Growth hormone improves lipoprotein concentration and arylesterase activity in mice with an atherogenic lipid profile induced by lactalbumin

Untargeted LC/MS-Based Metabolic Phenotyping of Hypopituitarism in Young Males

Objective: Hypopituitarism (Hypo-Pit) is partial or complete insufficiency of anterior pituitary hormones. Besides hormone metabolism, the global metabolomics in Hypo-Pit are largely unknown. We aimed to explore potential biomarkers to aid in diagnosis and personalized treatment.

Methods: Using both univariate and multivariate statistical methods, we identified 72 differentially abundant features through liquid chromatography coupled to high-resolution mass spectrometry, obtained in 134 males with Hypo-Pit and 90 age matched healthy controls.

Results: Hypopituitarism exhibits an increased abundance of metabolites involved in amino acid degradation and glycerophospholipid synthesis, but decreased content of metabolites in steroid hormone synthesis and fatty acid beta-oxidation. Significantly changed metabolites included creatine, creatinine, L-alanine, phosphocholines, androstenedione, hydroprenenolone, and acylcarnitines. In Hypo-Pit patients, the increased ratio of creatine/creatinine suggested reduced creatine uptake and impaired creatine utilization, whereas the decreased level of beta-hydroxybutyrate, acetylcarnitine (C2) and a significantly decreased ratio of decanoylcarnitine (C10) to free carnitine suggested an impaired beta-oxidation. Furthermore, the creatine/creatinine and decanoylcarnitine/carnitine ratio were identified as diagnostic biomarkers for Hypo-Pit with AUCs of 0.976 and 0.988, respectively. Finally, we found that the creatinine and decanoylcarnitine/carnitine ratio could distinguish cases that were sensitive vs. resistant to human chorionic gonadotropin therapy.

Conclusion: We provided a global picture of altered metabolic pathways in Hypo-Pit, and the identified biomarkers in creatine metabolism and beta-oxidation might be useful for the preliminary screening and diagnosis of Hypo-Pit.

Dietaryα-lactalbumin induced fatty liver by enhancing nuclear liver X receptorαβ/sterol regulatory element-binding protein-1c/PPARγexpression and minimising PPARα/carnitine palmitoyltransferase-1 expression and AMP-activated protein kinaseαphosphorylation associated with atherogenic dyslipidaemia, insulin resistance and oxidative stress in Balb/c mice

The effect and the role played by dietaryα-lactalbumin (α-LAC) on hepatic fat metabolism are yet to be fully elucidated. We reported previously thatα-LAC intake induced atherogenic dyslipidaemia in Balb/c mice. The aim of the present study was to investigate if this atherogenic effect could be due to a possibleα-LAC-induced hepatic steatosis. We examine the ability of dietaryα-LAC to induce liver steatosis, identifying the molecular mechanisms underlying hepatic lipid metabolism in association with the lipid profile, peripheral insulin resistance (IR) and changes in the hepatic oxidative environment. Male Balb/c mice (n6) were fed with diets containing either chow or 14 %α-LAC for 4 weeks. Theα-LAC-fed mice developed abdominal adiposity and IR. Moderate liver steatosis with increased TAG and NEFA contents was correlated with atherogenic dyslipidaemia. There was increased nuclear expression of liver X receptorαβ(LXRαβ), sterol regulatory element-binding protein-1c (SREBP-1c) and PPARγtranscription factors and of the cytosolic enzymes acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase involved in the hepaticde novolipogenesis. The opposite was found for the nuclear receptor PPARαand the mitochondrial enzyme carnitine palmitoyltransferase-1 (CPT-1), leading to reduced fatty acidβ-oxidation (FAO). These changes were associated with a significant decrease in both p-Thr172-AMP-activated protein kinaseα(AMPKα) (inactivation) and p-Ser79-ACC1 (activation) and with a more oxidative liver environment increasing lipid peroxidation and protein oxidation and reducing GSH:GSSG ratio in theα-LAC-fed mice. In conclusion, 4 weeks of 14 %α-LAC feeding induced liver steatosis associated with atherogenic dyslipidaemia, IR and oxidative stress by enhancing nuclear LXRαβ/SREBP-1c/PPARγexpression and diminishing PPARα/CPT-1 expression and AMPKαphosphorylation shifting the hepatic FAO toward fatty acid synthesis in Balb/c mice.

Effect of seaweed and cholesterol-enriched diets on postprandial lipoproteinaemia in rats

High postprandial lipaemia increases cardiovascular risk. Algae consumption may affect postprandial lipoproteinaemia. The effects of dietary alga and cholesterol supplementation on postprandial lipaemia and lipoproteinaemia and arylesterase (AE) activity in growing male Wistar rats were tested in the present study. Six groups of ten rats were fed a casein-based diet for 3 weeks. Three of the diets contained 2.4 % cholesterol-raising agent (Chol), while the other three did not (NChol). Seven percentage of the control diets (NChol-C and Chol-C) consisted of a cellulose-wheat starch mix (35:65), while the Nori alga diets (NChol-N and Chol-N) and Konbu diets (NChol-K and Chol-K) contained 7 % of each respective freeze-dried alga. Postprandial plasma was obtained after a 3 h diet withdrawal. Supplementary cholesterol and alga type significantly affected (at least P < 0.05) the cholesterol, TAG, phospholipid and protein contents of the various lipoprotein fractions. AE enzyme activity increased (P < 0.05) in NChol rats given Nori and Konbu diets. NChol-K, but not NChol-N, rats displayed higher (P < 0.05) plasma cholesterol, TAG and phospholipid levels than NChol-C animals. NChol-K rats presented higher TAG, phospholipid, protein and lipoprotein mass values than their NChol-C counterparts. Inclusion of algae in Chol diets decreased (P < 0.001) the postprandial hypertriacylglycerolaemia. The Chol-N diet affected most lipoprotein fraction contents. Chol-N rats had lower postprandial cholesterolaemia and a better lipoprotein profile (fewer LDL and a tendency toward more HDL and fewer cholesterol-enriched VLDL) than Chol-K rats, suggesting that Nori is the alga of choice in dietary treatment of hypercholesterolaemia.