Selective Phosphodiesterase Inhibitors Research Articles

Knockout of adenylyl cyclase isoform 5 or 6 differentially modifies the β1-adrenoceptor-mediated inotropic response

Although only β2-adrenergic receptors (βAR) dually couple with stimulatory G protein (Gs) and inhibitory G protein (Gi), inactivation of Gi enhances both β1AR and β2AR responsiveness. We hypothesize that Gi restrains spontaneous adenylyl cyclase (AC) activity independent of receptor activation. Subcellular localization of the AC5/6 subtypes varies contributing to the compartmentation of βAR signaling. The primary objectives were to determine: (1) if β1AR-mediated inotropic responses were dependent upon either AC5 or AC6; (2) if intrinsic Gi inhibition is AC subtype selective and (3) the role of phosphodiesterases (PDE) 3/4 to regulate β1AR responsiveness. β1AR-mediated increases in contractile force and cAMP accumulation in cardiomyocytes were measured from wild type, AC5 and AC6 knockout (KO) mice, with or without pertussis toxin (PTX) pretreatment to inactivate Gi and/or after selective inhibition of PDEs 3/4. Noradrenaline potency at β1ARs was increased in AC6 KO. PDE4 inhibition increased noradrenaline potency in wild type and AC5 KO, but not AC6 KO. PTX increased noradrenaline potency only in wild type but increased the maximal β1AR response in all mouse strains. PDE3 inhibition increased noradrenaline potency only in AC5 KO that was treated prior with PTX. β1AR-evoked cAMP accumulation was increased more by PDE4 inhibition than PDE3 inhibition in wild type and AC5 KO that was amplified by Gi inhibition. These data indicate that β1AR-mediated inotropic responses are not dependent upon either AC5 or AC6 alone. Inactivation of Gi enhanced β1AR-mediated inotropic responses despite not coupling to Gi, consistent with Gi exerting a tonic receptor independent inhibition upon AC5/6. PDE4 seems the primary regulator of β1AR signaling through AC6 in wild type. AC6 KO results in a reorganization of β1AR compartmentation characterized by signaling through AC5 regulated by Gi, PDE3 and PDE4 that maintains normal contractile function.

Roflumilast, a phosphodiesterase 4 inhibitor, attenuates cadmium-induced renal toxicity via modulation of NF-κB activation and induction of NQO1 in rats.

In the present study, the protective effect of Roflumilast (ROF, a selective phosphodiesterase (PDE-4) inhibitor) was investigated against cadmium (Cd)-induced nephrotoxicity in rats. A total of 24 rats were selected and randomly divided into four groups ( n = 6). Group 1 served as the control; groups 2-4 administered with CdCl2 (3 mg/kg, i.p.) for 7 days; groups 3 and 4 were co-administered with ROF in doses of 0.5 and 1.5 mg/kg, orally for 7 consecutive days. Nephrotoxicity was evaluated by measuring urine volume, urea and creatinine levels in urine and serum. Oxidative stress was confirmed by measuring malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) levels in kidney tissue followed by histopathological studies. CdCl2 administration results in a significant ( p < 0.01) decrease in urine volume, urea, and creatinine levels in urine, as well as GSH, SOD, and CAT levels in renal tissue. In addition, Cd also produced significantly increased ( p < 0.01) urea and creatinine levels in serum and TBARS levels in renal tissues. Rats treated with ROF significantly ( p < 0.01) restore the altered levels of kidney injury markers, nonenzymatic antioxidant, as well as depleted enzymes in dose-dependent manner. An increased expression of NF-κB p65 and decreased expression of GST and NQO1 in the Cd only treated group were significantly reversed by high dose of ROF (1.5 mg/kg). Histopathological changes were also ameliorated by ROF administration in Cd-treated groups. In conclusion, ROF treatment showed protective effect against renal damage and increased oxidative stress induced by Cd administration.

Phosphodiesterases as therapeutic targets for respiratory diseases.

Chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma, affect millions of people all over the world. Cyclic adenosine monophosphate (cAMP) which is one of the most important second messengers, plays a vital role in relaxing airway smooth muscles and suppressing inflammation. Given its vast role in regulating intracellular responses, cAMP provides an attractive pharmaceutical target in the treatment of chronic respiratory diseases. Phosphodiesterases (PDEs) are enzymes that hydrolyze cyclic nucleotides and help control cyclic nucleotide signals in a compartmentalized manner. Currently, the selective PDE4 inhibitor, roflumilast, is used as an add-on treatment for patients with severe COPD associated with bronchitis and a history of frequent exacerbations. In addition, other novel PDE inhibitors are in different phases of clinical trials. The current review provides an overview of the regulation of various PDEs and the potential application of selective PDE inhibitors in the treatment of COPD and asthma. The possibility to combine various PDE inhibitors as a way to increase their therapeutic effectiveness is also emphasized.

A Comparative Study on the Antinociceptive Effects of Phosphodiesterase Inhibitors on Sciatic Nerve Ligation Induced Neuropathic Pain in Mice

Introduction: The role of phosphodiesterase (PDE) inhibitors in reducing neuropathic pains is uncertain. In this study, the antinociceptive effects of theophylline, milrinone, and tadalafil were investigated on sciatic nerve ligation-induced neuropathic pain (NP).Methods: Male mice (25-30 g) were purchased and housed in controlled environmental conditions before and during the experiments. The mice received identical diet and water ad libitum. Two weeks after sciatic nerve ligation, either theophylline (75 mg/kg), milrinone (4.5 mg/kg), or tadalafil (20 mg/kg) was intraperitoneally (IP) injected for either 1, 3, or 7 consecutive days. Antinociceptive effects were evaluated using the hot plate test. Negative controls received time course IP injections of saline (5 mL/kg). A single dose of imipramine (40 mg/kg,) was intraperitoneally administrated to the mice in the positive control group. Results: As was found for this study, a single-dose IP injection of either theophylline (75 mg/kg), milrinone (4.5 mg/kg), or tadalafil (20 mg/kg) on day 14th following sciatic nerve ligation induced significant antinociceptive effects at 30 minutes (P &lt; 0.01), 60 minutes (P &lt; 0.01), and 90 minutes (P &lt; 0.05) compared to the control (saline– treated) animals. Accordingly, both 3- (on days 12–14) and 7-day (on days 8– 14) IP injections of tadalafil (20 mg/kg) induced significant antinociceptive effects at 30 minutes (P &lt; 0.05), 60 minutes (P &lt; 0.01), and 90 minutes (P &lt; 0.01) after sciatic nerve ligation compared to the control (saline–treated) animals. However, the 3- and 7-day IP injections of theophylline and milrinone did not reveal any significant differences compared to the control group. Conclusion: Taken together, the results of this study suggested that selective PDE inhibitors that act predominantly on cGMP pathway, may contribute to the management of sciatic nerve ligation–induced pain.

Surface Binding Energy Landscapes Affect Phosphodiesterase Isoform-Specific Inhibitor Selectivity

As human phosphodiesterase (PDE) proteins are attractive drug targets, a large number of selective PDE inhibitors have been developed. However, since the catalytic sites of PDE isoforms are conserved in sequence and structure, it remains unclear how these inhibitors discriminate PDE isoforms in a selective manner. Here we perform long-time scale molecular dynamics (MD) simulations to investigate the spontaneous association processes of a highly selective PDE2A inhibitor (BAY60–7550) with the catalytic pockets of six PDE isoforms. We found that the free-energy landscapes of PDE:BAY60–7550 interactions on the PDE surfaces are very different between various PDE isoforms; and the free-energy landscape of PDE2A forms a favorable low-energy pathway that not only drives BAY60–7550 toward the target binding site, but also guides BAY60–7750 to adopt its native binding conformation known from crystal structure. Thus, this study reveals that the inhibitor interactions with the PDE surface residues play an important role in its high selectivity for PDE2A, and thereby provides new fundamental insights into the PDE isoform-specific inhibitor selectivity.

TADAFER II: Tadalafil treatment for fetal growth restriction - a study protocol for a multicenter randomised controlled phase II trial

IntroductionThere is no proven therapy to reverse or ameliorate fetal growth restriction (FGR). Sildenafil, a selective phosphodiesterase 5 (PDE5) inhibitor, has been reported to potentially play a therapeutic role in...

Phosphodiesterase 4 inhibitor activates AMPK-SIRT6 pathway to prevent aging-related adipose deposition induced by metabolic disorder.

Rolipram is a selective phosphodiesterase 4 (PDE4) inhibitor that exerts a variety of effects, including anti-inflammatory, immunosuppressive, and anti-tumor effects. The aim of this study was to investigate the effect of rolipram on metabolic disorder and its underlying mechanisms. Metabolic disorder was induced in 8-week-old wild type BABL/c mice by administration of D-galactose for 4 weeks. Simultaneously the mice were administered vehicle or rolipram. Alternatively, beginning at 3 or 21 months, the mice were administered db-cAMP for 3 months, with or without a high-fat-diet (HFD) to induce metabolic disorder. In both models, better metabolic function was observed in rolipram-treated mice. Rolipram reduced adipose deposition and inflammation and reserved metabolic disorder. Treatment with rolipram increased the AMPK phosphorylation and SIRT6 levels in the liver and kidney while reducing NF-κB acetylation. In vitro, these effects were blocked by suppression of SIRT6 expression using specific siRNA. Increased cAMP levels reduced excessive adipose deposition, and improved adipose distribution in presenile mice. These findings provide a promising strategy for the treatment of aging-related metabolic dysfunctions and suggest that selective PDE4 inhibitors may be useful agents for the treatment of aging-related metabolic diseases.

Anti-inflammatory effects of roflumilast in chronic obstructive pulmonary disease (ROBERT): a 16-week, randomised, placebo-controlled trial

The clinical effects of roflumilast, a selective phosphodiesterase-4 inhibitor, are well established, but little is known about the anti-inflammatory mechanisms underlying the drug's efficacy. The aim of the ROflumilast Biopsy European Research Trial (ROBERT) was to assess the anti-inflammatory effects of roflumilast on bronchial mucosal inflammation in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) and chronic bronchitis. ROBERT was a randomised, double-blind, placebo-controlled trial done at 18 sites in five countries. Eligible patients were aged 40-80 years, had COPD, and had had a chronic productive cough for 3 months in each of the two previous years. Patients also had to have a post-bronchodilator predicted FEV1 30-80% and a post-bronchodilator FEV1/forced vital capacity ratio of 70% or less. Patients entered a 6-week run-in period before being randomly assigned (1:1) via a computerised central randomisation system to roflumilast 500 μg once daily or placebo for 16 weeks, in addition to bronchodilator therapy (inhaled corticosteroids were not permitted). Randomisation was stratified by concomitant use of long-acting β agonist. Both participants and investigators were masked to group assignment. Roflumilast and placebo were supplied as identical yellow, triangular tablets. Airway inflammation was assessed by quantification of inflammatory cells in bronchial biopsy samples and induced sputum samples. The primary endpoint was the change in the number of CD8 inflammatory cells in bronchial biopsy submucosa from randomisation to week 16 in the intention-to-treat population. Changes in cell counts of additional inflammatory markers, including eosinophils, were assessed as secondary endpoints. This trial is registered with ClinicalTrials.gov, number NCT01509677, and is closed to new participants, with follow-up completed. Between Jan 4, 2012, and Feb 11, 2016, 158 patients were randomly assigned: 79 to the roflumilast group, and 79 to the placebo group. At week 16, the change in the number of CD8 cells in the bronchial submucosa did not differ significantly between the roflumilast and placebo groups (treatment ratio 1·03 [95% CI 0·82-1·30]; p=0·79). However, compared with placebo, roflumilast was associated with a significant reduction in eosinophils in bronchial biopsy samples at week 16 (treatment ratio 0·53 [95% CI 0·34-0·82]; p=0·0046). Significant reductions in both absolute (p=0·0042) and differential (p=0·0086) eosinophil cell counts in induced sputum were also noted with roflumilast compared with placebo, but peripheral blood eosinophil counts were not significantly affected. We noted no other significant effects of roflumilast on bronchial mucosal inflammatory cells. The most common (ie, occurring in >5% patients) moderate adverse events were worsening of COPD (three [4%] patients in the roflumilast group vs seven [9%] in the placebo group), cough (six [8%] vs four [5%]), diarrhoea (four [5%] vs three [4%]), and nasopharyngitis (three [4%] vs five [6%]). Severe adverse events included worsening of COPD, which occurred in four (5%) patients in the roflumilast group and two (3%) in the placebo group. No deaths occurred during the study. Serious adverse events occurred in eight (10%) patients in the roflumilast group and five (6%) in the placebo group. 16 weeks of treatment with roflumilast did not affect the number of CD8 cells in bronchial submucosa compared with placebo. However, we noted significant reductions in eosinophil cell counts in bronchial biopsy samples and induced sputum, generating the hypothesis that the effect of roflumilast in COPD could be mediated by an effect on lung eosinophils. Takeda and AstraZeneca.

Features of treatment of patients with psoriasis with metabolic syndrome

The article provides information on the prevalence of metabolic syndrome in patients with psoriasis. The criteria for the diagnosis of metabolic syndrome are presented. The General mechanisms of inflam - mation development in psoriasis and diseases forming the metabolic syndrome are described. Systemic subclinical inflammatory process developing in psoriasis and metabolic syndrome is considered as the main pathogenetic mechanism of their mutual negative influence. The difficulties of treatment of patients with psoriasis with metabolic syndrome are largely associated with the choice of a safe and effective method of treatment. The description of the drug apremilast (OTEZLA®) is a selective inhibitor of the enzyme phosphodiesterase 4, which may be the best drug in the therapy of patients with psoriasis and metabolic syndrome.

Efficacy of Cilostazol in Prevention of Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage: A Meta-Analysis

ObjectivesCilostazol, a selective inhibitor of phosphodiesterase 3, may reduce symptomatic vasospasm and improve outcome in patients with aneurysmal subarachnoid hemorrhage considering its anti-platelet and vasodilatory effects. We aimed to analyze the effects of cilostazol on symptomatic vasospasm and clinical outcome among patients with aneurysmal subarachnoid hemorrhage (aSAH). Patients and MethodsWe searched PubMed and Embase databases to identify 1) prospective randomized trials, and 2) retrospective trials, between May 2009 and May 2017, that investigated the effect of cilostazol in patients with aneurysmal aSAH. All patients were enrolled after repair of a ruptured aneurysm by clipping or endovascular coiling within 72hours of aSAH. fixed-effect models were used to pool data. We used the I2 statistic to measure heterogeneity between trials. ResultsFive studies were included in our meta-analysis, comprised of 543 patients with aSAH (cilostazol [n=271]; placebo [n=272], mean age, 61.5years [SD, 13.1]; women, 64.0%). Overall, cilostazol was associated with a decreased risk of symptomatic vasospasm (0.31, 95% CI 0.20 to 0.48; P<0.001), cerebral infarction (0.32, 95% CI 0.20 to 0.52; P <0.001) and poor outcome (0.40, 95% CI 0.25 to 0.62; P<0.001). We observed no evidence for publication bias. Statistical heterogeneity was not present in any analysis. ConclusionCilostazol is associated with a decreased risk of symptomatic vasospasm and may be clinically useful in the treatment of delayed cerebral vasospasm in patients with aSAH. Our results highlight the need for a large multi-center trial to confirm the observed association.

Mechanisms Underlying the Clinical Effects of Apremilast for Psoriasis.

Psoriasis is a chronic, systemic, inflammatory disease with manifestations resulting from a dysregulated immune response. In psoriatic skin, expression of all phosphodiesterase 4 (PDE4) isoforms (A-D), part of a family of enzymes known to regulate cyclic adenosine monophosphate levels and immune homeostasis, is elevated compared with healthy controls. Agents that inhibit the enzymatic activity of PDE4, the predominant PDE in most immune cells, exert well-recognized anti-inflammatory effects. Apremilast is a selective PDE4 inhibitor approved for the treatment of adults with moderate to severe plaque psoriasis and/or psoriatic arthritis. In vitro and in vivo investigations have demonstrated the beneficial impact of apremilast treatment on PDE4 activity, inflammatory signal expression, and dermal psoriasiform signs. In patients with moderate to severe psoriasis, treatment with apremilast is associated with significant reductions in plasma levels of interleukin (IL)-17F, IL-17A, IL-22, and tumor necrosis factor-α compared with placebo as early as week 4; decreases in cytokine levels were sustained with continued treatment. Multivariate analyses demonstrated that while changes in IL-17F are the most important predictor of improvement in Psoriasis Area and Severity Index scores, apremilast exerts synergistic attenuating effects among a key group of cytokines involved in the pathology of psoriasis, and these effects correlate with improved skin symptoms. These in vitro and clinical data demonstrate that the beneficial effects of apremilast on known inflammatory mediators are associated with its clinical efficacy. J Drugs Dermatol. 2018;17(8):835-840. <p>THIS ARTICLE HAD BEEN MADE AVAILABLE FREE OF CHARGE. PLEASE SCROLL DOWN TO ACCESS THE FULL TEXT OF THIS ARTICLE WITHOUT LOGGING IN. NO PURCHASE NECESSARY. PLEASE CONTACT THE PUBLISHER WITH ANY QUESTIONS.</p>.

Beneficial effects of cilostazol on liver injury induced by common bile duct ligation in rats: Role of SIRT1 signaling pathway.

Liver fibrosis is a health challenge requiring alternative therapeutic approaches. Cilostazol is a selective phosphodiesterase-3 inhibitor and possesses antioxidant, anti-inflammatory and antifibrotic properties. Sirtuin 1 (SIRT1) is a member of the silent information regulator 2 family. Cilostazol upregulates SIRT1 expression. Cilostazol protects against the cholestatic liver insults caused by bile duct obstruction. Involvement of SIRT1 pathway in this protective effect has not been studied yet. So, we hypothesized that SIRT1 signaling may have a role in cilostazol protective effects against bile duct ligation-induced liver damages. Rats were subjected to common bile duct ligation then treated with cilostazol (9mg/kg or 27mg/kg) in the presence or absence of specific SIRT1 inhibitor EX527. Cilostazol improved liver function, reduced inflammation, enhanced antioxidant status, ameliorated cholestatic liver injury and upregulated hepatic SIRT1. However, these protective effects were abrogated by EX527, suggesting that SIRT1 signaling may have a role in these effects. In conclusion, cilostazol in a dose-dependent way produced hepatoprotective effects via anti-inflammatory, antioxidant, antifibrotic effects which were mediated, in part, through SIRT1 upregulation.

Prognostic factors of ulcer healing and amputation-free survival in patients with critical limb ischemia.

A multidisciplinary approach is required to treat critical limb ischemia. We determined the poor prognostic factors of ischemic ulcer healing after optimal arterial revascularization, and assessed the efficacy of the medication therapy using cilostazol, which is a selective inhibitor of phosphodiesterase 3. In this retrospective, single-center, cohort study, 129 limbs that underwent infrainguinal arterial revascularization for Rutherford class 5 critical limb ischemia were reviewed. The primary end point was the ulcer healing time after arterial revascularization. The secondary end point was the amputation-free survival rate. Of the 129 limbs, endovascular therapy was performed in 69 limbs, and surgical reconstructive procedures were performed in 60 limbs for initial therapy. Complete ulcer healing was achieved in 95 limbs (74%). The median ulcer healing time was 90 days. In multivariate analysis, no cilostazol use significantly inhibited ulcer healing ( p = 0.0114). A white blood cell count >10,000 ( p = 0.0185), a major defect after debridement ( p = 0.0215), and endovascular therapy ( p = 0.0308) were significant poor prognostic factors for ulcer healing. Additionally, ischemic heart disease ( p < 0.0001), albumin levels <3 g/dl ( p = 0.0016), no cilostazol use ( p = 0.0078), and a major defect after debridement ( p = 0.0208) were significant poor prognostic factors for amputation-free survival rate. Ulcer healing within 90 days after arterial revascularization is impaired by no cilostazol use, a white blood cell count >10,000, a major defect after debridement, and endovascular therapy. Furthermore, cilostazol improves amputation-free survival rate in patients with critical limb ischemia.

Phosphodiesterase inhibitors: Potential role in the respiratory distress of neonates.

Phosphodiesterases (PDEs) are a superfamily of enzymes that catalyze the hydrolysis of phosphodiester bonds of 3',5' cyclic adenosine and guanosine monophosphate (cAMP and cGMP). PDEs control hydrolysis of cyclic nucleotides in many cells and tissues. Inhibition of PDEs by selective or nonselective PDE inhibitors represents an effective targeted strategy for the treatment of various diseases including respiratory disorders. Recent data have demonstrated that PDE inhibitors can also be of benefit in respiratory distress in neonates. This article outlines the pharmacological properties of nonselective and selective PDE inhibitors and provides up-to-date information regarding their use in experimental models of neonatal respiratory distress as well as in clinical studies.

Correction to Discovery of N-Alkyl Catecholamides as Selective Phosphodiesterase-4 Inhibitors with Anti-neuroinflammation Potential Exhibiting Antidepressant-like Effects at Non-emetic Doses

Correction to Discovery of <i>N</i>-Alkyl Catecholamides as Selective Phosphodiesterase-4 Inhibitors with Anti-neuroinflammation Potential Exhibiting Antidepressant-like Effects at Non-emetic Doses

Compartmentalized cyclic nucleotides have opposing effects on regulation of hypertrophic phospholipase Cε signaling in cardiac myocytes

In cardiac myocytes activation of an exchange factor activated by cAMP (Epac) leads to activation of phospholipase Cε (PLCε)-dependent hydrolysis of phosphatidylinositol 4-phosphate (PI4P) in the Golgi apparatus a process critical for development of cardiac hypertrophy. Here we show that β-adrenergic receptor (βAR) stimulation does not stimulate this pathway in the presence of the broad spectrum phosphodiesterase (PDE) inhibitor IBMX, but selective PDE3 inhibition revealed βAR-dependent PI4P depletion. On the other hand, selective inhibition of PDE2 or PDE9A blocked endothelin-1 (ET-1) and cAMP-dependent PI4P hydrolysis by PLCε. Direct activation of protein kinase A (PKA), protein kinase G (PKG), or the atrial natriuretic factor (ANF) receptor abolished PI4P hydrolysis in response to multiple upstream stimuli. These results reveal distinct pools of cyclic nucleotides that either inhibit PLCε at the Golgi through PKA/PKG, or activate PLCε at the Golgi through Epac. These data together reveal a new mechanism by which ANF and selective PDE inhibitors can protect against cardiac hypertrophy.

CAMP Catalyzing Phosphodiesterases Control Cholinergic Muscular Activity But Their Inhibition Does Not Enhance 5-HT4 Receptor-Mediated Facilitation of Cholinergic Contractions in the Murine Gastrointestinal Tract.

Background: As the signal transduction of 5-HT4 receptors on cholinergic neurons innervating smooth muscle is controlled by phosphodiesterase (PDE) 4 in porcine stomach and colon, and human large intestine, the in vivo gastroprokinetic effects of a 5-HT4 receptor agonist might be enhanced by combination with a selective PDE4 inhibitor. The presence of 5-HT4 receptors on cholinergic neurons towards murine gastrointestinal circular muscle was recently shown. If the control of this receptor pathway by PDE4 is also present in mice, this might be a good model for in vivo testing of the combination therapy. Therefore this study investigates the role of cAMP catalyzing PDEs in smooth muscle cell activity and in the intraneuronal signal transduction of the 5-HT4 receptors in the gastrointestinal tract of C57Bl/6J mice.Methods: In circular smooth muscle strips from murine fundus, jejunum, and colon, submaximal cholinergic contractions were induced by either electrical field stimulation (EFS) or by carbachol (muscarinic receptor agonist). The influence of the PDE inhibitors IBMX (non-selective), vinpocetine (PDE1), EHNA (PDE2), cilostamide (PDE3), and rolipram (PDE4) was tested on these contractions and on the facilitating effect of a submaximal concentration of prucalopride (5-HT4 receptor agonist) on EFS-induced contractions.Results: In the three gastrointestinal regions, IBMX and cilostamide concentration-dependently decreased carbachol- as well as EFS-induced contractions. Some inhibitory effect was also observed with rolipram. In the fundus a non-significant trend for an enhancement of the facilitating effect of prucalopride on EFS-induced contractions was observed with IBMX, but none of the selective PDE inhibitors enhanced the facilitating effect of prucalopride in fundus, jejunum or colon.Conclusion: In analogy with the porcine gastrointestinal tract, in murine fundus, jejunum, and colon circular smooth muscle PDE3 is the main regulator of the cAMP turnover, with some contribution of PDE4. In contrast to the porcine gastrointestinal tract, the in vitro facilitation of electrically induced cholinergic contractions by 5-HT4 receptor stimulation could not be enhanced by specific PDE inhibition. The C57Bl/6J murine model is thus not suitable for in vivo testing of a 5-HT4 receptor agonist combined with a selective PDE4 inhibitor.

PT027 - Efficacy and safety of selective serotonin reuptake inhibitors and phosphodiesterase-5 inhibitors in men with premature ejaculation: A systematic review and network meta-analysis

PT027 - Efficacy and safety of selective serotonin reuptake inhibitors and phosphodiesterase-5 inhibitors in men with premature ejaculation: A systematic review and network meta-analysis

A simple and sensitive HPLC–MS/MS method for quantification of eggmanone in rat plasma and its application to pharmacokinetics

Allosteric phosphodiesterase 4 (PDE4) inhibitors are highly sought after due to their important anti-inflammatory and anti-cancer therapeutic effects. We recently identified Eggmanone, an extraordinarily selective allosteric PDE4 inhibitor displaying favorable drug properties. However, a specific analytic method of Eggmanone in serum and its pharmacokinetics have not been reported yet. In this study, we developed a rapid and sensitive high performance liquid chromatography–mass spectrometric (HPLC–MS/MS) method to determine Eggmanone concentrations in rat plasma. This assay method was validated in terms of specificity, linearity, sensitivity, accuracy, precision, matrix effect, recovery and stability, and was applied to a pharmacokinetic study in rats following intravenous injection of Eggmanone at doses of 1 and 3 mg/kg. The lower limit of quantification (LLOQ) of this assay was 5 ng/mL and the linear calibration curve was acquired with R2 > 0.99 between 5 and 1000 ng/m. The intra-day and inter-day precision was evaluated with the coefficient of variations less than 11.09%, whereas the mean accuracy ranged from 98.38% to 105.13%. The assay method exhibited good recovery and negligible matrix effect. The samples were stable under all the experimental conditions. The plasma concentrations of Eggmanone were detected and quantified over 24 h with the terminal elimination half-live of 3.57 ± 1.80 h and 5.92 ± 3.34 h for the low dose (1 mg/kg) and high dose (3 mg/kg) respectively. In summary, the present method provides a robust, fast and sensitive analytical approach for quantification of Eggmanone in plasma and was successfully applied to a pharmacokinetic study in rats.

Inhibition of Phosphodiesterase 4 by FCPR03 Alleviates Lipopolysaccharide-Induced Depressive-Like Behaviors in Mice: Involvement of p38 and JNK Signaling Pathways.

Inflammatory responses induced by peripheral administration of lipopolysaccharide (LPS) triggers depressive-like behavioral syndrome in rodents. Inhibition of phosphodiesterase 4 (PDE4) produces a robust anti-inflammatory effect in inflammatory cells. Unfortunately, archetypal PDE4 inhibitors cause intolerable gastrointestinal side-effects, such as vomiting and nausea. N-isopropyl-3-(cyclopropylmethoxy)-4-difluoromethoxy benzamide (FCPR03) is a novel, selective PDE4 inhibitor with little, or no, emetic potency. Our previous studies show that FCPR03 is effective in attenuating neuroinflammation in mice treated with LPS. However, whether FCPR03 could exert antidepressant-like effect induced by LPS is largely unknown. In the present study, mice injected intraperitoneally (i.p.) with LPS was established as an in vivo animal model of depression. The antidepressant-like activities of FCPR03 were evaluated using a tail suspension test, forced swimming test, and sucrose preference test. We demonstrated that administration of FCPR03 (1 mg/kg) produced antidepressant-like effects in mice challenged by LPS, as evidenced by decreases in the duration of immobility in the forced swim and tail suspension tests, while no significant changes in locomotor activity were observed. FCPR03 also increased sucrose preference in mice treated with LPS. In addition, treatment with FCPR03 abolished the downregulation of brain-derived neurotrophic factor induced by LPS and decreased the level of corticosterone in plasma. Meanwhile, periphery immune challenge by LPS induced enhanced phosphorylation of p38-mitogen activated protein kinase (p38) and c-Jun N-terminal kinase (JNK) in both the cerebral cortex and hippocampus in mice. Interestingly, treatment with FCPR03 significantly blocked the role of LPS and reduced the levels of phosphorylated p38 and JNK. Collectively, these results indicate that FCPR03 shows antidepressant-like effects in mice challenged by LPS, and the p38/JNK signaling pathway is possibly involved in this process. Our findings suggest that FCPR03 is a potential compound for the prevention or treatment of depression.