Luiz Carlos Rios Kucharski

EFFECT OF DIET COMPOSITION ON THE CARBOHYDRATE AND LIPID METABOLISM IN AN ESTUARINE CRAB, CHASMAGNATHUS GRANULATA (DANA, 1851)

Abstract 1. The effects of a 15-day period of adaptation to a high-protein (HP) or carbohydrate-rich (HC) diet on the carbohydrate and lipid metabolism of Chasmagnathus granulata were investigated. 2. The carbohydrate-rich diet increases the blood glucose levels, the muscle and hepatopancreas glycogen and total lipids of the muscle. 3. With a high protein diet, the glycemia and glycogen of the hepatopancreas and muscle are low, and the total lipids are raised in these tissues. 4. This finding demonstrates the importance of the substrate input in regulating the energy metabolism of this crab.

Seasonal variation in the energy metabolism in an estuarine crab, Chasmagnathus granulata (Dana, 1851)

1. 1. The effects of seasonal variation on the carbohydrate and lipid metabolism of the Chasmagnathus granulata were investigated. 2. 2. Glycemia is high in winter and summer and low in spring and fall. 3. 3. The glycogen content in the hepatopancreas and muscle is higher in fall and winter, and decreases during spring and summer. 4. 4. The muscle lipids are higher in summer, and decrease during fall and winter whereas hepatopancreas lipids are higher except in the fall. 5. 5. The crabs show change in the metabolic pattern of lipids and carbohydrates during the seasons of the year.

Effect of hyperosmotic shock on phosphoenolpyruvate carboxykinase gene expression and gluconeogenic activity in the crab muscle

Chasmagnathus granulata phosphoenolpyruvate carboxykinase (PEPCK) cDNA from jaw muscle was cloned and sequenced, showing a specific domain to bind phosphoenolpyruvate in addition to the kinase‐1 and kinase‐2 motifs to bind guanosine triphosphate (GTP) and Mg2+, respectively, specific for all PEPCKs. In the kinase‐1 motifs the GK was changed to RK. The first 19 amino acids of the putative enzyme contain hydrophobic amino acids and hydroxylated residues specific to a mitochondrial type signal. The PEPCK is expressed in hepatopancreas, muscles, nervous system, heart, and gills. Hyperosmotic stress for 24 h increased the PEPCK mRNA level, gluconeogenic and PEPCK activities in muscle.

The effect of aqueous extract of gross and commercial yerba mate (Ilex paraguariensis) on intra-abdominal and epididymal fat and glucose levels in male Wistar rats

This study analyzed the plasma lipid profile, glucose levels and fat deposits in male rats treated with aqueous extract of gross yerba mate, commercial yerba mate or water. Yerba mate treatment did not change body weight gain and lipid profile. The consumption of gross yerba mate significantly increased blood glucose (6.6 mmol/L) as compared to the water (4.8 mmol/L) and commercial group (5.2 mmol/L) and decreased epididymal and intra-abdominal deposits (10.1mg/g and 23.7 mg/g of weight) as compared to the water (15.4 mg/g and 36.9 mg/g of weight) and commercial group (12.5mg/g and 28 mg/g of weight). The results suggest that gross yerba mate reduces fat more efficiently but produces a greater increase in blood glucose when compared to commercial yerba mate and water groups.

The activity of mate saponins (Ilex paraguariensis) in intra-abdominal and epididymal fat, and glucose oxidation in male Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE Ilex paraguariensis A. St. Hilaire (mate) has traditionally been used in several South American countries to prepare tea-like beverages having stimulant effects on the CNS and appetite. In recent years, however, mate preparations have been recommended putatively as an appetite suppressant and slimming remedy. Moreover, studies carried out on either normal or diet-induced obese rats treated with mate extracts revealed anti-obesity and satiety effects, thus refuting ethnopharmacological data. In this work, the effect of mate on the intra-abdominal and epididymal fat, and glucose oxidation levels after oral administration in male Wistar rats, was studied using crude extract from leaves, unripe fruits, and a chemically well-defined purified saponin fraction (MSF). MATERIAL AND METHODS Saponin, polyphenol and methylxanthine contents in MSF were analyzed by HPLC-PDA and UPLC/Q-TOF-MS. Crude extracts from mate leaves (LAE) and unripe fruits (FHE) were assayed for comparison purposes. Male Wistar rats fed with standard diet and water ad libitum were used as the control group. RESULTS The fat weight and both liver and adipose glucose oxidation were reduced significantly by MSF (35, 90 and 60%, respectively), while LAE and FHE were less active. Also, a significant lowering of the blood triglycerides level was observed in rats treated with MSF and LAE. All creatinine, urea, and transaminase plasma levels remained unaffected no matter what mate preparation was considered. It is also worth pointing out that the glucose blood level was increased after treatment with FHE. This finding did not correlate either with the content of methylxanthines, polyphenols or saponins. CONCLUSION A reduction in both visceral fat weight and glucose oxidation of hepatic and adipose tissue in healthy rats fed with a standard diet could be ascribed to a purified mate saponin fraction from unripe fruits. These findings agree with former studies carried out with crude mate extracts and also suggest their potential use as an anti-obesity preparation. Nonetheless, further in vivo experiments are still required to corroborate its effect on human beings.

Age-related effects of DHEA on peripheral markers of oxidative stress.

Ageing is an inevitable biological process characterized by a general decline in various physiological functions. DHEA and DHEAS levels are maximal between the second and third life decades, then start to decline 2% per year, leaving a residual of 10–20% of the peak production by the eighth decade. Erythrocytes are exposed to frequent oxidative stress due to the oxygen radicals continuously generated by haemoglobin auto‐oxidation. We investigated DHEA chronic (10 mg/kg, subcutaneously, for 5 weeks) effects over oxidative stress markers in erythrocytes of male Wistar rats of 3, 13 and 18 month‐old. In the 13 month‐old group, we found increased lipid peroxidation (LPO), superoxide dismutase (SOD), glutathione‐S‐transferase and catalase activities when compared to the other age groups. DHEA produced a marked increase in LPO of 13 month‐old group when compared to its control. DHEA exerted this pro‐oxidant effects in all ages studied, especially in age 13 month‐old. It seems that at 13 month‐old there would be an important depletion of some specific anti‐oxidant in order to determine such susceptibility to DHEA effects. Since this approach allows a minimally invasive assessment, it would be useful as a routine method in human clinical studies investigating DHEA effects during the ageing process. Copyright

Lactate metabolism in the muscle of the crab Chasmagnathus granulatus during hypoxia and post-hypoxia recovery

The present study showed that the lactate/glucose ratio in the hemolymph of Chasmagnathus granulatus maintained in normoxia (controls) was 4.9, suggesting that lactate is an important substrate for this crab. Periods of hypoxia are part of the biological cycle of this crab, and lactate is the main end product of anaerobiosis in this crab. Our hypothesis was that this lactate would be, therefore, used by gluconeogenic pathway or can be oxidized or excreted to the aquatic medium during hypoxia and post-hypoxia periods in C. granulatus. The concentrations of hemolymphatic lactate in animals in normoxia are high, and are used as an energy substrate. In hypoxia, muscle gluconeogenesis and excretion of lactate to the aquatic medium would contribute significantly in regulating the concentration of circulating lactate. Utilization of these pathways would serve the objective of maintaining the acid-base equilibrium of the organism. Muscle gluconeogenesis participates, during the recovery process, in metabolizing the lactate produced during the period of hypoxia. Lactate excretion to the external medium, was one of the strategies used to decrease the higher hemolymphatic lactate levels. However, oxidation of lactate in the muscle is not a main strategy used by this crab to metabolize lactate in the recovery periods.

Effect of hyposmotic stress on the carbohydrate metabolism of crabs maintained on high protein or carbohydrate-rich diet

Abstract 1. 1. Blood glucose of crabs Chasmagnathus granulata fed on high protein (HP) diet and exposed to 0%. salinity decreases reaching nil values at 72 hr after salinity change. However, with a carbohydraterich (HC) diet the glycemia increases after salinity change. 2. 2. Glycogen concentration of hepatopancreas and muscle in crabs fed HP diet increases at 72 hr after salinity change. Muscle glycogen did not change significantly. 3. 3. Hepatopancreas and muscle glycogen in HC group is high but decreases at 24 hr after salinity change, and remains higher than the HP group until the end of the experiment.

DHEA effects on myocardial Akt signaling modulation and oxidative stress changes in aged rats.

The secretion of DHEA-synthesized mainly in the adrenal cortex-increases in the postnatal aging, peaks in the twenties and decreases with age afterwards. Exogenous DHEA can exert a dual effect depending on dose and on tissue. Akt is a serine/threonine kinase whose activity has been seen as an interventional approach for cardiomyopathic damage resulting from aging changes. In order to evaluate DHEA effects over myocardial Akt protein expression associated to oxidative stress markers during aging, male Wistar rats (3 and 18 months) were assigned into two groups: control or DHEA (10mg/kg, subcutaneously, for 5 weeks). In the aged group, we found increased lipid peroxidation and glutathione-S-transferase activity. DHEA produced an increase in p-Akt protein expression and a decrease in SOD activity in both ages. Akt pathway activation might be related to changes in oxidative stress parameters according to age.

Effects of hypo- or hyperosmotic stress on lipid synthesis and gluconeogenic activity in tissues of the crab Neohelice granulata.

The present study assesses the effects of osmotic stress on phosphoenolpyruvate carboxykinase (PEPCK), fructose 1,6-bisphosphatase (FBPase) and glucose 6-phosphatase (G6Pase) activities and (14)C-total lipid synthesis from (14)C-glycine in the anterior and posterior gills, jaw muscle, and hepatopancreas of Neohelice granulata. In posterior gills, 24-h exposure to hyperosmotic stress increased PEPCK, FBPase and G6Pase activities. Increase in (14)C-lipid synthesis was associated to the decrease in PEPCK activity after 72-h exposure to hyperosmotic stress. Hypo-osmotic stress decreased PEPCK and G6Pase activities in posterior gills; however, (14)C-lipids increased after 72-h exposure to stress. In anterior gills, decreases in the G6Pase activity after 72-h of hyperosmotic stress and in (14)C-lipogenesis after 144-h were observed, while PEPCK activity increased after 144 h. Exposure to hypo-osmotic stress increased (14)C-lipid synthesis and PEPCK activity in anterior gills. Muscle G6Pase activity increased after 72-h exposure to hypo-osmotic stress; however, no significant change was observed in the lipogenesis. PEPCK decreased in muscle after 144-h exposure to hyperosmotic, coinciding with increased (14)C-lipid synthesis. In the hepatopancreas, a decrease in the (14)C-lipogenesis occurred after 24-h exposure to hyperosmotic stress, accompanied by increase in (14)C-lipid synthesis. Additionally, PEPCK activity returned to control levels. The hepatopancreatic lipogenesis from amino acids was not involved in the metabolic adjustment during hypo-osmotic stress. However, gluconeogenesis is one of the pathways involved in the adjustment of the intracellular concentration of nitrogenated compounds.