Lipid profiles in brains from sheep with natural scrapie

Dietary carnosic acid, selenized yeast, selenate and fish oil affected the concentration of fatty acids, tocopherols, cholesterol and aldehydes in the brains of lambs

Abstract. The function of the brain is to exert centralized control over the other internal organs and tissues of the body. Thus, the objective of our studies was to evaluate changes in the concentration of fatty acids (FAs), cholesterol (CHOL), cholest-4-en-3-one (CHOL-4-3), tocopherols, malondialdehyde (MDA) and fatty aldehydes in the brains of lambs fed supplemented diets. Thirty male Corriedale lambs with a body weight of 30.5 ± 2.6 kg were allotted to five groups of six lambs and housed individually. After the preliminary period, for 35 days the animals were fed a diet containing 3 % rapeseed oil (RO) (the RO diet), a diet enriched with 2 % RO and 1 % fish oil (FO) (the FO diet) or the diets with combined addition of 2 % RO, 1 % FO, 0.1 % carnosic acid (CA) (the CA diet) and 0.35 ppm Se as the selenized yeast (SeY) (the CASeY diet) or selenate (SeVI) (the CASeVI diet). The CASeVI diet most efficiently increased the accumulation of FAs (including unsaturated FAs), CHOL-4-3 and fatty aldehydes in the lamb brain. This diet most effectively decreased the concentration of CHOL and MDA in the brain. The CASeY diet showed a different impact on the level of FAs, CHOL, CHOL-4-3, tocopherols, MDA and fatty aldehydes in the brain as compared with the CASeVI diet. The CA diet reduced the concentration of CHOL-4-3, the sums of fatty aldehydes, FAs, atherogenic- and thrombogenic-saturated FAs in the brain compared with the CASeVI diet; the CA diet most effectively increased the value of polyunsaturated FA (PUFA) peroxidation index in the brain. The RO diet most efficiently increased the concentration of CHOL and values of the ratios of saturated FAs to PUFAs and long-chain n-6PUFAs to long-chain n-3PUFAs in the brain.The current studies provide new useful information for nutritionists carrying out further investigations aimed at improving farm-animal health, growth performance, reproductive system and the nutritional quality of feed for ruminants.

(1)H NMR brain metabonomics of scrapie exposed sheep

While neurochemical metabolite modifications, determined by different techniques, have been diffusely reported in human and mice brains affected by transmissible spongiform encephalopathies (TSEs), this aspect has been little studied in the natural animal hosts with the same pathological conditions so far. Herein, we investigated, by high resolution (1)H NMR spectroscopy and multivariate statistical data analysis, the brain metabolite profile of sheep exposed to a scrapie agent in a naturally affected flock. On the basis of clinical examinations and western blotting analysis for the pathological prion protein (PrP(Sc)) in brain tissues, sheep were catalogued as not infected (H), infected with clinical signs (S), and infected without clinical signs (A). By discriminant analysis of spectral data, comparing S vs. H, we found a different metabolite distribution, with inosine, cytosine, creatine, and lactate being higher in S than in H brains, while the branched chain amino acids (leucine, isoleucine, and valine), phenylalanine, uracil, tyrosine, gamma-amino butyric acid, total aspartate (aspartate + N-acetyl aspartate) being lower in S. By a soft independent modelling of class analogy approach, 1 out of 3 A samples was assigned to class H. Furthermore, A brains were found to be higher in choline and choline-containing compounds. By means of partial least squares regression, an excellent correlation was found between the PrP(Sc) amount and the (1)H NMR metabolite profile of infected (S and A) sheep, and the metabolite mostly correlated with PrP(Sc) was alanine. The overall results, obtained using different chemometric tools, were able to describe a brain metabolite profile of infected sheep with and without clinical signs, compared to healthy ones, and indicated alanine as a biomarker for PrP(Sc) amounts in scrapie brains.

Diets with different lipid contents do not modify the neuronal membrane lipid raft profile in a scrapie murine model

In Transmissible Spongiform Encephalopathies (TSEs), the localization of the prion protein in the neuronal membrane lipid rafts (LR) seems to play a role in sustaining the protein misfolding. Changes in membrane properties, due to altered lipid composition, affect their organization and interaction between lipids and protein therein, and consequently also membrane resident protein functionality; dietary polyunsaturated fatty acids (PUFAs), gangliosides and cholesterol seem to influence these processes.

AIMS

In this work, the influence of administration of different feed, able to change the composition of lipid membrane, on the clinical progression of prion disease was studied.

MAIN METHODS

The activity of three diets (hyperlipidic with 6% fats; hypolipidic with 0.1% fats; and purified with 4% fats) was tested in CD1 mouse model experimentally infected with RML scrapie strain. Presence and distribution of typical central nervous system (CNS) lesions and deposits of PrP(sc) were evaluated by histopathological analysis and immunohistochemistry. Analysis of lipids was performed in homogenate and insoluble brain fraction of the neuronal membrane rich in LR.

KEY FINDINGS

Results show that a diet with a different lipid level has not a significant role in the development of the scrapie disease. All infected mice fed with different diets died in the same time span. Histology, immunohistochemistry, and neuropathological analyses of the infected brains did not show significant differences between animals subjected to different diets.

SIGNIFICANCE

Independently of the diet, the infection induced a significant modification of the lipid composition in homogenates, and a less noticeable one in insoluble brain fraction.