Effects of quercetin in preclinical models of Parkinson's disease: A systematic review

Parkinson's disease (PD) is a neurodegenerative disease that affects dopaminergic neurons, thus impairing dopaminergic signalling. Quercetin (QUE) has antioxidant and neuroprotective properties that are promising for the treatment of PD. This systematic review aimed to investigate the therapeutic effects of QUE against PD in preclinical models. The systematic search was performed in PubMed, Scopus and Web of Science. At the final screening stage, 26 articles were selected according to pre-established criteria. Selected studies used different methods for PD induction, as well as animal models. Most studies used rats (73.08%) and mice (23.08%), with 6-OHDA as the main strategy for PD induction (38.6%), followed by rotenone (30.8%). QUE was tested immersed in oil, nanosystems or in free formulations, in varied routes of administration and doses, ranging from 10 to 400 mg/kg and from 5 to 200 mg/kg in oral and intraperitoneal administrations, respectively. Overall, evidence from published data suggests a potential use of QUE as a treatment for PD, mainly through the inhibition of oxidative stress, neuroinflammatory response and apoptotic pathways.

Effects of curcumin to counteract levodopa-induced toxicity in zebrafish

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor dysfunction due to the death of dopaminergic neurons in the substantia nigra pars compacta. Currently, treatment of PD has focused on increasing dopamine levels, using a dopamine precursor, levodopa (L-DOPA) or stimulation of dopaminergic receptors. Prolonged use of L-DOPA is associated with the occurrence of motor complications and dyskinesia, attributed to neurotoxic effects of this drug. The aim of this study was to investigate the effects of curcumin (CUR), a lipophilic polyphenol, to counteract L-DOPA induced toxicity. Zebrafish larvae were pre-treated with CUR (0.05 µM) or vehicle dimethyl sulfoxide (DMSO) for 24 hr and subsequently exposed to L-DOPA (1 mM) or vehicle. Immediately and 24 hr after L-DOPA exposure, spontaneous swimming and dark/light behavioral tests were performed. In addition, levels of reactive oxygen species (ROS) and lipid peroxidation products were determined at the end of treatment. CUR significantly improved the motor impairment induced by 24 hr L-DOPA treatment, and reduced levels of ROS and lipoperoxidation products in zebrafish larvae. In conclusion, our results suggest that CUR acts as a neuroprotector against toxicity initiated by L-DOPA. Evidence suggests the observed effects of CUR are associated with its antioxidant properties.

Experimental models of chemically induced Parkinson's disease in zebrafish at the embryonic larval stage: a systematic review

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra that results in a decrease in dopamine levels, resulting in motor-type disturbances. Different vertebrate models, such as rodents and fish, have been used to study PD. In recent decades, Danio rerio (zebrafish) has emerged as a potential model for the investigation of neurodegenerative diseases due to its homology to the nervous system of humans. In this context, this systematic review aimed to identify publications that reported the utilization of neurotoxins as an experimental model of parkinsonism in zebrafish embryos and larvae. Ultimately, 56 articles were identified by searching three databases (PubMed, Web of Science, and Google Scholar). Seventeen studies using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 4 1-methyl-4-phenylpyridinium (MPP+), 24 6-hydroxydopamine (6-OHDA), 6 paraquat/diquat, 2 rotenone, and 6 articles using other types of unusual neurotoxins to induce PD were selected. Neurobehavioral function, such as motor activity, dopaminergic neuron markers, oxidative stress biomarkers, and other relevant parameters in the zebrafish embryo-larval model were examined. In summary, this review provides information to help researchers determine which chemical model is suitable to study experimental parkinsonism, according to the effects induced by neurotoxins in zebrafish embryos and larvae.

Thiazolidine-2,4-dione derivative exhibits antitumoral effect and reverts behavioral and metabolic changes in a model of glioblastoma

The aim of the present study was to evaluate the anti-glioma activity of 3-(4-fluorobenzyl)-5-(4-methoxybenzylidene)thiazolidine-2,4-dione (AV23) in a preclinical model of glioblastoma, as well as behavioral parameters and toxicological profile. The implantation of C6 cells in the left striatum of male Wistar rats was performed by stereotaxic surgery. After recovery, animals were treated with vehicle (canola oil) or AV23 (10 mg/kg/day) intragastrically for 15 days. It was found that AV23 reduced tumor volume by 90%. Serum biochemical parameters such as triglycerides, cholesterol, HDL-cholesterol, LDL-cholesterol, albumin, aspartate aminotransferase, urea, creatinine and total proteins were not changed; however, there was a slight increase in alanine aminotransferase. The compound AV23 reverted the hypoglycemia and the reduction in body weight caused by glioblastoma. Additionally, AV23 was able to revert the reduction of locomotion caused by the tumor implantation. Therefore, the compound AV23 can be considered a promising candidate in the treatment of glioblastoma.

The action of curcumin against damage resulting from cerebral stroke: a systematic review

Stroke is the second leading cause of morbidity and mortality globally. Treatments for stroke are limited, and preventive treatments are scarce. Curcumin (CUR) has several biological effects, as described in the literature, which highlight its antioxidant and neuroprotective effects. Therefore, this qualitative systematic review aimed to investigate the effects of CUR on damage caused by stroke in rodent models. A systematic search was performed on three databases PubMed, Scopus, and Web of Science. In addition, the risk-of-bias and quality of the studies were assessed using SYRCLE and Collaborative Approach for Meta-Analysis and Review of Animal Data from Experimental Studies, respectively. The selection, inclusion, and exclusion criteria were established by the authors. At the end of our systematic search of the three databases, we found a total of 728 articles. After excluding duplicates and triplicates and reading the abstracts, keywords, and full texts, 53 articles were finally included in this systematic review. CUR exerts several beneficial effects against the damage caused by both ischemic and hemorrhagic stroke, via different pathways. However, because of its low bioavailability, Free-form CUR only exerted significant effects when it was administered at high concentrations. In contrast, when CUR was administered using nanostructured systems, positive responses were observed even at low concentrations. The mechanisms of action of CUR, free or in nanostructure, are extremely important for the recovery of injured brain tissue after a stroke; CUR has neuroprotective, antioxidant, anti-inflammatory, and anti-apoptotic effects and helps to maintain the integrity of the blood-brain barrier. Finally, we concluded that CUR presents an extremely important and significant response profile against the damage caused by stroke, making it a possible therapeutic candidate for individuals affected by this disease.

Combination of Curcumin and Photodynamic Therapy Based on the Use of Red Light or Near-Infrared Radiation in Cancer: a Systematic Review

BACKGROUND

Photodynamic therapy (PDT) is a therapeutic intervention that can be applied to the treatment of cancer. The interaction between a photosensitizer (PS), ideal wavelength radiation and tissue molecular oxygen, triggers a series of photochemical reactions that are responsible for the production of reactive oxygen species. These highly reactive species can decrease proliferation and induce tumor cell death. The search for PS of natural origin extracted from plants becomes relevant, as they have photoactivation capacity, preferentially targeting tumor cells and because they do not present any or little toxicity to healthy cells.

OBJECTIVE

Our work aimed to carry out a qualitative systematic review to investigate the effects of curcumin (CUR), a molecule considered as PS of natural origin, on PDT, using red light or near infrared radiation, in tumor models.

METHODS

A systematic search was performed in three databases (PubMed, Scopus, and Web of Science) using the PICOT method, retrieving a total of 1,373 occurrences. At the end of the peer screening, using inclusion, exclusion, and eligibility criteria, 25 eligible articles were included in this systematic review.

RESULTS

CUR, whether in its free state, associated with metal complexes or other PS, and in a nanocarrier system, was considered a relevant PS for PDT using red light or near-infrared against tumoral models in vitro and in vivo, acting by increasing cytotoxicity, inhibiting proliferation, inducing cell death mainly by apoptosis, and changing oxidative parameters.

CONCLUSION

The results found in this systematic review suggest the potential use of CUR as a PS of natural origin to be applied in PDT against many neoplasms, encouraging further search in the field of PDT against cancer and serving as an investigative basis for upcoming pre-clinical and clinical applications.

Hydrogels containing soybean isoflavone aglycones-rich fraction-loaded nanoemulsions for wound healing treatment - in vitro and in vivo studies

Soybean isoflavone aglycones have been investigated as potential wound healing compounds for topical application. The aim of this study was to evaluate the wound healing properties of a soybean isoflavone aglycones-rich fraction (IAF) when incorporated into lipid nanoemulsions dispersed in acrylic-acid hydrogels. Formulations exhibited a mean droplet size in the sub 200 nm range, negative ζ-potential (-60 mV), and displayed non-Newtonian pseudoplastic behavior. The addition of a gelling agent decreased the IAF release from formulations and improved the retention of these compounds in intact porcine ear skin when compared with a control propylene glycol solution. No IAF were detected in receptor fluid of Franz-type diffusion cells. However, increasing amounts of IAF were noticed in both skin layers and the receptor fluid when the tissue was partially injured (tape stripping), or when the epidermis was completely removed. In vitro studies showed that IAF elicits an increased proliferation and migration of keratinocytes (HaCaT cell line). Subsequently, the healing effect of the formulations was evaluated in a model of dorsal wounds in rats, by assessing the size of the lesions, histology, inflammatory markers, and antioxidant activity. Overall findings demonstrated the potential of IAF-loaded formulations to promote wound healing by increasing angiogenesis by ∼200 %, reducing the lipid oxidation (TBARS) by ∼52 % and the inflammation (TNFα) by ∼35 %, while increasing re-epithelialization by ∼500 %, visualized by the epithelium thickness.

Multi-walled carbon nanotubes functionalized with pyrene-PEG via π-π interactions: toxicological assessment in zebrafish embryos

Multi-walled carbon nanotubes (MWCNT) have many promising biological applications, even though functionalization is needed for better biocompatibility. Functionalization of MWCNT with polyethylene glycol (PEG) is a promising and widely studied approach, but the best PEGylation method is still under investigation. In this work, we have tested the biological implications of MWCNT functionalized via π-stacking with pyrene-PEG (MWCNT-Pyr-PEG) in zebrafish embryos. As Pyr toxicity is well documented and represents a major concern for the safety of the proposed approach, we have also tested the effects of the exposure to the isolated conjugate (Pyr-PEG). The resulting suspensions were stable in saline medium and well dispersed. Zebrafish embryos at 24 h post-fertilization (hpf) were dechorionated and randomly assigned to seven experimental groups (n = 50 per group): control, MWCNT-Pyr-PEG at 0.2, 2.0, and 20.0 mg l^-1, and Pyr-PEG at the same concentrations, and exposures were performed in 96-well plates. Specimens were observed for heart rate, malformations, body length, mortality, traveled distance, and number of new movements. Heart rate was reduced in embryos exposed to any tested concentration of MWCNT-Pyr-PEG, while this effect was observed with Pyr-PEG from 2 mg l^-1. The highest concentration of MWCNT-Pyr-PEG also led to increased occurrence of malformations, shortened body length and reduced traveled distance. The functionalization approach shows promise due to the stability in saline media, even though toxic effects were observed in the highest tested concentrations, being the MWCNT the main actors underlying these outcomes.

Healing activity of hydrogel containing nanoemulsified β-caryophyllene

β-caryophyllene is a sesquiterpene present in the oil of many plant species, such as Copaifera sp., which has been shown to possesses potent anti-inflammatory action; however, its healing activity remains under study. The objectives of the present study were to produce a nanoemulsion containing β-caryophyllene followed by a hydrogel containing nanoemulsified β-caryophyllene, to evaluate the permeation profile in vitro, and to assess the in vivo healing activity, which is so far unexplored in the literature for pure β-caryophyllene and in pharmaceutical formulation. The nanoemulsion was obtained through high-pressure homogenization and the hydrogel by direct dispersion with hydroxyethylcellulose. Both formulations were characterized according to droplet size, polydispersity index, volume-weighted mean diameters, particle distribution, droplets diameters tracking, zeta potential, viscosity and bioadhesion behavior. β-caryophyllene content was determined by gas chromatography coupled with mass spectrometry (GC/MS). Both formulations presented a nanometric droplet size, negative zeta potential, high β-caryophyllene content, and were stable for 60 days. In agreement with the viscosity results, the hydrogel containing the β-caryophyllene nanoemulsion showed superior bioadhesiveness than the nanoemulsion. The skin permeation study in Franz cells demonstrated that isolated β-caryophyllene was unable to cross the stratum corneum and that its nanoemulsification promoted its permeation. On the other hand, in the simulated deeply wounded skin (dermis), no significant differences were observed between the formulations and isolated β-caryophyllene with respect to the amount of marker retention in the dermis, suggesting saturation of this skin layer. For the study of healing activity, the dorsal wound model was performed with an evaluation of the lesion size, anti-inflammatory markers, and antioxidant activity. The initial closure of the wound was achieved sooner in the group treated with the hydrogel containing the β-caryophyllene nanoemulsion, indicating its anti-inflammatory effect. The histological analysis indicated that on day 12 day of the lesion, the hydrogel presented similar results to those of the positive control group (Dersani® oil), proving effectiveness in cutaneous tissue repair.

Development of Nasal Lipid Nanocarriers Containing Curcumin for Brain Targeting

BACKGROUND

Curcumin (CUR) has properties that can be useful for the treatment of Alzheimer's disease. Such properties are the inhibition of amyloid-β-protein (Aβ) aggregation, Aβ-induced inflammation, and activities of β-secretase and acetylcholinesterase. However, previous studies have revealed that CUR exhibited low bioavailability and difficulties in reaching the brain.

OBJECTIVE

To overcome such drawbacks, this study aims at developing nasal lipid nanocarriers loaded with CUR to effectively target the brain.

METHODS

The lipid nanocarriers (NE) were prepared using the hot solvent diffusion associated with the phase inversion temperature methods. Physico-chemical and morphological characterizations and in vitro drug release of the nanocarriers were carried out. The CUR permeation/retention was analyzed in Franz-type diffusion cell using porcine nasal mucosa. Confocal laser scan and histopathological studies were also performed.

RESULTS

The results showed that the NE sizes ranged between 18 nm and 44 nm with negative zeta potential. The CUR content ranged from 0.24 to 1.50 mg/mL with an encapsulation efficiency of 99%. The profiles of CUR release indicated a biphasic kinetics. CUR-NE permeation across the porcine nasal mucosa was higher when compared to free CUR. These results have also been validated through an analysis on a confocal microscopy. In addition, no toxicity on the nasal mucosa has been observed in a histopathological analysis.

CONCLUSION

These results suggest that it is possible to develop NEs with a high content of CUR and small particle size. Such an encapsulation increases the potential of CUR permeation across the porcine nasal mucosa.

Protective role of free and quercetin-loaded nanoemulsion against damage induced by intracerebral haemorrhage in rats

Intracerebral haemorrhage (ICH) is a worldwide public health problem. Experimental studies have shown that oxidative stress plays an important role in the pathogenesis of ICH and could represent a target for its treatment. However, the blood-brain barrier is an obstacle to be overcome, as it hampers the administration of compounds to the central nervous system. In this study, we compared the effects of a quercetin-loaded nanoemulsion (QU-N) with the free form of the drug (QU-SP) in a collagenase-induced ICH rat model. Quercetin (QU) is a polyphenol that has an antioxidant effect in vitro, but due to its high lipophilicity, it has low bioavailability in vivo. In this study, animals submitted or not to ICH were treated with a single intraperitoneal QU dose (free or nanoemulsion) of 30 mg kg(-1). Motor assessment was evaluated by the open field, foot fault and beam walking behavioural tests. 72 h after surgery the haematoma size was evaluated and biochemical measurements were performed. Animals treated with QU-N had a significant improvement in the beam walking and open field tests. Also, QU-N was able to reduce the size of the haematoma, preserving the activity of glutathione S-transferase (GST), increasing GSH content, and the total antioxidant capacity. QU-SP recovered locomotor activity and increased the GSH content and the total antioxidant capacity. Thus, it can be observed that QU presented antioxidant activity in both formulations, but the incorporation into nanoemulsions increased its antioxidant effect, which was reflected in the improvement of the motor skills and in the haematoma size decrement. These results suggest that the nanoemulsion containing QU developed in this study could be promising for future studies on treatments for ICH.

Synthesis and antiproliferative activity of novel hybrid 3-substituted polyhydroquinoline-fatty acids

Synthesis and antiproliferative activity of novel hybrid 3-substituted polyhydroquinoline-fatty acids.

Isolation of adipose-derived stem cells: a comparison among different methods

Adipose-derived stromal cells (ASCs) are usually isolated by digestion with collagenase. We have compared alternative methods to isolate ASCs in a more economically viable protocol. Nine protocols using red blood cells lysis buffer solution, trypsin, collagenase and centrifugation were compared; the isolation rate, cell viability, expansion rate, immunophenotype and differentiation in adipogenic and osteogenic lineages were analyzed. ASCs were isolated and successfully maintained by digestion with trypsin. Cells presented similar immunophenotypes, adipogenic differentiation and in vitro proliferation but an osteogenic differentiation capacity up to seven times higher than ASCs isolated by collagenase. This alternative protocol is thus efficient and more cost-effective than the commonly-used methods and may represent a promising protocol for obtaining ASCs for bone tissue engineering.

Amyloid-β induced toxicity involves ganglioside expression and is sensitive to GM1 neuroprotective action

The effect of Aβ25-35 peptide, in its fibrillar and non-fibrillar forms, on ganglioside expression in organotypic hippocampal slice cultures was investigated. Gangliosides were endogenously labeled with D-[1-C(14)] galactose and results showed that Aβ25-35 affected ganglioside expression, depending on the peptide aggregation state, that is, fibrillar Aβ25-35 caused an increase in GM3 labeling and a reduction in GD1b labeling, whereas the non-fibrillar form was able to enhance GM1 expression. Interestingly, GM1 exhibited a neuroprotective effect in this organotypic model, since pre-treatment of the hippocampal slices with GM1 10 μM was able to prevent the toxicity triggered by the fibrillar Aβ25-35, when measured by propidium iodide uptake protocol. With the purpose of further investigating a possible mechanism of action, we analyzed the effect of GM1 treatment (1, 6, 12 and 24h) upon the Aβ-induced alterations on GSK3β dephosphorylation/activation state. Results demonstrated an important effect after 24-h incubation, with GM1 preventing the Aβ-induced dephosphorylation (activation) of GSK3β, a signaling pathway involved in apoptosis triggering and neuronal death in models of Alzheimer's disease. Taken together, present results provide a new and important support for ganglioside participation in development of Alzheimer's disease experimental models and suggest a protective role for GM1 in Aβ-induced toxicity. This may be useful for designing new therapeutic strategies for Alzheimer's treatment.

Amyloid-beta neurotoxicity in organotypic culture is attenuated by melatonin: involvement of GSK-3beta, tau and neuroinflammation

Alzheimer's disease (AD) is a progressive neurodegenerative disorder marked by accumulation of extracellular deposits of amyloid-beta (Abeta) peptide in brain regions that are important for memory and cognition. The buildup of Abeta aggregates in the AD is followed by the formation of intracellular neurofibrillary tangles and activation of neuroinflammatory reactions. The present study investigated whether melatonin possesses a neuroprotective effect against Abeta-induced toxicity. For this purpose, organotypic hippocampal slices were cultured and exposed to 25 microm of Abeta(25-35) in the absence or in the presence of melatonin (25, 50, or 100 microm). In addition, the authors have investigated the involvement of GSK-3beta, tau protein, astroglial, and microglial activation, and cytokine levels in the melatonin protection against Abeta-induced neurotoxicity. Melatonin prevented the cell damage in hippocampus induced by the exposure to Abeta(25-35). In addition, melatonin significantly reduced the activation of GSK-3beta, the phosphorylation of tau protein, the glial activation and the Abeta-induced increase of TNF-alpha and IL-6 levels. On the basis of these findings, we speculate that melatonin may provide an effective therapeutic strategy for AD, by attenuating Abeta-induced phosphorylation of tau protein, and preventing GSK-3beta activation and neuroinflammation.

Protective profile of oxcarbazepine against oxygen-glucose deprivation in organotypic hippocampal slice culture could involve PI3K cell signaling pathway

OBJECTIVE

Brain ischemia results in cellular degeneration and loss of brain function. Oxcarbazepine (OXC), one of the newer antiepileptic drugs, has been demonstrating its efficacy on wide spectrum neurological disorders. In this paper, we investigated the neuroprotective profile of OXC in an in vitro model of ischemia, which consists in the exposure of organotypic hippocampal slice cultures to oxygen and glucose deprivation.

METHODS

OXC (30 microM) was added to the medium before and/or during and/or after the oxygen and glucose deprivation induction. Cell death was quantified by propidium iodide uptake measurement. Immunoblotting was used to detect the phosphorylation of Akt.

RESULTS

Our results showed a decrease in propidium iodide incorporation when OXC was added before oxygen and glucose deprivation, suggesting a neuroprotective effect. This effect was prevented when cultures were previously treated with LY294002, an inhibitor of phosphoinositide-3-kinase (PI3K) pathway. We also analysed the effect of OXC on Akt phosphorylation. Immunoblotting revealed that OXC did not induce any change in phosphorylation/activation of Akt.

DISCUSSION

Our results reinforce the neuroprotective effect of OXC and add some evidence that its mechanism may involve the PI3K pathway, suggesting that such effect could be upstream Akt. This indicates that with respect to OXC neuroprotective, Akt may not play a crucial role in determining cell survival.

Effects of chronic restraint stress and estradiol replacement on glutamate release and uptake in the spinal cord from ovariectomized female rats

Glutamate is an excitatory neurotransmitter involved in neuronal plasticity and neurotoxicity. Chronic stress produces several physiological changes on the spinal cord, many of them presenting sex-specific differences, which probably involve glutamatergic system alterations. The aim of the present study was to verify possible effects of exposure to chronic restraint stress and 17beta-estradiol replacement on [3H]-glutamate release and uptake in spinal cord synaptosomes of ovariectomized (OVX) rats. Female rats were subjected to OVX, and half of the animals received estradiol replacement. Animals were subdivided in controls and chronically stressed. Restraint stress or estradiol had no effect on [3H]-glutamate release. The chronic restraint stress promoted a decrease and 17beta-estradiol induced an increase on [3H]-glutamate uptake, but the uptake observed in the restraint stress +17beta-estradiol group was similar to control. Furthermore, 17beta-estradiol treatment caused a significant increase in the immunocontent of the three glutamate transporters present in spinal cord. Restraint stress had no effect on the expression of these transporters, but prevented the 17beta-estradiol effect. We suggest that changes in the glutamatergic system are likely to take part in the mechanisms involved in spinal cord plasticity following repeated stress exposure, and that 17beta-estradiol levels may affect chronic stress effects in this structure.

A comparative study of beta-amyloid peptides Abeta1-42 and Abeta25-35 toxicity in organotypic hippocampal slice cultures

Accumulation of the neurotoxic amyloid beta-peptide (Abeta) in the brain is a hallmark of Alzheimer's disease (AD). Several synthetic Abeta peptides have been used to study the mechanisms of toxicity. Here, we sought to establish comparability between two commonly used Abeta peptides Abeta1-42 and Abeta25-35 on an in vitro model of Abeta toxicity. For this purpose we used organotypic slice cultures of rat hippocampus and observed that both Abeta peptides caused similar toxic effects regarding to propidium iodide uptake and caspase-3 activation. In addition, we also did not observe any effect of both peptides on Akt and PTEN phosphorylation; otherwise the phosphorylation of GSK-3beta was increased. Although further studies are necessary for understanding mechanisms underlying Abeta peptide toxicity, our results provide strong evidence that Abeta1-42 and the Abeta25-35 peptides induce neural injury in a similar pattern and that Abeta25-35 is a convenient tool for the investigation of neurotoxic mechanisms involved in AD.

Protective effect of resveratrol against oxygen-glucose deprivation in organotypic hippocampal slice cultures: Involvement of PI3-K pathway

Here we investigated the neuroprotective effect of resveratrol in an in vitro model of ischemia. We used organotypic hippocampal cultures exposed to oxygen-glucose deprivation (OGD). In OGD-vehicle exposed cultures, about 46% of the hippocampus was labeled with PI, indicating a robust percentage of cell death. When cultures were treated with resveratrol 10, 25 and 50 microM, the cell death was reduced to 22, 20 and 13% respectively. To elucidate a possible mechanism by which resveratrol exerts its neuroprotective effect, we investigated the phosphoinositide3-kinase (PI3-k) pathway using LY294002 (5 microM) and mitogen-activated protein kinase (MAPK) using PD98059 (20 microM). The resveratrol (50 microM) neuroprotection was prevented by LY294002 but was not by PD98059. Immunoblotting revealed that resveratrol 50 microM induced the phosphorylation/activation of Akt and extracellular signal-regulated kinase-1 and -2 (ERK1/2) and the phosphorylation/inactivation of glycogen synthase kinase-3beta (GSK-3beta). Our results suggest that PI3-k/Akt pathway are involved in the neuroprotective effect of resveratrol.

The effects of estradiol on estrogen receptor and glutamate transporter expression in organotypic hippocampal cultures exposed to oxygen--glucose deprivation

The molecular basis of estrogen-mediated neuroprotection against brain ischemia remains unclear. In the present study, we investigated changes in expression of estrogen receptors (ERs) alpha and beta and excitatory amino acid transporters (EAAT) 1 and 2 in rat organotypic hippocampal slice cultures treated with estradiol and subsequently exposed to oxygen--glucose deprivation (OGD). Pretreatment with 17beta-estradiol (10 nM) for 7 days protected the CA1 area of hippocampus against OGD (60 min), reducing cellular injury by 46% compared to the vehicle control group. Levels of ERalpha protein were significantly reduced by 20% after OGD in both vehicle- and estradiol-treated cultures, whereas ERbeta was significantly up-regulated by 25% in the estradiol-treated cultures. In contrast, EAAT1 and EAAT2 levels were unchanged in response to estradiol treatment in this model of OGD. These findings suggest that estrogen-induced neuroprotection against ischemia might involve regulation of ERbeta and, consequently, of the genes influenced by this receptor.

Cellular death in hippocampus in response to PI3K pathway inhibition and oxygen and glucose deprivation

We investigated the importance of the phosphoinositide3-kinase (PI3K) pathway in CA1 and dentate gyrus (DG) areas of hippocampus by exposing organotypic cultures to LY294002, a PI3K inhibitor, or to oxygen and glucose deprivation (OGD) for up to 21 hours. LY294002 induced increased propidium iodide (PI) uptake and caspase 3/7 activity in both regions, with a faster onset in DG. In contrast, cultures exposed to 60 min of OGD showed a PI uptake only in the CA1 area, beginning 13 h after the insult and increasing until 21 h. We did not observe any significant changes in AKT phosphorylation and immunocontent in CA1 or DG areas of organotypic cultures exposed to OGD, suggesting that the phosphorylation of this protein at Ser-473 is unrelated to the cellular damage induced by ischemia. Our results suggest that the inhibition of the PI3K pathway does not mimic the cell death profile observed with an ischemic model.

Increased resistance of glioma cell lines to extracellular ATP cytotoxicity

Glioblastomas are the most common form of primary tumors of the central nervous system (CNS) and despite treatment, patients with these tumors have a very poor prognosis. ATP and other nucleotides and nucleosides are very important signaling molecule in physiological and pathological conditions in the CNS. ATP is degraded very slowly by gliomas when compared to astrocytes, potentially resulting in the accumulation of extracellular ATP around gliomas. Cell lysis caused by excitotoxic death or by tumor resection may liberate intracellular ATP, a known mitotic factor for glioma cells. The aim of this study is to examine the effects on cytotoxicity induced by extracellular ATP in U138-MG human glioma cell line and C6 rat glioma cell line compared to hippocampal organotypic cell cultures. The cytotoxicity of ATP (0.1, 0.5, 5 mM) was measured using propidium iodide and LDH assays. Caspases assay was performed to identify apoptotic cell death. Results showed that the glioma cells present resistance to death induced by ATP when compared with a normal tissue. High ATP concentrations (5 mM) induced cell death after 24 h in organotypic cell cultures but not in glioma cell lines. Our data indicate that ATP released in these situations can induce cell death of the normal tissue surrounding the tumor, potentially opening space to the fast growth and invasion of the tumor.

BSP A1/A2-like proteins in ram seminal plasma

The objective of this study was to assess the protein profile of ovine seminal plasma using 2D-PAGE and verify if BSP A1/A2 are present in ovine seminal plasma. Seminal plasma was collected from three mature rams and pooled to eliminate individual differences. Seminal plasma samples were submitted to 2D-PAGE using 12% acrylamide gels. The image analysis software identified 21 protein spots on the air-dried gel, with molecular weight ranging from 15 to 115 kDa and pI 3.2 to 8.7. The most prominent spots were those <30 kDa. The most intensely stained spots were: 3 (18-19 kDa, pI 4.8-5.0), 5 (17-18 kDa, pI 5.0-5.2), 7 (15-16 kDa, pI 6.2-6.4), and 23 (105-108 kDa, pI 6.8-7.0). Three of these spots (spots 3, 5 and 7, respectively) accounted for 41.1% of the relative intensity of the spots of the gels, based on the intensity of the Comassie blue staining. Western blot analysis indicated that spots 3 and 5 were similar to BSP A1/A2 (16.5, pI 4.7-5.0 and 16 kDa, pI 4.9-5.2) identified in Manjunath's studies [Manjunath P, Sairam MR. Purification and biochimical characterization of three major acid proteins (BSP A1, BSP A2 and BSP A3) from bovine seminal plasma. Biochem J 7 (1987) 685-92.], based on the specific reaction of the polyclonal antibody to those spots.

Estradiol Protects Against Oxygen and Glucose Deprivation in Rat Hippocampal Organotypic Cultures and Activates Akt and Inactivates GSK-3?

Here we investigated the neuroprotective effect of 17beta-estradiol in an in vitro model of ischemia. We used organotypic hippocampal slice cultures, acute or chronically treated with 17beta-estradiol (10 nM), and exposed to oxygen and glucose deprivation (OGD). Cellular death was quantified by measuring uptake of propidium iodide (PI), a marker of dead cells. In OGD exposed cultures, treated only with vehicle, about 70% of the CA1 area of hippocampus was labeled with PI, indicating a great percentage of cellular death. When cultures were treated with 17beta-estradiol (acute or chronically), this cellular death was reduced to 15%. This effect was prevented by LY294002 but was not by PD98059. Immunoblotting revealed that both, chronic and acute, treatments with 17beta-estradiol induced the phosphorylation/activation of Akt and the phosphorylation/inactivation of GSK-3beta. Our results show a clear neuroprotective effect of 17beta-estradiol and suggest that this effect could involve PI3-K pathway.

Changes in heat shock protein 27 phosphorylation and immunocontent in response to preconditioning to oxygen and glucose deprivation in organotypic hippocampal cultures

Organotypic hippocampal cultures have been recently used to study in vitro ischaemic neuronal death. Sub-lethal periods of ischaemia in vivo confer resistance to lethal insults and many studies have demonstrated the involvement of heat shock proteins in this phenomenon. We used organotypic hippocampal cultures to investigate the involvement of heat shock protein (HSP) 27 in preconditioning to oxygen and glucose deprivation. Neuronal damage was assessed using propidium iodide fluorescence; HSP27 phosphorylation and immunocontent were obtained using (32)Pi labelling followed by sodium dodecylsulfate-polyacrylamide gel electrophoresis and immunoblotting. We observed that immunocontent of HSP27 was increased after lethal or sub-lethal treatment, indicating it is a response to metabolic stress. Treatments with 5 or 10 min of oxygen and glucose deprivation (OGD) or 1- microM N-methyl-D-aspartate (NMDA) induced tolerance to 40 min of OGD associated with an increase in HSP27 immunocontent and phosphorylation. These data suggest that, in vitro, phosphorylated HSP27 might be involved in preconditioning, probably acting as a modulator of actin filaments or by the blockage of neurodegenerative processes.