Acute 5-HT 2C Receptor Antagonist SB-242084 Treatment Affects EEG Gamma Band Activity Similarly to Chronic Escitalopram

Serotonin 2C receptors (5-HT2CRs) are implicated in the pathomechanism and treatment of anxiety and depression. Recently, as a new biomarker of depression, alterations in the gamma power of the electroencephalogram (EEG) have been suggested. Chronic treatment with the selective serotonin reuptake inhibitor (SSRI) antidepressant escitalopram has been shown to cause sleep-wake stage-dependent alterations in gamma power. However, despite the antidepressant potency of 5-HT2CR-antagonists, there is no data available regarding the effects of selective 5-HT2CR-antagonists on gamma activity. Therefore, we investigate the acute effect of the 5-HT2CR-antagonist SB-242084 on gamma power in different vigilance stages when given in monotherapy, or in combination with chronic escitalopram treatment. We administered SB-242084 (1 mg/kg, intraperitoneally) or vehicle to EEG-equipped rats after a 21-day-long pretreatment with escitalopram (10 mg/kg/day, via osmotic minipumps) or vehicle. Frontoparietal EEG, electromyogram, and motor activity were recorded during the first 3 h of passive phase, after the administration of SB-242084. Quantitative EEG analysis revealed that acute SB-242084 increased gamma power (30–60 Hz) in light and deep slow-wave sleep, and passive wakefulness. However, in active wakefulness, rapid eye movement sleep, and intermediate stage, no change was observed in gamma power. The profile of the effect of SB-242084 on gamma power was similar to that produced by chronic escitalopram. Moreover, SB-242084 did not alter chronic escitalopram-induced effects on gamma. In conclusion, the similarity in the effect of the 5-HT2CR-antagonist and chronic SSRI on gamma power provides further evidence for the therapeutic potential of 5-HT2CR-antagonists in the treatment of depression and/or anxiety

Storage conditions determine the characteristics of red blood cell derived extracellular vesicles

Extracellular vesicles (EVs) are released during the storage of red blood cell (RBC) concentrates and might play adverse or beneficial roles throughout the utilization of blood products (transfusion). Knowledge of EV release associated factors and mechanism amends blood product management. In the present work the impact of storage time and medium (blood preserving additive vs isotonic phosphate buffer) on the composition, size, and concentration of EVs was studied using attenuated total reflection infrared (ATR-IR) spectroscopy, microfluidic resistive pulse sensing (MRPS) and freeze-fraction combined transmission electron micrography (FF-TEM). The spectroscopic protein-to-lipid ratio based on amide and the C–H stretching band intensity ratio indicated the formation of various vesicle subpopulations depending on storage conditions. After short storage, nanoparticles with high relative protein content were detected. Spectral analysis also suggested differences in lipid and protein composition, too. The fingerprint region (from 1300 to 1000 cm−1) of the IR spectra furnishes additional information about the biomolecular composition of RBC-derived EVs (REVs) such as adenosine triphosphate (ATP), lactose, glucose, and oxidized hemoglobin. The difference between the vesicle subpopulations reveals the complexity of the REV formation mechanism. IR spectroscopy, as a quick, cost-effective, and label-free technique provides valuable novel biochemical insight and might be used complementary to traditional omics approaches on EVs

Acute escitalopram treatment inhibits REM sleep rebound and activation of MCH-expressing neurons in the lateral hypothalamus after long term selective REM sleep deprivation.

RATIONALE: Selective rapid eye movement sleep (REMS) deprivation using the platform-on-water ("flower pot") method causes sleep rebound with increased REMS, decreased REMS latency, and activation of the melanin-concentrating hormone (MCH) expressing neurons in the hypothalamus. MCH is implicated in the pathomechanism of depression regarding its influence on mood, feeding behavior, and REMS. OBJECTIVES: We investigated the effects of the most selective serotonin reuptake inhibitor escitalopram on sleep rebound following REMS deprivation and, in parallel, on the activation of MCH-containing neurons. METHODS: Escitalopram or vehicle (10 mg/kg, intraperitoneally) was administered to REMS-deprived (72 h) or home cage male Wistar rats. During the 3-h-long "rebound sleep", electroencephalography was recorded, followed by an MCH/Fos double immunohistochemistry. RESULTS: During REMS rebound, the time spent in REMS and the number of MCH/Fos double-labeled neurons in the lateral hypothalamus increased markedly, and REMS latency showed a significant decrease. All these effects of REMS deprivation were significantly attenuated by escitalopram treatment. Besides the REMS-suppressing effects, escitalopram caused an increase in amount of and decrease in latency of slow wave sleep during the rebound. CONCLUSIONS: These results show that despite the high REMS pressure caused by REMS deprivation procedure, escitalopram has the ability to suppress REMS rebound, as well as to diminish the activation of MCH-containing neurons, in parallel. Escitalopram caused a shift from REMS to slow wave sleep during the rebound. Furthermore, these data point to the potential connection between the serotonergic system and MCH in sleep regulation, which can be relevant in depression and in other mood disorders

Chronic escitalopram treatment attenuated the accelerated rapid eye movement sleep transitions after selective rapid eye movement sleep deprivation: a model-based analysis using Markov chains

BackgroundShortened rapid eye movement (REM) sleep latency and increased REM sleep amount are presumed biological markers of depression. These sleep alterations are also observable in several animal models of depression as well as during the rebound sleep after selective REM sleep deprivation (RD). Furthermore, REM sleep fragmentation is typically associated with stress procedures and anxiety. The selective serotonin reuptake inhibitor (SSRI) antidepressants reduce REM sleep time and increase REM latency after acute dosing in normal condition and even during REM rebound following RD. However, their therapeutic outcome evolves only after weeks of treatment, and the effects of chronic treatment in REM-deprived animals have not been studied yet.ResultsChronic escitalopram- (10 mg/kg/day, osmotic minipump for 24 days) or vehicle-treated rats were subjected to a 3-day-long RD on day 21 using the flower pot procedure or kept in home cage. On day 24, fronto-parietal electroencephalogram, electromyogram and motility were recorded in the first 2 h of the passive phase. The observed sleep patterns were characterized applying standard sleep metrics, by modelling the transitions between sleep phases using Markov chains and by spectral analysis.Based on Markov chain analysis, chronic escitalopram treatment attenuated the REM sleep fragmentation [accelerated transition rates between REM and non-REM (NREM) stages, decreased REM sleep residence time between two transitions] during the rebound sleep. Additionally, the antidepressant avoided the frequent awakenings during the first 30 min of recovery period. The spectral analysis showed that the SSRI prevented the RD-caused elevation in theta (5 inverted question mark9 Hz) power during slow-wave sleep. Conversely, based on the aggregate sleep metrics, escitalopram had only moderate effects and it did not significantly attenuate the REM rebound after RD.ConclusionIn conclusion, chronic SSRI treatment is capable of reducing several effects on sleep which might be the consequence of the sub-chronic stress caused by the flower pot method. These data might support the antidepressant activity of SSRIs, and may allude that investigating the rebound period following the flower pot protocol could be useful to detect antidepressant drug response. Markov analysis is a suitable method to study the sleep pattern

Size Measurement of Extracellular Vesicles and Synthetic Liposomes: The Impact of the Hydration Shell and the Protein Corona

Size characterization of extracellular vesicles (EVs) and drug delivery liposomes is of great importance in their applications in diagnosis and therapy of diseases. There are many different size characterization techniques used in the field, which often report different size values. Besides technological biases, these differences originate from the fact that various methods measure different physical quantities to determine particle size. In this study, the size of synthetic liposomes with nominal diameters of 50nm and 100nm, and red blood cell-derived EVs (REVs) were measured with established optical methods, such as dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA), and with emerging non-optical methods such as microfluidic resistive pulse sensing (MRPS) and very small-angle neutron scattering (VSANS). The comparison of the hydrodynamic sizes obtained by DLS and NTA with the sizes corresponding to the excluded volume of the particles by MRPS enabled the estimation of the thickness of the hydration shell of the particles. The comparison of diameter values corresponding to the boundary of the phospholipid bilayer obtained from VSANS measurements with MRPS size values revealed the thickness of the polyethylene glycol-layer in case of synthetic liposomes, and the thickness of the protein corona in case of REVs

Synthesis and Structure-Activity Relationships of Novel Ecdysteroid Dioxolanes as MDR Modulators in Cancer

Ecdysteroids, molting hormones of insects, can exert several mild, non-hormonal bioactivities in mammals, including humans. In a previous study, we have found a significant effect of certain derivatives on the ABCB1 transporter mediated multi-drug resistance of a transfected murine leukemia cell line. In this paper, we present a structure-activity relationship study focused on the apolar dioxolane derivatives of 20-hydroxyecdysone. Semi-synthesis and bioactivity of a total of 32 ecdysteroids, including 20 new compounds, is presented, supplemented with their complete 1H- and 13C-NMR signal assignment

Removal and identification of external protein corona members from RBC‐derived extracellular vesicles by surface manipulating antimicrobial peptides

Abstract In the last years, extracellular vesicles (EVs), secreted by various cells and body fluids have shown extreme potential in biomedical applications. Increasing number of studies suggest that a protein corona could adhere to the surface of EVs which can have a fundamental effect on their function, targeting and therapeutical efficacy. However, removing and identifying these corona members is currently a challenging task to achieve. In this study we have employed red blood cell‐derived extracellular vesicles (REVs) as a model system and three membrane active antimicrobial peptides (AMPs), LL‐37, FK‐16 and CM15, to test whether they can be used to remove protein corona members from the surface of vesicles. These AMPs were reported to preferentially exert their membrane‐related activity via one of the common helical surface‐covering models and do not significantly affect the interior of lipid bilayer bodies. The interaction between the peptides and the REVs was followed by biophysical techniques, such as flow‐linear dichroism spectroscopy which provided the effective applicable peptide concentration for protein removal. REV samples were then subjected to subsequent size exclusion chromatography and to proteomics analysis. Based on the comparison of control REVs with the peptide treated samples, seventeen proteins were identified as external protein corona members. From the three investigated AMPs, FK‐16 can be considered as the best candidate to further optimize EV‐related applicability of AMPs. Our results on the REV model system envisage that membrane active peptides may become a useful set of tools in engineering and modifying surfaces of EVs and other lipid‐based natural particles

Differential adaptation of REM sleep latency, intermediate stage and theta power effects of escitalopram after chronic treatment.

The effects of the widely used selective serotonin reuptake inhibitor (SSRI) antidepressants on sleep have been intensively investigated. However, only a few animal studies examined the effect of escitalopram, the more potent S-enantiomer of citalopram, and conclusions of these studies on sleep architecture are limited due to the experimental design. Here, we investigate the acute (2 and 10 mg/kg, i.p. injected at the beginning of the passive phase) or chronic (10 mg/kg/day for 21 days, by osmotic minipumps) effects of escitalopram on the sleep and quantitative electroencephalogram (EEG) of Wistar rats. The first 3 h of EEG recording was analyzed at the beginning of passive phase, immediately after injections. The acutely injected 2 and 10 mg/kg and the chronically administered 10 mg/kg/day escitalopram caused an approximately three, six and twofold increases in rapid eye movement sleep (REMS) latency, respectively. Acute 2-mg/kg escitalopram reduced REMS, but increased intermediate stage of sleep (IS) while the 10 mg/kg reduced both. We also observed some increase in light slow wave sleep and passive wake parallel with a decrease in deep slow wave sleep and theta power in both active wake and REMS after acute dosing. Following chronic treatment, only the increase in REMS latency remained significant compared to control animals. In conclusion, adaptive changes in the effects of escitalopram, which occur after 3 weeks of treatment, suggest desensitization in the function of 5-HT(1A) and 5-HT(1B) receptors