Potential neuroprotective effects of 2-hydroxypropyl-ß cyclodextrin against amyloid ß (1-42)-induced neurotoxicity on the rat hippocampus.

The neurodegenerative mechanisms of Alzheimer's disease (AD) are not fully understood, but it is believed that amyloid beta (Aß) peptide causes oxidative stress, neuroinflammation, and disrupts metabotropic glutamate receptor 5 (mGluR5) signaling by interacting with cholesterol and caveolin-1 (Cav-1) in pathogenic lipid rafts. This study examined the effect of 2-hydroxypropyl-ß-cyclodextrin (HP-CD) on cholesterol, oxidative stress (total oxidant status), neuroinflammation (TNF-α), and mGluR5 signaling molecules such as PKCß1, PKCß2, ERK1/2, CREB, BDNF, and NGF in Aß (1-42)-induced neurotoxicity. The Sprague-Dawley rats were divided into four groups: control (saline), Aß (1-42), HP-CD (100 mg/kg), and Aß (1-42) + HP-CD (100 mg/kg). All groups received bilateral stereotaxic injections of Aß (1-42) or saline into the hippocampus. After surgery, HP-CD was administered intraperitoneally (ip) for 7 days. Cholesterol, TNF-α, and TOS levels were measured in synaptosomes isolated from hippocampus tissue using spectrophotometry, fluorometry, and enzyme immunoassay, respectively. The gene expressions of Cav-1, mGluR5, PKCß1, PKCß2, ERK1/2, CREB, BDNF, and NGF in hippocampus tissue were evaluated using reverse transcription PCR after real-time PCR analysis. Treatment with Aß (1-42) significantly elevated cholesterol, TOS, TNF-α, Cav-1, PKCß2, and ERK1/2 levels. Additionally, mGluR5, CREB, and BDNF levels were shown to be lowered. HP-CD reduced cholesterol, TOS, and TNF-α levels while increasing mGluR5, CREB, and BDNF in response to Aß (1-42) treatment. These findings indicate that HP-CD may have neuroprotective activity due to the decreased levels of cholesterol, oxidative stress, and neuroinflammation, as well as upregulated levels of mGluR5, CREB, and BDNF.

Ex vivo protective effects of nicotinamide and 3-aminobenzamide on rat synaptosomes treated with Aß(1-42).

Alzheimer's disease (AD) is the most common form of dementia and is characterized by the presence of senile plaques and neurofibrillary tangles, along with synaptic loss. The underlying mechanisms of AD are not clarified yet, but oxidative stress and mitochondrial dysfunction are important factors. Overactivation of poly(adenosine diphosphate ribose) polymerase-1 (PARP-1) enzyme has been known to cause neuroinflammation and cell death in neurodegenerative processes. The aim of the present study was to investigate the protective effects of the PARP-1 inhibitors, 3-aminobenzamide (3-AB) and nicotinamide (NA), against amyloid ß peptide (1-42) (Aß(1-42))-induced oxidative damage and mitochondrial reduction capacity on isolated synaptosomes. Rats were injected intraperitoneally with 3-AB (30-100 mg kg(-1)), NA (100-500 mg kg(-1)) or with saline for 7 days. Synaptosomes were incubated with 10-30 µM Aß(1-42) or saline for 6 h at 37 °C. Ex vivo Aß(1-42) treatment significantly induced oxidative stress and mitochondrial dysfunction in synaptosomes of the saline group, while synaptosomes of 3-AB and NA groups showed significant decreases in lipid peroxidation, reactive oxygen species production and protein oxidation. Moreover, both NA and 3-AB were able to improve the mitochondrial reduction capacity against Aß(1-42). These data suggest that NA and 3-AB may have protective effects in neurodegenerative processes because of the reduced levels of oxidative stress and the improvement of mitochondrial function.

Establishment and Validation of an Automated System for the Antifactor IIa Assay: A Case Study of Potency Assessment of a Pharmaceutical Gel Formulation.

Antithrombotic agents and anticoagulant drugs, such as those from the heparin family, are employed in clinical settings for the prevention and treatment of clotting, thromboembolism, and wound healing. The potency assessment of antithrombotic agents is typically conducted using antifactor IIa assay with manual systems which are time-consuming and often lack repeatability. Here, we present a novel automated system that significantly enhances assay repeatability, attaining an outstandingly low relative standard deviation (RSD) % of only 0.6% for repeatability. This system has been applied to a pharmaceutical gel formulation for wound healing developed by Abdi Ibrahim Pharmaceuticals R&D Center as a case study for validation. The automated system demonstrated substantial improvements over manual systems in linearity (R2 = 0.9927), precision, accuracy, specificity, and robustness. The system aligns with the European Pharmacopoeia specifications, promising to enhance quality control across pharmaceutical formulations and conduct absorbance-based end-point assays within the pharmaceutical industry while offering increased throughput and cost-effectiveness.

Mu opioid receptor mRNA expression, binding, and functional coupling to G-proteins in human epileptic hippocampus.

Mu opioid receptors (MOR) are known to be involved in seizure activity. The main goal of the present study was to characterize the MOR mRNA expression, binding, as well as G protein activation mediated by these receptors in epileptic hippocampus of patients with pharmacoresistant mesial temporal lobe epilepsy (TLE). In contrast with autopsy samples, hippocampus obtained from patients with mesial TLE demonstrated enhanced MOR mRNA expression (116%). Saturation binding experiments revealed significantly higher (60%) B(max) values for the mesial TLE group, whereas the K(d) values were not statistically different. Although mesial TLE group demonstrated high levels of basal binding for the G proteins (136%), DAMGO-stimulated [(35)S]GTPγS binding did not demonstrate significant alterations. In conclusion, our present data provide strong evidence that the epileptic hippocampus of patients with pharmacoresistant mesial TLE presents significant alterations in MOR. Such changes may represent adaptive mechanisms to compensate for other as yet unknown alterations.

Effects of non-steroidal antiinflammatory drugs on D-serine-induced oxidative stress in vitro.

Inflammation is deleterious for organs with reduced capacity of regeneration, such as the brain. Recently, studies have focused on investigating the therapeutic effects of nonsteroidal anti-inflammatory drugs (NSAIDs) in Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. Excitotoxicity is the pathological process when receptors for the excitatory neurotransmitter glutamate, such as the N-methyl-D-aspartate (NMDA), receptors are overactivated. This process may be involved in neurodegenerative diseases. D-serine is one of the coagonist of NMDA receptors, and increased levels of D-serine are associated with excitotoxicity. In our study, the potential neuroprotective effects of mefenamic acid, acetaminophen, and naproxen sodium were investigated against D-serine-induced oxidative stress in the rat brain in vitro. To show their potential neuroprotective properties, NSAIDs were incubated with D-serine and reactive oxygen species (ROS), malondialdehyde, and protein carbonyl content of the brain after different treatments were measured. Our results demostrate that NSAIDs used in the present study significantly reduced ROS production, lipid peroxidation, and protein oxidation against D-serine treatment.

γ-glutamylcysteine ethyl ester protects cerebral endothelial cells during injury and decreases blood-brain barrier permeability after experimental brain trauma.

Oxidative stress is a pathway of injury that is common to almost all neurological conditions. Hence, methods to scavenge radicals have been extensively tested for neuroprotection. However, saving neurons alone may not be sufficient in treating CNS disease. In this study, we tested the cytoprotective actions of the glutathione precursor gamma-glutamylcysteine ethyl ester (GCEE) in brain endothelium. First, oxidative stress was induced in a human brain microvascular endothelial cell line by exposure to H(2)O(2). Addition of GCEE significantly reduced formation of reactive oxygen species, restored glutathione levels which were reduced in the presence of H(2)O(2), and decreased cell death during H(2)O(2)-mediated injury. Next, we asked whether GCEE can also protect brain endothelial cells against oxygen-glucose deprivation (OGD). As expected, OGD disrupted mitochondrial membrane potentials. GCEE was able to ameliorate these mitochondrial effects. Concomitantly, GCEE significantly decreased endothelial cell death after OGD. Lastly, our in vivo experiments using a mouse model of brain trauma show that post-trauma (10 min after controlled cortical impact) administration of GCEE by intraperitoneal injection results in a decrease in acute blood-brain barrier permeability. These data suggest that the beneficial effects of GCEE on brain endothelial cells and microvessels may contribute to its potential efficacy as a neuroprotective agent in traumatic brain injury.

D-serine treatment induces oxidative stress in rat brain.

D-serine plays a significant role in neuronal activity, including learning, memory, neuronal migration at developmental stages, and cell-death signaling. It has been also suggested that D-serine can potantiate the neurotoxicity induced by N-methyl-D-aspartate (NMDA) receptor activation due to its coagonist function. However, little is known about the role of D-serine in oxidative stress mechanisms. The aim of this study was to determine the possible neurotoxic or oxidative effects of the dose- (50-200 mg/kg) and time-dependent (2 or 6 hours) D-serine administration on lipid, protein, DNA, mitochondrial integrity (i.e., function), levels of antioxidant enzyme activities (e.g., catalase, glutathione peroxidase, and superoxide dismutase), and glutathione (GSH) in the rat brain. Our results showed that D-serine significantly increases the levels of lipid peroxidation, protein carbonyls, and DNA damage. In addition, D-serine treatment changes cellular antioxidant status due to the decreased levels of antioxidant enzymes, GSH, and mitochondrial function. Therefore, it is concluded that the regulation of D-serine levels in the brain may be an important target for the development of neuroprotective strategies against neurodegenerative processes where excitotoxicity is involved.

The levels of glutathione and nitrite-nitrate and the expression of Bcl-2 mRNA in ovariectomized rats treated by raloxifene against kainic acid.

The selective estrogen receptor modulators (SERMs) are compounds that activate the estrogen receptors with different estrogenic and antiestrogenic tissue-specific effects. The similar effects of SERMs on estrogen encourage the efforts in the research of neuroprotective effects of SERMs. In our study, the potential neuroprotective effects of raloxifene were investigated on the brain cortex of ovariectomized rats after kainic acid-induced oxidative stress. To show the neuroprotective effect of raloxifene against a neurodegenerative agent, kainic acid, expression of Bcl-2, total glutathione (GSH), and nitrite-nitrate levels were investigated in the rat brain cortex. Our results demostrate that raloxifene treatment against oxidative stress significantly increases the expression of Bcl-2 and the level of GSH in the brain cortex.

Studies on mefenamic acid microparticles: formulation, in vitro release, and in situ studies in rats.

In this study, we investigated the in vitro characteristics of mefenamic acid (MA) microparticles as well as their effects on DNA damage. MA-loaded chitosan and alginate beads were prepared by the ionotropic gelation process. Microsponges containing MA and Eudragit RS 100 were prepared by quasi-emulsion solvent diffusion method. The microparticles were characterized in terms of particle size, surface morphology, encapsulation efficiency, and in vitro release profiles. Most of the formulation variables manifested an influence on the physical characteristics of the microparticles at varying degrees. We also studied the effects of MA, MA-loaded microparticles, and three different polymers on rat brain cortex DNA damage. Our results showed that DNA damage was higher in MA-loaded Eudragit microsponges than MA-loaded biodegradable chitosan or alginate microparticles.

Neuroprotective Effects of Engineered Polymeric Nasal Microspheres Containing Hydroxypropyl-ß-cyclodextrin on ß-Amyloid (1-42)-Induced Toxicity.

ß-Amyloid (Aß) plaques are the key neurotoxic assemblies in Alzheimer disease. It has been suggested that an interaction occurs between membrane cholesterol and Aß aggregation in the brain. Cyclodextrins can remove cholesterol from cell membranes and change receptor function. This study aimed to investigate the effect of hydroxypropyl-ß-cyclodextrin (HP-CD) polymeric microspheres, based on chitosan or sodium alginate, on the levels of lipid peroxidation, reactive oxygen species production, and mitochondrial function in brain synaptosomes. The effect of microspheres on DNA fragmentation, the expression of Bcl-2, Bax, and Apex1 mRNAs in rat hippocampus after Aß(1-42) peptide-induced neurotoxicity was also evaluated. Comparison with HP-CD raw material was performed. Aß(1-42) treatment significantly decreased the mitochondrial activity of Apex1 and Bcl-2 mRNAs, induced DNA fragmentation, and increased mRNA levels of Bax. Treatment with HP-CD microspheres against Aß(1-42) significantly reduced DNA fragmentation and increased the Bcl-2/Bax mRNA ratio and mitochondrial function. In addition, HP-CD microspheres used against Aß(1-42) decreased the levels of lipid peroxidation and reactive oxygen species production. These results indicate that nasally administered spray-dried HP-CD microspheres are able to provide protection against Aß(1-42)-induced neurotoxicity, due to the suppressed levels of oxidative stress and apoptotic signals in the rat hippocampus.

STAT-dependent upregulation of 12/15-lipoxygenase contributes to neuronal injury after stroke.

Oxidative stress is a major brain injury mechanism after ischemic stroke. 12/15-lipoxygenase (12/15-LOX) is a key mediator of oxidative stress, contributing to neuronal cell death and vascular leakage. Nonetheless, the mechanism leading to its upregulation is currently unknown. We show here that Signal Transducers and Activators of Transcription (STATs), specifically STAT6 and possibly STAT1, increase transcription of 12/15-LOX in neuronal cells. Both p-STAT6 and -1 bound to specific STAT binding sites in the mouse 12/15-LOX promoter. Small interfering RNA (siRNA) knockdown showed STAT6 to be the dominant regulator, reducing 12/15-LOX promoter activation and cell death in oxidatively stressed HT22 cells. STAT6 siRNA efficiently prevented the increase of 12/15-LOX in murine primary neurons, both after induction of oxidative stress and after oxygen-glucose deprivation. Early activation of STAT6 and STAT1 in mice was consistent with a role in regulating 12/15-LOX in focal ischemia. Brains of human stroke patients showed increased p-STAT6 and p-STAT1 in the peri-infarct region, along with 12/15-LOX and markers of apoptosis. These results link STAT6 and STAT1 to the 12/15-LOX damage pathway and suggest disregulation of STAT-dependent transcription as injury mechanism in stroke. Selectively targeting STATs may thus be a novel therapeutic approach to reducing brain injury after a stroke.

Coenzyme Q10 concentrations in coronary artery disease.

OBJECTIVES: Ubiquinone-10 (CoQ10: the oxidized form of Coenyzme Q) is recognized as an antioxidant in the mitochondrial membrane and considered an anti-risk factor for coronary artery disease (CAD). The aim of this report is to determine the levels of plasma CoQ10 and the ratios of CoQ10 to plasma lipids in CAD patients and to compare them to a matched control group. METHODS: Sixty-four consecutive patients with CAD were studied and compared to 34 clinically healthy individuals. In addition to conventional lipid and lipoprotein analyses, plasma CoQ10 concentrations were measured by electrochemical high pressure liquid chromatography (EC-HPLC) after extraction of plasma with hexane-ethanol. RESULTS: Plasma CoQ10 concentrations in patients with CAD and controls were found as 0.77 and 0.41 micromol/l, respectively (P < 0.01). Also, the ratio of CoQ10 to low density lipoprotein (LDL) was found significantly lower in patients with CAD when compared to controls (P < 0.01). CONCLUSIONS: Our results indicate that a relation exists between low plasma CoQ10 concentration and coronary artery disease, yet this correlation is not strong enough to indicate a causal relationship.

Altered gene expressions in rat hippocampus after kainate injection with or without melatonin pre-treatment.

The expressions of Bcl-2, Bax and thioredoxin (Trx) mRNAs after kainic acid (KA) injection with or without melatonin pre-treatment were examined by real-time quantitative reverse transcription polymerase chain reaction in rat hippocampus. Bcl-2, Bax, and Trx mRNA expressions after KA injection were significantly increased. Additionally, it was observed that melatonin or melatonin pre-treatment had no significant effect on the regulation of Trx mRNA. Pre-treatment with melatonin at the 30th minute before KA injection resulted in a significant depletion in Bcl-2, Bax and Trx mRNA expressions. However, our results showed that melatonin pre-treatment increases the ratio of Bcl-2 to Bax mRNA in short-term period.

Quantification of thioredoxin mRNA expression in the rat hippocampus by real-time PCR following oxidative stress.

Thioredoxin (Trx) is a multifunctional protein with a redox-active disulfide/dithiol in the active site. Thioredoxin, with its redox-regulating and reactive oxygen species (ROS) scavenging activities, plays several important biologic roles both in intracellular and extracellular compartments. The purpose of this report was to quantify the relative expression of Trx in rat hippocampus following an oxidative stress-involving treatment such as kainic acid (KA) using real-time PCR and the 2(-DeltaDeltaC(T)) method. The relative changes in expression of Trx mRNA in KA-treated and control animals were significantly different as 2.02 +/- 0.77 and 1.0 +/- 0.26, respectively (P<0.05). Minimum and maximum n-fold changes in Trx expression in KA-treated and control animals were determined as (1.4-5.2) and (0.8-1.3), respectively. Thus, real-time PCR and the 2(-DeltaDeltaC(T)) method for data analysis from real-time PCR were found to be an accurate and sensitive method for quantifying Trx mRNA levels.

Electrochemical determination of glutathione in plasma at carbon nanotubes based screen printed electrodes.

Glutathione (GSH) is a major endogenous antioxidant highly active in human tissues and plays a key role in controlling cellular thiol redox system, maintaining the immune and detoxification system. The determination of GSH levels in tissue is important to estimate endogenous defenses against oxidative stress. In our study, the multi-walled carbon nanotube modified screen-printed electrodes (MWCNT-SPEs) were used to determine the levels of GSH in trichloroacetic acid (TCA)-treated or untreated samples of rat plasma. It was found that the deproteinization of samples with TCA improved the electrochemical detection of GSH particularly in plasma. The oxidation of GSH was measured by using differential pulse voltammetry (DPV) method in combination with MWCNT-SPE (n=3), and the detection limit of GSH was found to be 0.47 µM (S/N=3). The GSH levels in plasma samples were also measured spectrophotometrically in order to compare the effectiveness of electrochemical method and we obtained a high correlation between the two methods (R(2)=0.976).

Effects of resveratrol on hydrogen peroxide-induced oxidative stress in embryonic neural stem cells.

Resveratrol, a natural phenolic compound, has been shown to prevent cardiovascular diseases and cancer and exhibit neuroprotective effects. In this study, we examined the neuroprotective and antioxidant effects of resveratrol against hydrogen peroxide in embryonic neural stem cells. Hydrogen peroxide treatment alone increased catalase and glutathione peroxidase activities but did not change superoxide dismutase levels compared with hydrogen peroxide + resveratrol treatment. Nitric oxide synthase activity and concomitant nitric oxide levels increased in response to hydrogen peroxide treatment. Conversely, resveratrol treatment decreased nitric oxide synthase activity and nitric oxide levels. Resveratrol also attenuated hydrogen peroxide-induced nuclear or mitochondrial DNA damage. We propose that resveratrol may be a promising agent for protecting embryonic neural stem cells because of its potential to decrease oxidative stress by inducing higher activity of antioxidant enzymes, decreasing nitric oxide production and nitric oxide synthase activity, and alleviating both nuclear and mitochondrial DNA damage.

Kainic acid-induced seizure activity alters the mRNA expression and G-protein activation of the opioid/nociceptin receptors in the rat brain cortex.

The opioid/nociceptin receptors are involved in many neurological disorders such as Alzheimer's disease, Parkinson's disease and epilepsy. Kainic acid (KA) is an analog of the excitatory amino acid transmitter glutamate and the systemic administration of KA induces status epilepticus (SE) in rodents. In this study, we examined the alterations in the G-protein activity and the gene expression levels of mu, kappa, delta opioid and nociceptin receptors (MOPr, KOPr, DOPr and NOPr) as well as PNOC, the precursor polypeptide of nociceptin-OFQ (N/OFQ) in KA-induced seizures in the rat brain cortex. KA was used to create seizures with the dose of 10 mg/kg body weight i.p. Following the KA administration, the rats were observed for 3 h to assess seizure activity. Seizures occurred approximately 45 min after the KA injection. Only rats exhibiting full limbic seizures, forelimb clonus with rearing, were used in this study. All animals were decapitated 4 h after the administration of KA. Our [(35)S]GTPγS binding results showed that there was a significant difference in both the affinity and efficacy particularly one of NOPr stimulation following KA treatment. Slight, but significant increase was observed for MOPr. Moreover PNOC, NOPr and MOPr mRNA levels were increased by KA treatment but there were no significant changes in the levels of DOPr and KOPr mRNAs. These results show that the activities of opioid/nociceptin receptors can be modified by KA-treatment, and MOPr, PNOC and NOPr are the most responsive to KA-induced seizures in the rat brain cortex.

1,4-Substituted 4-(1H)-pyridylene-hydrazone-type inhibitors of AChE, BuChE, and amyloid-ß aggregation crossing the blood-brain barrier.

Given the fundamentally multifactorial character of Alzheimer's disease (AD), addressing more than one target for disease modification or therapy is expected to be highly advantageous. Here, following the cholinergic hypothesis, we aimed to inhibit both acetyl- and butyrylcholinesterase (AChE and BuChE) in order to increase the concentration of acetylcholine in the synaptic cleft. In addition, the formation of the amyloid ß fibrils should be inhibited and already preformed fibrils should be destroyed. Based on a recently identified AChE inhibitor with a 1,4-substituted 4-(1H)-pyridylene-hydrazone skeleton, a substance library has been generated and tested for inhibition of AChE, BuChE, and fibril formation. Blood-brain barrier mobility was ensured by a transwell assay. Whereas the p-nitrosubstituted compound 18C shows an anti-AChE activity in the nanomolar range of concentration (IC50=90 nM), the bisnaphthyl substituted compound 20L was found to be the best overall inhibitor of AChE/BuChE and enhances the fibril destruction.

Neuroprotection by mefenamic acid against D-serine: involvement of oxidative stress, inflammation and apoptosis.

Mefenamic acid, a non-steroidal antiinflammatory drug (NSAID), directly and dose-dependently exhibits neuroprotective activity. In our study, we investigated the effects of mefenamic acid against d-serine on oxidative stress in the hippocampus, cortex and cerebellum of rats. Furthermore, the potential inflammatory and apoptotic effects of d-serine and potential protective effect of mefenamic acid were determined at mRNA and protein levels of TNF-α, IL-1ß, Bcl-2 and Bax. We found that d-serine significantly increased oxidative stress, levels of inflammation- and apoptosis-related molecules in a region specific manner. Mefenamic acid treatment provided significant protection against the elevation of lipid peroxidation, protein oxidation, levels of TNF-α, IL-1ß and Bax. As a conclusion, we suggest that d-serine, as a potential neurodegenerative agent, may have a pivotal role in the regulation of oxidative stress, inflammation and apoptosis; and NSAIDs, such as mefenamic acid, may assist other therapeutics in treating disorders where d-serine-induced neurotoxic mechanisms are involved in.

Changes in the cannabinoid (CB1) receptor expression level and G-protein activation in kainic acid induced seizures.

It has been known for centuries that exogenous cannabinoids, such as tetrahydrocannabinol have anticonvulsant activity. Recent studies have advanced our understanding of the endogenous cannabinoid system and renewed the interest in cannabinoids as a potential treatment for epilepsy. The endogenous cannabinoid system is rapidly activated after seizure activity but still little is known about the molecular mechanisms underlying the role of the cannabinoid system in epilepsy. In this study epileptiform activity was induced by kainic acid (KA) and effects of the CB1 receptor agonists N-(2-Chloroethyl)-5Z,8Z,11Z,14Z-eicosatetraenamide (ACEA) on G-protein signaling using the agonist-stimulated [(35)S]GTPγS binding assay were evaluated. Control and KA treated rat hippocampus and cortex membranes were used. Our results showed that the ACEA displayed a high potency and efficacy in stimulating the G-proteins and when compared to the control animals, significant enhancements were observed in tissues from the KA treated animals. Potency and efficacy values were in particular increased in the hippocampus tissues. Furthermore, gene expression levels of the cannabinoid receptor 1 (CB1) receptor and cannabinoid receptor interacting protein 1 (CRIP1) were measured by RT-PCR, where both CB1 and CRIP1 expressions were found to be elevated in the KA treated animals.