Propylthiouracil-induced hypothyroidism during lactation alters leucine and mannose metabolism in rat cerebellar slices.

Thyroid hormone deficiency during perinatal development results in significant alterations in neurological functions. The relationship between such events and brain metabolism is not completely understood. The aim of this study was to investigate the effects of hypothyroidism on leucine, mannose, glucose and lactate metabolism in rat cerebellar slices. Experimental hypothyroidism was induced by exposing mothers and pups to propylthiouracil (PTU) until weaning - postnatal day 21. Metabolic analyses were performed in postnatal day 10 (PND10) and 21 (PND21) animals. A matching group of animals received the same oral treatment also after weaning until adulthood PND60 with T3 supplement during lactation (P1-P21). In PND21 animals, PTU treatment significantly increased the rate of leucine oxidation to CO2, although glucose and lactate oxidations were not affected. PTU treatment also increased the oxidation of leucine to CO2 at PND60 (adult animals). PND10 hypothyroidism animals showed a decrease in conversion of mannose to glycolipids and glycoprotein compared with the control group. However, PTU treatment increased the conversion of mannose to glycolipids and glycoprotein in PND21 animals. The replacement of T3 normalized mannose and leucine metabolism in adult rats. These results indicate that deficits in thyroid hormones during lactation could delay or alter brain development and metabolism.

Metabolic effects of sulforaphane oral treatment in streptozotocin-diabetic rats.

Diabetes has reached epidemic levels in the whole world, and the use of bioactive compounds that may have the capacity to prevent and treat diabetes is of great interest. Sulforaphane (SFN) is a compound which is found in cruciferous vegetables and that acts as both a potent antioxidant and regulator of gene expression. The aim of this study was to evaluate the effect of SFN in diabetes induced by streptozotocin (STZ). Male Wistar rats were gavaged with water or 0.1, 0.25, or 0.5 mg/kg of SFN before an injection of STZ (80 mg/kg). Animals treated with SFN showed fasting glycemia, insulin sensitivity, and hepatic glycogen concentrations, similar to the control group (nondiabetic), and different from the diabetic group. Diabetic animals also presented elevated levels of serum triacylglycerols (TAG), urea, and creatinine, and all SFN doses were able to reverse these alterations. However, the same doses of SFN accentuated alterations in total cholesterol, alanine, and aspartate aminotransferase levels, and had no effect on hepatic TAG, HDL cholesterol, and uptake of 2-deoxy glucose in adipose tissue and soleum muscle. Based on the effects inferred by the present data, SFN presented some positive effects against diabetes induction, although the impairment of hepatic function and cholesterol levels were aggravated after treatment with the compound.

Methylglyoxal alters glucose metabolism and increases AGEs content in C6 glioma cells.

Methylglyoxal is a dicarbonyl compound that is physiologically produced by enzymatic and non-enzymatic reactions. It can lead to cytotoxicity, which is mainly related to Advanced Glycation End Products (AGEs) formation. Methylglyoxal and AGEs are involved in the pathogenesis of Neurodegenerative Diseases (ND) and, in these situations, can cause the impairment of energetic metabolism. Astroglial cells play critical roles in brain metabolism and the appropriate functioning of astrocytes is essential for the survival and function of neurons. However, there are only a few studies evaluating the effect of methylglyoxal on astroglial cells. The aim of this study was to evaluate the effect of methylglyoxal exposure, over short (1 and 3 h) and long term (24 h) periods, on glucose, glycine and lactate metabolism in C6 glioma cells, as well as investigate the glyoxalase system and AGEs formation. Glucose uptake and glucose oxidation to CO(2) increased in 1 h and the conversion of glucose to lipids increased at 3 h. In addition, glycine oxidation to CO(2) and conversion of glycine to lipids increased at 1 h, whereas the incorporation of glycine in proteins decreased at 1 and 3 h. Methylglyoxal decreased glyoxalase I and II activities and increased AGEs content within 24 h. Lactate oxidation and lactate levels were not modified by methylglyoxal exposure. These data provide evidence that methylglyoxal may impair glucose metabolism and can affect glyoxalase activity. In periods of increased methylglyoxal exposure, such alterations could be exacerbated, leading to further increases in intracellular methylglyoxal and AGEs, and therefore triggering and/or worsening ND.

Effects of a highly palatable diet on lipid and glucose parameters, nitric oxide, and ectonucleotidases activity.

Obesity has reached epidemic proportions worldwide and is stimulated by the ready availability of food rich in fat and sugar (highly palatable diet). This type of diet increases the risks of obesity-associated pathologies, such as insulin resistance and cardiovascular disease. Nitric oxide, a potent endogenous vasodilator, is decreased in these pathologies, mostly as a result of insulin resistance. Ectonucleotidases are ecto and soluble enzymes that regulate the availability of the nucleotides ATP, ADP, and AMP and the nucleoside adenosine in the vascular system, thereby affecting vasoconstriction, vasodilatation, and platelet aggregation homeostasis. The aim of this study was to evaluate the effects of a highly palatable diet on serum lipid and glucose parameters, nitric oxide, and ectonucleotidase activity. Forty male Wistar rats were fed 1 of 2 diets for either 45 days or 4 months: standard chow (SC, n = 10) or a highly palatable diet enriched with sucrose (HP, n = 10). Body mass, visceral fat mass, glucose tolerance, cholesterol (total, high-density lipoprotein (HDL) and non-HDL), serum triacylglycerol, liver triacylglycerol, and free glycerol were increased in the HP group after 45 days and after 4 months, whereas insulin levels were not different between the groups at either time. Furthermore, levels of nitric oxide metabolites and ATP, ADP, and AMP hydrolysis were significantly lower in the HP group (p < 0.05) after 4 months. In conclusion, the consumption of the HP diet for 4 months induced overall corporal and metabolic changes, and decreased nitric oxide metabolites and ectonucleotidase activity, thereby promoting an appropriate environment for the development of cardiovascular diseases, without apparent changes in insulin levels.

Effects of glyoxal or methylglyoxal on the metabolism of amino acids, lactate, glucose and acetate in the cerebral cortex of young and adult rats.

The in vitro effects of glyoxal and methylglyoxal on the metabolism of glycine, alanine, leucine, glutamate, glutamine, glucose, lactate and acetate were evaluated in cortico-cerebral slices from young (10-day-old) or adult (3-month-old) rats. In a first set of experiments with cortico-cerebral slices from young animals, the compounds glyoxal or methylglyoxal at 400 microM, increased the oxidation of alanine, leucine and glycine to CO(2) and decreased the protein synthesis from these amino acids. Lipid synthesis from alanine, leucine and glycine was not changed in the cortico-cerebral slices from young rats after glyoxals exposure. Moreover, glutamine oxidation to CO(2) decreased by glyoxals exposure, but glutamate oxidation was not affected. In a second set of experiments with brain slices from adult animals, glycine metabolism (oxidation to CO(2), conversion to lipids or incorporation into proteins) was not changed by glyoxals exposure. In addition, the oxidation rates of glucose, lactate, acetate, glutamine and glutamate to CO(2) were also not modified. Taken together, these results indicate that glyoxal disrupts the energetic metabolism of the rat cerebral cortex in vitro. However, only young animals were susceptible to such events, suggesting that the immature cerebral cortex is less capable of dealing with glyoxal than the mature one.

[Model of experimental nonalcoholic steatohepatitis from use of methionine and choline deficient diet]. / Modelo experimental de esteatohepatite não-alcoólica com dieta deficiente em metionina e colina.

CONTEXT: There are still many unknown aspects about nonalcoholic steatohepatitis, especially regarding its pathophysiology and pharmacological treatment. Thus, experimental models are important for a better understanding of this disease and the evaluation of the effects of drugs. OBJECTIVE: To develop a model of experimental nonalcoholic steatohepatitis from use of methionine and choline deficient diet. METHODS: Fifty Wistar male rats were studied. A methionine and choline deficient diet has been processed in a craft. A group of 40 animals received the deficient diet for 90 days, and a group of 10 rats (control group) received the standardized ration in the same period. After, the animals were killed by decapitation, and laparotomy was performed. Hepatectomy was performed and the liver was studied by macroscopy and microscopy. The level of significance considered was of 0,05. RESULTS: The rats that received the deficient diet showed significant loss of weight with findings from malnutrition and all of them had at least some degree of macrovesicular steatosis. The diagnosis of nonalcoholic steatohepatitis was performed in 27 (70%) of the 39 rats that received this deficient diet (1 rat died during the study). None of the 10 rats that received the standardized diet had histological abnormalities. CONCLUSION: The diet restricted in methionine and choline induced steatosis and steatohepatitis in an animal model with low cost.

Caloric restriction increases hippocampal glutamate uptake and glutamine synthetase activity in Wistar rats.

Recent studies indicate that caloric restriction (CR) protects the central nervous system from several pathological conditions. The impairment of astroglial cell function, including glutamate uptake, glutamine synthetase (GS) activity and S100B secretion, may contribute to the progression of neurological disorders. The present study aimed to evaluate hippocampal astrocytic changes in response to CR diet, measuring astroglial parameters, such as glutamate uptake, GS activity and the immunocontent of GFAP and S100B. Blood biochemical parameters were also analyzed. Rats (60-day old) were fed ad libitum or on CR diets for 12 weeks. CR-fed rats showed approximately 16% less body weight gain than control rats. The CR diet was able to induce a significant increase in glutamate uptake (23%) and in GS activity (26%). There were no statistically significant differences in the immunocontent of either GFAP or S100B. In summary, the present study indicates that CR also modulates astrocyte functions by increasing glutamate uptake and GS activity, suggesting that CR might exert its neuroprotective effects against brain illness by modulation of astrocytic functions.

Desnutrição, maturação do sistema nervoso central e doenças neuropsiquiátricas / Malnutrition, central nervous system maturation and neuropsychiatric diseases

A nutrição exerce profundo impacto no desenvolvimento das estruturas e funções cerebrais. Além da programação metabólica induzida pela desnutrição fetal com o propósito de aumentar as chances de sobrevivência do feto e na vida pós-natal, estudos apontam a deficiência nutricional pré-natal como fator de risco para o desenvolvimento de doenças neuropsiquiátricas. Este artigo propõe-se a considerar aspectos da desnutrição relacionados ao desenvolvimento cerebral, à extensão temporal e funcional do impacto que a mesma acarreta, assim como estabelecer correlações com doenças neuropsiquiátricas, considerando artigos disponíveis na base de dados Medline de 1962 a 2005. Fatos derivados da desnutrição precoce apontam, em sua maioria, caráter permanente em algum grau, se não imediato, prospectivo e comprometedor da performance bioquímica, fisiológica e comportamental. Apesar dos denominados atrasos no desenvolvimento de parâmetros neurológicos, estes não constituem apenas erros funcionais isolados, uma vez que as inter-relações e conexões ideais são influenciadas, ampliando os erros temporais de ocorrência de eventos. A impressão da marca da desnutrição no código genético, ao aumentar os horizontes dos efeitos da desnutrição em uma perspectiva multigeneracional, amplifica os seus efeitos. Aspectos caracterizados como mecanismos compensatórios se, por um lado, apontam para uma habilidade em se adaptar ao estresse, por outro poderiam ser comprometidos na contingência de estresse adicional de ordem ambiental ou emocional. Considerações a respeito dos efeitos subliminares ou expressivos das doenças neuropsiquiátricas sobre a qualidade de vida consolidam a importância do desenvolvimento de pesquisas que se dirijam à compreensão dos impactos e mecanismos que modulam os efeitos da desnutrição sobre o neurodesenvolvimento.

Nutrition has a profound impact on the development of cerebral structures and functions. Over and above the metabolic programming induced by fetal malnutrition in order to increase the chances of survival of the fetus in post-natal life, studies point to pre-natal nutritional deficiency as a risk factor for the development of neuropsychiatric diseases. The present review aims to consider aspects of malnutrition in relation to cerebral development, the temporal and functional extension of its impact, as well as establishing correlations with neuropsychiatric diseases, considering articles of periodicals enlisted by Medline from 1962 to 2005. Events arising from early malnutrition display, for the most part, a permanent character to some degree, if not immediate, prospective and compromising of biochemical, physiological and behavioral performance. Despite the apparent delays in the development of neurological parameters, these do not represent mere isolated functional errors, as the ideal inter-relations and connections are influenced, extending the temporal errors of the occurrence of events. The impression of the mark of malnutrition at the level of the genetic code, in extending the horizon of the effects of malnutrition to a multigenerational level, amplifies its effects. Aspects characterized as compensatory mechanisms, while, on the one hand they display an ability to adapt to severe early stress, on the other they may be compromised in the eventuality of additional environmental or emotional stress. Concern with regard to the subliminal or expressive effects of neuropsychiatric diseases on the quality of life consolidate the importance of the development of research aimed at understanding and elucidating the impacts and mechanisms that modulate the effects of malnutrition on neurodevelopment.

Modelo experimental de esteatohepatite não-alcoólica com dieta deficiente em metionina e colina / Model of experimental nonalcoholic steatohepatitis from use of methionine and choline deficient diet

CONTEXTO: Ainda existem vários aspectos desconhecidos a respeito da esteatohepatite não-alcoólica, principalmente em relação à fisiopatologia e ao seu tratamento medicamentoso. Dessa forma, os modelos experimentais são importante para o melhor entendimento dessa doença, bem como para a avaliação do efeito das drogas. OBJETIVO: Desenvolver um modelo experimental de esteatohepatite não-alcoólica a partir do uso de dieta deficiente em metionina e colina. MÉTODOS: Foram utilizados 50 ratos machos da linhagem Wistar. A dieta deficiente em metionina e colina foi processada de forma artesanal. Um grupo de 40 animais recebeu a dieta durante 90 dias e utilizou-se um grupo controle com 10 ratos que recebeu ração padronizada pelo mesmo período. Após, os animais foram mortos por decapitação e foi realizada laparotomia com hepatectomia total e preparo do material para análise macroscópica e histológica. O nível de significância foi a = 0,05. RESULTADOS: Os ratos que receberam a dieta apresentaram perda significativa de peso, com achados de desnutrição e todos mostraram, pelo menos, algum grau de esteatose macrovesicular. O diagnóstico de esteatohepatite não-alcoólica foi realizado em 27 (70 por cento) dos 39 ratos que receberam a dieta. Nenhum dos 10 ratos que recebeu ração apresentou alterações histológicas. CONCLUSÃO:A dieta com restrição de metionina e colina desenvolvida apresenta índices elevados de indução de esteatose e esteatohepatite em modelo animal com baixo custo.

CONTEXT: There are still many unknown aspects about nonalcoholic steatohepatitis, especially regarding its pathophysiology and pharmacological treatment. Thus, experimental models are important for a better understanding of this disease and the evaluation of the effects of drugs. OBJECTIVE: To develop a model of experimental nonalcoholic steatohepatitis from use of methionine and choline deficient diet. METHODS: Fifty Wistar male rats were studied. A methionine and choline deficient diet has been processed in a craft. A group of 40 animals received the deficient diet for 90 days, and a group of 10 rats (control group) received the standardized ration in the same period. After, the animals were killed by decapitation, and laparotomy was performed. Hepatectomy was performed and the liver was studied by macroscopy and microscopy. The level of significance considered was of 0,05. RESULTS: The rats that received the deficient diet showed significant loss of weight with findings from malnutrition and all of them had at least some degree of macrovesicular steatosis. The diagnosis of nonalcoholic steatohepatitis was performed in 27 (70 percent) of the 39 rats that received this deficient diet (1 rat died during the study). None of the 10 rats that received the standardized diet had histological abnormalities. CONCLUSION: The diet restricted in methionine and choline induced steatosis and steatohepatitis in an animal model with low cost.

Different effect of high fat diet and physical exercise in the hippocampal signaling.

Obesity is an epidemic disease that may affect brain function. The present study examined the effect of high fat diet (HF) and physical exercise on peripheral tissue and hippocampal signaling. CF-1 mice (n = 4, per cage) were divided into groups receiving high fat (HF) or control (CD) diets for 5 months, with or without voluntary exercise. Serum triacylglycerol, total cholesterol, HDLc, liver triacylglycerol and glycogen concentrations were evaluated (n = 6). Also, the phosphorylation state of the AKT --> ERK 1/2 --> CREB pathway (AKT, pAKTser473, ERK 1/2, pERK 1/2, CREB and pCREB, n = 4-6) was analyzed in the hippocampus. HF diet caused an increase in AKT phosphorylation at ser473 (P < 0.05), while exercise increased the phosphorylation of ERK 1/2 (P < 0.05) and CREB (P < 0.05). As expected, exercise reversed some of the harmful effects of HF, i.e., increased liver deposition of fat (P < 0.05) and fat gain in the abdominal region (P < 0.05). In conclusion, the effects of exercise and HF diet on brain signaling appear to affect the hippocampal AKT --> ERK 1/2 --> CREB pathway in independent ways: HF intake caused increased phosphorylation of AKTser473, while exercise increased ERK 1/2 --> CREB signaling. The physiological relevance of these findings in brain function remains to be elucidated.

In vitro effect of quinolinic acid on energy metabolism in brain of young rats.

Quinolinic acid (QA) is found at increased concentrations in brain of patients affected by various common neurodegenerative disorders, including Huntington's and Alzheimer's diseases. Considering that the neuropathology of these disorders has been recently attributed at least in part to energy deficit, in the present study we investigated the in vitro effect of QA (0.1-100 microM) on various parameters of energy metabolism, such as glucose uptake, (14)CO(2) production and lactate production, as well as on the activities of the respiratory chain complexes I-V, the citric acid cycle (CAC) enzymes, creatine kinase (CK), lactate dehydrogenase (LDH) and Na(+),K(+)-ATPase and finally the rate of oxygen consumption in brain of 30-day-old rats. We initially observed that QA significantly increased glucose uptake (55%), whereas (14)CO(2) generation from glucose, acetate and citrate was inhibited (up to 60%). Furthermore, QA-induced increase of brain glucose uptake was prevented by the NMDA receptor antagonist MK-801. Complex II activity was also inhibited (up to 35%) by QA, whereas the other activities of the respiratory chain complexes, CAC enzymes, CK and Na(+),K(+)-ATPase were not affected by the acid. Furthermore, inhibition of complex II activity was fully prevented by pre-incubating cortical homogenates with catalase plus superoxide dismutase, indicating that this effect was probably mediated by reactive oxygen species. In addition, lactate production was also not altered by QA, in contrast to the conversion of pyruvate to lactate catalyzed by LDH, which was significantly decreased (17%) by this neurotoxin. We also observed that QA did not change state III, state IV and the respiratory control ratio in the presence of glutamate/malate or succinate, suggesting that its effect on cellular respiration was rather weak. The data provide evidence that QA provokes a mild impairment of brain energy metabolism in vitro and does not support the view that the brain energy deficiency associated to certain neurodegenerative disorders could be solely endorsed to QA accumulation.

Nociception and locomotor activity are increased in ketogenic diet fed rats.

Ketogenic diets have been used to treat epilepsy in children for almost 80 years. However, there are only few studies concerning behavioral effects of these diets, besides their efficacy in treating seizure disorders induced by kainic acid or pentylenetetrazol in rats. Here, rats were fed with a ketogenic diet and locomotion, anxiety and nociception were investigated after 10 weeks. Male Wistar rats were weight matched and divided into two groups: control rats, that received regular laboratory ration, and KD rats, that received ketogenic diet (70% fat, 24% protein and no carbohydrate). Behavioral tests were applied after 10-12 weeks of treatment, and included tests to evaluate exploration (habituation to the open field), anxiety (plus-maze), and nociception (tail-flick measurement). Performance of the animals in the open field revealed a significant difference in the number of crossings, suggesting a higher locomotor activity in animals fed with a ketogenic diet. No differences in anxiety were observed, as evaluated by the plus-maze test. Nociception was measured by the latency in the tail-flick test, and ketogenic rats presented a hypernociceptive response. Yet, these animals responded to a stressor with the classic analgesia, similarly to the controls. The response of ketogenic diet fed rats to the stressor, however, was more prolonged. Exposure to a ketogenic diet may induce higher locomotor activity, together with a hypernociceptive state in the animals, possibly as a result of some alteration in the neural systems involved in the modulation of these behaviors.

A laboratory class on metabolism for medical and nursing students

Num curso prático de bioquímica para alunos de enfermagem e medicina seräo realizadas determinaçöes de glicemia, corpos cetônicos sangüíneos (acetoacetato), concentraçäo de glicogênio hepático e síntese de corpos cetônicos em ratos alimentados e em ratos submetidos a um jejum de 24 ou 48 horas. O consumo de glicose e acetoacetato por fatias de córtex cerebral seräo também determinados. Este curso permite uma ampla discussäo das inter-relaçöes metabólicas que ocorrem entre diferentes órgäos e tecidos do organismo. Permite, também, discutir as situaçöes metabólicas que ocorrem no jejum, diabetes mellitus e dieta hipoglicídica. Estas aulas säo exeqüíveis num período de duas horas ou em dois períodos de duas horas e säo economicamente viáveis