Lipid profiles of taste and non-taste epithelial tissues from steer tongues

Dietary (poly)phenols as modulators of the biophysical properties in endothelial cell membranes: its impact on nitric oxide bioavailability in hypertension

Hypertension is a major contributor to premature death, owing to the associated increased risk of damage to the heart, brain and kidneys. Although hypertension is manageable by medication and lifestyle changes, the risk increases with age. In an increasingly aged society, the incidence of hypertension is escalating, and is expected to increase the prevalence of (cerebro)vascular events and their associated mortality. Adherence to plant-based diets improves blood pressure and vascular markers in individuals with hypertension. Food flavonoids have an inhibitory effect towards angiotensin-converting enzyme (ACE1) and although this effect is greatly diminished upon metabolization, their microbial metabolites have been found to improve endothelial nitric oxide synthase (eNOS) activity. Considering the transmembrane location of ACE1 and eNOS, the ability of (poly)phenols to interact with membrane lipids modulate the cell membrane's biophysical properties and impact on nitric oxide (· NO) synthesis and bioavailability, remain poorly studied. Herein, we provide an overview of the current knowledge on the lipid remodeling of endothelial membranes with age, its impact on the cell membrane's biophysical properties and · NO permeability across the endothelial barrier. We also discuss the potential of (poly)phenols and other plant-based compounds as key players in hypertension management, and address the caveats and challenges in adopted methodologies.

Interaction of polyphenols with model membranes: Putative implications to mouthfeel perception

Food polyphenols in fruits juices, tea, coffee, wine and beer confer sensory properties such as colour, astringency and bitterness. The development of functional healthy drinks without the unpleasant sensory feeling is boosting research for a clearer understanding on the interactions of polyphenols within the oral mucosa. In this study we investigated the interaction of astringent polyphenols, namely ECG, EGCG, procyanidin B4 and PGG, with lipids in model membranes by spectroscopic techniques. The membrane model was built varying the cholesterol content to mimic mouth regions and experiments were conducted at pH 5 to mimic the pH drop at the moment of beverage (e.g. green tea, red wine) intake. Fluorescence quenching results conducted on LUVs with cholesterol molar fractions ranging between 0.34 < χ_chol < 0.74 and similar size distributions (122.9 ± 3.7 nm) showed that interaction of polyphenols is structure- and concentration-dependent. Also, the decrease of partition constants (K_p) with increasing cholesterol content (χchol) suggest that the affinity of polyphenols is weaker in cholesterol-rich liposomes. STD results revealed that the interaction of EGCG and PGG with membrane lipids involved mainly galloyl residues. Overall, spectroscopic data show that polyphenols interact to higher extent with more polar regions found in buccal, flour of the mouth and gingiva regions than with more hydrophobic regions located in the palate and tongue supporting that lipid microenvironments play a role in oral sensory perception.

Changes in the lipid content of rat lymph after the ingestion of [14C] long-chain fatty acids

Rats were orally administered separately one dose of three labelled long-chain fatty acids: [1-14C] oleic, [1-14C] palmitic or [1-14C] stearic. Samples of lymph were obtained from previously cannulated thoracic ducts and analyzed for the composition and content of labelled fatty acids. Most of the newly recovered and labelled fatty acids were qualitatively and quantitatively similar regardless of which 14C-fatty acid had been administered. Over 20% of the administered fat were interconverted in six hours. The results suggest that the mucosa of the small intestine, the first sites of fatty acid absorption, is also one of the sites of various metabolic processes such as beta oxidation and synthesis which are responsible for some of the changes observed. These processes indicated that by shortening or lengthening the fatty acid composition, the content of the lymph became approximately the same regardless of the precursor fatty acid. The intestinal mucosa became the first tissue to help maintain lipid homeostasis in the rat.

Liver lipid profiles of adults taking therapeutic doses of aspirin

The distributions of lipids of hepatic specimens obtained at autopsy from 7 adult patients who had been taking large amounts of aspirin for arthritis were compared to 7 control samples obtained from livers of autopsied adults without prior liver disease. The total neutral lipid levels of control livers were approximately one-third lower than those observed for livers of patients on aspirin. In addition, the phospholipid content of control specimens was significantly greater than that of livers from adult patients that had been on a high dose of aspirin for a long time. Examination of individual lipid classes showed that the concentrations of free fatty acids, triacylglycerols, and mono- and diacylglycerols were highest in livers of patients with aspirin exposure, and that all phospholipids were diminished. Phosphatidylcholines and phosphatidylethanolamines showed the greatest decrease. These results suggest that the livers of patients taking large amounts of aspirin may accumulate fatty acids and neutral lipids due to an impairment in the oxidation of fatty acids by hepatocytes. The data obtained also suggest that needle biopsy of the liver with measurement of distribution of hepatic lipids, perhaps together with histopathologic examination, may provide useful diagnostic information.

Lipid metabolic interrelationships and phospholipase activity in gustatory epithelium of Ictalurus punctatus in vitro

The catfish, Ictalurus punctatus, is an important model for studying the biochemical mechanisms of taste at the peripheral level. The type, amount and metabolic activity of the lipids within this tissue play important roles in taste transduction by forming the matrix in which the receptors for taste stimuli are imbedded and by acting as precursors to second messengers. The metabolic interconversions that occur among the lipids on the taste organ (barbels) of this animal are reported here. When sodium [32P]phosphate was incubated with minced pieces of epithelium from the taste organ of I. punctatus, phospholipids became labeled. Maximal incorporation occurred near 20 min for lysophosphatidylcholines (LPC), phosphatidylcholines (PC) and phosphatidylinositols (PI). The phosphatidylethanolamines (PE) and phosphatidylserines (PS) became labeled more slowly. The label in LPC and PC declined from 20 min to 120 min, while that of the other fractions increased or was stable over the 20-120 min time period. Upon addition of 1,2-di-[1'-14C]palmitoyl-sn-glycero-3-phosphocholine to the medium, 14C was found within minutes in all of the phospholipids assayed. The amount of label incorporated increased with time, with maximum labeling for all phospholipids occurring at 15 min. However, 14C appeared predominantly first (by 5 min) in a neutral lipid fraction (fraction AG, consisting of free fatty acids, mono- and diglycerides, triglycerides and methyl esters), then declined rapidly as the phospholipids gradually incorporated more label. Within minutes of addition of 1-[1'-14C]palmitoyl-sn-glycero-3-phosphocholine (lysophosphatidylcholine) the 14C-label was detected in the neutral lipid fraction AG, then in the PC fraction, and later in the other phospholipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid characterization and 14C-acetate metabolism in catfish taste epithelium

The catfish, Ictalurus punctatus is an important model system for the study of the biochemical mechanisms of taste reception. A detailed lipid analysis of epithelial tissue from the taste organ (barbel) of the catfish has been performed. Polar lipids account for 62 +/- 1% of the total, neutrals for 38 +/- 1%. Phosphatidyl-cholines, serines and ethanolamines are the major constituents of the polar fraction. Plasmalogen concentration is high relative to that of non-neural tissues. [14C]-Acetate is incorporated into cell lipid fractions after incubation of barbel tissue at 37 degrees C for 60 min. Percentage amounts of most lipids change with time during this in vitro incubation. The phospholipids are the most metabolically active fractions. This work yields information for continuing reconstitution experiments and indicates that the taste epithelium of this important model system is a metabolically active tissue capable of supporting lipid turnover/synthesis.

A comparative study of three methods for the estimation of total plasmalogens in lingual taste epithelium and other tissues

The total plasmalogen content of lingual and other tissues was analyzed using the iodine-addition (Method 1), the p-nitrophenylhydrazone (Method 2), and the two-dimensional thin layer chromatography procedure (Method 3). Methods 1 and 2 were simple, rapid and reproducible, yielding values usually in close agreement with each other, and values higher than those of Method 3. Method 3 exhibited poor reproducibility. All three methods were of comparable sensitivity (less than 20 nmol of total plasmalogen per sample). According to Methods 1 and 2, there was more total plasmalogen in lingual epithelium containing taste buds compared with lingual epithelium devoid of taste buds. Plasmalogen content of bovine and rat brain, heart and liver agreed with literature values.

Comparison of fatty acid patterns of polar and neutral lipid classes and cyclo-oxygenase activity in taste and non-taste epithelium of steer tongues

Epithelial tissues and papilla from several regions of the steer tongue were isolated and the fatty acids from each lipid class in the polar and neutral fractions were assayed. The observed profiles indicated regional differences. Arachidonic acid and other fatty acids containing long carbon chains (greater than 22) were found in all tissues sampled, particularly in the phosphatidyls of the inositols, ethanolamines, cholines, and in the cholesterylesters. Production of prostaglandin E2 was measured through cyclo-oxygenase activity and the presence of plasmalogens was observed in the phosphatidylethanolamine and choline fractions. Higher rates of PGE2 synthesis and greater amounts of plasmologens were found in taste-related epithelial samples compared to lingual epithelial control samples not containing taste buds. The heterogeneity of patterns of lipids and fatty acids found in the epithelium of the tongue suggests possible zonal specialization to satisfy regional physiological needs.