Marlon R. Leite

Protective effect of caffeine and a selective A2A receptor antagonist on impairment of memory and oxidative stress of aged rats

In this study, the effects of caffeine (CAF) and SCH58261, a selective A(2A) receptor antagonist, on memory impairment and oxidative stress generated by aging in rats were investigated. Young and aged rats were treated daily per 10 days with CAF (30 mg/kg p.o.) or SCH58261 (0.5mg/kg, p.o.) or vehicle (1 ml/kg p.o.). Rats were trained and tested in a novel object recognition task. After the behavioral test, ascorbic acid and oxygen and nitrogen reactive species levels as well as Na(+)K(+) ATPase activity were determined in rat brain. The results demonstrated that the age-related memory deficit was reversed by treatment with CAF or SCH58261. Treatment with CAF or SCH58261 significantly normalized oxygen and nitrogen reactive species levels increased in brains of aged rats. Na(+)K(+) ATPase activity inhibited in brains of aged rats was also normalized by CAF or SCH58261 treatment. A decrease in basal ascorbic acid levels in brains of aged rats was not changed by CAF or SCH58261. These results demonstrated that CAF and SCH58261, modulators of adenosinergic receptors, were able to reverse age-associated memory impairment and to partially reduce oxidative stress.

Diphenyl diselenide improves scopolamine-induced memory impairment in mice.

This study was conducted to evaluate the effects of exposure to diphenyl diselenide (PhSe)2 on cognitive impairment induced by scopolamine, a muscarinic antagonist, using the Y-maze and Morris water maze tests in mice. One hour before the tests, mice were treated with (PhSe)2 (50 mg/kg, oral) and 30 min later memory impairment was induced by administration of scopolamine (1 mg/kg, intraperitoneal). (PhSe)2 (50 mg/kg, oral) significantly improved scopolamine-induced memory impairment in the Y-maze test. At the probe trial session in Morris water maze, (PhSe)2 (50 mg/kg, oral) significantly decreased the escape latency, increased the number of crossings in the platform local, and increased the time spent in the platform quadrant when compared with the scopolamine-treated group. General locomotor activity was similar in all groups. This study showed that (PhSe)2 ameliorated the impairments of spatial long-term memory and short-term memory, showed by the performance of mice in the Morris water maze and Y-maze tasks, respectively. These results suggest that (PhSe)2 may be useful for the treatment of cognitive impairment that may hold significant therapeutic value in alleviating certain memory deficits observed in Alzheimers disease.

Studies on preventive effects of diphenyl diselenide on acetaminophen-induced hepatotoxicity in rats

Organoselenium are compounds with important antioxidant activity and with many biological activities interesting from pharmacological point of view. The aim of this study was to evaluate the protective effect of diphenyl diselenide (PhSe)₂ on hepatotoxicity caused by administration of acetaminophen (AA) in rats. Rats received (PhSe)₂ orally (31mg/kg, dissolved in canola oil) for 2 days. After the second day of treatment, rats received AA orally (2g/kg) in unique dose. Twenty-four hours after the last administration of AA, plasma was used for biochemical assays aspartate (AST) and alanine aminotransferases (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), γ-glutamyl transferase (γ-GT) activities. Glutathione-S-transferase (GST), δ-aminolevulinic dehydratase (δ-ALA-D) and catalase activities as well as ascorbic acid and TBARS levels were determined in the liver of rats. (PhSe)₂ protected against the increase in AST, ALT, ALP, LDH and γ-GT activities induced by AA exposure to rats. The histological data showed that sections of liver from AA-exposed rats presented intense cellular necrosis, characterized by the presence of Kupffer cells and other infiltrating cells, mainly around of the centrilobular vein. (PhSe)₂ significantly attenuated AA-induced hepatic histopathological alterations. Administration of (PhSe)₂ protected against the increase in TBARS levels and the decrease in δ-ALA-D and GST activities as well as ascorbic acid content induced by AA exposure in rats. Catalase activity remained unaltered in all treated groups. The protective effect of (PhSe)₂ against hepatotoxicity caused by AA exposure in rats was demonstrated.

Diphenyl diselenide protects against glycerol-induced renal damage in rats

In this study we evaluated the effect of diphenyl diselenide (PhSe)2 on glycerol‐induced acute renal failure in rats. Rats were pre‐treated by gavage every day with (PhSe)2 (7.14 mg kg−1) for 7 days. On the eighth day, rats received an intramuscular injection of glycerol (8 mL kg−1). Twenty‐four hours afterwards, rats were euthanized and the levels of urea and creatinine were measured in plasma. Catalase (CAT), glutathione peroxidase (GPx), glutathione S‐transferase (GST), δ‐aminolevulinate dehydratase (δ‐ALA‐D) and Na+, K+‐ATPase activities and ascorbic acid levels were evaluated in renal homogenates. Histopathological evaluations were also performed. The results demonstrated that (PhSe)2 was able to protect against the increase in urea and creatinine levels and histological alterations in kidney induced by glycerol. (PhSe)2 protected against the inhibition in δ‐ALA‐D, CAT and GPx activities and the reduction in ascorbic acid levels induced by glycerol in kidneys of rats. In conclusion, the present results indicate that (PhSe)2 was effective in protecting against acute renal failure induced by glycerol. Copyright

Swimming exercise and diphenyl diselenide-supplemented diet affect the serum levels of pro- and anti-inflammatory cytokines differently depending on the age of rats

The increase in the inflammatory process is one of the main factors that contribute to aging. The aim of this study was to investigate the effects of a diphenyl diselenide (PhSe)2-supplemented diet (1p.p.m., 4weeks) and swimming exercise (3% of body weight, 20min per day, 4weeks) on the serum levels of cytokines in Wistar rats of different ages. The results demonstrated an increase in the levels of pro-inflammatory cytokines (IL-1β, IL-6, TNFα and INFγ) and a decrease in the levels of IL-10, an anti-inflammatory cytokine, with age. In middle-age rats, the swimming exercise and (PhSe)2-supplemented diet decreased serum levels of pro-inflammatory cytokines and increased the levels of IL-10. By contrast, in old rats the swimming exercise protocol increased the serum levels of pro-inflammatory cytokines and decreased the levels IL-10. Diet supplemented with (PhSe)2 did not alter the serum levels of cytokines in old rats. Middle-age and old rats subjected to swimming exercise and supplemented with (PhSe)2 in the diet had a decrease in the serum levels of pro-inflammatory cytokines and an increase in the levels of IL-10. This study demonstrated that swimming exercise and (PhSe)2-supplemented diet affect the serum levels of pro- and anti-inflammatory cytokines differently depending on the age of rats. (PhSe)2 supplemented in the diet had an anti-inflammatory effect, similar to that of induced by swimming exercise, in middle-age rats and reversed the pro-inflammatory effects of swimming exercise in old rats.

Caffeine and diphenyl diselenide improve long-term memory impaired in middle-aged rats

The aim of the present study was to evaluate the effects of diphenyl diselenide (PhSe)2 supplemented diet (10ppm) associated to the administration of caffeine (15mg/kg; i.g.) for 30days on the novel object recognition memory in middle-aged rats. The present findings showed that (PhSe)2-supplemented diet enhanced short-term memory, but not long-term memory, of middle-aged rats in the novel object recognition task. The (PhSe)2 supplemented diet associated with caffeine administration improved long-term memory, but did not alter short-term memory, impaired in middle-aged rats. Daily caffeine administration to middle-aged rats had no effect on the memory tasks. Diet supplemented with (PhSe)2 plus caffeine administration increased the number of crossings and rearings reduced in middle-aged rats. Caffeine administration plus (PhSe)2 diets were effective in increasing the number of rearings and crossings, respectively, in middle-aged rats, [(3)H] glutamate uptake was reduced in hippocampal slices of rats from (PhSe)2 and caffeine plus (PhSe)2 groups. In addition, animals supplemented with (PhSe)2 showed an increase in the pCREB/CREB ratio whereas pAkt/Akt ratio was not modified. These results suggest that the effects of (PhSe)2 on the short-term memory may be related to its ability to decrease the uptake of glutamate, influencing the increase of CREB phosphorylation. (PhSe)2-supplemented diet associated to the administration of caffeine improved long-term memory impaired in middle-aged rats, an effect independent of CREB and Akt phosphorylation.

Cyclization of Homopropargyl Chalcogenides by Copper(II) Salts: Selective Synthesis of 2,3‐Dihydroselenophenes, 3‐Arylselenophenes, and 3‐Haloselenophenes/thiophenes

Copper(II) halide mediated cyclization of homopropargyl chalcogenides gave three types of chalcogenophene derivatives. Selective product formation was achieved by controlling solvent, temperature, and atmosphere. By using CuBr2 and 1,2-dichloroethane at room temperature under ambient atmosphere, 4-bromo dihydroselenophene derivatives were obtained, whereas CuBr2 and 1,2-dichloroethane at reflux gave selectively 2-substituted selenophenes. When 1,2-dichloroethane was replaced by dimethylacetamide, 3-halo-selenophenes were obtained exclusively. The versatility of chalcogenophenes was also studied by reaction of 3-haloselenophenes with terminal alkynes under Sonogashira conditions affording the cross-coupled products. In addition, the reaction of 3-haloselenophenes with boronic acids gave the corresponding Suzuki-type products in good yields.

A diphenyl diselenide-supplemented diet and swimming exercise promote neuroprotection, reduced cell apoptosis and glial cell activation in the hypothalamus of old rats.

Aging is a process characterized by deterioration of the homeostasis of various physiological systems; although being a process under influence of multiple factors, the mechanisms involved in aging are not well understood. Here we investigated the effect of a (PhSe)2-supplemented diet (1ppm, 4weeks) and swimming exercise (1% of body weight, 20min per day, 4weeks) on proteins related to glial cells activation, apoptosis and neuroprotection in the hypothalamus of old male Wistar rats (27month-old). Old rats had activation of astrocytes and microglia which was demonstrated by the increase in the levels of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adaptor molecule 1 (Iba-1) in hypothalamus. A decrease of B-cell lymphoma 2 (Bcl-2) and procaspase-3 levels as well as an increase of the cleaved PARP/full length PARP ratio (poly (ADP-ribose) polymerase, PARP) and the pJNK/JNK ratio (c-Jun N-terminal kinase, JNK) were observed. The levels of mature brain-derived neurotrophic factor (mBDNF), the pAkt/Akt ratio (also known as protein kinase B) and NeuN (neuronal nuclei), a neuron marker, were decreased in the hypothalamus of old rats. Old rats that received a (PhSe)2-supplemented diet and performed swimming exercise had the hypothalamic levels of Iba-1 and GFAP decreased. The combined treatment also increased the levels of Bcl-2 and procaspase-3 and decreased the ratios of cleaved PARP/full length PARP and pJNK/JNK in old rats. The levels of mBDNF and NeuN, but not the pAkt/Akt ratio, were increased by combined treatment. In conclusion, a (PhSe)2-supplemented diet and swimming exercise promoted neuroprotection in the hypothalamus of old rats, reducing apoptosis and glial cell activation.

Diphenyl diselenide potentiates nephrotoxicity induced by mercuric chloride in mice

Following our long‐standing interest in the mechanisms involved in selenium toxicity, the aim of this work was to extend our previous studies to gain a better understanding of mercuric chloride (HgCl2) + diphenyl diselenide (PhSe)2 toxicity. Mice received one daily dose of HgCl2 (4.6 mg kg−1, subcutaneously) for three consecutive days. Thirty minutes after the last injection of HgCl2, mice received a single dose of (PhSe)2 (31.2 mg kg−1, subcutaneously). Five hours after (PhSe)2 administration, mice were euthanized and δ‐aminolevulinate dehydratase, catalase (CAT), glutathione S‐transferase (GST) and Na+, K+‐ATPase activities as well as thiobarbituric acid‐reactive substances (TBARS), ascorbic acid and mercury levels were determined in kidney and liver. Parameters in plasma (urea, creatinine, protein and erythropoietin), whole blood (hematocrit and hemoglobin) and urine (protein) were also investigated. HgCl2 + (PhSe)2 exposure caused a decrease in renal GST and Na+, K+‐ATPase activities and an increase in renal ascorbic acid and TBARS concentrations when compared with the HgCl2 group. (PhSe)2 potentiated the increase in plasma urea caused by HgCl2. HgCl2 + (PhSe)2 exposure caused a reduction in plasma protein levels and an increase in hemoglobin and hematocrit contents when compared with the HgCl2 group. There was a significant reduction in hepatic CAT activity and an increase in TBARS levels in mice exposed to HgCl2 + (PhSe)2 when compared with the HgCl2 group. The results demonstrated that (PhSe)2 did not modify mercury levels in mice. In conclusion, (PhSe)2 potentiated damage caused by HgCl2 affecting mainly the renal tissue. Copyright

The impact of a diphenyl diselenide-supplemented diet and aerobic exercise on memory of middle-aged rats.

Selenium is an essential trace element for human health and has received attention for its role as a nutrient. The combination of exercise and nutrients has been proposed to promote health. The aim of this study was to determine the effects of a diet supplemented with diphenyl diselenide (PhSe)2 and swimming exercise on memory of middle-aged rats. Male Wistar rats (12months) received standard diet chow supplemented with 1ppm of (PhSe)2 for 4weeks. Rats were submitted to swimming training (20min per day for 4weeks). After 4weeks, memory was evaluated in the object recognition test (ORT) and in the object location test (OLT). The hippocampal levels of phosphorylated cAMP-response element-binding protein (CREB) were determined. The results of the present study demonstrated that the association of (PhSe)2-supplemented diet and swimming exercise improved short-term memory, long-term memory and spatial learning, and this effect was not related to the increase in hippocampal p-CREB levels in middle-age rats. This study also revealed that middle-aged rats in the swimming exercise group had the best performance in short- and long-term memory. In conclusion, we demonstrated that swimming exercise, (PhSe)2-supplemented diet or the association of these factors improved learning and memory functioning. The hippocampal levels of CREB were not directly related to the benefits of swimming exercise and (PhSe)2-supplemented diet association in memory of middle-aged rats.