Estrogen attenuates oxidative stress-induced apoptosis in C6 glial cells

Perfluorooctane sulfonate (PFOS) and benzo[a]pyrene (BaP) synergistically induce neurotoxicity in C6 rat glioma cells via the activation of neurotransmitter and Cyp1a1-mediated steroid hormone synthesis pathways

Humans are often exposed to complex mixtures of multiple pollutants rather than a single pollutant. However, the combined toxic effects and the molecular mechanism of PFOS and BaP remain poorly understood. In this study, two typical environmental pollutants, perfluorooctane sulfonate acid (PFOS) and benzo [a]pyrene (BaP), were selected to investigate their combined neurotoxic effects on rat C6 glioma cells at environmentally relevant concentrations. The results showed that coexposure to low-dose PFOS and BaP induced greater toxicity (synergistic effect) than did single exposure. PFOS-BaP coexposure had stronger toxic effects on inducing oxidative stress and promoting early apoptosis. Targeted metabolomics confirmed that increased levels of the neurotransmitters 5-hydroxytryptophan, dopamine, tryptophan and serotonin disturb the phenylalanine, tyrosine and tryptophan biosynthesis pathways. Mechanistically, exposure to a low-dose PFOS-BaP binary mixture induces steroid hormone synthesis disorder through the activation of Cyp1a1 and Hsd17b8 (steroid hormone synthesis genes) and Dhcr24 and Dhcr7 (cholesterol synthesis genes). These findings are useful for comprehensively and systematically elucidating the biological safety of PFOS-BaP and its potential threats to human health.

Premarin Reduces Neurodegeneration and Promotes Improvement of Function in an Animal Model of Spinal Cord Injury

Spinal cord injury (SCI) causes significant mortality and morbidity. Currently, no FDA-approved pharmacotherapy is available for treating SCI. Previously, low doses of estrogen (17β-estradiol, E2) were shown to improve the post-injury outcome in a rat SCI model. However, the range of associated side effects makes advocating its therapeutic use difficult. Therefore, this study aimed at investigating the therapeutic efficacy of Premarin (PRM) in SCI. PRM is an FDA-approved E2 (10%) formulation, which is used for hormone replacement therapy with minimal risk of serious side effects. The effects of PRM on SCI were examined by magnetic resonance imaging, immunofluorescent staining, and western blot analysis in a rat model. SCI animals treated with vehicle alone, PRM, E2 receptor antagonist (ICI), or PRM + ICI were graded in a blinded way for locomotor function by using the Basso–Beattie–Bresnahan (BBB) locomotor scale. PRM treatment for 7 days decreased post-SCI lesion volume and attenuated neuronal cell death, inflammation, and axonal damage. PRM also altered the balance of pro- and anti-apoptotic proteins in favor of cell survival and improved angiogenesis and microvascular growth. Increased expression of estrogen receptors (ERs) ERα and ERβ following PRM treatment and their inhibition by ER inhibitor indicated that the neuroprotection associated with PRM treatment might be E2-receptor mediated. The attenuation of glial activation with decreased inflammation and cell death, and increased angiogenesis by PRM led to improved functional outcome as determined by the BBB locomotor scale. These results suggest that PRM treatment has significant therapeutic implications for the improvement of post-SCI outcome.

Redox modulation by plant polyphenols targeting vitagenes for chemoprevention and therapy: Relevance to novel anti-cancer interventions and mini-brain organoid technology

The scientific community, recently, has focused notable attention on the chemopreventive and therapeutic effects of dietary polyphenols for human health. Emerging evidence demonstrates that polyphenols, flavonoids and vitamins counteract and neutralize genetic and environmental stressors, particularly oxidative stress and inflammatory process closely connected to cancer initiation, promotion and progression. Interestingly, polyphenols can exert antioxidant or pro-oxidant cytotoxic effects depending on their endogenous concentration. Notably, polyphenols at high dose act as pro-oxidants in a wide type of cancer cells by inhibiting Nrf2 pathway and the expression of antioxidant vitagenes, such as NAD(P)H-quinone oxidoreductase (NQO1), glutathione transferase (GT), GPx, heme oxygenase-1 (HO-1), sirtuin-1 (Sirt1) and thioredoxin (Trx) system which play an essential role in the metabolism of reactive oxygen species (ROS), detoxification of xenobiotics and inhibition of cancer progression, by inducing apoptosis and cell cycle arrest according to the hormesis approach. Importantly, mutagenesis of Nrf2 pathway can exacerbate its "dark side" role, representing a crucial event in the initiation stage of carcinogenesis. Herein, we review the hormetic effects of polyphenols and nanoincapsulated-polyphenols in chemoprevention and treatment of brain tumors via activation or inhibition of Nrf2/vitagenes to suppress carcinogenesis in the early stages, and thus inhibit its progression. Lastly, we discuss innovative preclinical approaches through mini-brain tumor organoids to study human carcinogenesis, from basic cancer research to clinical practice, as promising tools to recapitulate the arrangement of structural neuronal tissues and biological functions of the human brain, as well as test drug toxicity and drive personalized and precision medicine in brain cancer.

Estrogen Protects Optic Nerve Head Astrocytes Against Oxidative Stress by Preventing Caspase-3 Activation, Tau Dephosphorylation at Ser422 and the Formation of Tau Protein Aggregates

Glaucoma is a neurodegenerative disorder that leads to the slow degeneration of retinal ganglion cells, and results in damage to the optic nerve and concomitant vision loss. As in other disorders affecting the viability of central nervous system neurons, neurons affected by glaucoma do not have the ability to regenerate after injury. Recent studies indicate a critical role for optic nerve head astrocytes (ONHAs) in this process of retinal ganglion cell degeneration. Cleavage of tau, a microtubule stabilizing protein and constituent of neurofibrillary tangles (NFT), plays a major part in the mechanisms that lead to toxicity in CNS neurons and astrocytes. Here, we tested the hypothesis that estrogen, a pleiotropic neuro- and cytoprotectant with high efficacy in the CNS, prevents tau cleavage, and hence, protects ONHAs against cell damage caused by oxidative stress. Our results indicate that estrogen prevents caspase-3 mediated tau cleavage, and thereby decreases the levels of the resulting form of proteolytically cleaved tau protein, which leads to a decrease in NFT formation, which requires proteolytically cleaved tau protein. Overall, our data propose that by stopping the reduction of estrogen levels involved with aging the sensitivity of the optic nerve to glaucomatous damage might be reduced. Furthermore, our data suggest that therapeutic use of estrogen may be beneficial in slowing or preventing the onset or severity of neurodegenerative diseases such as glaucoma and potentially also other degenerative diseases of the CNS through direct control of posttranslational modifications of tau protein.

Sulforaphane from Cruciferous Vegetables: Recent Advances to Improve Glioblastoma Treatment

Sulforaphane (SFN), an isothiocyanate (ITC) derived from cruciferous vegetables, particularly broccoli and broccoli sprouts, has been widely investigated due to its promising health-promoting properties in disease, and low toxicity in normal tissue. Although not yet fully understood, many mechanisms of anticancer activity at each step of cancer development have been attributed to this ITC. Given the promising data available regarding SFN, this review aimed to provide an overview on the potential activities of SFN related to the cellular mechanisms involved in glioblastoma (GBM) progression. GBM is the most frequent malignant brain tumor among adults and is currently an incurable disease due mostly to its highly invasive phenotype, and the poor efficacy of the available therapies. Despite all efforts, the median overall survival of GBM patients remains approximately 1.5 years under therapy. Therefore, there is an urgent need to provide support for translating the progress in understanding the molecular background of GBM into more complex, but promising therapeutic strategies, in which SFN may find a leading role.

Protective Effects of Fetal Zone Steroids Are Comparable to Estradiol in Hyperoxia-Induced Cell Death of Immature Glia

Impaired neurodevelopment in preterm infants is caused by prematurity itself; however, hypoxia/ischemia, inflammation, and hyperoxia contribute to the extent of impairment. Because preterm birth is accompanied by a dramatic decrease in 17β-estradiol (E2) and progesterone, preliminary clinical studies have been carried out to substitute these steroids in preterm infants; however, they failed to confirm significantly improved neurologic outcomes. We therefore hypothesized that the persistently high postnatal production of fetal zone steroids [mainly dehydroepiandrosterone (DHEA)] until term could interfere with E2-mediated protection. We investigated whether E2 could reduce hyperoxia-mediated apoptosis in three immature glial cell types and detected the involved receptors. Thereafter, we investigated protection by the fetal zone steroids DHEA, 16α-hydroxy-DHEA, and androstenediol. For DHEA, the involved receptors were evaluated. We examined aromatases, which convert fetal zone steroids into more estrogenic compounds. Finally, cotreatment was compared against single hormone treatment to investigate synergism. In all cell types, E2 and fetal zone steroids resulted in significant dose-dependent protection, whereas the mediating receptors differed. The neuroprotection by fetal zone steroids highly depended on the cell type-specific expression of aromatases, the receptor repertoire, and the potency of the fetal zone steroids toward these receptors. No synergism in fetal zone steroid and E2 cotreatment was detected in two of three cell types. Therefore, E2 supplementation may not be beneficial with respect to neuroprotection because fetal zone steroids circulate in persistently high concentrations until term in preterm infants. Hence, a refined experimental model for preterm infants is required to investigate potential treatments.

Gonadal steroids block the calpain-1-dependent intrinsic pathway of apoptosis in an experimental rat stroke model

OBJECTIVES

Apoptosis plays an important role in the progression of the ischemic penumbra after reperfusion. Estrogen and progesterone have neuroprotective effects against ischemic brain damage, however the exact mechanisms of neuroprotection and signaling pathways is not completely understood. In this study, we investigated the possible regulatory effects of a combined steroid treatment on extrinsic and intrinsic apoptotic signaling pathways after cerebral ischemia.

METHODS

Adult male Wistar rats were subjected to transient middle cerebral artery occlusion (tMCAO) using an intraluminal filament technique for 1 h followed by 23 h reperfusion. Estrogen and progesterone were immediately injected after tMCAO subcutaneously. Sensorimotor functional tests and the infarct volume were evaluated 24 h after ischemia. Protein expression of calpain-1 and Fas receptor (FasR), key members of intrinsic and extrinsic apoptosis, were determined in the penumbra region of the ischemic brain using western blot analysis, immunohistochemistry, and TUNEL staining.

RESULTS

Neurological deficits and infarct volume were significantly reduced following hormone therapy. Calpain-1 up-regulation and caspase-3 activation were apparent 24 h after ischemia in the peri-infarct area of the cerebral cortex. Steroid hormone treatment reduced infarct pathology and attenuated the induction of both proteases. FasR protein levels were not affected by ischemia and hormone application.

CONCLUSION

We conclude that a combined steroid treatment inhibits ischemia-induced neuronal apoptosis through the regulation of intrinsic pathways.

Administration of low dose estrogen attenuates persistent inflammation, promotes angiogenesis, and improves locomotor function following chronic spinal cord injury in rats

Spinal cord injury (SCI) causes loss of neurological function and, depending upon the severity of injury, may lead to paralysis. Currently, no FDA-approved pharmacotherapy is available for SCI. High-dose methylprednisolone is widely used, but this treatment is controversial. We have previously shown that low doses of estrogen reduces inflammation, attenuates cell death, and protects axon and myelin in SCI rats, but its effectiveness in recovery of function is not known. Therefore, the goal of this study was to investigate whether low doses of estrogen in post-SCI would reduce inflammation, protect cells and axons, and improve locomotor function during the chronic phase of injury. Injury (40 g.cm force) was induced at thoracic 10 in young adult male rats. Rats were treated with 10 or 100 μg 17β-estradiol (estrogen) for 7 days following SCI and compared with vehicle-treated injury and laminectomy (sham) controls. Histology (H&E staining), immunohistofluorescence, Doppler laser technique, and Western blotting were used to monitor tissue integrity, gliosis, blood flow, angiogenesis, the expression of angiogenic factors, axonal degeneration, and locomotor function (Basso, Beattie, and Bresnahan rating) following injury. To assess the progression of recovery, rats were sacrificed at 7, 14, or 42 days post injury. A reduction in glial reactivity, attenuation of axonal and myelin damage, protection of cells, increased expression of angiogenic factors and microvessel growth, and improved locomotor function were found following estrogen treatment compared with vehicle-treated SCI rats. These results suggest that treatment with a very low dose of estrogen has significant therapeutic implications for the improvement of locomotor function in chronic SCI. Experimental studies with low dose estrogen therapy in chronic spinal cord injury (SCI) demonstrated the potential for multi-active beneficial outcomes that could ameliorate the degenerative pathways in chronic SCI as shown in (a). Furthermore, the alterations in local spinal blood flow could be significantly alleviated with low dose estrogen therapy. This therapy led to the preservation of the structural integrity of the spinal cord (b), which in turn led to the improved functional recovery as shown (c).

Sequestering survivin to functionalized nanoparticles: a strategy to enhance apoptosis in cancer cells

Survivin belongs to the family of inhibitor of apoptosis proteins (IAP) and is present in most cancers while being below detection limits in most terminally differentiated adult tissues, making it an attractive protein to target for diagnostic and, potentially, therapeutic roles. Sub-100 nm poly(propargyl acrylate) (PA) particles were surface modified through the copper-catalyzed azide/alkyne cycloaddition of an azide-terminated survivin ligand derivative (azTM) originally proposed by Abbott Laboratories and speculated to bind directly to survivin (protein) at its dimer interface. Using affinity pull-down studies, it was determined that the PA/azTM nanoparticles selectively bind survivin and the particles can enhance apoptotic cell death in glioblastoma cell lines and other survivin over-expressing cell lines such as A549 and MCF7 relative to cells incubated with the original Abbott-derived small molecule inhibitor.

Estradiol Receptors Regulate Differential Connexin 43 Expression in F98 and C6 Glioma Cell Lines

Introduction

Glioma is the most common malignant primary brain tumour with male preponderance and poor prognosis. Glioma cells express variable amounts of connexin 43 (Cx43) and estrogen receptors (ERs). Both, Cx43 and ERs, play important roles in cell proliferation and migration. Therefore, we investigated the effects of 17-ß estradiol (E2) on Cx43 expression in two glioma cell lines with variable native expression of Cx43.

Materials and Methods

F98 and C6 rat glioma cells were cultured for 24 h in the presence of 10 nM or 100 nM E2, and the E2-antagonist, Fulvestrant. An MTT assay was performed to evaluate cell viability. ERα, ERβ and Cx43 protein expressions were analysed by western blotting and Cx43 mRNA expression was analysed by real-time polymerase chain reaction. To quantify cell migration, an exclusive zone migration assay was used. Functional coupling of cells via gap junctions was examined using whole-cell patch-clamp technique.

Results

E2 reduced Cx43 expression in C6 cells, but increased Cx43 expression in F98 cultures. These effects were mediated via ERs. Moreover, E2 promoted C6 cell migration, but it did not affect F98 cell migration. The expression level of ERα was found to be high in C6, but low in F98 cells. ERβ was exclusively expressed in C6 cells. In addition, E2 treatment induced a significant decrease of ERβ in C6 cultures, while it decreased ERα expression in F98 glioma cells.

Discussion

These findings show that E2 differentially modulates Cx43 expression in F98 and C6 glioma cells, likely due to the differential expression of ERs in each of these cell lines. Our findings point to the molecular mechanisms that might contribute to the gender-specific differences in the malignancy of glioma and could have implications for therapeutic strategies against glioma.

Estrogen regulates excitatory amino acid carrier 1 (EAAC1) expression through sphingosine kinase 1 (SphK1) transacting FGFR-mediated ERK signaling in rat C6 astroglial cells

Excitatory amino acid carrier 1 (EAAC1) is one important subtype of the excitatory amino acid transporters (EAATs), and its absence can increase the vulnerability to oxidative stress in neural tissue. Enhanced expression of EAAC1 can provide neuroprotection in multiple disorders, including ischemia and multiple sclerosis. However, the mechanism regulating EAAC1 expression is not fully understood. Using rat C6 astroglial cells, which specifically express EAAC1, we found that 17β-estradiol (E2) and (±)-1-[(3aR(∗),4S(∗),9bS(∗))-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone (G1), an agonist of the G-protein-coupled estrogen receptor (GPR30), strongly increased EAAC1 protein levels and protected cells from hydrogen peroxide (H2O2) toxicity. We further found that E2/G1 activated sphingosine kinase 1 (SphK1) via GPR30, resulting in the transcription of fibroblast growth factor 2 (FGF2), which stimulated its receptor (FGFR) and led to the phosphorylation of FGFR substrate 2α (FRS2α). This triggered downstream ERK1/2 signaling for the expression of EAAC1. Both the knockdown of FGF2 by siRNA and the pharmacological suppression of the FGFR-ERK cascade abolished the E2/G1 effect on EAAC1 expression. Overall, our work characterizes a signaling pathway by which E2 transactivates FGFR-ERK to induce EAAC1 expression in an FGF2-dependent manner. This occurs through SphK1 activation via GPR30 and leads to a resistance to H2O2 toxicity. This signal transduction pathway may provide novel insights into our understanding of the neuroprotective effects of E2 and may reveal new therapeutic targets or drugs for regulating the oxidative toxicity effects of various neurological diseases.

A novel component from citrus, ginger, and mushroom family exhibits antitumor activity on human meningioma cells through suppressing the Wnt/β-catenin signaling pathway

Recurrent meningiomas constitute an uncommon but significant problem after standard (surgery and radiation) therapy failure. Current chemotherapies (hydroxyurea, RU-486, and interferon-α) are only of marginal benefit. There is an urgent need for more effective treatments for meningioma patients who have failed surgery and radiation therapy. Limonin, Tangeritin, Zerumbone, 6-Gingerol, Ganoderic Acid A, and Ganoderic Acid DM are some of the plant derivatives that have anti-tumorgenic properties and cause cell death in meningioma cells in vitro. Due to its ease of administration, long-term tolerability, and low incidence of long-term side effects, we explored its potential as a therapeutic agent against meningiomas by examining their efficacy in vitro against meningioma cells. Treatment effects were assessed using MTT assay, Western blot analysis, caspases assay, and DNA fragmentation assay. Results indicated that treatments of IOMM-Lee and CH157MN meningioma cells with Limonin, Tangeritin, Zerumbone, 6-Gingerol, Ganoderic Acid A, and Ganoderic Acid DM induced apoptosis with enhanced phosphorylation of glycogen synthase kinase 3 β (GSK3β) via inhibition of the Wnt5/β-catenin pathway. These drugs did not induce apoptosis in normal human neurons. Other events in apoptosis included downregulation of tetraspanin protein (TSPAN12), survival proteins (Bcl-XL and Mcl-1), and overexpression apoptotic factors (Bax and caspase-3). These results provide preliminary strong evidence that medicinal plants containing Limonin, Tangeritin, 6-Gingerol, Zerumbone, Ganoderic Acid A, and Ganoderic Acid DM can be applied to high-grade meningiomas as a therapeutic agent, and suggests that further in vivo studies are necessary to explore its potential as a therapeutic agent against malignant meningiomas.

Hormonal contraceptive use and risk of glioma among younger women: a nationwide case-control study

AIM

Oral contraceptive use influences the risk for certain cancers. However, few studies have examined any link with risk of central nervous system tumours. We investigated the association between hormonal contraceptive use and glioma risk among premenopausal women in a population-based setting.

METHODS

Using national administrative and health registries in Denmark to conduct a nationwide case-control study, we identified all women ages 15 to 49 years with a first time diagnosis of histologically verified glioma between 2000 and 2009. Each case was age-matched to eight population controls using risk set sampling. Based on prescription data, exposure until 2 years prior to the index date was categorized according to hormonal contraceptive type, i.e. combined oestrogen-progestagen or progestagen only, and duration of use (<1, 1 to <5, ≥5 years). We used conditional logistic regression to compute odds ratios (ORs) with 95% confidence intervals (CIs) for glioma associated with hormonal contraceptive use, adjusting for potential confounders.

RESULTS

We identified 317 cases and 2126 controls. Ever use of hormonal contraceptive was associated with an OR of 1.5 (95% CI 1.2, 2.0) and the OR increased with duration of use (long term, ≥5 years: OR 1.9; 95% CI 1.2, 2.9). The association between long term hormonal contraceptive use and glioma risk was most pronounced for progestagen only therapy (OR 2.4; 95% CI 1.1, 5.1), especially when this regimen constituted the sole hormonal contraceptive therapy (OR 4.1; 95% CI 0.8, 20.8).

CONCLUSION

Long term hormonal contraceptive use may increase the risk of glioma.

Protective actions of 17β-estradiol and progesterone on oxidative neuronal injury induced by organometallic compounds

Steroid hormones synthesized in and secreted from peripheral endocrine glands pass through the blood-brain barrier and play a role in the central nervous system. In addition, the brain possesses an inherent endocrine system and synthesizes steroid hormones known as neurosteroids. Increasing evidence shows that neuroactive steroids protect the central nervous system from various harmful stimuli. Reports show that the neuroprotective actions of steroid hormones attenuate oxidative stress. In this review, we summarize the antioxidative effects of neuroactive steroids, especially 17β-estradiol and progesterone, on neuronal injury in the central nervous system under various pathological conditions, and then describe our recent findings concerning the neuroprotective actions of 17β-estradiol and progesterone on oxidative neuronal injury induced by organometallic compounds, tributyltin, and methylmercury.

MiR-7-1 potentiated estrogen receptor agonists for functional neuroprotection in VSC4.1 motoneurons

Protection of motoneurons is an important goal in the treatment of spinal cord injury (SCI). We tested whether neuroprotective microRNAs (miRs) like miR-206, miR-17, miR-21, miR-7-1, and miR-106a could enhance efficacy of estrogen receptor (ER) agonists such as 1,3,5-tris (4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT, ERα agonist), Way200070 (WAY, ERβ agonist), and estrogen (EST, ERα and ERβ agonist) in preventing apoptosis in the calcium ionophore (CI)-insulted ventral spinal cord 4.1 (VSC4.1) motoneurons. We determined that 200 nM CI induced 70% cell death. Treatment with 50 nM PPT, 100 nM WAY, and 150 nM EST induced overexpression of ERα, ERβ, and both receptors, respectively, at mRNA and protein levels. Treatment with ER agonists significantly upregulated miR-206, miR-17, and miR-7-1 in the CI-insulted VSC4.1 motoneurons. Transfection with miR-206, miR-17, or miR-7-1 mimic potentiated WAY or EST to inhibit apoptosis in the CI-insulted VSC4.1 motoneurons. Overexpression of miR-7-1 maximally increased efficacy of WAY and EST for down regulation of pro-apoptotic Bax and upregulation of anti-apoptotic Bcl-2. A search using microRNA database (miRDB) indicated that miR-7-1 could inhibit the expression of L-type Ca(2+) channel protein alpha 1C (CPα1C). miR-7-1 overexpression and WAY or EST treatment down regulated CPα1C but upregulated p-Akt to trigger cell survival signaling. The same therapeutic strategy increased expression of the Ca(2+)/calmodulin-dependent protein kinase II beta (CaMKIIβ) and the phosphorylated cAMP response element binding protein (p-CREB) so as to promote Bcl-2 transcription. Whole cell membrane potential and mitochondrial membrane potential studies indicated that miR-7-1 highly potentiated EST to preserve functionality in the CI-insulted VSC4.1 motoneurons. In conclusion, our data indicated that miR-7-1 most significantly potentiated efficacy of EST for functional neuroprotection and this therapeutic strategy could be used in the future to attenuate apoptosis of motoneurons in SCI.

Annexin A1 induces skeletal muscle cell migration acting through formyl peptide receptors

Annexin A1 (ANXA1, lipocortin-1) is a glucocorticoid-regulated 37-kDa protein, so called since its main property is to bind (i.e. to annex) to cellular membranes in a Ca(2+)-dependent manner. Although ANXA1 has predominantly been studied in the context of immune responses and cancer, the protein can affect a larger variety of biological phenomena, including cell proliferation and migration. Our previous results show that endogenous ANXA1 positively modulates myoblast cell differentiation by promoting migration of satellite cells and, consequently, skeletal muscle differentiation. In this work, we have evaluated the hypothesis that ANXA1 is able to exert effects on myoblast cell migration acting through formyl peptide receptors (FPRs) following changes in its subcellular localization as in other cell types and tissues. The analysis of the subcellular localization of ANXA1 in C2C12 myoblasts during myogenic differentiation showed an interesting increase of extracellular ANXA1 starting from the initial phases of skeletal muscle cell differentiation. The investigation of intracellular Ca(2+) perturbation following exogenous administration of the ANXA1 N-terminal derived peptide Ac2-26 established the engagement of the FPRs which expression in C2C12 cells was assessed by qualitative PCR. Wound healing assay experiments showed that Ac2-26 peptide is able to increase migration of C2C12 skeletal muscle cells and to induce cell surface translocation and secretion of ANXA1. Our results suggest a role for ANXA1 as a highly versatile component in the signaling chains triggered by the proper calcium perturbation that takes place during active migration and differentiation or membrane repair since the protein is strongly redistributed onto the plasma membranes after an rapid increase of intracellular levels of Ca(2+). These properties indicate that ANXA1 may be involved in a novel repair mechanism for skeletal muscle and may have therapeutic implications with respect to the development of ANXA1 mimetics.

Annexin A1 N-terminal derived peptide Ac2-26 stimulates fibroblast migration in high glucose conditions

Deficient wound healing in diabetic patients is very frequent, but the cellular and molecular causes are poorly defined. In this study, we have evaluated whether Annexin A1 derived peptide Ac2-26 stimulates fibroblast migration in high glucose conditions. Using normal human skin fibroblasts WS1 in low glucose (LG) or high glucose (HG) we observed the enrichment of Annexin A1 protein at cell movement structures like lamellipodial extrusions and interestingly, a significant decrease in levels of the protein in HG conditions. The analysis of the translocation of Annexin A1 to cell membrane showed lower levels of Annexin A1 in both membrane pool and supernatants of WS1 cells treated with HG. Wound-healing assays using cell line transfected with Annexin A1 siRNAs indicated a slowing down in migration speed of cells suggesting that Annexin A1 has a role in the migration of WS1 cells. In order to analyze the role of extracellular Annexin A1 in cell migration, we have performed wound-healing assays using Ac2-26 showing that peptide was able to increase fibroblast cell migration in HG conditions. Experiments on the mobilization of intracellular calcium and analysis of p-ERK expression confirmed the activity of the FPR1 following stimulation with the peptide Ac2-26. A wound-healing assay on WS1 cells in the presence of the FPR agonist fMLP, of the FPR antagonist CsH and in the presence of Ac2-26 indicated that Annexin A1 influences fibroblast cell migration under HG conditions acting through FPR receptors whose expression was slightly increased in HG. In conclusion, these data demonstrate that (i) Annexin A1 is involved in migration of WS1 cells, through interaction with FPRs; (ii) N- terminal peptide of Annexin A1 Ac2-26 is able to stimulate direct migration of WS1 cells in high glucose treatment possibly due to the increased receptor expression observed in hyperglycemia conditions.

The potential for estrogens in preventing Alzheimer's disease and vascular dementia

Estrogens are the best-studied class of drugs for potential use in the prevention of Alzheimer's disease (AD). These steroids have been shown to be potent neuroprotectants both in vitro and in vivo, and to exert effects that are consistent with their potential use in prevention of AD. These include the prevention of the processing of amyloid precursor protein (APP) into beta-amyloid (Aß), the reduction in tau hyperphosphorylation, and the elimination of catastrophic attempts at neuronal mitosis. Further, epidemiological data support the efficacy of early postmenopausal use of estrogens for the delay or prevention of AD. Collectively, this evidence supports the further development of estrogen-like compounds for prevention of AD. Several approaches to enhance brain specificity of estrogen action are now underway in an attempt to reduce the side effects of chronic estrogen therapy in AD.

Calpain inhibition protected spinal cord motoneurons against 1-methyl-4-phenylpyridinium ion and rotenone

Parkinson's disease (PD), characterized by selective midbrain nigrostriatal dopaminergic degeneration, is consistently associated with moderate systemic mitochondrial dysfunction. Downstream degeneration of spinal cord has also been suggested in PD, although the mechanisms have not been much investigated. In the present study, two mitochondrial toxicants, 1-methyl-4-phenylpyridinium ion (MPP(+)) and rotenone were tested in ventral spinal cord (VSC 4.1) motoneuronal cells. Cell death was assessed by morphological and biochemical means to discern a lower apoptosis-inducing concentration and lethal concentration of 50% cell death (LC(50)), which were subsequently compared in further cytoprotection experiments. Mitochondrial toxicants dose-dependently induced increase in intracellular free Ca(2+) level, which was conducive for increased expression and activities of Ca(2+)-activated neutral protease calpain and downstream caspase-3. Thus, mitochondrial damage triggered apoptotic mechanisms in spinal cord motoneurons. Inhibition of calpain by calpeptin significantly attenuated damaging effects of MPP(+) and rotenone on motoneurons, especially at low apoptosis-inducing concentrations of toxicants and partly at their LC(50), as demonstrated by absence of DNA ladder formation and decrease in terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells. Cytoprotection by calpeptin was observed with marked decreases in Bax: Bcl-2 ratio and activities of calpain and caspase-3, which affirmed the role of mitochondrial dysfunction and involvement of intrinsic pathway in mediation of apoptosis. These findings strongly suggested that parkinsonian toxicants MPP(+) and rotenone at low doses induced cascade of cell-damaging effects in spinal cord motoneurons, thus, highlighting the possibility of induction of apoptotic mechanisms in these cells, when subjected to mitochondrial stress. Cytoprotection rendered by calpeptin further validated the involvement of calpain in apoptosis and suggested calpain inhibition as a potential neuroprotective strategy.

Estrogen receptor agonists and estrogen attenuate TNF-α-induced apoptosis in VSC4.1 motoneurons

Tumor necrosis factor-alpha (TNF-α) may cause apoptosis and inflammation in amyotrophic lateral sclerosis (ALS) and spinal cord injury (SCI). Recent studies suggest that estrogen (EST) provides neuroprotection against SCI. We tested whether 1,3,5-tris (4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT) (EST receptor alpha (ERα) agonist), 2,3-bis (4-hydroxyphenyl) propionitrile (DPN) (EST receptor beta (ERβ) agonist), or EST itself would prevent apoptosis in VSC4.1 motoneurons following exposure to TNF-α. Cells were exposed to TNF-α and 15 min later treated with PPT, DPN, or EST. Posttreatment with 50 nM PPT, 50 nM DPN, or 150 nM EST prevented cell death in VSC4.1 motoneurons. Treatment of VSC4.1 motoneurons with PPT, DPN, or EST induced overexpression of ERα, ERβ, or both, which contributed to neuroprotection by upregulating expression of anti-apoptotic proteins (p-AKT, p-CREB, Bcl-2, and p-Src). Our analyses also revealed that EST agonists and EST increased phosphorylation of extracellular signal-regulated kinase (ERK). The L-type Ca(2+) channel inhibitor, nifedipine (10 μM), partially inhibited EST agonist and EST-induced increase in phosphorylated ERK expression. The mitogen-activated protein kinase inhibitor, PD98059 (5 μM), partially prevented ER agonists and EST from providing neuroprotection to TNF-α toxicity. Presence of the nuclear ER antagonist, ICI 182 780 (10 μM), blocked the neuroprotection provided by all three ER agonists tested. Taken together, our data indicate that both ERα and ERβ contribute to PPT, DPN, or EST-mediated neuroprotection with similar signaling profiles. Our data strongly imply that PPT, DPN, or EST can be used as effective neuroprotective agents to attenuate motoneuron death in ALS and SCI.

Sex differences in autoimmune diseases

Women are more susceptible to a variety of autoimmune diseases including systemic lupus erythematosus (SLE), multiple sclerosis (MS), primary biliary cirrhosis, rheumatoid arthritis and Hashimoto's thyroiditis. This increased susceptibility in females compared to males is also present in animal models of autoimmune diseases such as spontaneous SLE in (NZBxNZW)F1 and NZM.2328 mice, experimental autoimmune encephalomyelitis (EAE) in SJL mice, thyroiditis, Sjogren's syndrome in MRL/Mp-lpr/lpr mice and diabetes in non-obese diabetic mice. Indeed, being female confers a greater risk of developing these diseases than any single genetic or environmental risk factor discovered to date. Understanding how the state of being female so profoundly affects autoimmune disease susceptibility would accomplish two major goals. First, it would lead to an insight into the major pathways of disease pathogenesis and, secondly, it would likely lead to novel treatments which would disrupt such pathways.

17β-estradiol protects Schwann cells against H2O2-induced cytotoxicity and increases transplanted Schwann cell survival in a cervical hemicontusion spinal cord injury model

Schwann cell (SC) transplantation is a promising repair strategy after spinal cord injury (SCI); however, a large number of SCs do not survive following transplantation. Previous studies have shown that 17β-estradiol (E2) protects several cell types against cytotoxicity. Thus, this study evaluated the protective potential of E2 on SCs in vitro and investigated the effect of E2 on transplanted SC survival in a rat model of SCI. Primary SC cultures were found to robustly express estrogen receptors (ER) and incubation with E2 protected SCs against hydrogen peroxide-induced cell death. This protection was not inhibited by the ER antagonist ICI 182,780, suggesting that genomic signaling is not necessary for protection. In a subsequent experiment, cervical hemicontusion SCI was induced in male rats followed by sustained administration of E2 or placebo. Eight days after SCI, SCs were transplanted into the injury epicenter. E2 treatment significantly increased the number of surviving labeled transplanted SCs evaluated 7 days after transplantation. These data demonstrate that E2 protects SCs against oxidative stress and improves transplanted SC survival, which suggests that E2 administration may be an intervention of choice for enhancing survival of transplanted SCs after SCI.

Pro-apoptotic effect of methylguanidine on hydrogen peroxide-treated rat glioma cell line

Guanidino compounds, as methylguanidine (MG), may play an important role in the etiology of neurological complications which occur in uremic syndrome. Dementia is a neurological complication more common in uremic patients than in general population and several types of dementia are associated to astroglial apoptosis. Here we report the effect of MG on oxidative stress-induced apoptosis in rat glioma cell line (C6) in vitro. The oxidative stress was induced by hydrogen peroxide (H(2)O(2); 1 mM) and the cellular and molecular parameters were observed after 18 h. Uremic conditions were simulated by pre-incubation of C6 cells with MG (0.1-10 mM) 1h before H(2)O(2)-induced oxidative stress. MG alone did not affect cell viability, but it significantly increased cell death induced by H(2)O(2), as assessed by MTT assay. This effect could be related to the MG capability to enhance H(2)O(2) pro-apoptotic effect on C6 cells. The fluorescent dye FURA 2-AM test showed a significant raise in [Ca(2+)](i) in MG and H(2)O(2) co-treated C6 cells, mainly for depolarizing mitochondrial membrane potential. Furthermore, MG in a concentration-dependent manner, significantly increased H(2)O(2)-induced Bax expression, activation of caspase-3 and PARP in C6 cells. This study firstly reports that the uremic catabolyte MG could contribute to neurodegeneration associated to uremia enhancing the pro-apoptotic effect of H(2)O(2) and through an alteration in mitochondrial calcium homeostasis in glial cells.

Inhibition of the progesterone nuclear receptor during the bone linear growth phase increases peak bone mass in female mice

Augmentation of the peak bone mass (PBM) may be one of the most effective interventions to reduce the risk of developing osteoporosis later in life; however treatments to augment PBM are currently limited. Our study evaluated whether a greater PBM could be achieved either in the progesterone nuclear receptor knockout mice (PRKO) or by using a nuclear progesterone receptor (nPR) antagonist, RU486 in mice. Compared to their wild type (WT) littermates the female PRKO mice developed significantly higher cancellous and cortical mass in the distal femurs, and this was associated with increased bone formation. The high bone mass phenotype was partially reproduced by administering RU486 in female WT mice from 1–3 months of age. Our results suggest that the inhibition of the nPR during the rapid bone growth period (1–3 months) increases osteogenesis, which results in acquisition of higher bone mass. Our findings suggest a crucial role for progesterone signaling in bone acquisition and inhibition of the nPR as a novel approach to augment bone mass, which may have the potential to reduce the burden of osteoporosis.

Postinjury estrogen treatment of chronic spinal cord injury improves locomotor function in rats

Spinal cord injury (SCI) causes loss of neurological function and, depending on serverity, may cause paralysis. The only recommended pharmacotherapy for the treatment of SCI is high-dose methylprednisolone, and its use is controversial. We have previously shown that estrogen treatment attenuated cell death, axonal and myelin damage, calpain and caspase activities, and inflammation in acute SCI. The aim of this study was to examine whether posttreatment of SCI with estrogen would improve locomotor function by protecting cells and axons and reducing inflammation during the chronic phase following injury. Moderately severe injury (40 g . cm force) was induced in male Sprague-Dawley rats following laminectomy at T10. Three groups of animals were used: sham (laminectomy only), vehicle (dimethyl sulfoxide; DMSO)-treated injury group, and estrogen-treated injury group. Animals were treated with 4 mg/kg estrogen at 15 min and 24 hr postnjury, followed by 2 mg/kg estrogen daily for the next 5 days. After treatment, animals were sacrificed at the end of 6 weeks following injury, and 1-cm segments of spinal cord (lesion, rostral to lesion, and caudal to lesion) were removed for biochemical analyses. Estrogen treatment reduced COX-2 activity, blocked nuclear factor-kappaB translocation, prevented glial reactivity, attenuated neuron death, inhibited activation and activity of calpain and caspase-3, decreased axonal damage, reduced myelin loss in the lesion and penumbra, and improved locomotor function compared with vehicle-treated animals. These findings suggest that estrogen may be useful as a promising therapeutic agent for prevention of damage and improvement of locomotor function in chronic SCI. (c) 2010 Wiley-Liss, Inc.

Neuroprotective efficacy of estrogen in experimental spinal cord injury in rats

Spinal cord injury (SCI) leads to neurological deficits and motor dysfunction. Methylprednisolone, the only drug used for treating SCI, renders limited neuroprotection and remains controversial. Estrogen is one of the most potent multiactive neuroprotective agents and it is currently under investigation in our laboratory for its efficacy in SCI. The present review briefly summarizes our earlier findings on the therapeutic potential of pharmacological/supraphysiological levels of estrogen in SCI and outlines our ongoing research, highlighting the efficacy of physiological levels of estrogen against neuronal injury, axonal degeneration, and gliosis and also the molecular mechanisms of such neuroprotection in experimental SCI. Furthermore, our ongoing studies designed to explore the different translational potential of estrogen therapy suggest that this multiactive steroid may act as an adjunct therapy to promote angiogenesis, thus enhancing the functional recovery following chronic SCI. Taken together, these studies confirm that estrogen is a potential therapeutic agent for treating SCI.

Physiological low dose of estrogen-protected neurons in experimental spinal cord injury

A protective role for estrogen against neurodegeneration and neurotrauma has received enormous attention in recent years, unraveling multiple facets and thus establishing this steroid as a multiactive neuroprotectant. The present study briefly reports our findings on the neuroprotective efficacy of physiologically relevant low doses of estrogen in experimental spinal cord injury (SCI) in rats. The current finding further corroborates our earlier results on efficacy of pharmacological/supraphysiological levels of estrogen in SCI and adds to the significance of conducting preclinical studies on estrogen efficacy in SCI.

Role of estrogen receptors in pro-oxidative and anti-oxidative actions of estrogens: a perspective

BACKGROUND

Estrogens are steroid hormones responsible for the primary and secondary sexual characteristics in females. While pre-menopausal women use estrogens as the main constituents of contraceptive pills, post-menopausal women use the same for Hormone Replacement Therapy. Estrogens produce reactive oxygen species by increasing mitochondrial activity and redox cycling of estrogen metabolites. The phenolic hydroxyl group present at the C3 position of the A ring of estrogens can get oxidized either by accepting an electron or by losing a proton. Thus, estrogens might act as pro-oxidant in some settings, resulting in complicated non-communicable diseases, namely, cancer and cardiovascular disorders. However, in some other settings the phenolic hydroxyl group of estrogens may be responsible for the anti-oxidative beneficial functions and thus protect against cardiovascular and neurodegenerative diseases.

SCOPE OF REVIEW

To date, no single review article has mentioned the implication of estrogen receptors in both the pro-oxidative and anti-oxidative actions of estrogens.

MAJOR CONCLUSION

The controversial role of estrogens as pro-oxidant or anti-oxidant is largely dependent on cell types, ratio of different types of estrogen receptors present in a particular cell and context specificity of the estrogen hormone responses. Both pro-oxidant and anti-oxidant effects of estrogens might involve different estrogen receptors that can have either genomic or non-genomic action to manifest further hormonal response.

GENERAL SIGNIFICANCE

This review highlights the role of estrogen receptors in the pro-oxidative and anti-oxidative actions of estrogens with special emphasis on neuronal cells.

Estrogen treatment in multiple sclerosis

Currently available treatments for multiple sclerosis (MS) reduce inflammatory lesions on MRI and decrease clinical relapses but have limited effects on disability. Novel treatment options that target both the inflammatory as well as the neurodegenerative component of the disease are therefore needed. A growing body of evidence from basic science and clinical studies supports the therapeutic potential of estrogens in MS. Mechanisms of action include both immunomodulatory and directly neuroprotective pathways. A first pilot trial of oral estriol treatment showed encouraging results. There are now several phase II trials underway to further determine the efficacy of estrogen treatment in MS.

Estrogen attenuates glutamate-induced cell death by inhibiting Ca2+ influx through L-type voltage-gated Ca2+ channels

Estrogen-mediated neuroprotection is observed in neurodegenerative disease and neurotrauma models; however, determining a mechanism for these effects has been difficult. We propose that estrogen may limit cell death in the nervous system tissue by inhibiting increases in intracellular free Ca(2+). Here, we present data using VSC 4.1 cell line, a ventral spinal motoneuron and neuroblastoma hybrid cell line. Treatment with 1 mM glutamate for 24 h induced apoptosis. When cells were pre-treated with 100 nM 17beta-estradiol (estrogen) for 1 h and then co-treated with glutamate, apoptotic death was significantly attenuated. Estrogen also prevented glutamate-mediated changes in resting membrane potential and membrane capacitance. Treatment with either 17 alpha-estradiol or cell impermeable estrogen did not mimic the findings seen with estrogen. Glutamate treatment significantly increased both intracellular free Ca(2+) and the activities of downstream proteases such as calpain and caspase-3. Estrogen attenuated both the increases in intracellular free Ca(2+) and protease activities. In order to determine the pathway responsible for estrogen-mediated inhibition of these increases in intracellular free Ca(2+), cells were treated with several Ca(2+) entry inhibitors, but only the L-type Ca(2+) channel blocker nifedipine demonstrated cytoprotective effects comparable to estrogen. To expand these findings, cells were treated with the L-type Ca(2+) channel agonist FPL 64176, which increased both cell death and intracellular free Ca(2+), and estrogen inhibited both effects. From these observations, we conclude that estrogen limits glutamate-induced cell death in VSC 4.1 cells through effects on L-type Ca(2+) channels, inhibiting Ca(2+) influx as well as activation of the pro-apoptotic proteases calpain and caspase-3.

Chronic beta-AR activation-induced calpain activation and impaired eNOS-Akt signaling mediates cardiac injury in ovariectomized female rats

OBJECTIVE

To address the pathophysiological relevance of ovarian hormones in chronic beta-adrenergic stimulation-induced myocardial injury, we assessed impairments of Ca(2+)-mediated cell signaling in the left ventricle of ovariectomized female rats.

RESEARCH DESIGN/METHODS

Female Wistar rats were subjected to bilateral ovariectomy and sham operation. Six weeks after ovariectomy (OVX), both OVX and sham rats were treated with isoproterenol (5mg/kg, intraperitoneally), a nonselective beta-adrenergic agonist, once a day for 28 days.

RESULTS

We found that chronic beta-adrenergic stimulation caused enhanced breakdown of sarcolemmal proteins such as dystrophin and utrophin in OVX rats compared to sham-operated rats. Generation of calpain-mediated 150 kDa-breakdown product of spectrin confirmed calpain activation following isoproterenol treatment. Marked breakdown of endogenous calpain inhibitor, calpastatin, in OVX rats was consistent with the calpain activation following chronic beta-adrenergic stimulation. In addition to calpain activation, we also found marked reduction of endothelial nitric oxide synthase (eNOS) activity with concomitant deregulation by heat shock proteins 90 kDa and caveolin 3, both of which are eNOS-associated proteins. Finally, we documented decreased Akt phosphorylation with concomitant increased glycogen synthase kinase 3beta phosphorylation underlying cell injury following chronic beta-adrenergic stimulation.

CONCLUSION

Taken together chronic beta-adrenergic stimulation caused severe cardiac injury in OVX rats through calpain activation and impairments of Akt and eNOS signaling pathways.

Estrogen and testosterone therapies in multiple sclerosis

It has been known for decades that females are more susceptible than men to inflammatory autoimmune diseases, including multiple sclerosis (MS), rheumatoid arthritis, and psoriasis. In addition, female patients with these diseases experience clinical improvements during pregnancy with a temporary "rebound" exacerbation postpartum. These clinical observations indicate an effect of sex hormones on disease and suggest the potential use of the male hormone testosterone and the pregnancy hormone estriol, respectively, for the treatment of MS. A growing number of studies using the MS animal model experimental autoimmune encephalomyelitis (EAE) support a therapeutic effect of these hormones. Both testosterone and estriol have been found to induce anti-inflammatory as well as neuroprotective effects. Findings from two recent pilot studies of transdermal testosterone in male MS patients and oral estriol in female MS patients are encouraging. In this paper, we review the preclinical and clinical evidence for sex hormone treatments in MS and discuss potential mechanisms of action.

Cytoprotective effects of melatonin on C6 astroglial cells exposed to glutamate excitotoxicity and oxidative stress

To preserve the central nervous system (CNS) function after a traumatic injury, therapeutic agents must be administered to protect neurons as well as glial cells. Cell death in CNS injuries and diseases are attributed to many factors including glutamate toxicity and oxidative stress. We examined whether melatonin, a potent anti-oxidant and free radical scavenger, would attenuate apoptotic death of rat C6 astroglial cells under glutamate excitotoxicity and oxidative stress. Exposure of C6 cells to 500 microM L-glutamic acid (LGA) and 100 microm hydrogen peroxide (H(2)O(2)) for 24 hr caused significant increases in apoptosis. Apoptosis was evaluated by Wright staining and ApopTag assay. Melatonin receptor 1 appeared to be involved in the protection of these cells from excitotoxic and oxidative damage. Cells undergoing excitotoxic and oxidative stress for 15 min were then treated with 150 nM melatonin, which prevented Ca(2+)influx and cell death. Western blot analyses showed alterations in Bax and Bcl-2 expression resulting in increased Bax:Bcl-2 ratio during apoptosis. Western blot analyses also showed increases in calpain and caspase-3 activities, which cleaved 270 kD alpha-spectrin at specific sites to generate 145 kD spectrin breakdown product (SBDP) and 120 kD SBDP, respectively. However, 15-min post-treatment of C6 cells with melatonin dramatically reduced Bax:Bcl-2 ratio and proteolytic activities, decreasing LGA or H(2)O(2)-induced apoptosis. Our data showed that melatonin prevented proteolysis and apoptosis in C6 astroglial cells. The results suggest that melatonin may be an effective cytoprotective agent against glutamate excitotoxicity and oxidative stress in CNS injuries and diseases.

Protective effect of ultra low molecular weight heparin on glutamate-induced apoptosis in cortical cells

PURPOSE

To investigate the effect of ultra low molecular weight heparin (ULMWH) on glutamate induced apoptosis in rat cortical cells and to explore the possible mechanisms.

MATERIALS AND METHODS

Cell viability was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was first analyzed with Hoechst 33258 and then confirmed by DNA fragmentation. The concentration of free intracellular calcium ([Ca(2+)](i)) was determined with fura-2/AM fluorometry. The expression of Bcl-2 family protein and caspase-3 were evaluated with Western blot.

RESULTS

Typical apoptotic morphological change in rat cortical cells treated with 100 micromol/L glutamate for 24h was detected by Hoechst 33258 staining, which was then confirmed by the DNA ladder of agarose gel electrophoresis. The apoptotic rate of the glutamate treated cells was up to 33.21%, and 24 h of treatment with glutamate increased [Ca(2+)](i), down-regulated Bcl-2 expression, up-regulated Bax expression, and increased caspase-3 activation in rat cortical cells. Our research demonstrated that ULMWH pretreatment can prevent the glutamate-induced apoptosis, attenuate the increase of [Ca(2+)](i) not only in medium containing Ca(2+) but also in Ca(2+)-free medium, up-regulate the expression of Bcl-2, down-regulate the expression of Bax, and decrease caspase-3 activation.

CONCLUSION

ULMWH has neuroprotective capacity to antagonize glutamate-induced apoptosis in cortical cells, through decrease of Ca(2+) release and modulation of apoptotic processes.

Melatonin attenuates calpain upregulation, axonal damage and neuronal death in spinal cord injury in rats

Multiple investigations in vivo have shown that melatonin (MEL) has a neuroprotective effect in the treatment of spinal cord injury (SCI). This study investigates the role of MEL as an intervening agent for ameliorating Ca(2+)-mediated events, including activation of calpain, following its administration to rats sustaining experimental SCI. Calpain, a Ca(2+)-dependent neutral protease, is known to be involved in the pathogenesis of SCI. Rats were injured using a standard weight-drop method that induced a moderately severe injury (40 g.cm force) at T10. Sham controls received laminectomy only. Injured animals were given either 45 mg/kg MEL or vehicle at 15 min post-injury by intraperitoneal injection. At 48 hr post-injury, spinal cord (SC) samples were collected. Immunofluorescent labelings were used to identify calpain expression in specific cell types, such as neurons, glia, or macrophages. Combination of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) and double immunofluorescent labelings was used to identify apoptosis in specific cells in the SC. The effect of MEL on axonal damage was also investigated using antibody specific for dephosphorylated neurofilament protein (dNFP). Treatment of SCI animals with MEL attenuated calpain expression, inflammation, axonal damage (dNFP), and neuronal death, indicating that MEL provided neuroprotective effect in SCI. Further, expression and activity of calpain and caspse-3 were examined by Western blotting. The results indicated a significant decrease in expression and activity of calpain and caspse-3 in SCI animals after treatment with MEL. Taken together, this study strongly suggested that MEL could be an effective neuroprotective agent for treatment of SCI.

Increased calpain correlates with Th1 cytokine profile in PBMCs from MS patients

Multiple sclerosis (MS) is a devastating autoimmune demyelinating disease of the central nervous system (CNS). This study investigated whether expression and activity of the calcium-activated protease calpain correlated with Th1/Th2 dysregulation in MS patients during states of relapse and remission. Calpain expression and activity were significantly increased in peripheral blood mononuclear cells (PBMCs) from MS patients, compared to controls, with the highest expression and activity noted during relapse. Th1 cytokines were highest and Th2 cytokines were lowest in MS patients during relapse. Treatment with calpain inhibitor, calpeptin, decreased Th1 cytokines in PBMCs from MS patients. Calpain inhibitor also reduced degradation of myelin basic protein (MBP) by inhibiting the calpain secreted from MBP-specific T cells. Taken together, these results suggested calpain involvement in Th1/Th2 dysregulation in MS patients.

Inhibitory effects of pharmacological doses of melatonin on aromatase activity and expression in rat glioma cells

Melatonin exerts oncostatic effects on different kinds of neoplasias, especially on oestrogen-dependent tumours. Recently, it has been described that melatonin, on the basis of its antioxidant properties, inhibits the growth of glioma cells. Glioma cells express oestrogen receptors and have the ability to synthesise oestrogens from androgens. In the present study, we demonstrate that pharmacological concentrations of melatonin decreases the growth of C6 glioma cells and reduces the local biosynthesis of oestrogens, through the inhibition of aromatase, the enzyme that catalyses the conversion of androgens into oestrogens. These results are supported by three types of evidence. Firstly, melatonin counteracts the growth stimulatory effects of testosterone on glioma cells, which is dependent on the local synthesis of oestrogens from testosterone. Secondly, we found that melatonin reduces the aromatase activity of C6 cells, measured by the tritiated water release assay. Finally, by (RT)–PCR, we found that melatonin downregulates aromatase mRNA steady-state levels in these glioma cells. We conclude that melatonin inhibits the local production of oestrogens decreasing aromatase activity and expression. By analogy to the implications of aromatase in other forms of oestrogen-sensitive tumours, it is conceivable that the modulation of the aromatase by pharmacological melatonin may play a role in the growth of glioblastomas.

The anti-apoptosis effects of daidzein in the brain of D-galactose treated mice

The purpose of this study was to explore the neuroprotective effects of daidzein on the apoptotic pathway in the hippocampus and cortex of D-galactose treated mice. For this purpose we have examined the expression of bcl-2 mRNA, bax mRNA and caspase-3 in the hippocampus and cortex of D-galactose-treated mice after fed with 10 or 5 mg/kg of daidzein. The results of in situ hybridization experiments indicate that daidzein could help increase the transcriptions of bcl-2 and decrease the transcriptions of bax in those brain regions of D-galactose-treated mice. Furthermore, immunohistochemical studies showed that daidzein could reduce the expression of caspase-3 in both brain regions. These results suggest that daidzein in soybean can inhibit the D-gal induced apoptosis via Bcl-2/Bax apoptotic pathway and be a potential medical candidate for neurodegeneration therapy.

Methylprednisolone and indomethacin inhibit oxidative stress mediated apoptosis in rat C6 glioblastoma cells

Glioblastoma patients receive anti-inflammatory agent for alleviation of vasogenic edema and pain prior to surgery, radiotherapy, and chemotherapy. Oxidative stress is an important mechanism of action of some chemotherapeutic agents in the treatment of glioblastoma. So, we examined the modulatory effects of methylprednisolone (MP, a steroidal anti-inflammatory agent) and indomethacin (IM, a non-steroidal anti-inflammatory agent) on apoptosis in rat C6 glioblastoma cells following oxidative stress with hydrogen peroxide (H(2)O(2)). Exposure of C6 cells to 1 mM H(2)O(2) for 24 h caused significant amounts of morphological and biochemical features of apoptosis. Expressions of Bax and Bcl-2 at mRNA and protein levels were altered resulting in an increase in Bax : Bcl-2 ratio in apoptotic cells, which also exhibited overexpression of 80 kDa calpain and an increase in calpain-cleaved 145 kDa alpha-spectrin breakdown product. Immunofluorescent and propidium iodide labeling detected caspase-3-p20 fragment in apoptotic cells, indicating activation of caspase-3 as well. Treatment of cells with 1 microM MP or 10 microM IM alone did not induce apoptosis. Pretreatment (1 h) with either 1 microM MP or 10 microM IM significantly inhibited H(2)O(2) mediated apoptosis in C6 cells. Thus, pretreatment of glioblastoma with an anti-inflammatory agent, either steroidal or non-steroidal, may compromise the action of a chemotherapeutic agent that mediates therapeutic action via oxidative stress.

Estrogen treatment of spinal cord injury attenuates calpain activation and apoptosis

Spinal cord injury (SCI) is a devastating neurologic injury, and currently, the only recommended pharmacotherapy is high-dose methylprednisolone, which has limited efficacy. Estrogen is a multi-active steroid with anti-oxidant and anti-apoptotic effects. Estrogen may modulate intracellular Ca2+ and prevent inflammation. For this study, male rats were divided into three groups. Sham-group animals received a laminectomy at T12. Injured rats received both laminectomy and 40 gram centimeter force SCI. Estrogen-group rats received 4 mg/kg 17beta-estradiol (estrogen) at 15 min and 24 hr post-injury, and vehicle-group rats received equal volumes of dimethyl sulfoxide. Animals were sacrificed at 48 hr post-injury, and 1-cm segments of the lesion, rostral penumbra, and caudal penumbra were excised. The degradation of 68 kD neurofilament protein (NFP) and estrogen receptors (ER) was examined by Western blot analysis. Protein levels of calpain and the activities of calpain and caspase-3 were also examined. Levels of cytochrome c were determined in both cytosolic and mitochondrial fractions. Cell death with DNA fragmentation was examined using the TUNEL assay. At the lesion, samples from both vehicle and estrogen treated animals showed increased levels of 68 kD NFP degradation, calpain content, calpain activity, cytochrome c release, and degradation of ERalpha and ERbeta, as compared to sham. In the caudal penumbra, estrogen treatment significantly attenuated 68 kD NFP degradation, calpain content, calpain activity, levels of cytosolic cytochrome c, and ERbeta degradation. At the lesion, vehicle-treated animals displayed more TUNEL+ cells, and estrogen treatment significantly attenuated this cell death marker. We conclude that estrogen may inhibit cell death in SCI through calpain inhibition.

Caspase-3- and calpain-mediated tau cleavage are differentially prevented by estrogen and testosterone in beta-amyloid-treated hippocampal neurons

A growing body of evidence suggests that the proteolytic cleavage of the microtubule-associated protein tau, the main component of neurofibrillary tangles, might play a role in the molecular mechanisms underlying beta-amyloid (Abeta) -induced neurotoxicity in central neurons. In the present study, we analyzed whether sex hormones could prevent such tau cleavage, and hence, protect rat hippocampal neurons against Abeta toxicity. Our results indicated that estrogen and testosterone prevented caspase-3- and calpain-mediated tau cleavage, respectively. Thus, estrogen decreased the levels of caspase-3-cleaved 50-kDa truncated tau, while testosterone prevented the generation of a calpain-cleaved 17-kDa tau fragment. In addition, our results showed that the decrease in the levels of these tau proteolytic forms was accompanied by an increased cell survival in Abeta-treated neurons. Furthermore, our findings indicated that testosterone was more effective than estrogen in protecting hippocampal neurons against Abeta-induced cell death. Collectively, our data suggest that preventing the decline of estrogen and testosterone associated with normal aging might reduce the susceptibility of central neurons to Abeta-induced toxicity.

Acyl-based anandamide uptake inhibitors cause rapid toxicity to C6 glioma cells at pharmacologically relevant concentrations

Compounds blocking the uptake of the endogenous cannabinoid anandamide (AEA) have been used to explore the functions of the endogenous cannabinoid system in the CNS both in vivo and in vitro. In this study, the effects of four commonly used acyl-based uptake inhibitors [N-(4-hydroxyphenyl)arachidonylamide (AM404), N-(4-hydroxy-2-methylphenyl) arachidonoyl amide (VDM11), (5Z,8Z,11Z,14Z)-N-(3-furanylmethyl)-5,8,11,14-eicosatetraenamide (UCM707) and (9Z)-N-[1-((R)-4-hydroxybenzyl)-2-hydroxyethyl]-9-octadecen-amide (OMDM2)] and the related compound arvanil on C6 glioma cell viability were investigated. All five compounds reduced the ability of the cells to accumulate calcein, reduced the total nucleic acid content and increased the activity of lactate dehydrogenase recovered in the cell medium. AM404 (10 microm) and VDM11 (10 microm) acted rapidly, reducing cell viability after 3 h of exposure when cell densities of 5,000 per well were used. In contrast, UCM707 (30 microm), OMDM2 (10 microm) and the related compound arvanil (10 microm) produced a more slowly developing effect on cell viability, although robust effects were seen after 6-9 h of exposure. At higher cell densities, the toxicities of AM404 and UCM707 were reduced. Comparison of the compounds with arachidonic acid, arachidonic acid methyl ester, AEA, arachidonoyl glycine and oleic acid suggested that the toxicity of the arachidonoyl-based compounds was related primarily to the acyl side-chain rather than the head group. A variety of pre-treatments blocking possible metabolic pathways and receptor targets were tested, but the only consistent protective treatment against the effects of these compounds was the antioxidant N-acetyl-L-cysteine. It is concluded that AM404, VDM11, UCM707 and OMDM2 produce a rapid loss of C6 glioma cell viability over the same concentration range as is required for the inhibition of AEA uptake in vitro, albeit with a longer latency. Such effects should be kept in mind when acyl-derived compounds are used to probe the function of the endocannabinoid system in the CNS, particularly in chronic administration protocols.

Treatment with an estrogen receptor alpha ligand is neuroprotective in experimental autoimmune encephalomyelitis

Multiple sclerosis is an inflammatory, neurodegenerative disease for which experimental autoimmune encephalomyelitis (EAE) is a model. Treatments with estrogens have been shown to decrease the severity of EAE through anti-inflammatory mechanisms. Here we investigated whether treatment with an estrogen receptor alpha (ERalpha) ligand could recapitulate the estrogen-mediated protection in clinical EAE. We then went on to examine both anti-inflammatory and neuroprotective mechanisms. EAE was induced in wild-type, ERalpha-, or ERbeta-deficient mice, and each was treated with the highly selective ERalpha agonist, propyl pyrazole triol, to determine the effect on clinical outcomes, as well as on inflammatory and neurodegenerative changes. ERalpha ligand treatment ameliorated clinical disease in both wild-type and ERbeta knock-out mice, but not in ERalpha knock-out mice, thereby demonstrating that the ERalpha ligand maintained ERalpha selectivity in vivo during disease. ERalpha ligand treatment also induced favorable changes in autoantigen-specific cytokine production in the peripheral immune system [decreased TNFalpha, interferon-gamma, and interleukin-6, with increased interleukin-5] and decreased CNS white matter inflammation and demyelination. Interestingly, decreased neuronal staining [NeuN+ (neuronal-specific nuclear protein)/beta3-tubulin+/Nissl], accompanied by increased immunolabeling of microglial/monocyte (Mac 3+) cells surrounding these abnormal neurons, was observed in gray matter of spinal cords of EAE mice at the earliest stage of clinical disease, 1-2 d after the onset of clinical signs. Treatment with either estradiol or the ERalpha ligand significantly reduced this gray matter pathology. In conclusion, treatment with an ERalpha ligand is highly selective in vivo, mediating both anti-inflammatory and neuroprotective effects in EAE.

Glutamate-induced apoptosis in neuronal cells is mediated via caspase-dependent and independent mechanisms involving calpain and caspase-3 proteases as well as apoptosis inducing factor (AIF) and this process is inhibited by equine estrogens

BACKGROUND

Glutamate, a major excitatory amino acid neurotransmitter, causes apoptotic neuronal cell death at high concentrations. Our previous studies have shown that depending on the neuronal cell type, glutamate-induced apoptotic cell death was associated with regulation of genes such as Bcl-2, Bax, and/or caspase-3 and mitochondrial cytochrome c. To further delineate the intracellular mechanisms, we have investigated the role of calpain, an important calcium-dependent protease thought to be involved in apoptosis along with mitochondrial apoptosis inducing factor (AIF) and caspase-3 in primary cortical cells and a mouse hippocampal cell line HT22.

RESULTS

Glutamate-induced apoptotic cell death in neuronal cells was associated with characteristic DNA fragmentation, morphological changes, activation of calpain and caspase-3 as well as the upregulation and/or translocation of AIF from mitochondria into cytosol and nuclei. Our results reveal that primary cortical cells and HT22 cells display different patterns of regulation of these genes/proteins. In primary cortical cells, glutamate induces activation of calpain, caspase-3 and translocation of AIF from mitochondria to cytosol and nuclei. In contrast, in HT22 cells, only the activation of calpain and upregulation and translocation of AIF occurred. In both cell types, these processes were inhibited/reversed by 17beta-estradiol and Delta8,17beta-estradiol with the latter being more potent.

CONCLUSION

Depending upon the neuronal cell type, at least two mechanisms are involved in glutamate-induced apoptosis: a caspase-3-dependent pathway and a caspase-independent pathway involving calpain and AIF. Since HT22 cells lack caspase-3, glutamate-induced apoptosis is mediated via the caspase-independent pathway in this cell line. Kinetics of this apoptotic pathway further indicate that calpain rather than caspase-3, plays a critical role in the glutamate-induced apoptosis. Our studies further indicate that glutamate- induced changes of these proteins can be inhibited by estrogens, with Delta8,17beta-estradiol, a novel equine estrogen being more potent than 17beta-estradiol. To our knowledge, this is the first demonstration that glutamate-induced apoptosis involves regulation of multiple apoptotic effectors that can be inhibited by estrogens. Whether these observations can help in the development of novel therapeutic approaches for the prevention of neurodegenerative diseases with estrogens and calpain inhibitors remains to be investigated.

Activation of multiple molecular mechanisms for apoptosis in human malignant glioblastoma T98G and U87MG cells treated with sulforaphane

Glioblastoma is the most malignant and prevalent brain tumor that still remains incurable. Recent studies reported anti-cancer effect of the broccoli-derived compound sulforaphane. We explored the mechanisms of sulforaphane-mediated apoptosis in human glioblastoma T98G and U87MG cells. Wright staining and ApopTag assay confirmed apoptosis in glioblastoma cells treated with sulforaphane. Increase in intracellular free Ca2+ was detected by fura-2 assay, suggesting activation of Ca2+-dependent pathways for apoptosis. Western blotting was used to detect changes in expression of Bax and Bcl-2 proteins resulting in increased Bax:Bcl-2 ratio that indicated a commitment of glioblastoma cells to apoptosis. Upregulation of calpain, a Ca2+-dependent cysteine protease, activated caspase-12 that in turn caused activation of caspase-9. With the increased Bax:Bcl-2 ratio, cytochrome c was released from mitochondria to cytosol for sequential activation of caspase-9 and caspase-3. Increased calpain and caspase-3 activities generated 145 kD spectrin breakdown product and 120 kD spectrin breakdown product, respectively. Activation of caspase-3 also cleaved the inhibitor-of-caspase-activated-DNase. Accumulation of apoptosis-inducing-factor in cytosol suggested caspase-independent pathway of apoptosis as well. Two of the inhibitor-of-apoptosis proteins were downregulated because of an increase in 'second mitochondrial activator of caspases/Direct inhibitor-of-apoptosis protein binding protein with low pI.' Decrease in nuclear factor kappa B and increase in inhibitor of nuclear factor kappa B alpha expression favored the process of apoptosis. Collectively, our results indicated activation of multiple molecular mechanisms for apoptosis in glioblastoma cells following treatment with sulforaphane.

Overexpression of von Hippel-Lindau tumor suppressor protein and antisense HIF-1alpha eradicates gliomas

The von Hippel-Lindau tumor suppressor protein (pVHL) suppresses tumor formation by binding the alpha subunits of hypoxia-inducible-factors responsible for stimulating tumor angiogenesis and glycolysis, and targeting them for ubiquitination and proteasomal destruction. Loss of pVHL leads to tumorigenesis and development of sporadic renal cell carcinomas and central nervous system hemangioblastomas. In the present study, we investigated whether engineered overexpression of pVHL in C6 glioma cells, which already express endogenous pVHL, would suppress the tumorigenicity of this particular tumor cell type. C6 cells overexpressing VHL displayed a reduced growth rate (70% inhibition) compared to the parental cell line when subcutaneously implanted in athymic (nu/nu) mice. Growth inhibition was associated with a 50% reduction in the number of tumor vessels and a 60% increase in tumor cell apoptosis, due in part to downregulation of HIF-1, VEGF, and the antiapoptotic factor Bcl-2, respectively. Gene transfer of VHL suppressed the growth of established C6 gliomas, and synergized with antisense HIF-1 to completely eradicate tumors. The data suggest that VHL gene therapy and/or agents that increase VHL expression could have utility in the treatment of gliomas, particularly when combined with agents that inhibit the expression or function of HIF-1.