Separation and determination of alpha-synuclein monomeric and oligomeric species using two electrophoretic approaches.

Parkinson's disease (PD) is a frequent degenerative disorder that is diagnosed based on clinical symptoms. When the first symptoms appear, more than 70% of the dopaminergic cells are already lost. Therefore, it is of utmost importance to have reliable biomarkers to diagnose much earlier PD. In this context, alpha-synuclein (aSyn) is a protein of high interest because of its tendency to form oligomers and amyloid fibrils. The oligomeric forms seem to play a critical pathological role in PD. To date, most of studies aiming at detecting and quantifying aSyn oligomers were performed by immunoassays, mainly by ELISA using specific antibodies. In this study a capillary gel electrophoresis (CGE) coupled with fluorescence detection method was developed to detect and quantify the oligomeric forms of aSyn formed in vitro. All the results obtained were supported by SDS-PAGE analysis, a widely used and well-known technique but exhibiting a main drawback since it is not an automated technique. The repeatability and the intermediate precision of the method were evaluated, as well as the stability of the labeled and non-labeled aSyn samples. After careful screening and optimization of various labeling reagents, 4-fluoro-7-nitrobenzofurazan (NBD-F) was selected and used to establish a calibration curve with monomeric fluorescently-labeled aSyn. Finally, the method was used to study the effect of doxycycline on the oligomerization process. Altogether, our results show that CGE is a very promising automated technique to analyze aSyn monomers, as well as small oligomers.

Fluoxetine dose and administration method differentially affect hippocampal plasticity in adult female rats.

Selective serotonin reuptake inhibitor medications are one of the most common treatments for mood disorders. In humans, these medications are taken orally, usually once per day. Unfortunately, administration of antidepressant medications in rodent models is often through injection, oral gavage, or minipump implant, all relatively stressful procedures. The aim of the present study was to investigate how administration of the commonly used SSRI, fluoxetine, via a wafer cookie, compares to fluoxetine administration using an osmotic minipump, with regards to serum drug levels and hippocampal plasticity. For this experiment, adult female Sprague-Dawley rats were divided over the two administration methods: (1) cookie and (2) osmotic minipump and three fluoxetine treatment doses: 0, 5, or 10 mg/kg/day. Results show that a fluoxetine dose of 5 mg/kg/day, but not 10 mg/kg/day, results in comparable serum levels of fluoxetine and its active metabolite norfluoxetine between the two administration methods. Furthermore, minipump administration of fluoxetine resulted in higher levels of cell proliferation in the granule cell layer (GCL) at a 5 mg dose compared to a 10 mg dose. Synaptophysin expression in the GCL, but not CA3, was significantly lower after fluoxetine treatment, regardless of administration method. These data suggest that the administration method and dose of fluoxetine can differentially affect hippocampal plasticity in the adult female rat.

A validated microfluidics-based LC-chip-MS/MS method for the quantitation of fluoxetine and norfluoxetine in rat serum.

An increasing number of quantitative bioanalyses need to be performed on samples available in limited volumes, such as pharmacokinetic studies on small animals. In this context, microfluidic systems as the LC-chip device coupled to a mass spectrometer combine small sample volume requirements and high sensitivity. In this study, we present the development of a microfluidics-based method for fluoxetine (FLX) and norfluoxetine (NFL) quantitation dedicated to pharmacokinetic investigations in the rat serum. Using the methodology of experimental design, LC parameters were optimised in terms of peak resolution, analysis time, and sensitivity. An SPE method was then developed for serum samples on miniaturised 96-well plates containing a mixed-mode strong cation exchanger that provided very clean extracts with good analyte recovery (≥66.0%). The total SPE-LC-MS/MS process required only 20 µL per sample and the method provided a good sensitivity in a total run time of 12 min. Finally, the developed method for FLX and NFL quantitation in rat serum was fully validated. After having selected the most appropriate regression model on the basis of the accuracy profiles, method selectivity, trueness, precision, accuracy and linearity were demonstrated.

Optimization of micro-HPLC peak focusing for the detection and quantification of low hepcidin concentrations.

Micro-high-performance liquid chromatography is a miniaturized, economic and ecological chromatographic system allowing the use of reduced size chromatographic columns. Coupled with electrospray ionization tandem mass spectrometry, this technique can be used to detect and quantify low concentrations of peptides. In this study, hepcidin was used as the model compound and analysed using octadecylsilica stationary phase by means of a gradient elution mode at a flow rate of 4 µL/min. Several parameters were studied to optimize peak focusing. Using the methodology of experimental design, the mobile-phase gradient conditions and the sample composition were optimized in order to maximize the sensitivity and minimize retention time. Stability of the target peptide in solution was also demonstrated.

Hepcidin determination in dried blood by microfluidic LC-MS/MS: comparison of DBS and volumetric absorptive microsampling for matrix effect and recovery.

BACKGROUND: Dried blood analysis experiences a growing interest due to practical, ethical and financial advantages compared with classical wet plasma or serum analysis. Besides classical DBS, new alternatives are commercialized as volumetric absorptive microsampling (VAMS) that are expected to overcome hematocrit influence. RESULTS: The feasibility of hepcidin (a peptide hormone) extraction and determination from DBS and VAMS blood sampling was investigated. Experimental design was used to determine the optimal extraction conditions. Matrix effect and extraction recovery were studied and a special attention was paid to phospholipid removal. CONCLUSION: The data suggest that the combination of VAMS and phospholipid removal plates provides low matrix effect and high sensitivity, and constitutes an easy and promising protocol for hepcidin analysis.

Developmental fluoxetine exposure normalizes the long-term effects of maternal stress on post-operative pain in Sprague-Dawley rat offspring.

Early life events can significantly alter the development of the nociceptive circuit. In fact, clinical work has shown that maternal adversity, in the form of depression, and concomitant selective serotonin reuptake inhibitor (SSRI) treatment influence nociception in infants. The combined effects of maternal adversity and SSRI exposure on offspring nociception may be due to their effects on the developing hypothalamic-pituitary-adrenal (HPA) system. Therefore, the present study investigated long-term effects of maternal adversity and/or SSRI medication use on nociception of adult Sprague-Dawley rat offspring, taking into account involvement of the HPA system. Dams were subject to stress during gestation and were treated with fluoxetine (2×/5 mg/kg/day) prior to parturition and throughout lactation. Four groups of adult male offspring were used: 1. Control+Vehicle, 2. Control+Fluoxetine, 3. Prenatal Stress+Vehicle, 4. Prenatal Stress+Fluoxetine. Results show that post-operative pain, measured as hypersensitivity to mechanical stimuli after hind paw incision, was decreased in adult offspring subject to prenatal stress alone and increased in offspring developmentally exposed to fluoxetine alone. Moreover, post-operative pain was normalized in prenatally stressed offspring exposed to fluoxetine. This was paralleled by a decrease in corticosteroid binding globulin (CBG) levels in prenatally stressed offspring and a normalization of serum CBG levels in prenatally stressed offspring developmentally exposed to fluoxetine. Thus, developmental fluoxetine exposure normalizes the long-term effects of maternal adversity on post-operative pain in offspring and these effects may be due, in part, to the involvement of the HPA system.

Chronic fluoxetine treatment and maternal adversity differentially alter neurobehavioral outcomes in the rat dam.

The incidence of stress and stress-related disorders with the transition to motherhood, such as postpartum depression, is estimated to be 20%. Selective serotonin reuptake inhibitor (SSRI) medications are currently the antidepressant of choice to treat maternal mood disorders. However, little is known about the effects of these medications on the maternal brain and behavior. Therefore, the present study investigated how a commonly used SSRI, fluoxetine, affects neurobehavioral outcomes in the mother using a model of maternal adversity. To do this, gestationally stressed and non-stressed Sprague-Dawley rat dams were treated with either fluoxetine (5 mg/kg/day) or vehicle. Dams were divided into four groups: (1) Control + Vehicle, (2) Control + Fluoxetine, (3) Stress + Vehicle and (4) Stress + Fluoxetine. Fluoxetine or vehicle was administered to the dam during the postpartum period via osmotic minipump implants (Alzet) for 28 days. Results show that chronic fluoxetine treatment, after exposure to gestational stress, significantly decreased serum levels of corticosteroid binding globulin and increased hippocampal neurogenesis. In the absence of maternal stress, fluoxetine treatment alone significantly increased maternal arched-back nursing of pups, increased anxiety-related behavior, and decreased serum levels of corticosterone and corticosteroid binding globulin in the dam. This research provides important information on how SSRIs may act on the behavior, physiology, and neural plasticity of the mother. Although this is a first step in investigating the role of antidepressant treatment on the mother, much more work is needed before we can understand and improve the efficacy of these medications to treat mood disorders in pregnant and postpartum women.

Pre-study and in-study validation of a SPE-LC-MS-MS method for the determination of 5-S-cysteinyldopa, a melanoma biomarker, in human plasma.

The incidence of malignant melanoma has increased over the past decades, particularly in Caucasian population. This disease presents defavourable prognosis in terms of survey, especially when detection occurs at the metastatic phase. Reliable analytical methods for biomarker determination are thus an interesting tool in pathology detection and follow-up. In this context, a method using SPE-LC-ESI-MS-MS for the determination of 5-S-cysteinyldopa (5-SCD) in human plasma was optimized. The presence of matrix effect was investigated in details while 5-SCD stability was studied according to FDA requirements for the validation of bioanalytical methods. Pre-study and in-study validations of the entire method were then successfully performed by applying the approach based on total measurement error and accuracy profiles over a concentration ranges from 1.6 to 200 ng/ml. Good results with respect to accuracy, trueness and precision were obtained. The maximum risk of observing future measurements falling outside the acceptance limits during routine analysis was also estimated.