Cyclic Guanosine Monophosphate Levels Research Articles

Targeting cGMP/PKG signaling for the treatment or prevention of colorectal cancer with novel sulindac derivatives lacking cyclooxygenase inhibitory activity

Approximately 28 million people in the United States have precancerous colonic adenomas with many at high risk of developing colorectal cancer who could benefit from a pharmacological approach to prevent malignant progression. Clinical, epidemiological, and preclinical studies have reported or provided mechanistic evidence that nonsteroidal anti-inflammatory drugs (NSAIDs) can reduce adenoma formation and the risk of developing colorectal cancer. Unfortunately, the long-term use of NSAIDs is not recommended because of potentially fatal toxicities resulting from cyclooxygenase (COX) inhibition and the depletion of physiologically important prostaglandins. However, multiple investigators have concluded that the mechanism responsible for the antineoplastic activity of NSAIDs does not require COX inhibition, which suggests the feasibility of developing safer and more efficacious derivatives for the treatment or prevention of colorectal cancer by targeting such mechanisms. We have widely reported that the NSAID, sulindac, inhibits certain phosphodiesterase (PDE) isozymes to increase intracellular cyclic guanosine monophosphate (cGMP) levels and activate protein kinase G (PKG) at concentrations that inhibit cancer cell growth in vitro. PDE5 and PDE10 are potential targets given that both are overexpressed in colon adenomas and adenocarcinomas and essential for colon cancer cell proliferation. An extensive medicinal chemistry campaign was conducted to identify novel sulindac derivatives lacking COX inhibitory activity with increased potency and selectivity to inhibit cancer cell growth. From a large collection of over 1500 compounds sharing the indene scaffold of sulindac, a series of derivatives were identified that inhibit cancer cell growth with high potency and selectivity by a mechanism involving the activation of cGMP/PKG signaling. Development candidates have been identified that block the oncogenic effects from APC gene mutations responsible for most human colorectal cancers by suppressing β-catenin-dependent transcriptional activity. This review describes the scientific rationale for the development of sulindac derivatives lacking COX inhibitory activity with improved potency and selectivity to inhibit PDE5 and/or PDE10 for the treatment or prevention of colorectal cancer.

C-type natriuretic peptide suppresses ventricular arrhythmias in rats with acute myocardial ischemia

This study aimed to investigate the effects of C-type natriuretic peptide (CNP) on ventricular arrhythmias in rats with acute myocardial ischemia (AMI). Forty male Sprague-Dawley rats were randomly divided into sham group (n = 10), AMI group (n = 15) and AMI + CNP group (n = 15). AMI model was induced by ligating the left anterior descending branch of the coronary artery, and CNP was pumped through the femoral vein starting 30 min before ischemia and continuing until 1 h after AMI. The occurrence of ventricular arrhythmias after ischemia and heart rate variability (HRV) were recorded and analyzed. The plasma norepinephrine level was detected at 15 min after AMI. Ventricular electrophysiological parameters including ventricular effective refractory period (ERP), ERP dispersion, ventricular action potential duration (APD) alternans and ventricular fibrillation threshold (VFT) were measured one hour after AMI. Then, the expressions of cyclic guanosine monophosphate in myocardial tissue and left stellate ganglion were examined. Compared to sham group, AMI significantly shortened the ERP, augmented ERP dispersion, elevated APD alternans cycle length, reduced VFT, and increased the incidence of ventricular arrhythmias. Moreover, AMI increased the sympathetic component of HRV, raised plasma norepinephrine levels, and decreased the cyclic guanosine monophosphate levels in myocardium and left stellate ganglion. All those changes were attenuated by CNP treatment. These findings suggest that CNP protected against ventricular arrhythmias in rats with AMI, potentially by inhibiting ischemia-induced cardiac sympathetic hyperactivity and cardiac electrophysiology instability.

A Novel Method to Improve Perfusion of Ex Vivo Pumped Human Kidneys.

To determine if addition of the S-nitrosylating agent ethyl nitrite (ENO) to the preservation solution can improve perfusion parameters in pumped human kidneys. A significant percentage of actively stored kidneys experience elevations in resistance and decreases in flow rate during the ex vivo storage period. Preclinical work indicates that renal status after brain death is negatively impacted by inflammation and reduced perfusion-processes regulated by protein S-nitrosylation. To translate these findings, we added ENO to the preservation solution in an attempt to reverse the perfusion deficits observed in nontransplanted pumped human kidneys. After obtaining positive proof-of-concept results with swine kidneys, we studied donated human kidneys undergoing hypothermic pulsatile perfusion deemed unsuitable for transplantation. Control kidneys continued to be pumped a 4°C (ie, standard of care). In the experimental group, the preservation solution was aerated with 50 ppm ENO in nitrogen. Flow rate and perfusion were recorded for 10 hours followed by biochemical analysis of the kidney tissue. In controls, perfusion was constant during the monitoring period (ie, flow rate remained low and resistance stayed high). In contrast, the addition of ENO produced significant and sustained reductions in resistance and increases in flow rate. ENO-treated kidneys had higher levels of cyclic guanosine monophosphate, potentially explaining the perfusion benefits, and increased levels of interleukin-10, suggestive of an anti-inflammatory effect. S-Nitrosylation therapy restored the microcirculation and thus improved overall organ perfusion. Inclusion of ENO in the renal preservation solution holds promise to increase the number and quality of kidneys available for transplant.

Icariin attenuates isoproterenol-induced cardiac toxicity in Wistar rats via modulating cGMP level and NF-κB signaling cascade.

Icariin, a major component of Epimedium species, was evaluated using isoproterenol (ISO)-induced cardiotoxicity in Wistar rats. Rats were treated with icariin at the doses of 1, 5, and 10 mg kg-1 orally for 15 days. Afterward, rats were administered with ISO (85 mg kg-1, subcutaneous) on 14th and 15th day to produce cardiac injury. Sildenafil (0.7 mg kg-1, intraperitoneal) was used as a positive reference to compare the effects of icariin. ISO-treated rats showed significant changes in hemodynamic parameters. Elevated levels of cardiac troponin T, nitric oxide, and tumor necrosis factor-alpha in serum, positive expression of nuclear factor-kappa B (NF-κB) and inducible nitric oxide synthase in cardiac tissue, and a decrease in serum level of interleukin-10, manifested inflammation and associated cardiac injury. However, pretreatment with icariin and sildenafil significantly prevented the hemodynamic fall and showed improved contractile and lusitropic states. Furthermore, pretreatment groups also showed a reversal of other toxicity markers to normal. Additionally, pretreatment with icariin and sildenafil significantly increased the myocardial cyclic guanosine monophosphate (cGMP) levels. Our results thus indicated the potential role of icariin in the restoration of the ISO-induced cardiac toxicity and restored membrane integrity through modulation of cGMP and NF-κB signaling.

Sickle cell disease subjects and mouse models have elevated nitrite and cGMP levels in blood compartments

The hypothesis of decreased nitric oxide (NO) bioavailability in sickle cell disease (SCD) proposes that multiple factors leading to decreased NO production and increased consumption contributes to vaso-occlusion, pulmonary hypertension, and pain. The anion nitrite is central to NO physiology as it is an end product of NO metabolism and serves as a reservoir for NO formation. However, there is little data on nitrite levels in SCD patients and its relationship to pain phenotype. We measured nitrite in SCD subjects and examined its relationship to SCD pain. In SCD subjects, median whole blood, red blood cell and plasma nitrite levels were higher than in controls, and were not associated with pain burden. Similarly, Townes and BERK homozygous SCD mice had elevated blood nitrite. Additionally, in red blood cells and plasma from SCD subjects and in blood and kidney from Townes homozygous mice, levels of cyclic guanosine monophosphate (cGMP) were higher compared to controls. In vitro, hemoglobin concentration, rather than sickle hemoglobin, was responsible for nitrite metabolism rate. In vivo, inhibition of NO synthases and xanthine oxidoreductase decreased nitrite levels in homozygotes but not in control mice. Long-term nitrite treatment in SCD mice further elevated blood nitrite and cGMP, worsened anemia, decreased platelets, and did not change pain response. These data suggest that SCD in humans and animals is associated with increased nitrite/NO availability, which is unrelated to pain phenotype. These findings might explain why multiple clinical trials aimed at increasing NO availability in SCD patients failed to improve pain outcomes.

Effects of masitinib compared with tadalafil for the treatment of monocrotaline-induced pulmonary arterial hypertension in rats

Targeting vascular remodeling in pulmonary arterial hypertension (PAH) remains a challenge given the lack of potent anti-remodeling abilities of the therapeutic drugs. Although sildenafil has been shown to ameliorate cardiopulmonary remodeling, that of tadalafil is questionable. Masitinib, a tyrosine kinase inhibitor appears safer and more potent than imatinib for treatment of malignancies, but its efficacy on PAH is unknown. Therefore, we investigated the anti-remodeling properties of masitinib (5, 15, 50 mg/kg) and tadalafil (5, 10 mg/kg) using a monocrotaline-induced rat model of PAH. The 14-day treatment with masitinib (15, 50 mg/kg) resulted in significantly decreased right ventricular (RV) systolic pressure (RVSP) and hypertrophy (RVH), and pulmonary vascular remodeling, whereas tadalafil showed weaker anti-remodeling properties. Besides, masitinib significantly blocked the mitogen-associated protein kinase (MAPK) pathway, and reduced phosphodiesterase (PDE)-5 mRNA expression in the lungs. By contrast, tadalafil did not significantly inhibit the MAPK pathway. Further, the 28-day treatment extension revealed that masitinib-treated rats (15 mg/kg) had significantly lower RVSP, and higher heart rate and serum cyclic guanosine monophosphate (cGMP) level, whereas those treated with tadalafil (10 mg/kg) showed insignificantly lower RVSP and higher cGMP level. Moreover, the RVH indices, heart rates, body weight gains, and survival rates of rats in both groups were comparable. Collectively, these results suggest that the treatment with a low-dose masitinib was non-inferior than tadalafil. A lower dose of masitinib may represent a novel approach to target both the cardiopulmonary remodeling and the dysregulated vasoconstriction in PAH.

The Novel Phosphodiesterase 9A Inhibitor BI 409306 Increases Cyclic Guanosine Monophosphate Levels in the Brain, Promotes Synaptic Plasticity, and Enhances Memory Function in Rodents.

N-methyl-d-aspartate (NMDA) receptor-dependent long-term potentiation (LTP) is an established cellular model underlying learning and memory, and involves intracellular signaling mediated by the second messenger cyclic guanosine monophosphate (cGMP). As phosphodiesterase (PDE)9A selectively hydrolyses cGMP in areas of the brain related to cognition, PDE9A inhibitors may improve cognitive function by enhancing NMDA receptor-dependent LTP. This study aimed to pharmacologically characterize BI 409306, a novel PDE9A inhibitor, using in vitro assays and in vivo determination of cGMP levels in the brain. Further, the effects of BI 409306 on synaptic plasticity evaluated by LTP in ex vivo hippocampal slices and on cognitive performance in rodents were also investigated. In vitro assays demonstrated that BI 409306 is a potent and selective inhibitor of human and rat PDE9A with mean concentrations at half-maximal inhibition (IC50) of 65 and 168 nM. BI 409306 increased cGMP levels in rat prefrontal cortex and cerebrospinal fluid and attenuated a reduction in mouse striatum cGMP induced by the NMDA-receptor antagonist MK-801. In ex vivo rat brain slices, BI 409306 enhanced LTP induced by both weak and strong tetanic stimulation. Treatment of mice with BI 409306 reversed MK-801-induced working memory deficits in a T-maze spontaneous-alternation task and improved long-term memory in an object recognition task. These findings suggest that BI 409306 is a potent and selective inhibitor of PDE9A. BI 409306 shows target engagement by increasing cGMP levels in brain, facilitates synaptic plasticity as demonstrated by enhancement of hippocampal LTP, and improves episodic and working memory function in rodents. SIGNIFICANCE STATEMENT: This preclinical study demonstrates that BI 409306 is a potent and selective PDE9A inhibitor in rodents. Treatment with BI 409306 increased brain cGMP levels, promoted long-term potentiation, and improved episodic and working memory performance in rodents. These findings support a role for PDE9A in synaptic plasticity and cognition. The potential benefits of BI 409306 are currently being investigated in clinical trials.

NOS3 Deletion in Cav1 Deficient Mice Decreases Drug Sensitivity to a Nitric Oxide Donor and Two Nitric Oxide Synthase Inhibitors.

This study aims to investigate the pharmacologic consequence of genetic deletion of nitric oxide synthase 3 (NOS3) in caveolin 1 (Cav1)-/- mice (double knockout [DKO]) in response to a nitric oxide (NO) donor and two NOS inhibitors. NO donor sodium nitroprusside (SNP; 10-40 mg/mL), NOS inhibitor L-NG-nitroarginine methyl ester (L-NAME; 10-200 μM), and cavtratin (10-75 μM ) was administered topically to the eye while the contralateral eyes were vehicle controls. Intraocular pressure (IOP) was measured in both eyes by tonometry. Cyclic guanosine monophosphate (cGMP) level in outflow tissue was measured by ELISA assay. Protein expression were analyzed by western blot. Inducible NOS (iNOS) expression significantly increased in the DKO mice compared with the wild type (WT), Cav1 knockout (Cav1 KO), and NOS3 KO mice. In contrast to WT, Cav1 KO and NOS3 KO mice, SNP concentration of up to 30 mg/mL did not significantly affect IOP in DKO mice. However, higher concentration (40 mg/mL) SNP significantly reduced IOP by 14% (n = 8, P < 0.01). Similarly, only 200 μM L-NAME produced a significant increase in IOP (n = 10, P < 0.05). Cavtratin did not significantly change IOP in DKO and NOS3 KO mice. cGMP activity in DKO mice was significantly lower than Cav1 KO mice (n = 4, P < 0.05). In conclusion, our results demonstrated that genetic deletion of NOS3 in Cav1 deficient mice resulted in reduced sensitivity to the NO donor SNP and the two NOS inhibitors possibly due to compromised NOS and cGMP activity.

Cinaciguat in combination with insulin induces a favorable effect on implant osseointegration in type 2 diabetic rats

The osseointegration process of implant is seriously impaired in type 2 diabetes mellitus (T2DM) that causes high failure rate, and insufficiency exists in current insulin therapy, creating a demand for new bone-synergistic agent. Cinaciguat, a novel type of soluble guanylate cyclase (sGC) activator, plays a vital role in glucose metabolism, inflammation control and bone regeneration. We hypothesized that the combined application of cinaciguat and insulin could reverse poor implant osseointegration in diabetes. To test this hypothesis, streptozotocin-induced diabetic rats were placed implants in the femur, and divided into five groups: control, T2DM, cinaciguat-treated T2DM (7 μg/kg), insulin-treated T2DM (12 IU/kg), cinaciguat plus insulin combination-treated T2DM (7 μg/kg and 12 IU/kg respectively), according to different treatment received. The weight and glucose levels of rats were evaluated at fixed times, and plasma level of cyclic guanosine monophosphate (cGMP) was determined before euthanasia. Three months after therapy, the femurs were isolated for pull-out test, environmental scanning electron microscope observation, microscopic computerized tomography evaluation and various histology analysis. Results revealed that diabetic rats showed the highest blood glucose level and lowest cGMP content, which led to the worst structural damage and least osseointegration. Combined treatment could attenuate the diabetes induced hyperglycemia to be normal, restore the cGMP content, protein kinase G II (PKG II) expression, phosphodiesterase-5 (PDE5) activity and ameliorate the mechanical strength, the impaired bone microarchitecture and osseointegration to the highest level. Meanwhile, monotreatment (insulin or cinaciguat) also showed restorative effect, but less. Our findings demonstrated that the cGMP/PKG II signaling pathway activated by cinaciguat mediated the favorable effects of the combined application on improving implant fixation under T2DM condition.

Natriuretic peptide signaling is involved in the expression of oxidative metabolism-related and muscle fiber constitutive genes in the gastrocnemius muscle

Natriuretic peptides regulate cyclic guanosine monophosphate (cGMP) levels via their receptors and have various physiological effects. Natriuretic peptide receptor C (NPR-C) increases cGMP signaling by functioning as a clearance receptor. We analyzed the role of natriuretic peptides in the skeletal muscle, which increases in mass with bone elongation, of NPR-C− mice. High-fat diet (HFD)-fed NPR-C− mice exhibited obesity resistance and higher oxygen consumption. PGC1α gene expression was upregulated in the gastrocnemius muscle of HFD-fed NPR-C− mice compared with HFD-fed NPR-C+ (wild-type) mice. Gene expression of proliferator-activated receptor delta and estrogen-related receptor α, which upregulate oxidative metabolism, was increased in the gastrocnemius muscle of NPR-C− mice, irrespective of diet. Expression of myosin heavy chain 7, a component of type I slow-twitch fiber, was enhanced. Natriuretic peptide signaling may influence oxidative metabolism-related and slow-twitch fiber constitutive gene expression in the fast-twitch gastrocnemius muscle but not in slow-twitch muscles such as the soleus.

Marjoram Relaxes Rat Thoracic Aorta Via a PI3-K/eNOS/cGMP Pathway.

Despite pharmacotherapeutic advances, cardiovascular disease (CVD) remains the primary cause of global mortality. Alternative approaches, such as herbal medicine, continue to be sought to reduce this burden. Origanum majorana is recognized for many medicinal values, yet its vasculoprotective effects remain poorly investigated. Here, we subjected rat thoracic aortae to increasing doses of an ethanolic extract of Origanum majorana (OME). OME induced relaxation in a dose-dependent manner in endothelium-intact rings. This relaxation was significantly blunted in denuded rings. N(ω)-nitro-l-arginine methyl ester (L-NAME) or 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ) significantly reduced the OME-induced vasorelaxation. Cyclic guanosine monophosphate (cGMP) levels were also increased by OME. Moreover, wortmannin or LY294002 significantly reduced OME-induced vasorelaxation. Blockers of ATP-sensitive or Ca2+-activated potassium channels such as glibenclamide or tetraethylamonium (TEA), respectively, did not significantly affect OME-induced relaxation. Similarly, verapamil, a Ca2+ channel blocker, indomethacin, a non-selective cyclooxygenase inhibitor, and pyrilamine, a H1 histamine receptor blocker, did not significantly modulate the observed relaxation. Taken together, our results show that OME induces vasorelaxation via an endothelium-dependent mechanism involving the phosphoinositide 3-kinase (PI3-K)/ endothelial nitric oxide (NO) synthase (eNOS)/cGMP pathway. Our findings further support the medicinal value of marjoram and provide a basis for its beneficial intake. Although consuming marjoram may have an antihypertensive effect, further studies are needed to better determine its effects in different vascular beds.

Long-Term Aspirin Administration Has No Effect on Erectile Function: Evidence from Adult Rats and Ageing Rat Model

As the broad spectrum pharmacological action, aspirin has been one of the most widely used medicines since its initial synthesis; however, the association between aspirin and erectile function is still controversial. We aim to explore whether long-term aspirin administration deteriorates or preserves erectile function from adult rats and ageing rat model. Twenty adult rats (10 weeks of age) and twenty ageing rats (80 weeks of age) were randomly divided into four groups as follows: Adult-Control (normal saline [NS]), Adult-Aspirin (aspirin, 10 mg/kg/d), Ageing-Control (NS), and Ageing-Aspirin (aspirin, 10 mg/kg/d) groups (n = 10 per group). For all rats, erectile function was assessed by maximum intracavernous pressure (ICP), total area under ICP curve (AUC), ICP/mean arterial pressure (MAP) ratio, and MAP. The total treatment duration was one month. Protein expression levels of cyclooxygenase-1 (COX-1), COX-2, endothelial nitric oxide synthase (eNOS), and nNOS of the corpus cavernosum were detected by Western blot. ELISA kits were used to determine 6-keto PGF1a, PGE2, TXB2, cyclic adenosine monophosphate (cAMP), and cyclic guanosine monophosphate (cGMP) levels. Total nitric oxide (NO) concentration was measured using a fluorometric assay kit. As a result, Ageing-Control rats revealed significantly decreased ICP, AUC, and ICP/MAP ratios compared to Adult-Control rats, and these effects were accompanied by reduced eNOS protein expression and lower total NO and cGMP levels; however, no difference was found in nNOS protein expression. For adult rat groups, aspirin significantly inhibited the production of 6-keto PGF1a, PGE2, and TXB2; however, it neither changed the ICP, AUC, or ICP/ MAP ratios nor altered the protein expression of eNOS, nNOS, COX-1, and COX-2. Meanwhile, aspirin did not influence the concentrations of total NO, cAMP, or cGMP. The same tendency was also found in the ageing rat model, which confirmed that aspirin did not alter erectile function. Our data suggested that long-term aspirin administration did not strengthen or weaken erectile function in adult rats or ageing rat model. Thus, it had no impact on erectile function.

Ginsenoside Re inhibits PDGF-BB-induced VSMC proliferation via the eNOS/NO/cGMP pathway

Ginsenoside Re (GS-Re), which is a major monomeric member of the ginseng trialcohol saponin family, is one of the main active components of ginseng and plays an important role in protecting the cardiovascular system. Here, we report a novel function by which GS-Re regulates the eNOS/NO/cGMP pathway, which affects the platelet-derived growth factor-BB (PDGF-BB)-induced proliferation of vascular smooth muscle cells (VSMCs). GS-Re inhibited PDGF-BB-induced VSMC proliferation in a concentration-dependent manner without cytotoxicity, and the endothelial nitric oxide synthase (eNOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) antagonized the antiproliferative effect of GS-Re. The flow cytometry analysis suggested that GS-Re regulates VSMC proliferation by influencing the cell cycle transition from G0/G1 to S phase and decreasing the expression of G0/G1-specific regulatory proteins, including proliferating cell nuclear antigen (PCNA), cyclin D1, and CDK4, in PDGF-BB-treated VSMCs, consequently upregulating the protein expression of p21. After GS-Re treatment, the levels of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) and the phos-eNOS Ser1177/eNOS protein ratio were obviously increased. In addition, treatment with L-NAME blocked the eNOS/NO/cGMP signaling pathway, and the protein levels of PCNA, cyclin D1, and CDK4 were markedly increased in GS-Re-treated VSMCs, while p21 expression was decreased in PDGF-BB-induced VSMCs. Overall, these findings reveal that GS-Re can inhibit the proliferation of VSMCs through G0/G1 cell cycle arrest, which is closely related to eNOS/NO/cGMP pathway activation. The present results provide basic pharmacological evidence of the potential prevention and treatment of cardiovascular diseases by GS-Re.

Electrophysiologic and molecular mechanisms of a frameshift NPPA mutation linked with familial atrial fibrillation

A frameshift (fs) mutation in the natriuretic peptide precursor A (NPPA) gene, encoding a mutant atrial natriuretic peptide (Mut-ANP), has been linked with familial atrial fibrillation (AF) but the underlying mechanisms by which the mutation causes AF remain unclear. We engineered 2 transgenic (TG) mouse lines expressing the wild-type (WT)-NPPA gene (H-WT-NPPA) and the human fs-Mut-NPPA gene (H-fsMut-NPPA) to test the hypothesis that mice overexpressing the human NPPA mutation are more susceptible to AF and elucidate the underlying electrophysiologic and molecular mechanisms. Transthoracic echocardiography and surface electrocardiography (ECG) were performed in H-fsMut-NPPA, H-WT-NPPA, and Non-TG mice. Invasive electrophysiology, immunohistochemistry, Western blotting and patch clamping of membrane potentials were performed. To examine the role of the Mut-ANP in ion channel remodeling, we measured plasma cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) levels and protein kinase A (PKA) activity in the 3 groups of mice. In H-fsMut-NPPA mice mean arterial pressure (MAP) was reduced when compared to H-WT-NPPA and Non-TG mice. Furthermore, injection of synthetic fs-Mut-ANP lowered the MAP in H-WT-NPPA and Non-TG mice while synthetic WT-ANP had no effect on MAP in the 3 groups of mice. ECG characterization revealed significantly prolonged QRS duration in H-fsMut-NPPA mice when compared to the other two groups. Trans-Esophageal (TE) atrial pacing of H-fsMut-NPPA mice showed increased AF burden and AF episodes when compared with H-WT-NPPA or Non-TG mice. The cardiac Na+ (NaV1.5) and Ca2+ (CaV1.2/CaV1.3) channel expression and currents (INa, ICaL) and action potential durations (APD90/APD50/APD20) were significantly reduced in H-fsMut-NPPA mice while the rectifier K+ channel current (IKs) was markedly increased when compared to the other 2 groups of mice. In addition, plasma cGMP levels were only increased in H-fsMut-NPPA mice with a corresponding reduction in plasma cAMP levels and PKA activity. In summary, we showed that mice overexpressing an AF-linked NPPA mutation are more prone to develop AF and this risk is mediated in part by remodeling of the cardiac Na+, Ca2+ and K+ channels creating an electrophysiologic substrate for reentrant AF.

Erectile dysfunction attenuation by naringenin in streptozotocin-induced diabetic rats.

Diabetes mellitus is associated with sexual dysfunction, which leads to infertility in animal models. The aim of this study was to evaluate sexual behavior in diabetic rats administered with naringenin. Rats were classified into five groups including healthy controls, those with STZ-induced diabetes, and those with STZ-induced diabetes then treated with 25, 50, or 100mgkg-1 day-1 of naringenin. Male rats were introduced to sexually receptive females, and data were collected regarding sexual behavior and erectile activity. Blood samples were taken and histopathological analyses were carried out. ANOVA and the Student-Newman-Keuls t test were used for statistical comparisons. Sexual behavioral, mount latency, intromission latency, ejaculation latency, and postejaculatory interval were significantly increased in diabetic rates compared with controls (p<0.001). The NG-treated rats showed a significant improvement in testosterone and cyclic guanosine monophosphate levels, and testicular oxidative stress and inflammatory biomarkers were corrected in a dose-dependent manner compared with controls. The treatment protocol used in this study led to the elimination of sexual impairment resulting from DM, and naringenin showed significant antiinflammatory and antioxidant effects in testicular cells. PRACTICAL APPLICATIONS: Erectile dysfunction occurs in more than 50% of men who are diagnosed with diabetes mellitus. The prevalence of ED is 25% in patients younger than 50years and 75% in those older than 50years. Chronic DM leads to oxidative stress, which has significant effects on sexual behavior, spermatogenesis, and sperm biology. Phenolic compounds have been reported to reduce streptozotocin-induced oxidative stress in experimental animal models. In addition, they have significant effects on the generation of sperm (spermatogenesis), which is involved in the pathogenesis of chronic DM. Our study was designed to examine the effect of naringenin, a flavone flavonoid, on oxidative stress, the inflammatory process, sexual behavior, erectile activity through spermatogenesis, and cavernous cyclic guanosine monophosphate in streptozotocin-induced diabetic rats.

İsatinin İskemi ve Reperfüzyon Hasarı Üzerine Etkisi: İzole Kalpte Deneysel Bir Çalışma

Introduction: Isatin is an endogen indole that is found in body fluids and reported as a neuroprotective, anticonvulsant, and sedative agent. The aim of the present study was to investigate the effects of isatin on left ventricle functions before and after low-flow ischemia in the isolated rat heart. Patients and Methods: Male Wistar rats were divided into four groups. Isatin (I, 50 mg/kg intraperitoneally) was administered in the I and I-atrial natriuretic peptide (ANP) groups 20 min before the hearts were placed on the Langendorff apparatus. Serum physiologic was administered to the control (C) and ANP groups. Low-flow ischemia was applied in all groups. ANP (0.1 μM/L) was added to perfusion solution in the ANP and I + ANP groups 15 min before ischemia. Left ventricular developed pressure (LVDP) and maximum and minimum pressure changes were recorded before and after ischemia. Cyclic guanosine monophosphate (cGMP) levels were measured in the perfusate in all groups. Results: LVDP and minimum pressure change values of the I group were found to be similar to the C group at 60 min of reperfusion. The level of cGMP in the I group was similar to the C group but lower than the ANP and I + ANP groups before and after ischemia. Conclusion: The administration of isatin prior to cardiac ischemia does not significantly alter cardiac function during the reperfusion period in rat heart. The results of the present study showed that isatin may not appear to have a disturbing effect on cardiac functions after low-flow ischemia.

Aspirin eugenol ester inhibits agonist-induced platelet aggregation in vitro by regulating PI3K/Akt, MAPK and Sirt 1/CD40L pathways

Aspirin eugenol ester (AEE) was a promising drug candidate for treating inflammation, pain and fever and preventing cardiovascular diseases with fewer side effects than its precursors. Previous researches indicated that AEE could markedly inhibit agonist-induced platelet aggregation in vitro and ex vivo, however, the anti-platelet aggregation mechanisms of AEE remain to be defined. Here, AEE in vitro effects on agonist-induced granule-secretion, intercellular Ca2+ mobilization and thromboxane A2 (TXA2) generation were examined. Vasodilator-stimulated phosphoprotein (VASP), mitogen-activated protein kinase (MAPK), Akt, Sirt 1 and CD40L expressions were also studied.In agonist-activated platelets in vitro, AEE markedly attenuated granule secretion markers (P-selectin expression and ATP release), intercellular Ca2+ mobilization and thromboxane B2 (TXB2) formation. AEE also attenuated CD40L activation, suppressed extracellular-signal-regulated protein kinase 2 (ERK2), c-Jun N-terminal kinase 1 (JNK1) and Akt phosphorylation, and recovered Sirt1 expression, but the activation of p38, VASPSer157 and VASPSer239, and the levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were not affected by AEE. Overall, this study demonstrates that AEE inhibits agonist-induced platelet aggregation in vitro by regulating PI3K/Akt, MAPK and Sirt 1/CD40L pathways.

Pharmacological Management of Dementia with Lewy Bodies.

Dementia with Lewy bodies (DLB) is a complex disease that involves a variety of cognitive, behavioral and neurological symptoms, including progressive memory loss, visual hallucinations, parkinsonism, cognitive fluctuations and rapid eye movement sleep behavior disorder (RBD). These symptoms may appear in varying combinations and levels of severity in each patient who is seen in the clinic, making diagnosis and treatment a challenge. DLB is the third most common of all the neurodegenerative diseases behind both Alzheimer’s disease and Parkinson’s disease (PD). The median age of onset for DLB (76.3 years) is younger than that seen in PD dementia (81.4 years). New pathological studies have shown that most DLB patients have variable amounts of Alzheimer’s changes in their brains, explaining the wide variability in this disease’s clinical presentation and clinical course. This review discusses the three cholinesterase inhibitors that have been shown to be effective in managing the cognitive and behavioral symptoms of DLB: rivastigmine, galantamine and donepezil. Memantine is able to improve clinical global impression of change in those with mild to moderate DLB. Levodopa can treat the parkinsonism of some DLB patients, but the dose is often limited due to the fact that it can cause agitation or worsening of visual hallucinations. A recent phase 2 clinical trial showed the benefit of zonisamide when it is added as an adjunct to levodopa for treating DLB parkinsonism. While atypical antipsychotic drugs may not always be helpful as monotherapy in managing the agitation associated with DLB, low doses of valproic acid can be effective when added as an adjunct to drugs like quetiapine. Pimavanserin may prove to be a useful treatment for psychosis in DLB patients, but like other antipsychotic drugs that are used in dementia patients, there is a small increased risk of mortality. RBD, which is a common core clinical feature of DLB, can be managed with either melatonin or clonazepam. Two agents targeting alpha-synuclein (NPT200-11 and ambroxol) currently hold promise as disease-modifying therapies for DLB, but they are yet to be tested in clinical trials. An agent (E2027) that offers hope of neuroprotection by increasing central cyclic guanosine monophosphate (cGMP) levels is currently being examined in clinical trials in DLB patients.

The Effect of Chemerin on Cardiac Parameters and Gene Expressions in Isolated Perfused Rat Heart

Background:Chemerin is a novel chemoattractant adipokine expressed in cardiovascular system, and its receptor has been detected in the epicardial adipose tissue.Aims:To determine the effects of chemerin on the cardiac parameters and gene expressions in the isolated perfused rat heart.Study Design:Animal experiment.Methods:The hearts were retrogradely perfused with Langendorff technique to measure the cardiac parameters. The experimental groups were acutely treated with 10, 100, and 1000 nM doses of chemerin. Another group was given 10 μM L-nitric oxide synthase inhibitor for 5 min before 1000 nM chemerin administration. The real-time polymerase chain reaction was performed for detecting the expression of target genes.Results:All doses of chemerin significantly decreased the left ventricular developed pressure (max 35.33 Δ%, p<0.001), and +dP/dtmax (max 31.3 Δ%, p<0.001), which are the indexes of cardiac contractile force. In addition, 1000 nM chemerin reduced the coronary flow (max 31 Δ%, p<0.001). N(W)-nitro-L-arginine methyl ester antagonized the negative inotropic effect of chemerin on contractility. Chemerin induced a 2.16-fold increase in endothelial nitric oxide synthase mRNA and increased the cyclic guanosine monophosphate levels (p<0.001) but decreased the PI3Kγ gene expression (1.8-fold, p<0.001). Furthermore, all doses of chemerin decreased the CaV1.2 gene expression (1.69-fold, p<0.001).Conclusion:Acute chemerin treatment induces a negative inotropic action with the involvement of nitric oxide pathway, CaV1.2, and PI3Kγ on isolated rat heart.

Rethinking to riluzole mechanism of action: the molecular link among protein kinase CK1δ activity, TDP-43 phosphorylation, and amyotrophic lateral sclerosis pharmacological treatment.

Rethinking to riluzole mechanism of action: the molecular link among protein kinase CK1δ activity, TDP-43 phosphorylation, and amyotrophic lateral sclerosis pharmacological treatment.