Dietary n-3 polyunsaturated fatty acids revert renal responses induced by a combination of 2 protocols that increase the amounts of advanced glycation end product in rats.

Renal dysfunction is a severe complication that is caused by diabetes mellitus. Many factors associate the progression of this complication with high levels of proinflammatory and pro-oxidant substances, such as advanced glycation end products (AGEs), which form a heterogeneous group of compounds that can accumulate in tissues such as retinas, joints, and kidneys. The hypothesis of this study is that n-3 polyunsaturated fatty acids (n-3 PUFAs) have a nephroprotective effect on rats after exposing them to a combination of 2 protocols that increase the AGE amounts: a high-fat diet enriched with AGEs and a diabetes rat model. Adult Wistar rats were divided into 6 groups that received the following diets for 4 weeks: (1) control group; 2) HAGE: high AGE fat-containing diet group; (3) HAGE + n-3: high AGE fat-containing diet plus n-3 PUFAs group; (4) diabetic group; (5) Db + HAGE: high AGE fat-containing diet diabetic group; and (6) Db + HAGE + n-3: high AGE fat-containing diet plus n-3 PUFAs diabetic group. Diabetes mellitus was induced by an intraperitoneal injection of alloxan (150 mg kg(-1)). In diabetic and nondiabetic rats, the high HAGE fat-containing diet increased the serum creatinine, tumor necrosis factor-α, thiobarbituric acid reactive substances, and reactive oxygen species levels, as well as the superoxide dismutase/catalase + glutathione peroxidase ratio and the superoxide dismutase 2 and receptor for advanced glycation end products immunocontent of the kidneys. n-3 Polyunsaturated fatty acids attenuated these alterations and influenced the receptor for advanced glycation end products/oxidative stress/tumor necrosis factor-α axis. In summary, this study showed that the extrinsic AGE pathway (HAGE diet) had a greater effect on renal metabolism than the intrinsic AGE pathway (diabetes induction) and that n-3 PUFAs appear to prevent renal dysfunction via antioxidant and anti-inflammatory pathways.

Antiproliferative and cytotoxic effects of purple pitanga (Eugenia uniflora L.) extract on activated hepatic stellate cells.

The presence of phenolic compounds in fruit- and vegetable-rich diets has attracted researchers' attention due to their health-promoting effects. The objective of this study was to evaluate the effects of purple pitanga (Eugenia uniflora L.) extract on cell proliferation, viability, mitochondrial membrane potential, cell death and cell cycle in murine activated hepatic stellate cells (GRX). Cell viability by 3-(4,5-dimethylthiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was significantly decreased on cells treated with 50 and 100 µg ml(-1) of purple pitanga extract for 48 and 72 h, and the percentage of dead cell stained with 7-amino-actinomycin D was significantly higher in treated cells. The reduction of cell proliferation was dose dependent, and we also observed alterations on cell cycle progression. At all times studied, GRX cells treated with 50 and 100 µg ml(-1) of purple pitanga showed a significant reduction in cellular mitochondrial content as well as a decrease in mitochondrial membrane potential. Furthermore, our results indicated that purple pitanga extract induces early and late apoptosis/necrosis and necrotic death in GRX cells. This is the first report describing the antiproliferative, cytotoxic and apoptotic activity for E. uniflora fruits in hepatic stellate cells. The present study provides a foundation for the prevention and treatment of liver fibrosis, and more studies will be carried to elucidate this effect.

Dietary n-3 long-chain polyunsaturated fatty acids modify phosphoenolpyruvate carboxykinase activity and lipid synthesis from glucose in adipose tissue of rats fed a high-sucrose diet.

Long-chain polyunsaturated n-3 fatty acids (n-3 LCPUFAs) have hypolipidemic effects and modulate intermediary metabolism to prevent or reverse insulin resistance in a way that is not completely elucidated. Here, effects of these fatty acids on the lipid profile, phosphoenolpyruvate carboxykinase (PEPCK) activity, lipid synthesis from glucose in epididymal adipose tissue (Ep-AT) and liver were investigated. Male rats were fed a high-sucrose diet (SU diet), containing either sunflower oil or a mixture of sunflower and fish oil (SU-FO diet), and the control group was fed a standard diet. After 13 weeks, liver, adipose tissue and blood were harvested and analysed. The dietary n-3 LCPUFAs prevented sucrose-induced increase in adiposity and serum free fat acids, serum and hepatic triacylglycerol and insulin levels. Furthermore, these n-3 LCPUFAs decreased lipid synthesis from glucose and increased PEPCK activity in the Ep-AT of rats fed the SU-FO diet compared to those fed the SU diet, besides reducing lipid synthesis from glucose in hepatic tissue. Thus, the inclusion of n-3 LCPUFAs in the diet may be beneficial for the prevention or attenuation of dyslipidemia and insulin resistance, and for reducing the risk of related chronic diseases.

Ω3-Polyunsaturated fatty acids prevent lipoperoxidation, modulate antioxidant enzymes, and reduce lipid content but do not alter glycogen metabolism in the livers of diabetic rats fed on a high fat thermolyzed diet.

Ω3-Polyunsaturated fatty acids (Ω3-PUFAs) are known to act as hypolipidaemics, but the literature is unclear about the effects that Ω3-PUFAs have on oxidative stress in obese and diabetic patients. In this study, our aim was to investigate the effects of Ω3-PUFAs on oxidative stress, including antioxidant enzyme activity and hepatic lipid and glycogen metabolism in the livers of diabetic and non-diabetic rats fed on a high fat thermolyzed diet. Rats were divided into six groups: (1) the control group (C), (2) the control diabetic group (D), (3) the high fat thermolyzed diet group (HFTD), which were fed a diet that was enriched in fat that was heated for 60 min at 180°C, (4) the high fat thermolyzed diet diabetic group (D + HFTD), (5) the high fat thermolyzed diet + Ω3 polyunsaturated fatty acid group (HFTD + Ω3), and (6) the high fat thermolyzed diet + Ω3 polyunsaturated fatty acid diabetic group (D + HFTD + Ω3). The most important finding of this study was that Ω3-PUFAs are able to reduce triglycerides, non-esterified fatty acid, lipoperoxidation levels, advanced glycation end products, SOD/CAT enzymatic ratio, and CAT immunocontent and increase SOD2 levels in the livers of diabetic rats fed with a HFTD. However, Ω3-PUFAs did not alter the observed levels of protein damage, blood glucose, or glycogen metabolism in the liver. These findings suggest that Ω3-PUFAs may represent an important auxiliary adjuvant in combating some diseases like diabetes mellitus, insulin resistance, and non-alcoholic fatty liver disease.

Exercise increases insulin signaling in the hippocampus: physiological effects and pharmacological impact of intracerebroventricular insulin administration in mice.

Increasing evidence indicates that physical exercise induces adaptations at the cellular, molecular, and systemic levels that positively affect the brain. Insulin plays important functional roles within the brain that are mediated by insulin-receptor (IR) signaling. In the hippocampus, insulin improves synaptic plasticity, memory formation, and learning via direct modulation of GABAergic and glutamatergic receptors. Separately, physical exercise and central insulin administration exert relevant roles in cognitive function. We here use CF1 mice to investigate (i) the effects of voluntary exercise on hippocampal insulin signaling and memory performance and (ii) whether central insulin administration alters the effects of exercise on hippocampal insulin signaling and memory performance. Adult mice performed 30 days of voluntary exercise on running wheel and afterward both, sedentary and exercised groups, received intracerebroventricular (icv) injection of saline or insulin (0.5-5 mU). Memory performance was assessed using the inhibitory avoidance and water maze tasks. Hippocampal tissue was measured for [U-(14)C] glucose oxidation and the immunocontent of insulin receptor/signaling (IR, pTyr, pAktser473). Additionally, the phosphorylation of the glutamate NMDA receptor NR2B subunit and the capacity of glutamate uptake were measured, and immunohistochemistry was used to determine glial reactivity. Exercise significantly increased insulin peripheral sensitivity, spatial learning, and hippocampal IR/pTyrIR/pAktser473 immunocontent. Glucose oxidation, glutamate uptake, and astrocyte number also increased relative to the sedentary group. In both memory tasks, 5 mU icv insulin produced amnesia but only in exercised animals. This amnesia was associated a rapid (15 min) and persistent (24 h) increase in hippocampal pNR2B immunocontent that paralleled the increase in glial reactivity. In conclusion, physical exercise thus increased hippocampal insulin signaling and improved water maze performance. Overstimulation of insulin signaling in exercised animals, however, via icv administration impaired behavioral performance. This effect was likely the result of aberrant phosphorylation of the NR2B subunit.

Omega-3 fatty acids deprivation affects ontogeny of glutamatergic synapses in rats: relevance for behavior alterations.

Essential omega-3 polyunsaturated fatty acids (omega3) are crucial to brain development and function, being relevant for behavioral performance. In the present study we examined the influence of dietary omega3 in the development of the glutamatergic system and on behavior parameters in rats. Female rats received isocaloric diets, either with omega3 (omega3 group) or a omega3 deficient diet (D group). In ontogeny experiments of their litters, hippocampal immunocontent of ionotropic NMDA and AMPA glutamatergic receptors subunits (NR2 A\B and GluR1, respectively) and the alpha isoform of the calcium-calmodulin protein kinase type II (alphaCaMKII) were evaluated. Additionally, hippocampal [(3)H]glutamate binding and uptake were assessed. Behavioral performance was evaluated when the litters were adult (60 days old), through the open-field, plus-maze, inhibitory avoidance and flinch-jump tasks. The D group showed decreased immunocontent of all proteins analyzed at 02 days of life (P2) in comparison with the omega3 group, although the difference disappeared at 21 days of life (except for alphaCaMKII, which content normalized at 60 days old). The same pattern was found for [(3)H]glutamate binding, whereas [(3)H]glutamate uptake was not affected. The D group also showed memory deficits in the inhibitory avoidance, increased in the exploratory pattern in open-field, and anxiety-like behavior in plus-maze. Taken together, our results suggest that dietary omega3 content is relevant for glutamatergic system development and for behavioral performance in adulthood. The putative correlation among the neurochemical and behavioral alterations caused by dietary omega3 deficiency is discussed.

Dietary omega-3 fatty acids attenuate cellular damage after a hippocampal ischemic insult in adult rats.

The role of omega-3 polyunsaturated fatty acids (3PUFAs) on brain function is increasingly demonstrated. Here, the effect of dietary deprivation of essential 3PUFAs on some parameters related to neuroprotection was investigated. Rats were fed with two different diets: omega-3 diet and omega-3-deprived diet. To assess the influence of 3PUFAs on brain responses to ischemic insult, hippocampal slices were subjected to an oxygen and glucose deprivation (OGD) model of in vitro ischemia. The omega-3-deprived group showed higher cell damage and stronger decrease in the [(3)H]glutamate uptake after OGD. Moreover, omega-3 deprivation influenced antiapoptotic cell response after OGD, affecting GSK-3beta and ERK1/2, but not Akt, phosphorylation. Taken together, these results suggest that 3PUFAs are important for cell protection after ischemia and also seem to play an important role in the activation of antiapoptotic signaling pathways.

Gestational and postnatal low protein diet alters insulin sensitivity in female rats.

Nutrition during pregnancy and lactation can program an offspring's metabolism with regard to glucose and lipid homeostasis. A suboptimal environment during fetal, neonatal and infant development is associated with impaired glucose tolerance, type 2 diabetes and insulin resistance in later adult life. However, studies on the effects of a low protein diet imposed from the beginning of gestation until adulthood are scarce. This study's objective was to investigate the effects of a low protein diet imposed from the gestational period until 4 months of age on the parameters of glucose tolerance and insulin responsiveness in Wistar rats. The rats were divided into a low protein diet group and a control group and received a diet with either 7% or 25% protein, respectively. After birth, the rats received the same diet as their mothers, until 4 months of age. In the low protein diet group it was observed that: (i) the hepatic glycogen concentration and hepatic glycogen synthesis from glycerol were significantly greater than in the control group; (ii) the disposal of 2-deoxyglucose in soleum skeletal muscle slices was 29.8% higher than in the control group; (iii) there was both a higher glucose tolerance in the glucose tolerance test; and (iv) a higher insulin responsiveness in than in the control group. The results suggest that the low protein diet animals show higher glucose tolerance and insulin responsiveness relative to normally nourished rats. These findings were supported by the higher hepatic glycogen synthesis and the higher disposal of 2-deoxyglucose in soleum skeletal muscle found in the low protein diet rats.

High fat and highly thermolyzed fat diets promote insulin resistance and increase DNA damage in rats.

Many studies have demonstrated that DNA damage may be associated with type 2 diabetes mellitus (T2DM) and its complications. The goal of this study was to evaluate the effects of the potential relationship between fat (thermolyzed) intake, glucose dyshomeostasis and DNA injury in rats. Biochemical parameters related to glucose metabolism (i.e., blood glucose levels, insulin tolerance tests, glucose tolerance tests and fat cell glucose oxidation) and general health parameters (i.e., body weight, retroperitoneal and epididymal adipose tissue) were evaluated in rats after a 12-month treatment with either a high fat or a high thermolyzed fat diet. The high fat diet (HFD) and high fat thermolyzed diet (HFTD) showed increased body weight and impaired insulin sensitivity at the studied time-points in insulin tolerance test (ITT) and glucose tolerance test (GTT). Interestingly, only animals subjected to the HFTD diet showed decreased epididymal fat cell glucose oxidation. We show which high fat diets have the capacity to reduce glycogen synthesis by direct and indirect pathways. HFTD promoted an increase in lipid peroxidation in the liver, demonstrating significant damage in lipids in relation to other groups. Blood and hippocampus DNA damage was significantly higher in animals subjected to HFDs, and the highest damage was observed in animals from the HFTD group. Striatum DNA damage was significantly higher in animals subjected to HFDs, compared with the control group. These results show a positive correlation between high fat diet, glucose dyshomeostasis, oxidative stress and DNA damage.

Ketogenic diet-fed rats have increased fat mass and phosphoenolpyruvate carboxykinase activity.

The ketogenic diet (KD), characterized by high fat and low carbohydrate and protein contents, has been proposed to be beneficial in children with epilepsy disorders not helped by conventional anti-epileptic drug treatment. Weight loss and inadequate growth is an important drawback of this diet and metabolic causes are not well characterized. The aim of this study was to examine body weight variation during KD feeding for 6 wk of Wistar rats; fat mass and adipocyte cytosolic phosphoenolpyruvate carboxykinase (PEPCK) activity were also observed. PEPCK activity was determined based on the [H(14)CO(3) (-)]-oxaloacetate exchange reaction. KD-fed rats gained weight at a less rapid rate than normal-fed rats, but with a significant increment in fat mass. The fat mass/body weight ratio already differed between ketogenic and control rats after the first week of treatment, and was 2.4 x higher in ketogenic rats. The visceral lipogenesis was supported by an increment in adipocyte PEPCK, aiming to provide glycerol 3-phosphate to triacylglycerol synthesis and this fat accumulation was accompanied by glucose intolerance. These data contribute to our understanding of the metabolic effects of the KD in adipose tissue and liver and suggest some potential risks of this diet, particularly visceral fat accumulation.

Effects of undernutrition on glutamatergic parameters in the cerebral cortex of young rats.

Perinatal undernutrition impairs maturational events in the development of the brain, resulting in a variety of brain dysfunctions, which affect cognitive functions. This study investigated the effects of pre- and post-natal undernutrition (diet: 8% protein; control group: 25% protein) on some glutamatergic and behavioral parameters of 21-day-old rats. In the cerebral cortex, undernutrition reduced the Na-independent [(3)H]Glutamate binding in cellular membranes and [(3)H]Glutamate vesicular uptake, without affecting the [(3)H]Glutamate uptake by slices preparation. Behavioral parameters were affected, showing a strong amnesic effect both in the short- and long-term memory of inhibitory avoidance tasks, and a significant reduction in the number of crossings in an open field. The effects of perinatal undernutrition in 21-day-old rats, which alter some glutamatergic parameters may be related to the impairment of memory in certain behavioral tasks.

Inhibition of brain energy metabolism by the branched-chain amino acids accumulating in maple syrup urine disease.

In the present work we investigated the in vitro effect of the branched-chain amino acids (BCAA) accumulating in maple syrup urine disease (MSUD) on some parameters of energy metabolism in cerebral cortex of rats. 14CO2 production from [1-14C]acetate, [1-5-14C]citrate and [U-14C]glucose, as well as glucose uptake by the brain were evaluated by incubating cortical prisms from 30-day-old rats in the absence (controls) or presence of leucine (Leu), valine (Val) or isoleucine (Ile). All amino acids significantly reduced 14CO2 production by around 20-55%, in contrast to glucose utilization, which was significantly increased by up to 90%. Furthermore, Leu significantly inhibited the activity of the respiratory chain complex IV, whereas Val and Ile markedly inhibited complexes II-III, III and IV by up to 40%. We also observed that trolox (alpha-tocopherol) and creatine totally prevented the inhibitory effects provoked by the BCAA on the respiratory chain complex activities, suggesting that free radicals were involved in these effects. The results indicate that the major metabolites accumulating in MSUD disturb brain aerobic metabolism by compromising the citric acid cycle and the electron flow through the respiratory chain. We presume that these findings may be of relevance to the understanding of the pathophysiology of the neurological dysfunction of MSUD patients.

Experimental hypothyroidism inhibits delta-aminolevulinate dehydratase activity in neonatal rat blood and liver.

The aim of this study was to investigate the potential relationship between hypothyroidism and delta-aminolevulinate dehydratase (delta-ALA-D) activity in rat blood and liver. Experimental hypothyroidism was induced in weanling rats by exposing their mothers to propylthiouracil (PTU) diluted in tap water (0.05% w/ v), ad libitum, during the lactational period (PTU group). Control (euthyroid) group included weanling rats whose mothers received just tap water, ad libitum, during the lactational period. Reverted-hypothyroid group (PTU + 3,3',5-triiodo-L-thyronine [T(3)]) included weanling rats whose mothers were exposed to PTU similarly to those in the hypothyroid group, but pups received daily subcutaneous injections of T(3) (20 microg/kg, from Postnatal Days 2-20). After the treatment, serum T(3) levels were drastically decreased (around 70%) in the PTU group, and this phenomenon was almost reverted by exogenous T(3). PTU decreased blood delta-ALA-D activity by 75%, and T(3) treatment prevented such phenomena. Erythrocytes and hemoglobin levels were increased by 10% in PTU-treated animals and higher increments (around 25%) were observed in these parameters when exogenous T(3) was coadministered. Dithiothreitol did not change blood delta-ALA-D activity of PTU-exposed animals when present in the reaction medium, suggesting no involvement of the enzyme's essential thiol groups in PTU-induced delta-ALA-D inhibition. PTU did not affect blood delta-ALA-D activity in vitro. These results are the first to show a correlation between hypothyroidism and decreased delta-ALA-D activity and point to this enzyme as a potential molecule involved with hypothyroidism-related hematological changes.

Evidence for a synergistic action of glutaric and 3-hydroxyglutaric acids disturbing rat brain energy metabolism.

Glutaric acidemia type I is an inherited metabolic disorder caused by a severe deficiency of the mitochondrial glutaryl-CoA dehydrogenase activity leading to accumulation of predominantly glutaric and 3-hydroxyglutaric acids in the brain tissue of the affected patients. Considering that a toxic role was recently postulated for quinolinic acid in the neuropathology of glutaric acidemia type I, in the present work we investigated whether the combination of quinolinic acid with glutaric or 3-hydroxyglutaric acids or the mixture of glutaric plus 3-hydroxyglutaric acids could alter brain energy metabolism. The parameters evaluated in cerebral cortex from young rats were glucose utilization, lactate formation and (14)CO(2) production from labeled glucose and acetate, as well as the activities of pyruvate dehydrogenase and creatine kinase. We first observed that glutaric (5 mM), 3-hydroxyglutaric (1 mM) and quinolinic acids (0.1 microM) per se did not alter these parameters. Similarly, no change of these parameters occurred when combining glutaric with quinolinic acids or 3-hydroxyglutaric with quinolinic acids. In contrast, co-incubation of glutaric plus 3-hydroxyglutaric acids increased glucose utilization, decreased (14)CO(2) generation from glucose, inhibited pyruvate dehydrogenase activity as well as total and mitochondrial creatine kinase activities. The glutaric plus 3-hydroxyglutaric acids-induced inhibitory effects on creatine kinase were prevented by the antioxidants glutathione and catalase plus superoxide dismutase, indicating the participation of reactive oxygen species. Our data indicate a synergic action of glutaric and 3-hydroxyglutaric acids disturbing energy metabolism in cerebral cortex of young rats.

Inhibition of CO(2) production from glucose by arginine in brain slices of rats.

In the present study we evaluated the in vivo effect of arginine on CO(2) production from glucose in a medium with physiological and high extracellular K(+) concentrations. We also tested the influence of the nitric oxide synthase inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME), on the effects elicited by arginine in order to investigate the possible participation of NO and/or its derivatives on the effects of arginine on CO(2) production from glucose. Sixty-day-old rats were treated with a single intraperitoneal injection of saline (control; group I), arginine (0.8 g/kg; group II), L-NAME (2.0 mg/kg; group III) or arginine (0.8 g/kg) plus L-NAME (2.0 mg/kg; group IV) and were killed 1 h later. Results showed that arginine administration inhibited CO(2) production from glucose at physiological extracellular K(+) concentration and L-NAME prevented such effect. In contrast, arginine administration had no effect on CO(2) production from glucose at high extracellular K(+) concentration. Based on these data, we also investigated the in vitro effect of arginine on CO(2) production from glucose in a medium with physiological extracellular K(+) concentration in hippocampus slices. Results showed that arginine (0.1-1.5 mM) when added to the incubation medium did not alter CO(2) production from glucose in hippocampus slices of untreated rats. In addition, we also demonstrated that arginine inhibits Na(+), K(+)-ATPase activity. The data indicate that the reduction of CO(2) production by arginine was probably mediated by NO and/or its derivatives, which could act inhibiting the activity of Na(+), K(+)-ATPase. The results suggest that arginine impairs energy metabolism in hippocampus slices of rats.

Effect of 2-deoxy-D-glucose on aminoacids metabolism in rats' cerebral cortex slices.

We studied the effect of different concentrations of 2-deoxy-D-glucose on the L-[U-14C]leucine, L-[1-14C]leucine and [1-14C]glycine metabolism in slices of cerebral cortex of 10-day-old rats. 2-deoxy-D-glucose since 0.5 mM concentration has inhibited significantly the protein synthesis from L-[U-14C]leucine and from [1-14C]glycine in relation to the medium containing only Krebs Ringer bicarbonate. Potassium 8.0 mM in incubation medium did not stimulate the protein synthesis compared to the medium containing 2.7 mM, and at 50 mM diminishes more than 2.5 times the protein synthesis compared to the other concentration. Only at the concentration of 5.0 mM, 2-deoxy-D-glucose inhibited the CO2 production and lipid synthesis from L-[U-14C] leucine. This compound did not inhibit either CO2 production, or lipid synthesis from [1-14C]glycine. Lactate at 10 mM and glucose 5.0 mM did not revert the inhibitory effect of 2-deoxy-D-glucose on the protein synthesis from L-[U-14C]leucine. 2-deoxy-D-glucose at 2.0 mM did not show any effect either on CO2 production, or on lipid synthesis from L-[U-14C]lactate 10 mM and glucose 5.0 mM.

Effects of protein malnutrition on oxidative status in rat brain.

OBJECTIVES: This study evaluated the effects of protein malnutrition on oxidative status in rat brain areas. METHODS: We investigated various parameters of oxidative status, free radical content (dichlorofluorescein formation), indexes of damage to lipid (thiobarbituric acid-reactive substances assay), and protein damage (tryptophan and tyrosine content) in addition to total antioxidant reactivity levels and antioxidant enzyme activities of superoxide dismutase, glutathione peroxidase, and catalase in different cerebral regions (cortex, hippocampus, and cerebellum) from rats subjected to prenatal and postnatal protein malnutrition (control 25% casein and protein malnutrition 7% casein). RESULTS: Protein malnutrition altered various parameters of oxidative stress, especially damage to macromolecules. Free radical content was unchanged by protein malnutrition. There was an increase in levels of thiobarbituric acid-reactive substances, the index of lipid peroxidation, in the cerebellum and cerebral cortex (P < 0.05) from protein-malnourished rats. Moreover, significant decreases in tryptophan and tyrosine in all tested brain structures (P < 0.05) were observed. Catalase activity was significantly decreased in the cerebellum (P < 0.05). In addition, a significant decrease in total antioxidant reactivity levels (P < 0.05) was observed in the cerebral cortex from protein-malnourished rats. CONCLUSIONS: The present data indicated that protein malnutrition increased oxidative damage to lipids and proteins from the studied brain areas. These results may be an indication of an important mechanism for changes in brain development that are caused by protein malnutrition.

Metabolism of amino acids by cultured rat Sertoli cells.

Sertoli cells support spermatogenesis both spatially and energetically; for this reason, these cells have important adaptations. The energetic metabolism of Sertoli cells was adapted to provide lactate and pyruvate to developing germ cells, because these substrates are essential for spermatocytes and spermatids. In this study, we investigated whether Sertoli cells use alanine, leucine, valine, and glycine as energetic substrates and whether the simultaneous addition of other nutrients, such as glucose and glutamine, might affect the metabolism of these amino acids. Alanine, leucine, valine, and glutamine are almost totally oxidized to CO2 by these cells. In contrast, glycine has been demonstrated to be a poor energetic substrate, being mainly incorporated into proteins, and their metabolism did not change in the presence of palmitic acid, glucose, and/or glutamine. The metabolism of the 3 other amino acids was modified by palmitic acid; besides, glucose changed alanine, leucine, and valine oxidation. Glutamine decreased the oxidation of alanine, leucine, and valine to CO2. Conversely, both alanine and leucine decreased the oxidation of glutamine. Our present findings show that Sertoli cells can adapt its energy metabolism to the oxidative substrates available to fulfill their role in spermatogenic energetic supply.

Gestational and postnatal malnutrition affects sensitivity of young rats to picrotoxin and quinolinic acid and uptake of GABA by cortical and hippocampal slices.

It is widely known that a complex interaction between excitatory and inhibitory systems is required to support the adequate functioning of the brain and that significant alterations induced by early protein restriction are complex, involving many systems. Based on such assumptions, we investigated the effects of maternal protein restriction during pregnancy and lactation followed by offspring protein restriction on some GABAergic and glutamatergic parameters, which mediate inhibitory and excitatory transmission, respectively. The sensitivity of young malnourished rats to convulsant actions of the GABA(A) receptor antagonist picrotoxin (PCT; s.c.) and to N-methyl-d-aspartate (NMDA) receptor agonist quinolinic acid (QA; i.c.v) and also gamma-amino-n-butyric acid (GABA) and glutamate uptake by cortical and hippocampal slices were evaluated in P25 old rats. Early protein malnutrition induced higher sensitivity to picrotoxin, which could be associated with the observed higher GABA uptake by cortical, and hippocampal slices in malnourished rats. In contrast, we observed lower sensitivity to quinolinic acid in spite of unaltered glutamate uptake by the same cerebral structures. Picrotoxin enhanced GABA uptake in hippocampus in well- and malnourished rats; however, it did not affect cortical GABA uptake. Our data corroborate our previous report, showing that malnutrition depresses the glutamatergic activity, and point to altered modulation of GABAergic neurotransmission. Such findings allow us to speculate that malnutrition may affect the excitatory and inhibitory interaction.

Increased locomotor response to amphetamine, but not other psychostimulants, in adult mice submitted to a low-protein diet.

Protein malnutrition results in a variety of brain dysfunctions, ultimately affecting cognitive functions. The effects of protein malnutrition in brain response to psychostimulants have been less studied in adult animals. We therefore aimed to study the response to psychoactive drugs on the locomotor activity (a behavior paradigm) of adult protein malnourished mice. Two-month-old mice were divided in two groups: (a) low-protein group (LP), which received 6% of protein diet, and (b) a control group that received a 25% of protein diet. After 3 months, they were tested for locomotor activity after an i.p. injection of one of psychoactive drugs: D-amphetamine (5.0 mg/kg), apomorphine (2.0 mg/kg), dizocilpine (0.25 mg/kg), or caffeine (30 mg/kg). Mice submitted to the LP diet presented prolonged induction of hyperlocomotion caused by amphetamine (about 350% between 90 and 180 min post drug injection as compared with well-nourished mice, p<0.01) but presented unaltered response to apomorphine, caffeine, and dizocilpine. These data point to altered catecholamine metabolism induced by protein restriction in adult mice. The results are discussed based on previous works, presenting theoretical hypotheses about the possible mechanisms involved in the present findings.