Gianni Tomassi

Induction of Apoptosis in Human Pancreatic Cancer Cells by Docosahexaenoic Acid

Abstract: Polyunsaturated fatty acids have been indicated to induce anti‐proliferative and/or apoptotic effects in various tumor cells. We showed that, at a 200‐μM concentration, both alpha‐linoleic (18:2 n‐6; LA) or docosahexaenoic (22:6 n‐3; DHA) acid inhibited cell growth, while only DHA induced apoptosis in the human Paca‐44 pancreatic cancer cell line. Investigating the mechanism underlying DHA‐induced apoptosis, we showed that DHA induced a rapid and dramatic (>60%) intracellular depletion of reduced glutathione (GSH), without affecting oxidized glutathione (GSSG). Moreover, using two specific inhibitors of carrier‐mediated GSH extrusion, cystathionine or methionine, we observed that GSH depletion occurred via an active GSH extrusion, and that inhibition of GSH efflux completely reversed apoptosis. These results provide the first evidence for a possible causative role of GSH depletion in DHA‐induced apoptosis.

Lipid peroxidation in liver microsomes of rats fed soybean, olive, and coconut oil☆

Abstract The effect of varying unsaturation degree of dietary lipid on the oxidative response of rat liver microsomes was studied. Three groups of growing male rats were maintained for 6 weeks on 15% fat diets containing either soybean oil, olive oil, or coconut oil, with the same level of vitamin E. After 6 weeks, microsomal malondialdehyde, vitamin E, and fatty acid composition were measured in liver microsomes. The relative abundance of saturated and unsaturated fatty acids in the microsomes reflected the composition of the dietary lipid. When dietary requirement for vitamin E was satisfied, the increased polyunsaturated fatty acid intake from vegetable oils did not enhance lipid peroxidation in physiological conditions, as demonstrated by similar malondialdehyde concentrations found in the three groups. However, the somewhat lower vitamin E content measured in soybean oil-fed rats confirms an enhanced requirement for dietary antioxidant caused by the increased intake of polyunsaturated fatty acids. The susceptibility of liver microsomes to lipid peroxidation stimulated by the ADP/iron/ascorbate system was also studied. Membranes of soybean oil-fed rats exhibited the highest peroxidation rate, as shown by oxygen consumption and malondialdehyde and 4-hydroxy-2,3-trans-neonenal production, because of the lower concentration of vitamin E and of the higher content of polyunsaturated fatty acids. Microsomes of olive oil- and coconut oil-fed rats showed highest protection against lipid peroxidation.

Influence of Dietary Thermally Oxidized Soybean Oil on the Oxidative Status of Rats of Different Ages

Young and aging rats were fed for different periods (10, 90, 180 and 365 days) diets containing 15% of fresh or heated soybean oil. Thiobarbituric reactive substances (TBA-RS), lipofuscin, superoxide dismutase (SOD), vitamin A, vitamin E and microsomal and mitochondrial fatty acids in liver, brain and serum were measured. Heated oil diets induced significant increase of TBA-RS levels in liver, with earlier effects in aging rats and affected SOD activity in aging rats only after a long period of feeding. Circulating and stored vitamin A were reduced in both young and aging rats, with earlier effects in young animals. Serum and liver vitamin E was significantly reduced in all test groups. The results indicate that heated unsaturated oil produces reduction in the antioxidative defense system and that vitamin E status is the earliest indicator of the oxidative effect regardless of age.

Dietary fish oil enhances plasma and LDL oxidative modification in rats

Incorporation of long-chain polyunsaturated fatty acids (PUFA) in low density lipoprotein (LDL) might induce a decrease in its resistance against oxidative modification because of their high degree of unsaturation. To investigate the in vivo and in vitro influence of dietary ω --3 fatty acids on plasma and LDL susceptibility to oxidative modification, a diet containing 15% wt/wt fish oil was fed to rats together with diets containing 15% wt/wt soybean oil or coconut oil for 6 weeks. The plasma lipid concentration was significantly lower after fish oil feeding compared with the two control diets. Fish oil fed rats exhibited significantly lower total (peroxyl) radical-trapping antioxidant activity (TRAP) than both soybean oil and coconut oil fed animals ( P ω --3 fatty acids induce a decrease in the plasma antioxidant potential and an increase in the ex vivo susceptibility of LDL to oxidative modification.

Effect of dietary oils on brain enzymatic activities (2′-3′-cyclic nucleotide 3′-phosphodiesterase and acetylcholinesterase) and muscarinic receptor sites in growing rats

Abstract Dietary fats affect the fatty acid composition of brain membranes, but the consequences of the fatty acid changes on brain functional activities are poorly understood and not yet established. In order to investigate the effects of diet-induced changes on myelin deposition and on the cholinergic system, the present experiment was designed. Three groups of 10 male Sprague-Dawley rats (initial weight 100 ± 5 g) were fed for 6 weeks diets containing 15% (wt/wt) fish oil (FO), soybean oil (SO), and coconut oil (CO) rich in n-3 fatty acids (38%), n-6 fatty acids (55%), and saturated fatty acids (84%), respectively. The 2′-3′-cyclic nucleotide 3′-phosphodiesterase activity (CNPase) in the whole brain and in the cerebral cortex and the acetylcholinesterase activity (AChE) were determined along with the density and affinity of muscarinic receptor sites. The CNPase activity was significantly higher in the SO-fed group than in the other two groups (62.5 versus 47.0 and 54.4 μmol/hr/mg of protein), and the activity was correlated positively with Σ n-6 and negatively with Σ n-3. The AChE activity, the density, and the affinity of the receptor muscarinic receptor sites were not statistically different among the three groups. The results indicate the favorable effect of soybean oil and the adverse effect of fish oil on myelin deposition and the absence of effect of dietary oils on the cholinergic system.

Cholesterol-rich diet enhances peripheral blood mononuclear cell proliferation, vitamin E, and glutathione levels in rabbits

Abstract The role of dietary cholesterol in the modulation of both cell-mediated immunity and oxidative status is still not completely understood. In this study the effect of high levels of dietary cholesterol on cell-mediated immunity and on antioxidant levels was investigated in rabbits. For 3 months two groups of five animals each were fed a standard diet that was either supplemented with 0.5% cholesterol or not supplemented. Vitamin E and glutathione concentrations were measured on plasma and on peripheral blood mononuclear cells (PBMC). Proliferative response through [ 3 H]-thymidine incorporation was measured on PBMC. The cholesterol rich diet increased the activation of immune cells and the levels of vitamin E and glutathione in both PBMC and plasma. The possible involvements of these two antioxidative components in regulating cholesterol-induced atherosclerosis and immune function are discussed.

Diets rich in whole wheat improve redox status and enhance immune responses in rats

Abstract Whole wheat and refined wheat differ substantially for dietary fibre and polyphenol contents, however, the exact relationship between the in vitro contents and in vivo functions have not been well established. Two groups of growing rats were fed for 6 weeks with diets containing 53% of whole durum and refined durum wheat flours. In plasma and in mesenteric lymphocytes parameters of redox status and in lymphocytes the rate of cell proliferation and the type of immune response were measured. Plasma antioxidant activity showed that whole wheat was able to increase antioxidative status with respect to refined wheat and to reduce the carbonyl content. The diets rich in whole wheat can improve proliferative responses with respect to refined wheat. The results indicated that a constant intake of whole wheat may have important implications for health, by acting as modulator of immune function and redox status.

Energy Values of Foods

The human organism, like other higher animal organisms, derives the energy needed for its essential vital functions from the oxidation of organic substrates. In effect, the only form of energy that humans are able to utilise is the chemical energy contained in C-C or C-H bonds, while plants and vegetables can utilise solar energy in order to synthesise the complex molecules needed for their growth and survival [1].

Diet-Induced Thermogenesis

Since the time of Lavoisier, it has been known that the ingestion of foods by animals and humans produces an increase in oxygen consumption. This increase in metabolic rate, originally called ‘specific dynamic action’ (SDA) is now widely referred to as the ‘thermic effect’ (TE) of food or ‘diet-induced thermogenesis’ (DIT) [1]. This effect starts generally 1 h after ingestion, reaches a maximum after 3 h later, and continues at this level for several hours [2]. The DIT is a component of the total energy expenditure, which includes energy expenditure required for performance of cellular and organ functions (basal metabolism [BM]), physical activity, and thermoregulation of body temperature. Supplementary energy is required for metabolic processes taking place during growth, pregnancy, and lactation [3]. In quantitative terms DIT represents about 10% of total energy expenditure (15% together with cold-induced thermogenesis).

Research communicationEffect of dietary oils on brain enzymatic activities (2′-3′-cyclic nucleotide 3′-phosphodiesterase and acetylcholinesterase) and muscarinic receptor sites in growing rats

Abstract Dietary fats affect the fatty acid composition of brain membranes, but the consequences of the fatty acid changes on brain functional activities are poorly understood and not yet established. In order to investigate the effects of diet-induced changes on myelin deposition and on the cholinergic system, the present experiment was designed. Three groups of 10 male Sprague-Dawley rats (initial weight 100 ± 5 g) were fed for 6 weeks diets containing 15% (wt/wt) fish oil (FO), soybean oil (SO), and coconut oil (CO) rich in n-3 fatty acids (38%), n-6 fatty acids (55%), and saturated fatty acids (84%), respectively. The 2′-3′-cyclic nucleotide 3′-phosphodiesterase activity (CNPase) in the whole brain and in the cerebral cortex and the acetylcholinesterase activity (AChE) were determined along with the density and affinity of muscarinic receptor sites. The CNPase activity was significantly higher in the SO-fed group than in the other two groups (62.5 versus 47.0 and 54.4 μmol/hr/mg of protein), and the activity was correlated positively with Σ n-6 and negatively with Σ n-3. The AChE activity, the density, and the affinity of the receptor muscarinic receptor sites were not statistically different among the three groups. The results indicate the favorable effect of soybean oil and the adverse effect of fish oil on myelin deposition and the absence of effect of dietary oils on the cholinergic system.