The Mechanism of Leptin Resistance in Obesity and Therapeutic Perspective.

Leptin resistance is induced via leptin signaling blockade by chronic overstimulation of the leptin receptor and intracellular signaling defect or increased hypothalamic inflammation and suppressor of cytokine signaling (SOCS)-3 expression. High-fat diet triggers leptin resistance induced by at least two independent causes: first, the limited ability of peripheral leptin to activate hypothalamic signaling transducers and activators of transcription (STAT) signaling and secondly a signaling defect in leptin-responsive hypothalamic neurons. Central leptin resistance is dependent on decreased leptin transport efficiency across the blood brain barrier (BBB) rather than hypothalamic leptin insensitivity. Since the hypothalamic phosphorylated STAT3 (pSTAT3) represents a sensitive and specific readout of leptin receptor-B signaling, the assessment of pSTAT3 levels is the gold standard. Hypertriglyceridemia is one of important factors to inhibit the transport of leptin across BBB in obesity. Mismatch between high leptin and the amount of leptin receptor expression in obesity triggers brain leptin resistance via increasing hypothalamic inflammation and SOCS-3 expression. Therapeutic strategies that regulate the passage of leptin to the brain include the development of modifications in the structure of leptin analogues as well as the synthesis of new leptin receptor agonists with increased BBB permeability. In the hyperleptinemic state, polyethylene glycol (PEG)-modified leptin is unable to pass through the BBB. Peripheral histone deacetylase (HDAC) 6 inhibitor, tubastatin, and metformin increase central leptin sensitization. While add-on therapy with anagliptin, metformin and miglitol reduce leptin concentrations, the use of long-acting leptin analogs, and exendin-4 lead to the recovery of leptin sensitivity. Contouring surgery with fat removal, and bariatric surgery independently of the type of surgery performed provide significant improvement in leptin concentrations. Although approaches to correcting leptin resistance have shown some success, no clinically effective application has been developed to date. Due to the impairment of central and peripheral leptin signaling, as well as the extensive integration of leptin-sensitive metabolic pathways with other neurons, the effectiveness of methods used to eliminate leptin resistance is extremely limited.

Aerosol of Enoximone/Hydroxypropyl-ß-Cyclodextrin Inclusion Complex, Biopharmaceutical Evidence for ARDS Applicability.

BACKGROUND: Phosphodiesterase (PDE) inhibitors are gaining interest in the context of pulmonary pathologies. In particular, the PDE3 inhibitor enoximone (ENXM) has shown potential relative to the cure of asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS). Despite its administration via inhalation being planned for use against COVID-19 related ARDS (C-ARDS), presently, no inhalable medicine containing ENXM is available. OBJECTIVES: This study aims to develop a new formulation suitable for pulmonary administration of ENXM. METHODS: A solution for nebulization, based on the complex between ENXM and Hydroxypropyl-ß-Cyclodextrin (HPßCD) (ENXM/HPßCD) is developed. The obtained solution is characterized in terms of aerodynamic distributions and biopharmaceutical features. RESULTS: The evaluation of the aerosol droplets indicates a good bronchi-lung distribution of the drug. Biological evaluations of the air-liquid interface (ALI) in an in vitro lung cell model demonstrates that ENXM/HPßCD is capable of a local direct effect, increasing intracellular cyclic adenosine monophosphate (cAMP) levels and protecting from oxidative stress. CONCLUSIONS: This study offers a promising advance in the optimization of enoximone delivery to the lungs.

Novel Mechanism of Cyclic Nucleotide Crosstalk Mediated by PKG-dependent Proteasomal Degradation of the Hsp90 Client Protein Phosphodiesterase 3A.

Endothelial cAMP-specific phosphodiesterase PDE3A is one of the major negative regulators of the endothelial barrier function in acute lung injury (ALI) models. However, the mechanisms underlying its regulation still need to be fully resolved. We show here that the PDE3A is a newly described client of the molecular chaperone hsp90. In endothelial cells (EC), hsp90 inhibition by geldanamycin (GA) led to a disruption of the hsp90/PDE3A complex, followed by a significant decrease in PDE3A protein levels. The decrease in PDE3A protein levels was ubiquitin-proteasome-dependent and required the activity of the E3 ubiquitin ligase C-terminus of Hsc70-interacting protein (CHIP). GA treatment also enhanced the association of PDE3A with hsp70, which partially prevented PDE3A degradation. GA-induced decreases in PDE3A protein levels correlated with decreased PDE3 activity and increased cAMP levels in EC. We also demonstrated that PKG-dependent phosphorylation of PDE3A at Ser654 can signal the dissociation of PDE3A from hsp90 and PDE3A degradation. This was confirmed by endogenous PDE3A phosphorylation and degradation in 8-Br-cGMP- or 8-CPT-cGMP- and Bay 41-8543 -stimulated EC and comparisons of wildtype- and phospho-mimic S654D mutant PDE3A protein stability in transiently transfected HEK293 cells. In conclusion, we have identified a new mechanism of PDE3A regulation mediated by the ubiquitin-proteasome system. Further, the degradation of PDE3A is controlled by the phosphorylation of S654 and the interaction with hsp90. We speculate that targeting the PDE3A/hsp90 complex could be a therapeutic approach for ALI.

Protein Kinase A Regulates Platelet Phosphodiesterase 3A through an A-Kinase Anchoring Protein Dependent Manner.

Platelet activation is critical for haemostasis, but if unregulated can lead to pathological thrombosis. Endogenous platelet inhibitory mechanisms are mediated by prostacyclin (PGI2)-stimulated cAMP signalling, which is regulated by phosphodiesterase 3A (PDE3A). However, spatiotemporal regulation of PDE3A activity in platelets is unknown. Here, we report that platelets possess multiple PDE3A isoforms with seemingly identical molecular weights (100 kDa). One isoform contained a unique N-terminal sequence that corresponded to PDE3A1 in nucleated cells but with negligible contribution to overall PDE3A activity. The predominant cytosolic PDE3A isoform did not possess the unique N-terminal sequence and accounted for >99% of basal PDE3A activity. PGI2 treatment induced a dose and time-dependent increase in PDE3A phosphorylation which was PKA-dependent and associated with an increase in phosphodiesterase enzymatic activity. The effects of PGI2 on PDE3A were modulated by A-kinase anchoring protein (AKAP) disruptor peptides, suggesting an AKAP-mediated PDE3A signalosome. We identified AKAP7, AKAP9, AKAP12, AKAP13, and moesin expressed in platelets but focussed on AKAP7 as a potential PDE3A binding partner. Using a combination of immunoprecipitation, proximity ligation techniques, and activity assays, we identified a novel PDE3A/PKA RII/AKAP7 signalosome in platelets that integrates propagation and termination of cAMP signalling through coupling of PKA and PDE3A.

Phosphodiesterase 3 inhibitors do not influence lactate kinetics and clinical outcomes in patients with septic shock: A multicentre cohort study.

PURPOSE: We investigated the association between the administration of phosphodiesterase 3 inhibitors (PDE3i) and lactate kinetics, resolution of organ failure, ICU and hospital length of stay (LOS) and hospital mortality in a retrospective cohort of patients with septic shock and persistently elevated lactate concentrations. MATERIAL AND METHODS: Patients with septic shock and two arterial lactate concentrations ≥4 mmol/L with at least 4 h between measurements were eligible. Clinical data of the first four days of admission were collected in an online database. For each patient, the area between the actual lactate concentrations and 2.2 mmol/L (AUClact2.2), was calculated for three days. RESULTS: Data on 229 patients from 10 hospitals were collected, of whom 123 received PDE3i (54%). First, a linear multivariate model was developed to predict AUClact2.2 (R2 = 0.57). Adding PDE3i as a cofactor did not affect R2. Second, 60 patients receiving PDE3i at any time between days 0 and 2 were compared to 60 propensity matched no-PDE3i patients. Third, 30 patients who received PDE3i from ICU admission to day 3 were compared to 30 propensity-matched no-PDE3i patients. These analyses showed no differences in AUClact2.2, SOFA scores, ICU or hospital LOS or hospital mortality between treatment groups. CONCLUSIONS: No association was found between the administration of PDE3i and lactate kinetics, resolution of organ failure, ICU or hospital LOS or hospital mortality.

METTL3's role in cervical cancer development through m6A modification.

N6-methylated adenosine (m6A) is a crucial RNA modification in eukaryotes, particularly in cancer. However, its role in cervical cancer (CC) is unclear. We aimed to elucidate the part of m6A in CC by analyzing methyltransferase-like 3 (METTL3) expression, identifying downstream targets, and exploring the underlying mechanism. We assessed METTL3 expression in CC using western blotting, quantitative polymerase chain reaction (qPCR), and immunohistochemistry. In vitro and in vivo experiments examined METTL3's role in CC. We employed RNA sequencing, methylated RNA immunoprecipitation sequencing, qPCR, and RNA immunoprecipitation qPCR to explore METTL3's mechanism in CC. METTL3 expression was upregulated in CC, promoting cell proliferation and metastasis. METTL3 knockdown inhibited human cervical cancer by inactivating AKT/mTOR signaling pathway. METTL3-mediated m6A modification was observed in CC cells, targeting phosphodiesterase 3A (PDE3A). METTL3 catalyzed m6A modification on PDE3A mRNA through YTH domain family protein 3 (YTHDF3). Our study indicated the mechanism of m6A modification in CC and suggested the METTL3/YTHDF3/PDE3A axis as a potential clinical target for CC treatment.

Disruption of Phosphodiesterase 3A Binding to SERCA2 Increases SERCA2 Activity and Reduces Mortality in Mice With Chronic Heart Failure.

BACKGROUND: Increasing SERCA2 (sarco[endo]-plasmic reticulum Ca2+ ATPase 2) activity is suggested to be beneficial in chronic heart failure, but no selective SERCA2-activating drugs are available. PDE3A (phosphodiesterase 3A) is proposed to be present in the SERCA2 interactome and limit SERCA2 activity. Disruption of PDE3A from SERCA2 might thus be a strategy to develop SERCA2 activators. METHODS: Confocal microscopy, 2-color direct stochastic optical reconstruction microscopy, proximity ligation assays, immunoprecipitations, peptide arrays, and surface plasmon resonance were used to investigate colocalization between SERCA2 and PDE3A in cardiomyocytes, map the SERCA2/PDE3A interaction sites, and optimize disruptor peptides that release PDE3A from SERCA2. Functional experiments assessing the effect of PDE3A-binding to SERCA2 were performed in cardiomyocytes and HEK293 vesicles. The effect of SERCA2/PDE3A disruption by the disruptor peptide OptF (optimized peptide F) on cardiac mortality and function was evaluated during 20 weeks in 2 consecutive randomized, blinded, and controlled preclinical trials in a total of 148 mice injected with recombinant adeno-associated virus 9 (rAAV9)-OptF, rAAV9-control (Ctrl), or PBS, before undergoing aortic banding (AB) or sham surgery and subsequent phenotyping with serial echocardiography, cardiac magnetic resonance imaging, histology, and functional and molecular assays. RESULTS: PDE3A colocalized with SERCA2 in human nonfailing, human failing, and rodent myocardium. Amino acids 277-402 of PDE3A bound directly to amino acids 169-216 within the actuator domain of SERCA2. Disruption of PDE3A from SERCA2 increased SERCA2 activity in normal and failing cardiomyocytes. SERCA2/PDE3A disruptor peptides increased SERCA2 activity also in the presence of protein kinase A inhibitors and in phospholamban-deficient mice, and had no effect in mice with cardiomyocyte-specific inactivation of SERCA2. Cotransfection of PDE3A reduced SERCA2 activity in HEK293 vesicles. Treatment with rAAV9-OptF reduced cardiac mortality compared with rAAV9-Ctrl (hazard ratio, 0.26 [95% CI, 0.11 to 0.63]) and PBS (hazard ratio, 0.28 [95% CI, 0.09 to 0.90]) 20 weeks after AB. Mice injected with rAAV9-OptF had improved contractility and no difference in cardiac remodeling compared with rAAV9-Ctrl after aortic banding. CONCLUSIONS: Our results suggest that PDE3A regulates SERCA2 activity through direct binding, independently of the catalytic activity of PDE3A. Targeting the SERCA2/PDE3A interaction prevented cardiac mortality after AB, most likely by improving cardiac contractility.

A novel estrogen receptor 1: sphingomyelin phosphodiesterase acid-like 3B pathway mediates rituximab response in myositis patients.

OBJECTIVES: The B-cell depleting biologic, rituximab, is used to treat refractory autoimmune myositis. However, the beneficial effects of rituximab appear to outweigh the known contribution of B cells in myositis. We aimed to elucidate how myositis patients respond differently to rituximab and possible alternative mechanisms of action. METHODS: Here we have: (i) comprehensively investigated concurrent mRNA and microRNA expression in muscle biopsies taken at baseline and 16 weeks post treatment in 10 patients who were part of the rituximab in myositis (RIM) trial; and (ii) investigated the beneficial effect of rituximab on myositis muscle cells. RESULTS: Our analyses identified an increased number of changes in gene expression in biopsies from patients who had a clinical response to rituximab (n = 5) compared with non-responders (n = 5). The two groups had completely different changes in microRNA and mRNA expression following rituximab therapy, with the exception of one mRNA, BHMT2. Networks of mRNA and microRNA with opposite direction of expression changes highlighted ESR1 as upregulated in responders. We confirmed ESR1 upregulation upon rituximab treatment of immortalized myotubes and primary human dermatomyositis muscle cells in vitro, demonstrating a direct effect of rituximab on muscle cells. Notably, despite showing a response to rituximab, human dermatomyositis primary muscle cells did not express the rituximab target, CD20. However, these cells expressed a possible alternative target of rituximab, sphingomyelinase-like phosphodiesterase 3 b (SMPDL3B). CONCLUSION: In addition to B-cell depletion, rituximab may be beneficial in myositis due to increased ESR1 signalling mediated by rituximab binding to SMPDL3B on skeletal muscle cells.

Effects of cilostazol, a Phosphodiesterase-3 inhibitor, on kidney function and redox imbalance in acute kidney injury caused by Bothrops alternatus venom.

The mechanisms of pathogenesis of acute kidney injury (AKI) in snakebites is multifactorial and involves hemodynamic disturbances, with release of free radical causing cytotoxic effects. The phosphodiesterase-3 (PDE3) inhibitor, Cilostazol, has been reported to provide protection against renal oxidative stress. OBJECTIVE: We evaluated the protective effects of cilostazol against Bothrops alternatus snake venom (BaV)-induced nephrotoxicity. METHODS: Wistar rat kidneys (n = 6, 260-300 g) were isolated and perfused with Krebs-Henseleit solution containing 6 g/100 mL of bovine serum albumin. After 30 min, the kidneys were perfused with BaV to a final concentration of 1 and 3 µg/mL, and subsequently evaluated for perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), and percentage of electrolyte tubular sodium and chloride transport (%TNa+, %TCl-). Oxidative stress and renal histological analyses were performed. RESULTS: BaV caused a reduction in all the evaluated renal parameters (PP, RVR, GFR, UF, %TNa+, and %TCl-). Although only the effects on PP and UF were reversed with cilostazol treatment, the decrease in the malondialdehyde levels, without changes in glutathione levels, further reduced the venom-induced renal tissue changes. CONCLUSION: Our data suggest that PDE3 is involved in BaV-induced nephrotoxicity, as cilostazol administration significantly ameliorated these effects.

Cilostamide, a phosphodiesterase 3A inhibitor, sustains meiotic arrest of rat oocytes by modulating cyclic adenosine monophosphate level and the key regulators of maturation promoting factor.

Cilostamide, a phosphodiesterase 3A (Pde3A) inhibitor, is known to increase intraoocyte cyclic adenosine monophosphate (cAMP) level which is involved in sustaining meiotic arrest of the oocytes. To explore the mechanisms involved in the cilostamide-mediated meiotic arrest of the oocytes, the present study describes the effects of cilostamide on cAMP level and related factors involved in maturation of the oocytes at its different meiotic stages; diplotene, metaphase I (MI) and metaphase II (MII). The oocytes from these three stages were collected from rat ovary and incubated with 10 µM cilostamide for 3 h in CO2 incubator. The levels of cAMP, cyclic guanosine monophosphate (cGMP) and the key players of maintaining meiotic arrest during oocyte maturation; Emi2, Apc, Cyclin B1, and Cdk1, were analyzed in diplotene, MI and MII stages. Pde3A was found to be expressed at all three stages but with the lowest level in MI oocyte. As compared to the control sets, the cAMP concentration was found to be highest in MII whereas cGMP was highest in the diplotene stage of cilostamide-treated group. The treated group showed declined reactive oxygen species level as compared with the control counterparts. Relatively increased levels of the Emi2, Cyclin B1, and phosphorylated thr161 of Cdk1 versus declined levels of phosphorylated thr14/tyr15 of Cdk1 in diplotene and MII stage oocytes are known to be involved in maintaining meiotic arrest and all these factors were found to undergo similar pattern of change due to the treatment with cilostamide. The findings thus suggest that cilostamide treatment promotes meiotic arrest by Pde3A inhibition led increase of both cAMP and cGMP level vis-a-vis modulation of the related regulatory factors such as Emi2, CyclinB1, and phosphorylated status of Cdk1 in diplotene and MII stage oocytes. Such a mechanism of meiotic arrest could allow the oocyte to prepare itself for meiotic maturation and thereby to improve oocyte quality.

Treatment of Cardiovascular Dysfunction with PDE3-Inhibitors in Moderate and Severe Hypothermia-Effects on Cellular Elimination of Cyclic Adenosine Monophosphate and Cyclic Guanosine Monophosphate.

Introduction: Rewarming from accidental hypothermia is often complicated by hypothermia-induced cardiovascular dysfunction, which could lead to shock. Current guidelines do not recommend any pharmacological treatment at core temperatures below 30°C, due to lack of knowledge. However, previous in vivo studies have shown promising results when using phosphodiesterase 3 (PDE3) inhibitors, which possess the combined effects of supporting cardiac function and alleviating the peripheral vascular resistance through changes in cyclic nucleotide levels. This study therefore aims to investigate whether PDE3 inhibitors milrinone, amrinone, and levosimendan are able to modulate cyclic nucleotide regulation in hypothermic settings. Materials and methods: The effect of PDE3 inhibitors were studied by using recombinant phosphodiesterase enzymes and inverted erythrocyte membranes at six different temperatures-37°C, 34°C, 32°C, 28°C, 24°C, and 20°C- in order to evaluate the degree of enzymatic degradation, as well as measuring cellular efflux of both cAMP and cGMP. The resulting dose-response curves at every temperature were used to calculate IC50 and Ki values. Results: Milrinone IC50 and Ki values for cGMP efflux were significantly lower at 24°C (IC50: 8.62 ± 2.69 µM) and 20°C (IC50: 7.35 ± 3.51 µM), compared to 37°C (IC50: 22.84 ± 1.52 µM). There were no significant changes in IC50 and Ki values for enzymatic breakdown of cAMP and cGMP. Conclusion: Milrinone, amrinone and levosimendan, were all able to suppress enzymatic degradation and inhibit extrusion of cGMP and cAMP below 30°C. Our results show that these drugs have preserved effect on their target molecules during hypothermia, indicating that they could provide an important treatment option for hypothermia-induced cardiac dysfunction.

Mechanistic insights on cytotoxicity of KOLR, Cinnamomum pauciflorum Nees leaf derived active ingredient, by targeting signaling complexes of phosphodiesterase 3B and rap guanine nucleotide exchange factor 3.

Protein signaling complexes play important roles in prevention of several cancer types and can be used for development of targeted therapy. The roles of signaling complexes of phosphodiesterase 3B (PDE3B) and Rap guanine nucleotide exchange factor 3 (RAPGEF3), which are two important enzymes of cyclic adenosine monophosphate (cAMP) metabolism, in cancer have not been fully explored. In the current study, a natural product Kaempferol-3-O-(3'',4''-di-E-p-coumaroyl)-α-L-rhamnopyranoside designated as KOLR was extracted from Cinnamomum pauciflorum Nees leaves. KOLR exhibited higher cytotoxic effects against BxCP-3 pancreatic cancer cell line. In BxPC-3 cells, the KOLR could enhance the formation of RAPGEF 3/ PDE3B protein complex to inhibit the activation of Rap-1 and PI3K-AKT pathway, thereby promoting cell apoptosis and inhibiting cell metastasis. Mutation of RAPGEF3 G557A or low expression of PDE3B inactivated the binding action of KOLR resulting in KOLR resistance. The findings of this study show that PDE3B/RAPGEF3 complex is a potential therapeutic cancer target.

The cGAS-STING signaling in cardiovascular and metabolic diseases: Future novel target option for pharmacotherapy.

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling exert essential regulatory function in microbial-and onco-immunology through the induction of cytokines, primarily type I interferons. Recently, the aberrant and deranged signaling of the cGAS-STING axis is closely implicated in multiple sterile inflammatory diseases, including heart failure, myocardial infarction, cardiac hypertrophy, nonalcoholic fatty liver diseases, aortic aneurysm and dissection, obesity, etc. This is because of the massive loads of damage-associated molecular patterns (mitochondrial DNA, DNA in extracellular vesicles) liberated from recurrent injury to metabolic cellular organelles and tissues, which are sensed by the pathway. Also, the cGAS-STING pathway crosstalk with essential intracellular homeostasis processes like apoptosis, autophagy, and regulate cellular metabolism. Targeting derailed STING signaling has become necessary for chronic inflammatory diseases. Meanwhile, excessive type I interferons signaling impact on cardiovascular and metabolic health remain entirely elusive. In this review, we summarize the intimate connection between the cGAS-STING pathway and cardiovascular and metabolic disorders. We also discuss some potential small molecule inhibitors for the pathway. This review provides insight to stimulate interest in and support future research into understanding this signaling axis in cardiovascular and metabolic tissues and diseases.

Diosgenin reduces phosphodiesterase 3B (PDE3B) through AMP-activated protein kinase/ mechanistic target of rapamycin (AMPK/mTOR) signaling pathway to ameliorate streptozotocin-induced pancreatic ß-cell apoptosis and dysfunction.

Diabetes mellitus is a metabolic disease caused by defective insulin secretion and/or insulin action. And insulin is the main hormone released by the pancreatic ß-cells. Diosgenin (DG) is a phytochemical with pharmacological activity that increases insulin secretion in streptozotocin (STZ)-induced pancreatic ß-cells of diabetic rats. In this paper, we investigated the effect and mechanism of DG on cell apoptosis and dysfunction in STZ-induced pancreatic ß-cells. Cell viability was detected by CCK-8, apoptosis by flow cytometry, and apoptosis-related protein expression by Western blot. Western blot and RT-qPCR were performed to detect the expression of related genes. The results showed that in STZ-induced INS-1 cells, DG could improve cell viability, inhibit apoptosis, attenuate oxidative stress levels and increase insulin secretion. Notably, PDE3B was highly expressed in STZ-induced INS-1 cells, while DG could significantly inhibit PDE3B expression in a dose-dependent manner. More importantly, overexpression PDE3B remarkably reversed the effect of DG on STZ-induced INS-1 cells. It is thus clear that DG might inhibit STZ-treated pancreatic ß-cell apoptosis and reduce dysfunction via downregulating PDE3B, which provided a more reliable theoretical basis for the treatment of diabetes mellitus with DG.

Post-stroke treatment with K-134, a phosphodiesterase 3 inhibitor, improves stroke outcomes in the stroke-prone spontaneously hypertensive rat model-A comparative evaluation of antiplatelet drugs.

Post-stroke antiplatelet therapy has been proved to reduce the risk of recurrent stroke; however, it may also increase the incidence of intracranial hemorrhage that could offset any benefits. Therefore, the balance between the benefits and risks of antiplatelet drugs is a critical issue to consider. In the present study, we have compared the effects of post-stroke administration of antiplatelet agents on functional outcomes in the stroke-prone spontaneously hypertensive rat (SHRSP), an established animal model that mimics human lacunar stroke and cerebral small vessel disease. We confirmed that a potent phosphodiesterase 3 (PDE3) inhibitor, K-134, significantly improved post-stroke survival rate and survival time, attenuated stroke-induced neurological deficits, and decreased the incidence of cerebral lesion caused by intracerebral hemorrhage and softening. Similarly, cilostazol showed beneficial effects, though to a lower extent with respect to the survival outcome and neurological symptoms. On the other hand, a P2Y12 inhibitor, clopidogrel significantly improved survival outcomes at the higher dose but caused massive bleeding in the brain at both low and high doses. In contrast, no hemorrhagic lesion was observed in K-134-treated SHRSPs despite its antiplatelet activity. Our findings indicate that K-134 may have a superior post-stroke therapeutic outcome in comparison to other antiplatelet drugs.

The effect of post-reperfusion levosimendan in an experimental intestinal ischemia-reperfusion model.

BACKGROUND: Levosimendan has been reported to have a positive effect on ischemia-reperfusion injury. Herein, we aimed to evaluate the effects of levosimendan applied after reperfusion in an experimental intestinal injury-reperfusion (IR) model. METHODS: Twenty-one Wistar-albino male rats were separated into three groups: Sham group (n = 7): solely superior mesenteric artery (SMA) was dissected after laparotomy; intestinal ischemia-reperfusion group (IIR, n = 7): SMA was clamped for 60 min and unclamped for 120 min to cause ischemia-reperfusion; IIR + levosimendan group (IIR + L, n = 7): levosimendan was administered in ischemia-reperfusion model. The mean arterial pressures (MAP) were measured in all groups. MAP measurements were performed at the end of stabilization, at the 15th, 30th, and 60th minute of ischemia; at the 15th, 30th, 60th, and 120th minute of reperfusion; and at the end of levosimendan bolus application and when levosimendan infusion concluded. Reperfusion injury was evaluated with tissue malondialdehyde (MDA) and by Chiu score. RESULTS: MAP at 15 min, 30 min, and 60 min of reperfusion was lower in IIR and IIR + L groups compared with basal inter-group measurements. Decline in MAP at 30 min after reperfusion was statistically significant in IIR and IIR + L groups when compared with the sham group. There was no significant difference between MDA levels in the groups. Chiu score was significantly lower in the sham group when compared to IIR and IIR + L groups and higher in IIR when compared to the IIR + L group. CONCLUSION: Levosimendan leads to a decrease in intestinal damage although it did not affect lipid peroxidation and MAP when administered after reperfusion in an experimental intestinal IR model.

Reversal of spatial memory impairment by phosphodiesterase 3 inhibitor cilostazol is associated with reduced neuroinflammation and increased cerebral glucose uptake in aged male mice.

The nucleotide second messenger 3', 5'-cyclic adenosine monophosphate (cAMP) and 3', 5'-cyclic guanosine monophosphate (cGMP) mediate fundamental functions of the brain, including learning and memory. Phosphodiesterase 3 (PDE3) can hydrolyze both cAMP and cGMP and appears to be involved in the regulation of their contents in cells. We previously demonstrated that long-term administration of cilostazol, a PDE3 inhibitor, maintained good memory performance in aging mice. Here, we report on studies aimed at determining whether cilostazol also reverses already-impaired memory in aged male mice. One month of oral 1.5% cilostazol administration in 22-month-old mice reversed age-related declines in hippocampus-dependent memory tasks, including the object recognition and the Morris water maze. Furthermore, cilostazol reduced neuroinflammation, as evidenced by immunohistochemical staining, and increased glucose uptake in the brain, as evidence by positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG). These results suggest that already-expressed memory impairment in aged male mice that depend on cyclic nucleotide signaling can be reversed by inhibition of PDE3. The reversal of age-related memory impairments may occur in the central nervous system, either through cilostazol-enhanced recall or strengthening of weak memories that otherwise may be resistant to recall.

Effects of prematuration culture with a phosphodiesterase-3 inhibitor on oocyte morphology and embryo quality in in vitro maturation.

OBJECTIVE: The study assessed the developmental potential of germinal vesicle (GV) oocytes subjected to in vitro maturation (IVM) after prematuration culture with cilostamide (a phosphodiesterase-3 inhibitor) and the impact of cilostamide exposure on the morphology of meiosis II (MII) oocytes and subsequent embryo quality. METHODS: In total, 994 oocytes were collected from 63 patients. Among 307 GV oocytes, 140 oocytes were selected for the experimental group and 130 oocytes for the control group. The denuded GV-stage oocytes were cultured for 6 hours with cilostamide in the experimental group and without cilostamide in the control group. After 6 hours, the oocytes in the experimental group were washed and transferred to fresh IVM medium. The maturational status of the oocytes in both groups was examined at 26, 36, and 48 hours. Fertilization was assessed at 18 hours post-intracytoplasmic sperm injection. Embryo quality was assessed on days 3 and 5. RESULTS: In total, 92.1% of the oocytes remained in the GV stage, while 6.4% converted to the MI stage (p<0.01) after cilostamide exposure. In both groups, more MII oocytes were observed at 36 hours (25.8% vs. 21.5%) than at 26 hours (10.8% vs. 14.6%) and 48 hours (13% vs. 7.9%) (p>0.05). With the advent of cilostamide, blastocyst quality was better in the experimental group than in the control group (p<0.05). CONCLUSION: Cilostamide effectively blocked nuclear maturation and promoted cytoplasmic growth. Prematuration culture with cilostamide enabled synchronization between cytoplasmic and nuclear maturity, resulting in better blastocyst outcomes.