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Biomedical subjects

M Maranesi

Publications and source records attributed to M Maranesi.

At least 19 recordsLinked to original sources
PubMed2005

Correlation between dietary polyunsaturated fatty acids and plasma homocysteine concentration in vitamin B6-deficient rats.

BACKGROUND AND AIM: Vitamin B6 as cofactor of Delta6 desaturase is involved in polyunsaturated fatty acid metabolism; moreover, it is a cofactor of the trans-sulfuration pathway of homocysteine. Some studies report that low concentrations of pyridoxine, by increasing homocysteine levels, are associated with coronary artery disease, and carotid and arterial lesions. The aim of this study was to verify whether different dietary amounts of polyunsaturated fatty acids associated with low content of vitamin B6 could modulate homocysteinemia. METHODS AND RESULTS: Thirty-two rats were divided into two groups, one fed a diet with adequate vitamin B6 content the other a diet containing low amount of the same vitamin. Within each group, rats were divided into two subgroups differing in the polyunsaturated fatty acid content of the diet (63 and 33%, respectively). The vitamin B6-deficient diet induced an increase in homocysteine concentration compared to the vitamin B6-normal diet. This increase was tenfold in the subgroup fed high polyunsaturated fatty acid levels and twofold in the other subgroup. The fatty acid composition of liver phospholipids showed a lower arachidonic acid relative molar content and a lower 20:4/18:2 ratio in vitamin B6-deficient groups compared with B6-normal groups. CONCLUSIONS: On the basis of the different biological functions of pyridoxine and considering that some factors closely related to atherosclerosis are vitamin B(6) dependent, adequate pyridoxine availability could be necessary to assure a normal long chain fatty acid metabolism and to reduce the risk linked to hyperhomocysteinemia.

Animals↗
PubMed2005

Leptin receptor expression and in vitro leptin actions on prostaglandin release and nitric oxide synthase activity in the rabbit oviduct.

In this study, we have examined the presence and the distribution of receptors for leptin (Ob-R) in the oviduct of rabbits, and the effects of leptin on the release of prostaglandin (PG) F2alpha and PGE2 and on the activity of nitric oxide (NO) synthase (NOS) by oviducts cultured in vitro. Rabbits were killed during the follicular phase and the oviducts were incubated in vitro with leptin, PGF2alpha, PGE2, NO donor and inhibitors of NOS and cyclo-oxigenase (COX). Using immunohistochemistry, Ob-R-like positive reaction was observed only in the cytoplasm of secretory cells, having stronger intensity in the infundibulum and ampulla tracts than in the isthmus. Both leptin and NO donor inhibited PGE2 release, whereas they enhanced PGF2alpha release; NOS inhibitor alone or with leptin increased PGE2 and decreased PGF2alpha production; NOS activity was enhanced by leptin, while PGs did not affect this enzyme. This study suggests that the oviduct could be a potential target for endocrine regulation by leptin, whose circulating levels may act as a metabolic signal modulating oviductal PG release through mediation of the NOS/NO system.

Animals↗
PubMed1999

Influence of dietary n-3 polyunsaturated fatty acids on plasma lipemic effect of vitamin B6 deficiency.

Since many connections exist between vitamin B6 and lipid metabolism, we aim to investigate the lipemic effect of different dietary intakes of polyunsaturated fatty acids in rats fed a vitamin B6 deficient diet. Diets were either vitamin B6 deficient (-B6) or vitamin B6 sufficient, pair-fed to the deficient group (PF) and ad libitum (N). The diets were combined with normal lipid (LC: soya bean-coconut-palm oils) and fish oil (FO: soya bean-fish oil). The fish oil diet with sufficient vitamin B6 content caused an increase in n-3 long chain polyunsaturated fatty acids and a decrease in arachidonic acid. In the -B6 group fed a normal lipid diet, the arachidonic acid percentage decreased and the linoleic acid percentage increased; in the -B6 group fed fish oil these changes in fatty acid composition, already consequent upon dietary intake of n-3 long chain polyunsaturated fatty acids, did not show further variations. In the dietary condition of vitamin B6 deficiency, plasma cholesterol content increased in rats fed a lipid control diet, whereas no hypocholesterolemic effect was observed in those fed a fish oil diet. Plasma triglyceride contents were not influenced by dietary lipid quality because, in all conditions, the lower food intake of the PF groups caused a decrease and vitamin B6 deficiency caused an elevation in triglyceride contents which reached those of the ad libitum groups. The study highlights the interaction between vitamin B6 and polyunsaturated fatty acids and the opportunity of dietary intake of fish oil to counterbalance some effects of vitamin B6 deficiency.

Animals↗
PubMed1999

Effect of dietary oils containing different amounts of precursor and derivative fatty acids on prostaglandin E2 synthesis in liver, kidney and lung of rats.

The availability of the fatty acids which are precursors of prostaglandins is affected by dietary intake. We have studied, in particular, the effects of dietary intake of lipids with different amounts of precursor and derivative fatty acids on the synthesis of prostaglandin E2 (PGE2) in rat liver, kidney and lung. Fifteen-month-old rats were fed for 3 months diets containing different amounts of oleic, linoleic, alpha linolenic, gamma linolenic and stearidonic acids. The fatty acid compositions of total phospholipids and prostaglandin E2 levels of liver, kidney and lung were investigated. In the organs studied, the intake of lipids at different amount of precursor/derivative fatty acids caused variations in the fatty acid composition of phospholipids. PGE2 showed different values which did not seem directly affected by tissue availability of arachidonate but by the effect of dietary lipids on the metabolic pool of polyunsaturated fatty acids (PUFAs).

Animals↗
PubMed1996

Effect of diets containing different amounts of precursor and derivative fatty acids on serum TXB2.

Dietary precursor and derivative polyunsaturated fatty acids influence metabolic parameters, such as eicosanoid synthesis. We have studied the effect of dietary intakes of lipids containing different amounts of precursor and derivative fatty acids (olive oil, olive-blackcurrant-fish oil mixture, blackcurrant-fish oil mixture, MCT (medium chain triglycerides)-soyabean oil mixture) on serum thromboxane B2 (TXB2) in four groups of rats. Plasma fatty acid composition showed differences related to dietary intakes. TXB2 levels were similar in all conditions except in the group receiving the mixture of olive-blackcurrant-fish oils which showed lower values.

Animals↗
PubMed1994

Mitochondrial activities of rat heart during ageing.

Some analytical and functional parameters of rat heart mitochondrial have been investigated at six different periods of ageing from 2 to 26 months. The fatty acid composition of the mitochondrial membranes reveals a percentage increase of polyunsaturated fatty acids (20:4 n-6, 22:6 n-3) up to 12 months, followed by a decrease; however, fluorescence polarization of the membrane probe diphenylhexatriene is not changed, revealing that membrane fluidity is not significantly affected. No major change in ubiquinone-9 and in cytochrome content is apparent, indicating that the relative ratio of the respiratory chain components is unmodified. Nevertheless, significant changes in enzyme specific activities are detected: NADH cytochrome c reductase and cytochrome oxidase activities increase up to 12 months, then decrease at 18-26 months; ubiquinol cytochrome c reductase exhibits a peak at 18 months, followed by a decrease. All these activities follow a similar trend during the whole life span of the rat, even though the 'maximum' is different. No significant changes have been found in ATP synthase. Succinate-cytochrome c reductase steadily increases over the whole life span. The results, showing activity decreases in the respiratory enzymes having subunits encoded by mitochondrial DNA, are compatible with the 'mitochondrial' theory of ageing.

Aging↗
PubMed1994

The effect of dietary lipid changes on the fatty acid composition and function of liver, heart and brain mitochondria in the rat at different ages.

A correlation between dietary lipids and cellular enzyme activities is a problem that has only been partially addressed by nutritionists. Therefore, changes in the fatty acid composition and the activities of some key metabolic enzymes (ubiquinol-2-cytochrome c reductase (EC 1.10.2.2), cytochrome oxidase (EC 1.9.3.1) and ATPase (EC 3.6.1.3)) in the mitochondria of liver, heart and brain of rats fed on diets differing extensively in their polyunsaturated fatty acid compositions have been investigated. The results showed that fatty acid compositional changes brought about by the dietary differences were associated with extensive changes in the activities of these key enzymes in the mitochondria. The extent of the influence differed considerably with the period over which the diets were fed. The role of dietary lipids to effect changes through the preservation of membrane structural integrity is discussed.

Adenosine Triphosphatases↗
PubMed1994

Interaction of licorice on glycyrrhizin pharmacokinetics.

The effects of components of aqueous licorice root extract (LE) on the pharmacokinetics of glycyrrhizin (G) and glycyrrhetic acid (GA) were investigated in rats and humans. The aim of this work was to define the role of pharmacokinetics in G toxicity. In the procedure, G and GA were detected in biological fluids by means of recently improved HPLC methods. Significantly lower G and GA plasma levels were found in rats and humans treated with LE compared to the levels obtained with those in which G alone was administered. The pharmacokinetic curves showed significant differences in the areas under the plasma-time curve (AUC), Cmax, and Tmax parameters. The data obtained from urine samples are in agreement with the above results and confirm a reduced bioavailability of G present in LE compared to pure G. This should be attributed to the interaction during intestinal absorption between the G constituent and the several components in LE. The modified bioavailability could explain the various clinical adverse effects resulting from the chronic oral administration of G alone as opposed to LE.

Administration, Oral↗
PubMed1994

Interaction among dietary vitamin B6, proteins and lipids: effects on liver lipids in rats.

Vitamin B6 is involved in protein and lipid metabolism. Yet the effect of pyridoxine deficiency has been studied in relation to separate dietary parameters, we aim to investigate the effect of pyridoxine deficiency associated with a high intake of proteins and/or low EFA content in the diet. Vitamin B6 and PLP contents, fatty acid compositions of lipids and phospholipids were determined in liver of groups of rats fed on diets with different amounts of proteins (20-40%) and EFA (2-35%). The results show a complex interaction among tested nutritional factors with a prevailing influence of dietary proteins on lipid content of liver and of low EFA intake and vitamin B6 on PUFA metabolism. The effects of pyridoxine deficiency on lipid metabolism were dependent on the EFA content of the diet.

Animals↗
PubMed1993

Interaction between vitamin B6 deficiency and low EFA dietary intake on kidney phospholipids and PGE2 in the rat.

Vitamin B6 is involved in the metabolism of long chain polyunsaturated fatty acids and phospholipids. We have studied the interaction between pyridoxine deficiency and low amounts of dietary essential fatty acids (EFA) in the rat. The fatty acid composition of kidney phospholipids of pyridoxine deficient animals shows a decrease of 20:3 n9 and an increase of 20:4 n6 in comparison with control and pair fed animals. This variation of fatty acid composition could be due to the simultaneous effect of vitamin B6 deficiency, which reduces the oxidation of linolenate, and of a low intake of EFAs which stimulates delta-6-desaturase. The dietary treatment also influences kidney Prostaglandin E2 (PGE2) levels which are higher in vitamin B6 deficient animals. This effect could be correlated with a higher response to sympathetic stimulation caused by the simultaneous presence of vitamin B6 deficiency and low EFA availability. Also the higher level of arachidonate could be involved in promoting PGE2 synthesis.

Animals↗
PubMed1992

Mitochondrial and microsomal cholesterol mobilization after oxidative stress induced by adriamycin in rats fed with dietary olive and corn oil.

The influence of three different dietary fats (8%) and of endogenous lipid peroxidation with regard to cholesterol concentrations in liver mitochondria and microsomes and in serum has been investigated in the rat. Although the different diet fat used did not produce any effect on serum cholesterol, it was possible to show that each experimental diet differently influenced the microsomal and mitochondrial levels of cholesterol. The highest mitochondrial and microsomal cholesterol content was found in case of diet supplemented with virgin olive oil and the lowest with rectified olive oil. An endogenous oxidative stress induced by adriamycin was able to produce a clear decrease in microsomal and mitochondrial cholesterol level and a sharp increase in serum concentration in all three groups. However, dietary fats and adriamycin had no effect on the microsomal and mitochondrial membrane viscosity as detected by fluorescence polarization. These results are consistent with the hypothesis that mitochondrial and microsomal cholesterol can exchange with exogenous pools when phospholipid peroxidation occurs.

Animals↗
PubMed1991

Influence of dietary fatty acids on phospholipid composition and prostaglandin E synthesis in rat kidneys.

The effects of oils with different amounts of n6 and n3 fatty acid precursors and derivatives were evaluated on phospholipid composition and PGE2 synthesis of rat kidneys. Dietary lipids were: olive oil, an olive-blackcurrant-fish oil mixture and a blackcurrant-fish oil mixture. We observed in the kidneys of rats fed the blackcurrant-fish oil mixture a significant decrease in PGE2 synthesis, while arachidonate values did not show significant variations. A decrease of PGE2 synthesis could be due to competitive and inhibitory effects of fatty acids other than arachidonate, observed in the kidney phospholipid composition in our dietary conditions.

Animals↗
PubMed1991

The effect of diet upon the fatty acid composition of cranial and spinal nerve lipids.

The possible basal differences in lipid class and fatty acid composition between a cranial nerve (the trigeminal nerve) and two spinal nerves (the ulnar and sciatic nerves) as well as the effects of dietary lipids on the same nerves were studied. A basal (BD) and four experimental diets containing respectively hydrogenated coconut oil (HCO), grapestone oil (GSO), olive oil (OO) and linseed oil (LSO) were used. Trigeminal lipids fatty acid composition differs significantly from sciatic and ulnar ones in the percentages of 16:0, 16:1, 18:0, 18:2 n-6, 20:0, 20:1, 20:4 n-6, 24:0, 24:1 and 22:6 n-3. Also the proportions of triacylglycerols and free cholesterol strongly differ in trigeminal and spinal nerves whereas no significant difference was detected between ulnar and sciatic nerve lipids. Following the administration of the four experimental diets for 60 days, no significant change was observed in the fatty acid pattern of trigeminal lipids while the spinal ones showed a significant increase in the proportions of the fatty acids present in large quantities in the dietary oils used (i.e.: oleic acid in the OO samples). These changes are probably linked with the rapid metabolic turnover of triacylglycerols, present in larger amounts in spinal nerve lipids.

Animals↗
PubMed1990

Dietary lipid effects on microsome fatty acid composition of liver and brain, on liver glucose-6-phosphatase, and on brain 5'-nucleotidase activity in the rat.

The effects of incorporation of dietary oils with different n6/n3 ratio and polyunsaturated fatty acids content into rat liver and brain microsomes has been studied. The investigation of membrane fatty acid composition of liver microsomes and that of brain microsomes gave different results. In particular, liver microsomes of rats fed fish oil showed a relatively higher content of 20:5n3 and 22:6n3, and a lower content of 20:4n6. Under these conditions, a reduced glucose-6-phosphatase activity was measured. Brain microsomal fatty acid composition was only slightly affected by dietary lipid intake. The 5'-nucleotidase activity of those particles was similar, although statistically different values were found in fish-oil-fed rats and in olive-oil-fed rats. The effects of membrane fatty acid composition on membrane-bound enzyme activity are discussed.

Journal Article↗
PubMed1989

Dietary-induced changes in lipid and fatty acid composition can modify chronaxie values in the rat sciatic nerve.

The present investigation aimed at clarifying the possible correlations among dietary lipids, peripheral fatty acid composition of nerve lipids and an index of the nervous tissue excitability, the chronaxie. The experiments were performed on female albino rats fed diets containing olive oil (OO) and fish oil (FO) along two generations. Total lipids fatty acid composition of the sciatic nerves from the two groups differed in the proportions of 18:1(n-9), 20:1(n-9), 22-1, 20:5(n-3) and 22:6(n-3). Also the lipid class composition showed significant differences among FO and OO specimens (free cholesterol more concentrated in the OO lipids; triacylglycerols more concentrated in the FO ones). The sciatic nerve isolated from FO rats showed a significant decrease in the chronaxie values if compared to the OO specimens. These results could follow from dietary-induced changes in the perineural permeability and/or possible modifications in the cable properties of the peripheral nerve fibers related to the myelin sheath composition.

Animals↗
PubMed1988

Effect of n-6 and n-3 dietary fatty acids on phospholipid composition of plasma, platelets and aorta in the rat.

Female Wistar rats were fed with diets containing as dietary lipids 10% of hydrogenated coconut oil, grape-seed oil, olive oil, linseed oil and fish oil, respectively, for a period of 60 days. At the end of dietary treatment plasma, platelets and aorta phospholipids were extracted and fatty acid spectra determined. Plasma and platelet phospholipids showed the largest diet dependent changes. Anyway in aorta samples too, phospholipids showed marked increase in oleic (olive oil group) linoleic (grape-seed oil group) and alpha linoleic (linseed oil group) acids percentage. Conversely decreased amounts of arachidonic acid were detected in rats fed with diets containing linseed and fish oils. In these samples eicosapentenoic acid partly replaced arachidonic one.

Animals↗