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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2008-1086v1 86/11/3014    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by O’Neil, M. R. Articles by Vonnahme, K. A. Search for Related Content PubMed PubMed Citation Articles by O’Neil, M. R. Articles by Vonnahme, K. A.

Impacts of linseed meal and estradiol-17β on mass, cellularity, angiogenic factors, and vascularity of the jejunum¹

Department of Animal Sciences, North Dakota State University, Fargo 58105

² Corresponding author: kim.vonnahme{at}ndsu.edu

To evaluate the estrogenic potential of the phytoestrogen secoisolariciresinol diglycoside (SDG) found in linseed meal (LSM) on jejunal mass, cellular proliferation, vascularity, and expression of angiogenic factors and their receptors, 48 ovariectomized ewes (54.6 ± 1.1 kg) were fed a diet containing 12.5% LSM for 0, 1, 7, or 14 d and implanted with estradiol-17β (E₂) for 0, 6, or 24 h before tissue collection. Angiogenic factors and receptors measured included vascular endothelial growth factor (VEGF), VEGF receptor-1 (FLT), VEGF receptor-2 (KDR), fibroblast growth factor (FGF), FGF receptor 2 IIIc (FGFR), angiopoietin (ANG)-1, ANG-2, ANG receptor (Tie-2), endothelial nitric oxide synthase (eNOS), and soluble guanylate cyclase (sGC). There was a LSM x E₂ interaction (P = 0.003) on the jejunal cellular proliferation index. Jejunal cellular proliferation increased (P < 0.002) in ewes not fed LSM and implanted with E₂ for 6 or 24 h compared with ewes implanted for 0 h but did not increase when LSM was fed for 1, 7, or 14 d. Neither feeding LSM nor implanting ewes with E₂ altered vascular area density (P > 0.75) or vascular surface area (P > 0.29) of the jejunal villi. Expression of mRNA for the angiogenic factors VEGF, FGF, FGFR, ANG-1, ANG-2, and Tie-2 were not altered (P > 0.33) by feeding LSM or implanting ewes with E₂. Implanting ewes with E₂ for 6 h increased (P = 0.04) eNOS expression compared with ewes implanted for 0 h. Feeding LSM and implanting ewes with E₂ interacted to alter mRNA expression of FLT (P = 0.04), KDR (P < 0.001), and sGC (P = 0.04). When LSM was fed for 1, but not 0, 7, or 14 d, expression of FLT mRNA decreased (P < 0.03) when ewes were implanted with E₂ for 24 h compared with ewes implanted for 0 or 6 h. Expression of KDR mRNA was suppressed in ewes fed LSM for 1 (P = 0.03) or 7 d (P = 0.0007) and implanted with E₂ for 24 h compared with ewes implanted for 0 h. When LSM was fed for 14 d, implanting ewes for 6 h increased (P = 0.04) KDR expression compared with ewes implanted for 0 h. Ewes fed LSM for 0 and 1 d experienced an increase in sGC mRNA expression when implanted for 6 h (P = 0.001) compared with ewes implanted for 0 h. When implanted for 24 h, levels were similar (P = 0.80) to those observed when ewes were implanted for 0 h. Expression of sGC was not altered by E₂ when LSM was fed for 1, 7, or 14 d (P > 0.11). The impacts of E₂ and LSM on nutrient uptake and growth during physiologically important time points are unknown.

Key Words: angiogenesis • cellular proliferation • estrogen • linseed meal • phytoestrogen