Showing papers by "Ana Maria Oliveira Battastini published in 2011"

Synthesis of dihydropyrimidin-2-one/thione library and cytotoxic activity against the human U138-MG and Rat C6 glioma cell lines

Abstract: Two series of 4-aryl-3,4-dihydropyrimidin-2(1H)-(thio)ones including monastrol (1a), have been synthesized by an environment-friendly methodology based on the combined use of citric acid or oxalic acid and TEOF (triethylorthoformate). The library was evaluated as inhibitor of cell proliferation on two glioma cell lines (human-U138-MG and Rat-C6). The compounds derived from thiourea 1f and 1d were more cytotoxic than monastrol. The compound derived from urea 2d showed the highest cytotoxic activity among the analyzed compounds.

Mesenchymal stem cell-conditioned medium triggers neuroinflammation and reactive species generation in organotypic cultures of rat hippocampus.

Abstract: Cell therapy using bone marrow-derived mesenchymal stem cells (MSCs) seems to be a new alternative for the treatment of neurodegenerative diseases. Despite several promising results with their use, possible side effects are still unknown. In a previous work, we have shown that MSC-conditioned medium is toxic to hippocampal slice cultures and aggravates cell death induced by oxygen and glucose deprivation. In this work, we investigated whether the inflammatory response and/or reactive species formation could be involved in that toxicity. Rat organotypic hippocampal cultures were exposed for 24 h to conditioned medium from MSCs isolated from rat bone marrow. A marked glial activation was observed after exposure of cultures to MSC-conditioned medium, as evidenced by glial fibrillary acid protein (GFAP) and isolectin B(4) increase. Tumor necrosis factor-α and interleukin-6 levels were increased in the culture medium, and 2,7-dihydrodichlorofluorescein diacetate oxidation (indicating reactive species generation) and inducible nitric oxide synthase (iNOS) immunocontent were also higher after exposure of cultures to MSC-conditioned medium. Antioxidants (ascorbic acid and TROLOX(®)), N(ω)-nitro-l-arginine methyl ester hydrochloride, and anti-inflammatory drugs (indomethacin and dexamethasone) reduced cell death in hippocampal organotypic cultures after their exposure to MSC-conditioned medium. The results obtained here suggest that MSC-secreted factors trigger reactive species generation and neuroinflammation in organotypic cultures of hippocampus, introducing a note of caution in the use of these cells for neurological application.

Ecto-5'-nucleotidase/CD73 knockdown increases cell migration and mRNA level of collagen I in a hepatic stellate cell line.

Abstract: Ecto-5′-nucleotidase (eNT/CD73, E.C.3.1.3.5) is a glycosyl phosphatidylinositol (GPI)-linked cell-surface protein with several functions, including the local generation of adenosine from AMP, with the consequent activation of adenosine receptors and the salvaging of extracellular nucleotides. It also apparently functions independently of this activity, e.g., in the mediation of cell-cell adhesion. Liver fibrosis can be considered as a dynamic and integrated cellular response to chronic liver injury and the activation of hepatic stellate cells (HSCs) plays a role in the fibrogenic process. eNT/CD73 and adenosine are reported to play an important role in hepatic fibrosis in murine models. Knockdown of eNT/CD73 leads to an increase in mRNA expression of tissue non-specific alkaline phosphatase (TNALP), another AMP-degrading enzyme and thus no alteration is seen in the total ecto-AMPase activity of the cell. eNT/CD73 knockdown also leads to changes in the expression of collagen I and a clear alteration of cell migration. We suggest that eNT/CD73 protein expression controls cell migration and collagen expression in a mechanism independent of changes in nucleotide metabolism.

Incorporation of resveratrol into lipid-core nanocapsules improves its cerebral bioavailability and reduces the Aβ-induced toxicity

Abstract: vitro, BQCA increased carbachol potency approx. 90-fold at 10 ÂmM (n 1⁄4 6). In vivo, a maximal brain level of 270 nM was observed 40 min after i.p. administration at 10 mg/kg. Based on in vitro experiments, at level BQCA should produce about 3-fold increase of the agonist potency; it reduced a scopolamine-induced hyper locomotion. Further, BQCA reversed a deficit observed in the two models of memory impairment. Moreover, BQCA showed no side effect at 10 mg/kg and above in spontaneous locomotion as well as in the salivation test. Conclusions: Altogether, these data suggest that theM1 PAMBQCAmay be of interest for the treatment of memory deficits observed in Alzheimer’s disease.

Physiological level of norepinephrine increases adenine nucleotides hydrolysis in rat blood serum.

Abstract: Extracellular adenosine 5′-triphosphate (ATP) and its breakdown products, adenosine 5′-diphosphate (ADP) and adenosine, have significant effects on a variety of biological processes. NTPDase enzymes, responsible for adenine nucleotides hydrolysis, are considered the major regulators of purinergic signaling in the blood. Previous work by our group demonstrated that ATP and ADP hydrolysis in rat blood serum are higher during the dark (activity) phase compared to the light (rest) phase. In nocturnal animals (e.g., rats), important physiological changes occur during the dark phase, such as increased circulating levels of melatonin, corticosterone, and norepinephrine (NE). This study investigated the physiological effects, in vivo and in vitro, of melatonin, dexamethasone, and NE upon nucleotides hydrolysis in rat blood serum. For in vivo experiments, the animals received a single injection of saline (control), melatonin (0.05 mg/kg), dexamethasone (0.1 mg/kg), or NE (0.03 mg/kg). For in vitro experiments, melatonin (1.0 nM), dexamethasone (1.0 μM), or NE (1.0 nM) was added directly to the reaction medium with blood serum before starting the enzyme assay. The results demonstrated that ATP and ADP hydrolysis in both in vitro and in vivo experiments were significantly higher with NE treatment compared to control (in vitro: ATP = 36.63%, ADP = 22.43%, P < 0.05; in vivo: ATP = 44.1%, ADP = 37.28%, P < 0.001). No significant differences in adenine nucleotides hydrolysis were observed with melatonin and dexamethasone treatments. This study suggests a modulatory role of NE in the nucleotidases pathway, decreasing extracellular ATP and ADP, and suggests that NE might modulate its own release by increasing the activities of soluble nucleotidases.

Effects of restraint stress on the daily rhythm of hydrolysis of adenine nucleotides in rat serum.

Abstract: Background: Adenosine 5-triphosphate (ATP) and its breakdown products ADP and adenosine can act as extracellular messengers in a range of biological processes. Extracellular adenine nucleotides are metabolized by a number of enzymes including NTPDases and 5’-nucleotidase, which are considered to be the major regulators of purinergic signaling in the blood. Previous work by our group demonstrated that ATPase and ADPase activities in rat serum exhibit a 24-h temporal pattern, with higher enzyme activity during the dark (activity) phase. It was found that stress can cause disruptions in biological circadian rhythms and in the cardiovascular system. Therefore, the aim of the present study was to examine the influence of acute stress exposure upon temporal patterns of NTPDase and 5-nucleotidase enzyme activities in rat blood serum. Methods: Adult male Wistar rats were divided into 4 groups: ZT0, ZT6, ZT12 and ZT18. Each group was subdivided in 4 groups: control, immediately, 6 h and 24 h after one hour of restraint stress. ATP, ADP and AMP hydrolysis were assayed in the serum. Results: All stressed groups showed significant decreases in all enzyme activities at ZT 12 and ZT 18 when compared with control. Conclusion: Acute stress provokes a decrease in nucleotidase activities dependent on the time that this stress occurs and this effect appears to persist for at least 24 hours. Stress can change levels of nucleotides, related to increased frequency of cardiovascular events during the activity phase. Altered levels of nucleotides in serum may be involved in cardiovascular events more frequent during the activity phase in mammals, and with their etiology linked to stress.

The Role of Ectonucleotidases in Glioma Cell Proliferation

Abstract: Glioma invasion is a multifactorial process consisting of numerous genetic and physiological alterations, which affect glioma cell interactions with neurons, glia, and vascular cells. Purinergic signaling is emerging as an important component to give invasive potential to glioma cells. Specific purinergic receptor subtypes have been implicated in a variety of biological effects, including proliferation, differentiation, trophic actions and immune/inflammatory responses. Signaling events induced by extracellular nucleotides are controlled by the action of ectonucleotidases. These enzymes operate in concert for the complete nucleotide hydrolysis to nucleoside and represent a powerful manner to control the effects mediated by extracellular purines. It was demonstrated that glioma cell lines have altered extracellular ATP, ADP and AMP catabolism, presenting low rates of extracellular ATP hydrolysis and high rates of extracellular AMP hydrolysis when compared to astrocytes. Therefore, the ATP released by tumor adjacent cells, often damaged by growing tumors or due to ongoing inflammation together with the low glioma ability to hydrolyze extracellular ATP could result in powerful purinergic receptor activation, which in turn modulates glioma cell proliferation and neuronal toxicity. In addition, the high expression and activity of ecto-5ʹ-NT/CD73 in glioma cells and the extracellular adenosine generation could also be involved in the immunosupression process, angiogenesis and glioma invasion. These alterations could have important consequences in the activation of purinergic receptors and modulate events related to glioma advance. Although more studies are necessary, the ectonucleotidases may be considered as new molecular markers of gliomas and future target for pharmacological or gene therapy.