Since the 1950s, one of the goals of adipose tissue research has been to determine lipolytic and lipogenic activity as the primary metabolic pathways affecting adipocyte health and size and thus representing potential therapeutic targets for the treatment of obesity and associated diseases. Nowadays, there is a relatively large number of methods to measure the activity of these pathways and involved enzymes, but their applicability to different biological samples is variable. Here, we review the characteristics of mean lipogenic and lipolytic enzymes, their inhibitors, and available methodologies for assessing their activity, and comment on the advantages and disadvantages of these methodologies and their applicability in vivo, ex vivo, and in vitro, i.e., in cells, organs and their respective extracts, with the emphasis on adipocytes and adipose tissue.

• Klíčová slova
• acetyl-CoA carboxylase, activity measurement, adipose triglyceride lipase, fatty-acid synthase, hormone-sensitive lipase, inhibitor,
• MeSH
• lidé MeSH
• lipogeneze * MeSH
• lipolýza * MeSH
• obezita metabolismus   MeSH
• tuková tkáň metabolismus   MeSH
• tukové buňky metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) are increased in starvation and diabetes mellitus. However, the pathogenesis has not been explained. It has been shown that BCAA catabolism occurs mostly in muscles due to high activity of BCAA aminotransferase, which converts BCAA and α-ketoglutarate (α-KG) to branched-chain keto acids (BCKAs) and glutamate. The loss of α-KG from the citric cycle (cataplerosis) is attenuated by glutamate conversion to α-KG in alanine aminotransferase and aspartate aminotransferase reactions, in which glycolysis is the main source of amino group acceptors, pyruvate and oxaloacetate. Irreversible oxidation of BCKA by BCKA dehydrogenase is sensitive to BCKA supply, and ratios of NADH to NAD+ and acyl-CoA to CoA-SH. It is hypothesized that decreased glycolysis and increased fatty acid oxidation, characteristic features of starvation and diabetes, cause in muscles alterations resulting in increased BCAA levels. The main alterations include (i) impaired BCAA transamination due to decreased supply of amino groups acceptors (α-KG, pyruvate, and oxaloacetate) and (ii) inhibitory influence of NADH and acyl-CoAs produced in fatty acid oxidation on citric cycle and BCKA dehydrogenase. The studies supporting the hypothesis and pros and cons of elevated BCAA concentrations are discussed in the article.

• Klíčová slova
• alanine, glucose, insulin, insulin resistance, obesity, pyruvate,
• MeSH
• alanin metabolismus   MeSH
• diabetes mellitus metabolismus   MeSH
• glykolýza MeSH
• hladovění metabolismus   MeSH
• inzulin metabolismus   MeSH
• inzulinová rezistence MeSH
• kyseliny ketoglutarové metabolismus   MeSH
• lidé MeSH
• mastné kyseliny metabolismus   MeSH
• obezita metabolismus   MeSH
• oxidace-redukce MeSH
• pyruváty farmakokinetika   MeSH
• svaly enzymologie   metabolismus   MeSH
• transaminasy metabolismus   MeSH
• větvené aminokyseliny metabolismus   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• alanin MeSH
• branched-chain-amino-acid transaminase MeSH Prohlížeč
• inzulin MeSH
• kyseliny ketoglutarové MeSH
• mastné kyseliny MeSH
• pyruváty MeSH
• transaminasy MeSH
• větvené aminokyseliny MeSH

BACKGROUND: The intake of meat, particularly processed meat, is a dietary risk factor for diabetes. Meat intake impairs insulin sensitivity and leads to increased oxidative stress. However, its effect on postprandial gastrointestinal hormone (GIH) secretion is unclear. We aimed to investigate the acute effects of two standardized isocaloric meals: a processed hamburger meat meal rich in protein and saturated fat (M-meal) and a vegan meal rich in carbohydrates (V-meal). We hypothesized that the meat meal would lead to abnormal postprandial increases in plasma lipids and oxidative stress markers and impaired GIH responses. METHODS: In a randomized crossover study, 50 patients suffering from type 2 diabetes (T2D) and 50 healthy subjects underwent two 3-h meal tolerance tests. For statistical analyses, repeated-measures ANOVA was performed. RESULTS: The M-meal resulted in a higher postprandial increase in lipids in both groups (p<0.001) and persistent postprandial hyperinsulinemia in patients with diabetes (p<0.001). The plasma glucose levels were significantly higher after the V-meal only at the peak level. The plasma concentrations of glucose-dependent insulinotropic peptide (GIP), peptide tyrosine-tyrosine (PYY) and pancreatic polypeptide (PP) were higher (p<0.05, p<0.001, p<0.001, respectively) and the ghrelin concentration was lower (p<0.001) after the M-meal in healthy subjects. In contrast, the concentrations of GIP, PYY and PP were significantly lower after the M-meal in T2D patients (p<0.001). Compared with the V-meal, the M-meal was associated with a larger increase in lipoperoxidation in T2D patients (p<0.05). CONCLUSION/INTERPRETATION: Our results suggest that the diet composition and the energy content, rather than the carbohydrate count, should be important considerations for dietary management and demonstrate that processed meat consumption is accompanied by impaired GIH responses and increased oxidative stress marker levels in diabetic patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT01572402.

• MeSH
• diabetes mellitus 2. typu krev   patologie   MeSH
• dieta veganská škodlivé účinky   MeSH
• gastrointestinální hormony krev   MeSH
• ghrelin krev   MeSH
• glukagonu podobný peptid 1 krev   MeSH
• inzulin krev   MeSH
• krevní glukóza MeSH
• lidé středního věku MeSH
• lidé MeSH
• lipidy krev   MeSH
• manipulace s potravinami MeSH
• maso škodlivé účinky   MeSH
• postprandiální období MeSH
• triglyceridy krev   MeSH
• žaludeční inhibiční polypeptid krev   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• randomizované kontrolované studie MeSH
• Názvy látek
• gastrointestinální hormony MeSH
• ghrelin MeSH
• glukagonu podobný peptid 1 MeSH
• inzulin MeSH
• krevní glukóza MeSH
• lipidy MeSH
• triglyceridy MeSH
• žaludeční inhibiční polypeptid MeSH