidogenic enzymes, cholesterol side chain cleavage and 3β-hydroxysteroid dehydrogenase were unchanged. This data suggests that n-3 PUFAs modulate steroidogenesis through altering the expression of proteins involved in cholesterol transport and/or metabolism.

1. Chin et al. (2005) Dietary Polyunsaturated Fatty Acids Inhibit Ovarian Progesterone Secretion through Changes in Ovarian StAR Protein Expression in the Ewe. 87th Annual meeting of the Endocrine society, P3–254.

This work is supported by the Wellcome Trust (Grant Ref. 070564).