Feeding rats a diet enriched with saturated fatty acids prevents the inhibitory effects of acute and chronic ethanol exposure on the in vitro uptake of hexoses and lipids

The association between alcohol consumption and blood lipids in Chinese children and adolescent: findings from the China Health and Nutrition Survey

BACKGROUND

Alcohol consumption by children and adolescents is receiving increasing attention. It may cause dyslipidemia, a risk factor for cardiovascular disease. However, the association between alcohol consumption and blood lipids in children and adolescents is unclear, and so we aimed to characterize this association.

METHODS

Data from the China Health and Nutrition Survey were extracted from children and adolescents aged 7-18 years for whom information was available on alcohol consumption. The population was divided into drinking and nondrinking groups. The χ2, Student's t, or Mann-Whitney U test was used to compare groups. Univariate and multivariate linear regression and propensity score matching (PSM) analysis were used to identify the association between alcohol consumption and blood lipids.

RESULTS

This study included 408 children and adolescents with 35 drinkers and 373 nondrinkers. The drinkers had significantly lower values of total cholesterol (TC) (3.8 mmol/L for nondrinkers versus 3.5 mmol/L for drinkers, p = 0.002) and high-density lipoprotein cholesterol (HDL-C) (1.3 mmol/L for nondrinkers versus 1.2 mmol/L for drinkers, p = 0.007), but not for low-density lipoprotein cholesterol (LDL-C) (2.1 mmol/L for nondrinkers versus 2.0 mmol/L for drinkers, p = 0.092) or triglyceride (TG) (0.9 mmol/L for nondrinkers versus 0.8 mmol/L for drinkers, p = 0.21). The univariate and multivariate analyses led to the same conclusions. After PSM there was still a significant negative association between alcohol consumption and TC or HDL-C.

CONCLUSION

Alcohol consumption in children and adolescents exhibited significant negative associated with TC and HDL-C, but not with LDL-C or TG. These findings need to be confirmed in future prospective research, and the health effects of blood lipid changes caused by drinking in children and adolescents need to be clarified.

The Influence of Alcohol Consumption on Intestinal Nutrient Absorption: A Comprehensive Review

Chronic alcohol use has been attributed to the development of malnutrition. This is in part due to the inhibitory effect of ethanol on the absorption of vital nutrients, including glucose, amino acids, lipids, water, vitamins, and minerals within the small intestine. Recent advances in research, along with new cutting-edge technologies, have advanced our understanding of the mechanism of ethanol's effect on intestinal nutrient absorption at the brush border membrane (BBM) of the small intestine. However, further studies are needed to delineate how ethanol consumption could have an impact on altered nutrient absorption under various disease conditions. Current research has elucidated the relationship of alcohol consumption on glucose, glutamine, vitamins B1 (thiamine), B2 (riboflavin), B9 (folate), C (ascorbic acid), selenium, iron, and zinc absorption within the small intestine. We conducted systematic computerized searches in PubMed using the following keywords: (1) "Alcohol effects on nutrient transport"; (2) "Alcohol mediated malabsorption of nutrients"; (3) "Alcohol effects on small intestinal nutrient transport"; and (4) "Alcohol mediated malabsorption of nutrients in small intestine". We included the relevant studies in this review. The main objective of this review is to marshal and analyze previously published research articles and discuss, in-depth, the understanding of ethanol's effect in modulating absorption of vital macro and micronutrients in health and disease conditions. This could ultimately provide great insights in the development of new therapeutic strategies to combat malnutrition associated with alcohol consumption.

A comparison of the different animal models of fetal alcohol spectrum disorders and their use in studying complex behaviors

Prenatal ethanol exposure (PNEE) has been linked to widespread impairments in brain structure and function. There are a number of animal models that are used to study the structural and functional deficits caused by PNEE, including, but not limited to invertebrates, fish, rodents, and non-human primates. Animal models enable a researcher to control important variables such as the route of ethanol administration, as well as the timing, frequency and amount of ethanol exposure. Each animal model and system of exposure has its place, depending on the research question being undertaken. In this review, we will examine the different routes of ethanol administration and the various animal models of fetal alcohol spectrum disorders (FASD) that are commonly used in research, emphasizing their strengths and limitations. We will also present an up-to-date summary on the effects of prenatal/neonatal ethanol exposure on behavior across the lifespan, focusing on learning and memory, olfaction, social, executive, and motor functions. Special emphasis will be placed where the various animal models best represent deficits observed in the human condition and offer a viable test bed to examine potential therapeutics for human beings with FASD.

Morphological, kinetic, membrane biochemical and genetic aspects of intestinal enteroplasticity

The process of intestinal adaptation (“enteroplasticity”) is complex and multifaceted. Although a number of trophic nutrients and non-nutritive factors have been identified in animal studies, successful, reproducible clinical trials in humans are awaited. Understanding mechanisms underlying this adaptive process may direct research toward strategies that maximize intestinal function and impart a true clinical benefit to patients with short bowel syndrome, or to persons in whom nutrient absorption needs to be maximized. In this review, we consider the morphological, kinetic and membrane biochemical aspects of enteroplasticity, focus on the importance of nutritional factors, provide an overview of the many hormones that may alter the adaptive process, and consider some of the possible molecular profiles. While most of the data is derived from rodent studies, wherever possible, the results of human studies of intestinal enteroplasticity are provided.

Dietary lipids alter the effect of steroids on the transport of fructose following intestinal resection in rats

BACKGROUND

Glucocorticosteroids alter intestinal morphology and transport. We tested the hypothesis that the desired intestinal adaptive response following intestinal resection may be enhanced further by the locally active steroid budesonide, and by feeding a saturated as compared with a polyunsaturated fatty acid diet.

METHODS

An in-vitro uptake method was used to assess intestinal fructose uptake by rats of semisynthetic diets enriched in saturated or polyunsaturated fatty acids, and injected with budesonide or control solution.

RESULTS

Budesonide increased ileal fructose uptake in chow and PUFA-fed animals, but reduced jejunal fructose uptake in rats fed SFA. GLUT5 and GLUT2 protein and mRNA did not correlate with changes in fructose uptake. Steroids reduced jejunal proglucagon expression in animals fed chow. Animals fed SFA and given budesonide had a reduction in jejunal ODC mRNA compared with those fed PUFA or chow.

CONCLUSIONS

(1) budesonide increases ileal fructose uptake following intestinal resection, and this beneficial effect is prevented by feeding SFA rather than PUFA; (2) fructose uptake does not correlate with GLUT5 and GLUT2 protein and mRNA; (3) ODC and proglucagon may be involved in this adaptive response.

Aging and the intestine

Over the lifetime of the animal, there are many changes in the function of the body’s organ systems. In the gastrointestinal tract there is a general modest decline in the function of the esophagus, stomach, colon, pancreas and liver. In the small intestine, there may be subtle alterations in the intestinal morphology, as well as a decline in the uptake of fatty acids and sugars. The malabsorption may be partially reversed by aging glucagon-like peptide 2 (GLP2) or dexamethasone. Modifications in the type of lipids in the diet will influence the intestinal absorption of nutrients: for example, in mature rats a diet enriched with saturated as compared with polysaturated fatty acids will enhance lipid and sugar uptake, whereas in older animals the opposite effect is observed. Thus, the results of studies of the intestinal adaptation performed in mature rats does not necessarily apply in older animals. The age-associated malabsorption of nutrients that occurs with aging may be one of the several factors which contribute to the malnutrition that occurs with aging.

Intestinal mucosal adaptation

Intestinal failure is a condition characterized by malnutrition and/or dehydration as a result of the inadequate digestion and absorption of nutrients. The most common cause of intestinal failure is short bowel syndrome, which occurs when the functional gut mass is reduced below the level necessary for adequate nutrient and water absorption. This condition may be congenital, or may be acquired as a result of a massive resection of the small bowel. Following resection, the intestine is capable of adaptation in response to enteral nutrients as well as other trophic stimuli. Identifying factors that may enhance the process of intestinal adaptation is an exciting area of research with important potential clinical applications.

Dietary lipids alter the effect of steroids on the transport of glucose after intestinal resection: Part I. Phenotypic changes and expression of transporters

BACKGROUND/PURPOSE

Glucocorticosteroids alter the function of the intestine. This study was undertaken to assess the effect on D-glucose uptake of budesonide (Bud), prednisone (Pred), or dexamethasone (Dex) in animals with a 50% intestinal resection and fed chow or a diet enriched with saturated (SFA) or polyunsaturated fatty acids (PUFA).

METHODS

In vitro ring uptake technique, Western blots, and Northern blots were performed.

RESULTS

Bud increased the jejunal D-glucose uptake, and this effect was prevented by feeding PUFA. SGLT1 and Na+/K+ ATPase protein and mRNA abundance did not correlate with the change in the rate of uptake of glucose.

CONCLUSIONS

(1) Bud increased the jejunal glucose uptake, (2) the activity of the sugar transporter does not correlate with the abundance of protein or their respective mRNAs, (3) th Bud effect on glucose uptake is prevented by feeding PUFA. Thus, the desired intestinal adaptive response after intestinal resection may be enhanced further by the administration of the locally acting steroid budesonide and by feeding a saturated compared with a polyunsaturated fatty acid diet.

Effects of exogenous fatty acids and cholesterol on aminopeptidase activities in rat astroglia

Several studies have addressed the interaction between fatty acids and lipids with central nervous system peptides. Because aminopeptidases (AP) are involved in the regulation of neuropeptides, this work studies several AP expressed in cultured astroglia, after exogenous addition of oleic and linoleic fatty acids and cholesterol to the culture medium. Alanyl-AP, arginyl-AP, cystyl-AP, leucyl-AP, tyrosyl-AP and pyroglutamyl-AP activities were analysed in whole cells using the corresponding aminoacyl-beta-naphthylamides as substrates. Oleic acid inhibits alanyl-AP, cystyl-AP and leucyl-AP activities, whereas linoleic acid inhibits alanyl-AP, arginyl-AP and tyrosyl-AP activities. Neither oleic acid nor linoleic acid modifies pyroglutamyl-AP activity. In contrast, cholesterol increases arginyl-AP, cystyl-AP, leucyl-AP, tyrosyl-AP and pyroglutamyl-AP activities, although it does not modify alanyl-AP activity. The changes reported here suggest that oleic and linoleic fatty acids and cholesterol can modulate peptide activities via their degradation route involving aminopeptidases; each of them being differentially regulated.

Alcohol and lipids

Alcoholic fatty liver and hyperlipemia result from the interaction of ethanol and its oxidation products with hepatic lipid metabolism. An early target of ethanol toxicity is mitochondrial fatty acid oxidation. Acetaldehyde and reactive oxygen species have been incriminated in the pathogenesis of the mitochondrial injury. Microsomal changes offset deleterious accumulation of fatty acids, leading to enhanced formation of triacylglycerols, which are partly secreted into the plasma and partly accumulate in the liver. However, this compensatory mechanism fades with progression of the liver injury, whereas the production of toxic metabolites increases, exacerbating the lesions and promoting fibrogenesis. The early presence of these changes confers to the fatty liver a worse prognosis than previously thought. Alcoholic hyperlipemia results primarily from increased hepatic secretion of very-low-density lipoprotein and secondarily from impairment in the removal of triacylglycerol-rich lipoproteins from the plasma. Hyperlipemia tends to disappear because of enhanced lipolytic activity and aggravation of the liver injury. With moderate alcohol consumption, the increase in high-density lipoprotein becomes the predominant feature. Its mechanism is multifactorial (increased hepatic secretion and increased extrahepatic formation as well as decreased removal) and explains part of the enhanced cholesterol transport from tissues to bile. These changes contribute to, but do not fully account for, the effects on atherosclerosis and/or coronary heart disease attributed to moderate drinking.

Modulation of learning and neuronal membrane composition in the rat by essential fatty acid preparation: time-course analysis

Previous studies have shown that chronic administration of SR-3 (a 1:4 mixture of alpha-linolenic and linoleic acid) affects spatial learning, thermoregulation, pain threshold and protection from seizures. The mode of action is unknown. One possible explanation is that the preparation induces changes in the fatty acids profile and in the cholesterol level in the neuronal membrane. This study used 15 independent groups of rats (n = 12) which were given either saline, mineral oil (vehicle) or SR-3 (25 mg/kg) for 0, 1, 2, 3, or 4 weeks. The learning performance was measured in the Morris Water tank and the fatty acids profile and the cholesterol level were examined by the GC method in synaptosomes obtained from the frontal cortex of the rats. SR-3 improved the learning performance and induced major changes in the neuronal membrane composition, such as an increase in the total level of fatty acids, an increase in the level of essential fatty acids and a decrease in the cholesterol level. Those changes occurred after 3 weeks of treatment. The biochemical variables can predict the behavioral variables but not vice versa. The changes in the neuronal membrane may result in a modification of the membrane fluidity, which may, in turn, enhance cognitive and neuropharmacological effects.

Fatty acids and brain peptides

The role of fatty acids (FA) as a mediator and modulator of central nervous system activity in general, and peptides in particular, is only recently becoming understood. This paper reviews numerous findings concerned with the activity of fatty acids, particularly with their interaction with diverse neurochemical systems and their consequences for better understanding neurotransmitters, hormones and peptides. The effects include FA as precursors in the manufacture of neurochemical elements, including enzymes, neurotransmitters, and hormones. Of particular interest is the important changes in neuronal membrane composition that have been attributed to FA. Such changes may account for the changes in thermoregulation, learning, and other functions that accompany dietary manipulation of FA intake. While the total level of FA has been the object of many investigations, this report addresses the need to focus on the ratio of FA, especially alpha-linolenic/linoleic acid, which has been shown to be a critical factor in a number of research studies.

Effects of chronic alcohol consumption on enzyme activities and active methionine absorption in the small intestine of pregnant rats

The present study evaluates the effect of chronic alcohol intake on the intestinal transport of methionine during pregnancy. For this purpose, we have used an in vitro technique that allows measurement of the unidirectional influx of the amino acids across the brush-border membrane of the rat mid-jejunum, and the basolateral membrane enzyme Na+, K+-ATPase was also evaluated in the duodenum and jejunum. For chronic alcohol treatment, the rats were fed a liquid diet containing ethanol (36% of calories) or an isocaloric diet-(pair-fed control) for 5 weeks before and during pregnancy. Animals were killed at 21 days of gestation. Results from the kinetic analysis revealed that chronic ethanol treatment reduces the maximum transport (Jm) of methionine uptake when compared with controls. Further experiments performed in the presence and absence of sodium have shown that ethanol selectively inhibited Na+-dependent methionine transport. At the same time, this treatment significantly reduced the levels of Na+, K+-ATPase in ethanol-fed rats compared with the controls. Alterations in methionine intestinal transport in pregnant alcohol-fed rats may contribute to the ethanol-induced fetal growth abnormalities.

Essential fatty acid preparation reduces cholesterol and fatty acids in rat cortex

Previous studies have shown that chronic administration of SR-3 (a 1:4 mixture of alpha-linolenic and linoleic acid) affects spatial learning, thermoregulation, pain threshold, and protection from seizures. The mode of action of SR-3 is unknown. One possible explanation is that SR-3 induces changes in the FA profile and in the cholesterol level in neuronal membranes. This study used 10 independent groups of rats (ni = 12) given 4 weeks of either saline, mineral oil (vehicle), alpha-tocopherol (antioxidant), alpha-linolenic acid, linoleic acid, or one of 5 different ratios of alpha-linolenic acid:linoleic acid (1:3, 1:4, 1:5, 1:6, 1:7) as free fatty acids. FA profile and cholesterol level were examined by GC method in synaptosomes obtained from the frontal cortex of the rats. The mineral oil treated group served as the control group. No difference was found in the FA profile or cholesterol level except for the SR-3 treated group. The ratio of 1:4 was found to have a significant influence on decreasing the cholesterol level and in inducing major changes in the FA profile, such as an increase in EFA. These effects of SR-3 may result in modification of the membrane fluidity, which may, in turn, enhance cognitive and neuropharmacological effects.

Opposite effects of dietary saturated and unsaturated fatty acids on ethanol-pharmacokinetics, triglycerides and carnitines

OBJECTIVE

The objective of this study was to determine the effects of saturated fatty acid (SFA) and unsaturated fatty acid (UFA) diets on ethanol pharmacokinetics. Hepatic ADH and plasma carnitines were also evaluated as possible indicators of the mechanism involved.

METHODS

Sprague-Dawley male rats were fed modified AIN76 diets containing 10% coconut oil (SFA) or corn oil (UFA) for 120 days. A single dose (3 g/kg bw) of ethanol (13% solution) was orally administered using a gastric canula on day 30, 90, 105 and 120. Tail vein blood samples were collected at various intervals following ethanol dose and were analyzed for blood-ethanol concentration (BEC). In an analogous trial rats were given these diets for 70 days and blood samples were collected on day 35 and 63 for triglycerides, cholesterol and carnitine determination. The animals were killed on day 70 to collect liver for ADH determination.

RESULTS

Compared to the UFA group, the SFA group exhibited significantly higher BEC, larger area under the curve, longer half-life of ethanol, and lower rates of ethanol elimination. Plasma carnitines were also higher in the SFA vs UFA group. However, hepatic ADH activity was not different between the groups.

CONCLUSION

Dietary SFA protects liver from alcohol injury by retarding ethanol metabolism, and carnitine may be involved.