Cyclic Guanosine Monophosphate Content Research Articles

Effects of the phosphodiesterase 2 inhibitor BI 474121 on central nervous system cyclic guanosine monophosphate concentrations: Translational studies.

Phosphodiesterase 2 (PDE2) regulates intracellular cyclic adenosine monophosphate and guanosine monophosphate (cAMP/cGMP) levels, which contribute to processes crucial for learning and memory. BI 474121, a potent and selective PDE2 inhibitor, is in development for treating cognitive impairment associated with schizophrenia. The effects of BI 474121 on cGMP concentrations were first assessed in rat cerebrospinal fluid (CSF) to demonstrate central nervous system (CNS) and functional target engagement. Next, a Phase I study in healthy participants assessed the pharmacokinetics of BI 474121 in CSF vs. plasma, the pharmacodynamics of BI 474121 by measuring cGMP concentrations in the CSF, and the safety of BI 474121. In rats, BI 474121 was associated with a dose-dependent increase (71% at the highest dose tested [3.0mg kg-1]) in cGMP levels in the CSF relative to vehicle (P < 0.001). In healthy participants, the maximum-measured concentration CSF-to-plasma ratio for BI 474121 exposure was similar following single oral doses of BI 474121 2.5, 10, 20 and 40 mg (dose-adjusted geometric mean: 8.96% overall). BI 474121 2.5-40 mg administration in healthy participants also increased cGMP levels in CSF (maximum exposure-related change from baseline ratio, BI 474121: 1.44-2.20 vs. placebo: 1.26). The most common treatment-emergent adverse event (AE) was mild-to-moderate post-lumbar puncture syndrome, which resolved with standard treatment. No AEs of special interest were observed. BI 474121 crosses the blood-brain barrier to inhibit PDE2, supporting cGMP as a translational marker to monitor CNS target engagement. These findings promote further clinical development of BI 474121. gov number (NCT04672954).

The regulatory effects of arginine on ovary development in the Chinese mitten crab Eriocheir sinensis

This study aimed to investigate the effects of arginine (Arg) on the vitellogenesis and ovarian maturation of Chinese mitten crab. Six isonitrogenous and isolipidic diets (1.83, 2.52, 3.26, 3.96, 4.81 and 5.52 % Arg) were fed to adult female Chinese mitten crab (60.05 ± 4.33 g). The feeding period lasted for eleven weeks. The results showed that gonadosomatic index of crabs increased with increasing dietary Arg concentrations from 1.83 % to 2.52 % and significantly decreased from 2.52 % to 5.52 %. The quadratic regression analysis based on gonadosomatic index estimated that the optimal Arg requirement for adult female crabs was 2.60 %. Dietary supplementation with 2.52 % Arg significantly increased the crude protein concentration in the ovary. A dose of 2.52 % Arg significantly decreased the vitellogenesis-inhibiting hormone (VIH) content in the hemolymph. Arg (2.52 %) significantly upregulated the Vg and protein kinase A (PKA) gene expressions and increased the cyclic adenosine monophosphate (cAMP) concentration in the hepatopancreas. Moreover, dietary supplementation with 2.52 % Arg significantly decreased the cyclic guanosine monophosphate (cGMP) concentration and downregulated protein kinase G (PKG) and p38 mitogen-activated protein kinase (p38 MAPK) gene expression. Arg at 2.52 % significantly increased hemolymph Vg content and the gene expression of the vitellogenin receptor (VgR). In conclusion, Arg at 2.52 % improved vitellogenesis and ovarian maturation by reducing the VIH content and regulating Vg expression via the cGMP/cAMP pathway.

Decoding the influence of low temperature on biofilm development: The hidden roles of c-di-GMP

Biofilms are widely used and play important roles in biological processes. Low temperature of wastewater inhibits the development of biofilms derived from wastewater activated sludge. However, the specific mechanism of temperature on biofilm development is still unclear. This study explored the mechanism of temperature on biofilm development and found a feasible method to enhance biofilm development at low temperature. The amount of biofilm development decreased by approximately 66 % and 55 % at 4 °C and 15 °C, respectively, as compared to 28 °C. The cyclic dimeric guanosine monophosphate (c-di-GMP) concentration also decreased at low temperature and was positively correlated with extracellular polymeric substance (EPS) content, formation, and adhesion strength. Microbial community results showed that low temperature inhibited the normal survival of most microorganisms, but promoted the growth of some psychrophile bacteria like Sporosarcina, Caldilineaceae, Gemmataceae, Anaerolineaceae and Acidobacteriota. Further analysis of functional genes demonstrated that the abundance of functional genes related to the synthesis of c-di-GMP (K18968, K18967 and K13590) decreased at low temperature. Subsequently, the addition of exogenous spermidine increased the level of intracellular c-di-GMP and alleviated the inhibition effect of low temperature on biofilm development. Therefore, the possible mechanism of low temperature on biofilm development could be the inhibition of the microorganism activity and reduction of the communication level between cells, which is the closely related to the EPS content, formation, and adhesion strength. The enhancement of c-di-GMP level through the exogenous addition of spermidine provides an alternative strategy to enhance biofilm development at low temperatures. The results of this study enhance the understanding of the influence of temperature on biofilm development and provide possible strategies for enhancing biofilm development at low temperatures.

FEATURES OF RELATIONS OF MELATONIN WITH THE STATE OF INTRACELLULAR REGULATORSOF THE FUNCTIONAL ACTIVITY OF WHOLE BLOOD MONONUCLEAR CELLS IN CORONARY HEART DISEASE

Introduction. Coronary heart disease (CHD), leading among the causes of death in adulthood and old age, is an urgent medical and social problem. The pathogenesis of most forms of coronary heart disease is based on stenosing atherosclerosis of the coronary arteries, which develops against the background of dyslipidemia and arterial hypertension and is accompanied by the activation of immunocompetent cells (ICCs) of the vascular wall with the development of a subclinical inflammatory reaction, as well as the production of pro-inflammatory factors such as interleukins, chemokines, growth factors and etc. In turn, ICC activity is determined by the state of their intracellular molecular cascades, which transmit signals into the cell and ensure its reactivity to various external stimuli, such as mitogens, cytokines, pathogen components, etcIt has been shown that the central nervous system plays an important role in the regulation of ICC activity due to the production of neurohumoral molecules, such as melatonin, endorphin, sero-tonin, etc., which ensure the coordination of immune responses and their control by the central nervous system. The aim of this study was to study the relationship between melatonin production and intracellular factors that regulate the pro-inflammatory activi-ty of whole blood mononuclear cells and their metabolism in patients with coronary artery disease. Material and methods. As part of the cohort study, 58 patients of both sexes with coronary artery disease aged 49 to 67 years and 20 practically healthy individuals of both sexes were examined. In accordance with the purpose of the study, the concentration of focal adhesion protein kinase (FAK), 5'AMP-activated protein kinase (AMPK), AKT1 protein kinase, signal transducers and transcription activators (STAT) was determined in nuclear cy-toplasmic lysates of whole blood mononuclear cells: STAT3, STAT5A and STAT6, c-Jun N-terminal protein kinase 1 and 2 isoforms (JNK), mitogen-activated protein kinase p38 (p38), extracellular growth kinase 1 and 2 isoforms (ERK), Janus kinase type 2 (JAK2), nuclear transcription factor NF -kB, caspase-1, cyclooxygenase-2 (COX-2), p70-S6K1 protein kinase, p53, p27, p21 proteins. In addition, the concentration of cyclic adenosine monophos-phate (cAMP) and cyclic guanosine monophosphate (cGMP) was determined in cell supernatants. Melatonin concentration was determined in blood se-rum. The material for the study was venous blood taken from the cubital vein in the morning from 6.00 to 6.15. Results. The analysis showed that in patients with coronary artery disease, in comparison with practically healthy individuals, in MNCs of whole blood, there was an increased level of protein kinases FAK, AKT, JNK, ERK, p70-S6K1, factor STAT6, protein p21, against which there was a decrease in the content of STAT3, STAT5A, JAK2, transcription factor NF-kB and caspase-1. These changes were accompanied by increased levels of cGMP and cAMP. Against this background, a decrease in the content of factors was revealed in the MNC. A high concentration of melatonin in patients with CAD was as-sociated with a decrease in the content of protein kinases AMPK, AKT, Jak2, ERK1, protein p21, caspase-1, and cAMP in MNCs, which was observed against the background of an increase in the level of protein p27 and nuclear factor NF-kB. The results of the correlation analysis indicate a different na-ture of the relationship between the level of melatonin and such factors as caspase-1, protein kinases ERK, JAK2, as well as the transcription factor NF-kB and p21 protein, depending on the characteristics of melatonin production in patients with coronary artery disease. Conclusions. In patients with coronary artery disease, melatonin exhibits a modulating effect on the energy balance of ICCs and their metabolism, helps limit pro-inflammatory activity by limiting the functional activity of MAPK/SAPK signaling pathways in MNCs.

Role of alpha-7 nicotinic acetylcholine receptor down-regulation in cyclic nucleotide reduction in memory-related brain regions of Alzheimer’s rats

In this study, we investigated the effect of the downregulation of α7 nicotinic acetylcholine receptors (α7nAChRs) by Streptozotocin (STZ) on the level of cyclic nucleotides. Three groups of six rats each—Control, Sham (received an Intracerebroventricular injection of artificial cerebrospinal fluid, and STZ were formed. Except for the control group, all rats were anesthetized with 45 mg/kg of pentobarbitone. The STZ was administered intracerebroventricularly at a dose of 3 mg/kg to STZ group rats on Day 1 as well as Day 3 of an experimental period of 18 days. By using the Morris Water Maze (MWM) along with the Y-maze test, behavioral parameters were assessed, and biochemical analysis was assessed within the hippocampus, prefrontal cortex as well as amygdala of the rat brain. Statistical analysis was performed using repeated measures with one-way and two-way analysis of variance. Bonferroni and Student Newman–Keuls post hoc test was used to determine significance between experimental groups, with a significance threshold of p &lt; 0.05. STZ administration resulted in a notable decline in the cognitive function of rats, as evidenced by longer transfer latency, reduced duration spent, and decreased overall distance covered within the designated quadrant (in percentage) in the MWM assessment. Moreover, STZ lowered the spontaneous change in behavior observed in the rodents during the Y-maze evaluation and decreased Cyclic Adenosine Monophosphate and Cyclic Guanosine Monophosphate (cyclic nucleotides) concentrations within the HIP, PFC, and Amygdale of rat brain regions. The α7nAChR downregulation may form a basis that could serve as a foundation for cognitive impairments alongside reduced cyclic nucleotides’ concentration in specific areas of the rat brain. Thus, cyclic nucleotides could be a probable target to stimulate the α7nAChR mediated mechanism in STZ-mediated conditions.

Inhibiting bacterial biofilm formation by stimulating c-di-GMP regulation using citrus peel extract from Jeju Island

Biofilms consist of single or multiple species of bacteria embedded in extracellular polymeric substances (EPSs), which affect the increase in antibiotic resistance by restricting the transport of antibiotics to the bacterial cells. An alternative approach to treatment with antimicrobial agents is using biofilm inhibitors that regulate biofilm development without inhibiting bacterial growth. In this study, we found that citrus peel extract from Jeju Island (CPEJ) can inhibit bacterial biofilm formation. According to the results, CPEJ concentration-dependently reduces biofilm formation without affecting bacterial growth. Additionally, CPEJ decreased the production of extracellular polymeric substances but increased bacterial swarming motility. These results led to the hypothesis that CPEJ can reduce intracellular bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) concentration. The results showed that CPEJ significantly reduced the c-di-GMP level through increased phosphodiesterase activity. Altogether, these findings suggest that CPEJ as a biofilm inhibitor has new potential for pharmacological (e.g. drug and medication) and industrial applications (e.g. ship hulls, water pipes, and membrane processes biofouling control).

Vardenafil-Loaded Bilosomal Mucoadhesive Sponge for Buccal Delivery: Optimization, Characterization, and In Vivo Evaluation.

Vardenafil (VDF) is a relatively new phosphodiesterase-5 inhibitor that has limited oral bioavailability (≈15%). The objective of this study was to develop bilosome-based mucoadhesive buccal sponge for augmenting the oral bioavailability of VDF. VDF-loaded bilosomes were fabricated and optimized using a Box-Behnken design. The optimized VDF-loaded bilosomal formulation was assessed for surface morphology, particle size, thermal characteristics, and in vitro release. Afterwards, the optimized bilosomal formulation was incorporated into a cellulose-based matrix to obtain buccal sponge, which was evaluated for ex vivo permeation studies, in vivo oral bioavailability, and in vivo serum concentration of cyclic guanosine monophosphate (cGMP). The mean particle size and entrapment efficiency (%) of optimized bilosome formulation were 282.6 ± 9.5 nm and 82.95 ± 3.5%, respectively. In vitro release studies at pH 6.8 emphasized the potential of optimized bilosomal formulation to sustain VDF release for 12 h. Ex vivo permeation study using sheep buccal mucosa indicated significant enhancement in penetration of VDF from bilosomal buccal sponge compared to plain VDF gel. Pharmacokinetic study in Albino rats showed ~5 fold increase in relative bioavailability with bilosomal buccal sponge, compared to VDF suspension. In addition, VDF-loaded bilosomal buccal sponge triggered higher serum levels of cGMP, a biomarker of VDF in vivo efficacy, compared to oral VDF suspension. To sum up, bilosomes might represent a potential nanocarrier for buccal delivery of VDF, enhancing its oral bioavailability and therapeutic efficacy.

Effects of cGMP/Akt/GSK-3β signaling pathway on atrial natriuretic peptide secretion in rabbits with rapid atrial pacing.

Atrial natriuretic peptide (ANP) plays a pivotal role in the regulation of the cardiovascular system. The ANP level increases during atrial fibrillation (AF), suggesting that AF may provoke ANP secretion, but its potential mechanism is still unclear. In the present study, the potential mechanisms of rapid atrial pacing (RAP) regulating ANP secretion was explored. Rabbits were subjected to burst RAP, ANP secretion increased whereas cyclic guanosine monophosphate (cGMP) concentrations decreased during RAP. The p-Akt and p-GSK-3β levels decreased in atrial tissues. Natriuretic peptide receptor A (NPR-A) protein and particulate guanylate cyclase (PGC) activity were detected. The sensitivity of NPR-A to ANP decreased, leading to the decrease of PGC activity. Also, the isolated atrial perfusion system were made in the rabbit model, cGMP was shown to inhibit ANP secretion, and the Akt inhibitor LY294002 (LY) and GSK-3β inhibitor SB216763 (SB) attenuated the inhibitory effects of cGMP on ANP secretion and enhanced the inhibitory effects of cGMP on atrial dynamics. In conclusion, NPR-A interacts with ANP to regulate PGC expression, and influence the expression of cGMP during RAP, which involves in the Akt/GSK-3β signaling pathway. From the aforementioned points we conclude that cGMP regulates ANP secretion by the Akt/GSK-3β signaling pathway during atrial pacing.

Double-blind controlled dietary cross-over intervention with differentially fertilised intact lettuce leaves shows acute reduction in blood pressure in young adults, associated with faster uptake of nitrate than of phenolics

PurposeTo compare acute effects on blood pressure (BP) of ingestion of visually similar lettuce with controlled high and low content of either nitrate or phenolic compounds.MethodsIn a randomised cross-over design, 19 healthy participants (22–31 years) received 50 g of lettuce containing either 530 mg (8.4 mmol) nitrate + 11 mg (0.03 mmol) phenolic compounds (HNLP); or 3 mg nitrate (0.05 mmol) + 77 mg (0.2 mmol) phenolic compounds (LNHP), obtained by differential fertilisation. Ambulatory BP was recorded along with plasma, salivary and urinary nitrate and nitrite and plasma concentrations of cyclic guanosine monophosphate (cGMP), phenolic metabolites, Trolox equivalent antioxidant capacity (TEAC) and ferric reducing antioxidant power (FRAP).ResultsCompared with LNHP, 3 h post ingestion of HNLP, plasma nitrate increased 0.31 ± (95%CI) 0.12 mM (+ 240%), and salivary nitrate 5.5 ± 1.4 mM (+ 910%); accumulated urinary nitrate excretion increased 188 ± 72 mg (+ 296%) (all P < 0.001). Systolic BP was reduced 4.9 ± 4.2 mmHg (P = 0.031) between 3 and 6 h after ingestion of HNLP compared with LNHP; systolic BP differences were negatively correlated (P = 0.004) with differences in saliva nitrate concentrations. LNHP increased plasma phenolics at 6 h, predominantly 3ʹ-methoxycinnamic acid-4ʹ-glucuronide (ferulic acid-4ʹ-glucuronide), 116%, 204 ± 138 nM more than HNLP (P = 0.001); increased cGMP 14% (P = 0.019); and reduced FRAP 3.1% (P = 0.009).ConclusionThe acute BP difference within 6 h of consumption matched the plasma/saliva nitrate peak, not the slower changes of plasma phenolics. This is the first double-blind controlled dietary intervention demonstrating differential effects on human physiology by consumption of an intact plant food, where compositional differences were obtained by controlling growing conditions, indicating potential opportunities for health claims relating to precision/vertical farming.Clinical trial registrationThe trial was retrospectively registered on ClinicalTrials.gov, with identifier NCT02701959, on March 8, 2016.

Ganoderma lucidum polysaccharide ameliorated diabetes mellitus-induced erectile dysfunction in rats by regulating fibrosis and the NOS/ERK/JNK pathway

BackgroundDiabetes mellitus-induced erectile dysfunction (DMED) is a frequent complication of diabetes mellitus (DM), with limited therapy at present. This study aimed to explore the role and mechanism of Ganoderma lucidum polysaccharide (GLP) on DMED.MethodsDMED was induced in the experimental rats [male 12-week-old Sprague-Dawley (SD) rats] by treatment with streptozotocin (60 mg/kg) and apomorphine (APO). Next, rats in the GLP low dose (GLP-L)/GLP high dose (GLP-H) groups were treated with GLP (100 or 400 mg/kg/d, respectively) for 8 weeks. Subsequently, erectile function was assessed by APO and electrostimulation of the cavernous nerve (CN). Serum or penile testosterone (T), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and cyclic guanosine monophosphate (cGMP) contents were evaluated by enzyme-linked immunosorbent assay (ELISA). The levels of oxidative stress indicators in the corpus cavernosum (CC) were measured by corresponding kits, and histological changes in the CC were observed by hematoxylin-eosin (HE) and Masson staining. Additionally, the apoptosis index, caspase-3, caspase-9, and eNOS expression, and mitochondrial membrane potential (MMP) were also detected. Furthermore, quantitative polymerase chain reaction (qPCR) and western blot assays were conducted to determine the NOS, TGF-β1 mRNA expression, ERK1/2, eNOS, JNK phosphorylation, and arginase II protein expression.ResultsThe erectile function test revealed that erectile dysfunction (ED) was alleviated in the DMED rats following treatment with GLP. Moreover, GLP upregulated the T and cGMP content, improved the oxidative stress and histological injuries of CC, and also inhibited the apoptosis and MMP loss of penile tissues in DMED rats. Furthermore, GLP treatment enhanced the mRNA expression of NOS and TGF-β1 and suppressed the phosphorylation of ERK1/2, eNOS, and JNK, as well as the protein expression of arginase II in DMED rats.ConclusionsGLP ameliorated DMED by repairing the CC pathological damage and upregulating NOS expression and ERK/JNK phosphorylation, indicating that GLP may be a candidate drug for DMED therapy.

Судинно-реологічні властивості крові при анкілозуючому спондиліті

Актуальність. Анкілозуючий спондиліт є чинником ризику тяжкої васкулярної патології, для якої характерне порушення ендотеліальної функції судин, але клініко-патогенетична роль цих змін залишається вивченою недостатньо. Мета дослідження: оцінити характер ендотеліальної дисфункції судин та адсорбційно-реологічних властивостей крові у хворих на анкілозуючий спондиліт, визначити її особливості за наявності ангіопатії, встановити зв’язок із клініко-інструментальними показниками судинної патології й станом імунітету. Матеріали та методи. Під спостереженням перебували 79 хворих віком від 15 до 66 років (у середньому 38 років), серед яких було 95 % чоловіків і 5 % жінок. Тривалість хвороби від перших її проявів становила 11 років, І ступінь активності мав місце в 32 % спостережень, ІІ — в 39 % і ІІІ — в 29 %, а співвідношення повільно прогресуючого до швидко прогресуючого перебігу патологічного процесу становило 4 : 1. Периферичний моноолігоартрит констатовано у 47 % хворих, поліартрит — у 53 %. Імуноферментним методом вивчали в сироватці крові рівні ендотеліального фактору зростання, ендотеліну-1, тромбоксану-А2, гомоцистеїну, простацикліну, циклічного гуанозинмонофосфату, Е- і P- селектину, а методом міжфазної тензіореометрії визначали поверхневі параметри в’язкості, пружності, натягу, релаксації й модуля в’язкоеластичності. Результати. Ендотеліальна дисфункція судин розвивається у кожного другого хворого на анкілозуючий спондиліт і за наявності клініко-інструментальної судинної патології супроводжується зростанням в крові концентрації циклічного гуанозинмонофосфату і ще більшим зменшенням параметрів простациклінемії. Ступінь вираженості порушень ендотеліальної функції судин у таких хворих пов’язаний із тривалістю захворювання, активністю патологічного процесу, ураженням периферичної нервової системи, вираженістю спондилопатії й сакроілеїту, при цьому існують кореляційні зв’язки між окремими імунними показниками та судинно-реологічними властивостями крові. Останні при анкілозуючому спондиліті беруть участь у патогенетичних побудовах ентезопатій, тендовагінітів, увеїту і склериту, визначають темпи прогресування суглобового синдрому та інтегральну тяжкість ангіопатії, а вміст циклічного гуанозинмонофосфату в крові має прогностичну значущість.

Ferulic acid ameliorates lipopolysaccharide-induced tracheal injury via cGMP/PKGII signaling pathway

BackgroundTracheal injury is a common clinical condition that still lacks an effective therapy at present. Stimulation of epithelial sodium channel (ENaC) increases Na+ transport, which is a driving force to keep tracheal mucosa free edema fluid during tracheal injury. Ferulic acid (FA) has been proved to be effective in many respiratory diseases through exerting anti-oxidant, anti-inflammatory, and anti-thrombotic effects. However, these studies rarely involve the level of ion transport, especially ENaC.MethodsC57BL/J male mice were treated intraperitoneally with normal saline or FA (100 mg/kg) 12 h before, and 12 h after intratracheal administration of lipopolysaccharide (LPS, 5 mg/kg), respectively. The effects of FA on tracheal injury were not only assessed through HE staining, immunofluorescence assay, and protein/mRNA expressions of ENaC located on tracheas, but also evaluated by the function of ENaC in mouse tracheal epithelial cells (MTECs). Besides, to explore the detailed mechanism about FA involved in LPS-induced tracheal injury, the content of cyclic guanosine monophosphate (cGMP) was measured, and Rp-cGMP (cGMP inhibitor) or cGMP-dependent protein kinase II (PKGII)-siRNA (siPKGII) were applied in primary MTECs, respectively.ResultsHistological examination results demonstrated that tracheal injury was obviously attenuated by pretreatment of FA. Meanwhile, FA could reverse LPS-induced reduction of both protein/mRNA expressions and ENaC activity. ELISA assay verified cGMP content was increased by FA, and administration of Rp-cGMP or transfection of siPKGII could reverse the FA up-regulated ENaC protein expression in MTECs.ConclusionsFerulic acid can attenuate LPS-induced tracheal injury through up-regulation of ENaC at least partially via the cGMP/PKGII pathway, which may provide a promising new direction for preventive and therapeutic strategy in tracheal injury.

Vasodilatory Effect of Guanxinning Tablet on Rabbit Thoracic Aorta is Modulated by Both Endothelium-Dependent and -Independent Mechanism.

Vasodilatory therapy plays an important role in the treatment of cardiovascular diseases, especially hypertension and coronary heart disease. Previous research found that Guanxinning tablet (GXNT), a traditional Chinese compound preparation composed of Salvia miltiorrhiza (Danshen) and Ligusticum chuanxiong (Chuanxiong), increase blood flow in the arteries, but whether vasodilation plays a role in this effect remains unclear. Here, we found that GXNT significantly alleviated the vasoconstriction of isolated rabbit thoracic aorta induced by phenylephrine (PE), norepinephrine (NE), and KCl in a dose-dependent manner with or without endothelial cells (ECs). Changes in calcium ion levels in vascular smooth muscle cells (VSMCs) showed that both intracellular calcium release and extracellular calcium influx through receptor-dependent calcium channel (ROC) declined with GXNT treatment. Experiments to examine potassium channels suggested that endothelium-denuded vessels were also regulated by calcium-activated potassium channels (Kca) and ATP-related potassium channels (KATP) but not voltage-gated potassium channels (kv) and inward rectifying potassium channels (KIR). For endothelium-intact vessels, the nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) contents in vascular tissue obviously increased after GXNT treatment, and pretreatment with the NO synthase inhibitor Nw-nitro-L-arginine methyl ester (L-NAME) or guanylyl cyclase inhibitor methylthionine chloride (MB) significantly inhibited vasodilation. An assessment of NO-related pathway protein expression revealed that GXNT enhanced the expression of phosphorylated endothelial NO synthase (eNOS) in a dose-dependent manner but had no effect on total eNOS, p-Akt, Akt, or PI3K levels in human umbilical vein ECs (HUVECs). In addition to PI3K/AKT signaling, Ca2+/calmodulin (CaM)-Ca2+/CaM-dependent protein kinase II (CaMKII) signaling is a major signal transduction pathway involved in eNOS activation in ECs. Further results showed that free calcium ion levels were decreased in HUVECs with GXNT treatment, accompanied by an increase in p-CaMKII expression, implying an increase in the Ca2+/CaM-Ca2+/CaMKII cascade. Taken together, these findings suggest that the GXNT may have exerted their vasodilative effect by activating the endothelial CaMKII/eNOS signaling pathway in endothelium-intact rings and calcium-related ion channels in endothelium-denuded vessels.

Prolonged isoflurane anesthesia-induced acidosis decreases penile intracavernous pressure in rats.

Intracavernous pressure measurement following cavernous nerve electrostimulation has been extensively adopted for the evaluation of erectile function in animals. However, the effect of measurement time and acidosis during anesthesia is still lacking. To explore the effect of measurement time and acidosis during anesthesia. Fifty-six male Sprague-Dawley rats were used and anesthetized by a spontaneous inhalation of isoflurane. In the first step, rats were randomly divided into four groups: a control group and three time-delayed measurement groups (intracavernous pressure measurement beginning at 15, 30, and 45min after cavernous nerve exposure). In the second step, rats were randomly divided into three groups: a control group and two time-delayed measurement groups. Two intravenous fluid support strategies were used in time-delayed measurement groups: a normal saline solution and an isotonic Na2 CO3 solution. Isoflurane-anesthetized rats developed systemic acidosis that worsens with time during intracavernous pressure measurement, which results in a significant decrease in the maximum intracavernous pressure value, intracavernous pressure/mean arterial pressure ratio, and total intracavernous pressure measured. The Na2 CO3 infusion could effectively correct acidosis. The decrease in intracavernous pressure was related to the reduced nitric oxide synthase activity, decreased cyclic guanosine monophosphate concentration, and reactive oxygen species activation in rat penis under acidosis conditions. Prolonged isoflurane anesthesia-induced acidosis markedly depresses the erectile response to cavernous nerve electrostimulation in rats. In this situation, it is recommended to supplement with a Na2 CO3 infusion to maintain a normal acid-base balance.

Current Modulation of Guanylate Cyclase Pathway Activity-Mechanism and Clinical Implications.

For years, guanylate cyclase seemed to be homogenic and tissue nonspecific enzyme; however, in the last few years, in light of preclinical and clinical trials, it became an interesting target for pharmacological intervention. There are several possible options leading to an increase in cyclic guanosine monophosphate concentrations. The first one is related to the uses of analogues of natriuretic peptides. The second is related to increasing levels of natriuretic peptides by the inhibition of degradation. The third leads to an increase in cyclic guanosine monophosphate concentration by the inhibition of its degradation by the inhibition of phosphodiesterase type 5. The last option involves increasing the concentration of cyclic guanosine monophosphate by the additional direct activation of soluble guanylate cyclase. Treatment based on the modulation of guanylate cyclase function is one of the most promising technologies in pharmacology. Pharmacological intervention is stable, effective and safe. Especially interesting is the role of stimulators and activators of soluble guanylate cyclase, which are able to increase the enzymatic activity to generate cyclic guanosine monophosphate independently of nitric oxide. Moreover, most of these agents are effective in chronic treatment in heart failure patients and pulmonary hypertension, and have potential to be a first line option.

Effects of magnesium biotinate supplementation on serum insulin, glucose and lipid parameters along with liver protein levels of lipid metabolism in rats.

The objective of this study was to investigate the effects of a novel form of biotin (magnesium biotinate) on serum glucose, lipid profile, and hepatic lipid metabolism-related protein levels in rats. Forty-two rats were divided into six groups and fed a standard diet-based egg white powdered diet supplemented with either d-biotin at 0.01, 1, or 100 mg/kg BW or magnesium biotinate at 0.01, 1, or 100 mg/kg BW for 35 days. Neither form of biotin influenced (p > 0.05) serum glucose or insulin concentrations. Serum total cholesterol and triglyceride decreased with biotin from both sources (p < 0.05). Concentrations were lower with magnesium biotinate when comparing the 1 mg/kg dose (p < 0.05). Serum, liver, and brain biotin and liver cyclic guanosine monophosphate (cGMP) concentrations were greater when rats were treated with magnesium biotinate versus d-biotin, particularly when comparing the 1 and 100 mg/kg dose groups (p < 0.05). Both biotin forms decreased the liver SREBP-1c and FAS and increased AMPK-α1, ACC-1, ACC-2, PCC, and MCC levels (p < 0.05). The magnitudes of responses were more emphasized with magnesium biotinate. Magnesium biotinate, compared with a commercial d-biotin, is more effective in reducing serum lipid concentrations and regulating protein levels of lipid metabolism-related biomarkers.

Tadalafil modulates intracerebroventricular streptozotocin-induced cognition and memory impairment in the young and middle middle-aged rats

Background: Learning and memory may decline due to Alzheimer’s disease (AD) in older adults. A reduction in cyclic guanosine monophosphate concentration and an increase in phosphodiesterase activity have been reported in the process of aging. Although phosphodiesterase (PDE) type 5 inhibitor, Tadalafil is used to treat erectile dysfunction; PDE inhibitors possibly prevent cognition impairment in aging. This study was designed to investigate the effects of tadalafil on memory in middle-aged and young healthy and AD rats. Methods: Memory impairment was induced by intracerebroventricular (ICV) administration of streptozotocin (STZ; 3 mg/kg) in AD rats. Male Wistar rats (middle-aged and young) were distributed into six groups as follows: two control, two AD, and two AD+tadalafil (1 mg/kg) groups. Saline or tadalafil was administered once a day orally for 40 consecutive days. Animals were tested using novel object recognition (NOR), passive avoidance learning (PAL), and Morris water maze (MWM) tests. Results: Aged AD rats exhibited a significant impairment in cognition in the NOR test and impaired learning and memory in PAL and MWM tests compared with the control aged rats. Tadalafil treatment in aged AD rats significantly improved the discrimination index in the NOR test, decreased the time spent in the dark compartment in the PAL test, and increased time spent in the target quadrant in MWM tests compared with aged AD rats. In young AD rats, treatment with tadalafil significantly enhanced cognition, learning, and memory in the NOR, PAL, and MWM tests compared with young AD rats treated with saline. Conclusion: Tadalafil treatment in aged rats improves cognition and memory after STZ-induced (ICV) memory impairment. It can be concluded that chronic treatment with tadalafil is protective against cognitive, learning, and memory impairment in both young and aged subjects.

Empagliflozin Ameliorates Diastolic Dysfunction and Left Ventricular Fibrosis/Stiffness in Nondiabetic Heart Failure: A Multimodality Study

ObjectivesThe purpose of this study was to investigate the effect of empagliflozin on diastolic function in a nondiabetic heart failure with reduced ejection fraction (HFrEF) scenario and on the pathways causing diastolic dysfunction. BackgroundThis group demonstrated that empagliflozin ameliorates adverse cardiac remodeling, enhances myocardial energetics, and improves left ventricular systolic function in a nondiabetic porcine model of HF. Whether empagliflozin also improves diastolic function remains unknown. Hypothetically, empagliflozin would improve diastolic function in HF mediated both by a reduction in interstitial myocardial fibrosis and an improvement in cardiomyocyte stiffness (titin phosphorylation). MethodsHF was induced in nondiabetic pigs by 2-h balloon occlusion of proximal left anterior descending artery. Animals were randomized to empagliflozin or placebo for 2 months. Cardiac function was evaluated with cardiac magnetic resonance (CMR), 3-dimensional echocardiography, and invasive hemodynamics. In vitro relaxation of cardiomyocytes was studied in primary culture. Myocardial samples were obtained for histological and molecular evaluation. Myocardial metabolite consumption was analyzed by simultaneous blood sampling from coronary artery and coronary sinus. ResultsDespite similar initial ischemic myocardial injury, the empagliflozin group showed significantly improved diastolic function at 2 months, assessed by conventional echocardiography (higher e′ and color M-mode propagation velocity, lower E/e′ ratio, myocardial performance Tei index, isovolumic relaxation time, and left atrial size), echocardiography-derived strain imaging (strain imaging diastolic index, strain rate at isovolumic relaxation time and during early diastole, and untwisting), and CMR (higher peak filling rate, larger first filling volume). Invasive hemodynamics confirmed improved diastolic function with empagliflozin (better peak LV pressure rate of decay (–dP/dt), shorter Tau, lower end-diastolic pressure-volume relationship (EDPVR), and reduced filling pressures). Empagliflozin reduced interstitial myocardial fibrosis at the imaging, histological and molecular level. Empagliflozin improved nitric oxide signaling (endothelial nitric oxide synthetase [eNOS] activity, nitric oxide [NO] availability, cyclic guanosine monophosphate (cGMP) content, protein kinase G [PKG] signaling) and enhanced titin phosphorylation (which is responsible for cardiomyocyte stiffness). Indeed, isolated cardiomyocytes exhibited better relaxation in empagliflozin-treated animals. Myocardial consumption of glucose and ketone bodies negatively and positively correlated with diastolic function, respectively. ConclusionsEmpagliflozin ameliorates diastolic function in a nondiabetic HF porcine model, mitigates histological and molecular remodeling, and reduces both left ventricle and cardiomyocyte stiffness.

A phosphodiesterase 11 (Pde11a) knockout mouse expressed functional but reduced Pde11a: Phenotype and impact on adrenocortical function

Phosphodiesterases catalyze the hydrolysis of cyclic nucleotides and maintain physiologic levels of intracellular concentrations of cyclic adenosine and guanosine mono-phosphate (cAMP and cGMP, respectively). Increased cAMP signaling has been associated with adrenocortical tumors and Cushing syndrome. Genetic defects in phosphodiesterase 11A (PDE11A) may lead to increased cAMP signaling and have been found to predispose to the development of adrenocortical, prostate, and testicular tumors. A previously reported Pde11a knockout (Pde11a−/−) mouse line was studied and found to express PDE11A mRNA and protein still, albeit at reduced levels; functional studies in various tissues showed increased cAMP levels and reduced PDE11A activity. Since patients with PDE11A defects and Cushing syndrome have PDE11A haploinsufficiency, it was particularly pertinent to study this hypomorphic mouse line. Indeed, Pde11a−/− mice failed to suppress corticosterone secretion in response to low dose dexamethasone, and in addition exhibited adrenal subcapsular hyperplasia with predominant fetal-like features in the inner adrenal cortex, mimicking other mouse models of increased cAMP signaling in the adrenal cortex. We conclude that a previously reported Pde11a−/− mouse showed continuing expression and function of PDE11A in most tissues. Nevertheless, Pde11a partial inactivation in mice led to an adrenocortical phenotype that was consistent with what we see in patients with PDE11A haploinsufficiency.

Long-term nitrate administration increases expression of browning genes in epididymal adipose tissue of male type 2 diabetic rats

Expression of browning genes are lower in both humans and animals with type 2 diabetes (T2D). This study aims at determining effects of long-term nitrate administration on protein and mRNA levels of uncoupling protein 1 (UCP1), peroxisome proliferator activated receptor gamma (PPAR-γ), and PPAR-γ coactivator 1 alpha (PGC1-α) in epididymal adipose tissue (eAT) of rats with T2D. Male Wistar rats were divided into 4 groups (n = 6/group): Control, diabetes, control + nitrate (CN), and diabetes + nitrate (DN). T2D was induced using high fat diet combined with a low-dose of streptozotocin (30 mg/kg body weight). Sodium nitrate was administrated at a dose of 100 mg/L for 6 months in nitrate-treated rats. Fasting serum glucose and insulin concentrations were measured at months 0 (i.e. at start of the protocol), 3, and 6. At month 6, protein and mRNA levels of UCP1, PPAR-γ, and PGC1-α were measured in eAT samples. In addition, tissue concentration of cyclic guanosine monophosphate (cGMP) was measured and histological analyses were done at month 6. In rats with T2D, 6-month administration of nitrate decreased serum glucose and insulin concentrations by 13% and 23%, respectively and increased cGMP level by 85%. Rats with T2D had lower mRNA and protein levels of PPAR-γ (62%, P < 0.0001 and 18%, P = 0.0472), PGC1-α (49%, P = 0.0019 and 21%, P = 0.0482), and UCP1 (35%, P = 0.0613 and 30%, P = 0.0031) in eAT; 6-month nitrate administration restored these decreased levels to near control values. In addition, nitrate increased adipocyte density by 193% and decreased adipocyte area by 53% in rats with T2D. In conclusion, long-term low-dose nitrate administration increased mRNA and protein expressions of browning genes in white adipose tissue of male rats with T2D; these findings partly explain favorable metabolic effects of nitrate administration in diabetes.