Alterations in plasma lipoproteins and apolipoproteins associated with estrogen‐induced hyperlipidemia in the laying hen

Hermier, Dominique; Forgez, Patricia; Williams, John; Chapman, M. John

doi:10.1111/j.1432-1033.1989.tb14996.x

Cited by 53 publications

(25 citation statements)

References 42 publications

(33 reference statements)

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“…These results indicate that isoflavones and the metabolite Eq have lipid-lowering effects in mammals, as well as in chickens. This was in contrast to the results in chickens fed estradiol, which led to a marked elevation in plasma lipids, with the greatest increases in TG and LDLC concentrations (Hermier et al, 1989;Park and Cho, 1990). Estrogen use in mammals, however, has been reported to decrease TG and LDLC levels and to increase HDLC levels (Haffner and Valdez, 1995).…”

Section: Discussioncontrasting

confidence: 73%

The effect of equol injection in ovo on lipid metabolism and hepatic lipogenic gene expression in broilers

Wei

Zhang

et al. 2012

Animal

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This study investigated the effects of in ovo administration of equol (Eq) on post-hatch growth and hepatic lipid metabolism in broiler chickens. Fertilized eggs (146 eggs/group) were injected with 0 mg (control, Con), 20 mg (low dose, L) and 100 mg (high dose, H) Eq in the albumen on the 7th day of incubation. Except a trend increase in the weight of total fat (P 5 0.09), Eq had no effect on growth or liver weight in broilers at 49 days of age. Males presented higher liver and BWs and lower total fat and relative liver weights than females (P , 0.01). However, there were no significant effects of Eq or Eq-gender interactions on growth performance or tissues weight (P . 0.05). With respect to lipid parameters in the serum, the results showed that female broilers presented higher triacyglycerol (TG) and low-density lipoprotein cholesterol concentrations than males, whereas there was no gender difference in serum total cholesterol (TC) or high-density lipoprotein cholesterol (HDLC) concentration (P . 0.05). Eq administration significantly decreased serum TG and TC but increased HDLC concentrations in serum of broilers at 49 days of age (P , 0.05), whereas there were no interactions between gender and Eq (P . 0.05). To elucidate the mechanism behind the significant changes of serum TG and TC levels, the expression of genes involved in lipid metabolism in the liver was investigated in female chickens using reverse transcription-PCR. Carnitine palmitoyl transferase I (CPTI) messenger RNA (mRNA) was significantly upregulated by 20 and 100 mg Eq (P , 0.05). High-dose Eq significantly decreased fatty acid synthase (FAS) and enhanced cholesterol-7alpha-hydroxylase (CYP7A1) mRNA levels in the liver (P , 0.05). Eq had no significant effects on acetyl-CoA carboxylase, sterol regulatory element binding protein-1c, malic enzyme, low-density lipoprotein receptor or 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA in the liver (P . 0.05). These results in female broilers suggest that Eq decreased blood TG by upregulating CPTI and downregulating FAS mRNA expression in the liver, and that high serum cholesterol levels stimulated CYP7A1 gene transcription in the liver.

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Section: Discussioncontrasting

confidence: 73%

The effect of equol injection in ovo on lipid metabolism and hepatic lipogenic gene expression in broilers

Wei

Zhang

et al. 2012

Animal

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“…Plasma triglyceride has commonly been measured in nondomesticated birds as an index of total plasma VLDL, which consists of both the generic and yolk-targeted forms of VLDL (Williams and Christians, 1997;Williams and Martyniuk, 2000;Challenger et al, 2001). Despite the marked increase in circulating lipid levels reported during egg production (Griffin and Hermier, 1988;Walzem et al, 1994Walzem et al, , 1999Walzem, 1996), in vivo studies on laying poultry hens have detected only low circulating levels of intermediate-density and low-density lipoproteins, both by-products of the metabolism of generic VLDL, suggesting that VLDLy is resistant to metabolism by laying hens (Hermier et al, 1989;Walzem et al, 1994;Walzem, 1996). These studies provide evidence that the marked increase in total VLDL during avian egg production or following estrogen administration is the result of increased synthesis of the estrogen-dependent VLDLy component of total VLDL.…”

Section: Measurement Of Resting Metabolic Ratementioning

confidence: 99%

The metabolic cost of avian egg formation: possible impact of yolk precursor production?

Vézina

Salvante

Williams

2003

Journal of Experimental Biology

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Physiological mechanisms underlying one of the major assumptions of life history theory, namely that an increased effort in current reproduction may have a negative impact on future reproductive success, are not well understood (Stearns, 1992). One reason for this lack of knowledge is that, in avian systems, most of the research attention has been focused on manipulations of reproductive effort at the incubation or chickprovisioning stages (Monaghan and Nager, 1997) and, thus, the potential physiological costs incurred earlier in breeding, i.e. during follicle development and egg production, have received very little attention. Recent research, however, has shown that the energy cost of egg production in birds may be significant Vézina and Williams, 2002). We recently showed that the physiological process of egg formation in female European starlings (Sturnus vulgaris) is responsible for a 22% increase in resting metabolic rate (RMR) in laying individuals (Vézina and Williams, 2002). We further demonstrated that 18% of the variation in elevated laying RMR was explained by the maintenance and activity cost of the working oviduct (Vézina and Williams, 2003) and emphasized that this organ is probably costly enough that selection has led to a very tight size-function relationship, explaining its rapid pattern of recrudescence and regression. However, 82% of the variation in laying RMR remains unexplained, suggesting that other energy-consuming physiological mechanisms must be responsible, at least in part, for the metabolic cost of egg production (Vézina and Williams, 2003).Another component of egg production that is likely to be energetically costly is the increased liver activity involved in protein and lipid production for oogenesis. During the process of egg formation, the hypothalamus initiates a hormonal cascade by releasing gonadotropin-releasing hormone (GnRH), which induces the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland (Williams, 1998;Scanes, 2000). These hormones stimulate the ovary to produce estrogens (Williams, 1998), which then trigger the production of the egg-yolk precursors, vitellogenin (VTG) and yolk-targeted very-lowdensity lipoprotein (VLDLy), by the liver (Bergink et al., 1974;Deeley et al., 1975;Wallace, 1985;Walzem, 1996;Williams, 1998), which are then secreted into the blood. During rapid yolk development, plasma VTG and VLDLy are taken up by the ovary and are processed within the follicles into yolk, the nutrient and energy source for the developing avian embryo Little is known about the energy costs of egg production in birds. We showed in previous papers that, during egg production, European starlings (Sturnus vulgaris) undergo a 22% increase in resting metabolic rate (RMR) and that the maintenance and activity costs of the oviduct are responsible for 18% of the variation in elevated laying RMR. Therefore, other energy-consuming physiological mechanisms must be responsible for the remaining unexplained variation in elevated laying ...

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“…Apo-II, an apolipoprotein, which is unique to avian species and is expressed during the laying cycle, has been extensively investigated (Burley et al, 1984;Nimpf et al, 1988;Hermier et al, 1989;Schneider et al, 1990;Barber et al, 1991;Dugaiczyk et al, 1993;Wijnholds et al, 1993). Estrogen induction of apo-II biosynthesis (Burley et al, 1984;Nimpf et al, 1988;Hermier et al, 1989), concurrent with dramatic changes in lipid metabolism at the onset of lay, eg, increases in hepatic lipogenesis and in the production of egg yolk precursors , indicated its role in oogenesis.…”

Section: Discussionmentioning

confidence: 99%

“…Estrogen induction of apo-II biosynthesis (Burley et al, 1984;Nimpf et al, 1988;Hermier et al, 1989), concurrent with dramatic changes in lipid metabolism at the onset of lay, eg, increases in hepatic lipogenesis and in the production of egg yolk precursors , indicated its role in oogenesis.…”

Section: Discussionmentioning

confidence: 99%

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Plasma apolipoprotein VLDL-II and egg production in laying hens: establishment of an ELISA method

Pinchasov¹,

Elmaliah²,

Bezdin³

1994

Reprod. Nutr. Dev.

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Summary ― The developmental pattern of apolipoprotein in the plasma with regard to lipid concentration was characterized during the transition of pullet females to the laying phase in commercial laying hens (Gallus domesticus). Apo-I I was isolated from the plasma of estrogen-administered roosters, and a rapid ELISA was developed for its quantification in chickens. The sensitivity of the assay was 5 ng/ml, and the inter-and intra-assay coefficients of variation were 4 and 8%, respectively. Whereas no detectable levels of apo-11 could be monitored in the blood plasma of immature chickens, the level increased slightly to 23 weeks of age and sharply at the onset of lay. This profile reflects the dramatic changes in lipid metabolism at the onset of lay, and concurs with the concentration of total lipids in the plasma and with egg production rate. Plasma apo-II of 2 laying strains differing in body weights but compared at approximately similar egg production rates, tended to be slightly higher in heavy vs light-weight type hens. Oogenesis was speculated to be the main factor affecting both apo-II and total lipid profiles in chicken plasma, enabling efficient delivery of VLDL to the egg. apolipoprotein VLDL-11 / chicken / hen / egg production rate / lipid

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Alterations in plasma lipoproteins and apolipoproteins associated with estrogen‐induced hyperlipidemia in the laying hen

Cited by 53 publications

References 42 publications

The effect of equol injection in ovo on lipid metabolism and hepatic lipogenic gene expression in broilers

The effect of equol injection in ovo on lipid metabolism and hepatic lipogenic gene expression in broilers

The metabolic cost of avian egg formation: possible impact of yolk precursor production?

Plasma apolipoprotein VLDL-II and egg production in laying hens: establishment of an ELISA method

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