Targeting phosphodiesterases for cognition enhancement:a translational approach

Cyclic adenosine monophosphate(cA MP) and/or cyclic guanosine monophosphate(cG MP)have been suggested to play specific roles in processes of memory. These cyclic nucleotides are hydrolyzed by specific enzymes,ie phosphodiesterases(PDEs). Thus,selective PDE inhibitors preventing the breakdown of cAMP and/or cGMP could improve memory. Studies with different timing of treatment with specific PDE inhibitors indicated that distinct underlying signaling pathways for early and late consolidation processes exist corresponding to specific time-windows for memory consolidation into longterm memory. There is evidence that the underlying mechanisms of PDE inhibition on the observed behavioral effects are independent of possible cerebrovascular effects. Most likely the underlying mechanisms are a cGMP/PKG pathway for early consolidation processes and a cAMP/PKA pathway for late consolidation processes. In addition,the early-phase cG MP/PKG signaling actually requires late-phase cAMP/PKA-signaling in long-term memory formation. Recently,the effects of specific PDE inhibitors are explored on other cognitive domains including acquisition processes/short-term memory and information processing. It will be shown that elevation of central cG MP levels or cA MP levels after treatment with a specific PDE inhibitor both improve acquisition processes/short-term memory. In vitro studying the effects of PDE inhibitors on long-term potentiation,the physiological substrate of memory,supportthe in vivo data and further show that AMPA receptor trafficking very likely mediates the memory enhancing effects. In a translational approach we initially also investigated the effects of cG MP elevation via PDE5 inhibition with vardenafil or sildenafil on cognition in humans. However,in contrast to studies with rodents and monkeys,PDE5 inhibition had no effect in humans on cognition including memory processes. It is clear that the transition of a drug from preclinical to clinical creates translational hurdles. Nevertheless,based on the expression patterns of its isoforms in the brain,PDE4,which is cAMP specific,appears more interesting for CNS targeting than PDE5. Indeed we found that a low dose of the PDE inhibitor roflumilast clearly improved cognition in humans. Interestingly,this pro-cognitive effect was not associated with emetic side effects(nausea,vomiting),which are commonly associated with PDE4 inhibition. Based on our data we suggest that the future for disease-specific PDE4 enzyme inhibition lies in the development of PDE4 isoform-specific inhibitors without emetic effects. Within the context as described above,the latest results of specific PDE inhibitors on cognitive processes will be presented and its implications will be discussed for finding and testing new cognition enhancers.

Regulation and function of cyclic nucleotide phosphodiesterases in pathological vascular remodeling

Pathological vascular remodeling is characterized by thickening or thinning of the vessel wall through altering cellular and non-cellular components,which associates with various blood circulation disorders in brain,heart,lung,and peripheral vasculatures. Pathological vascular remodeling occurs in response to a variety of vascular insults such as mechanical(angioplasty or stenting) or biological(lipids,diabetes,smoking,or virus) injuries. It is a polygenic process involving multiple cell types in the vessel wall or circulation,including endothelial cells(ECs),smooth muscle cells(SMCs),fibroblasts,leukocytes,and platelets. One of hallmarks is the transition of vascular smooth muscle cells(SMCs)from a differentiated/quiescent contractile phenotype to a myofibroblast-like dedifferentiated/active so-called synthetic phenotype. Synthetic SMCs are proliferatory,migratory,secretory and inflammatory,playing key roles in the pathogenesis of vascular remodeling. In the normal vessel,ECs synthesize and secrete biological substances such as prostacyclins(PGI_2) and nitric oxide(NO) that not only function as vasodilators but also inhibit SMC phenotype transition and other properties associated with the synthetic phenotype. Cyclic nucleotides cAMP and cGMP are primary mediators of PGI_2 and NO,respectively,and play critical roles in control vascular structural integrity and function. Cyclic nucleotides are controlled by selective activation or inhibition of distinct cyclic nucleotide phosphodiesterase(PDE) isozymes catalyzing the degradation reaction. To date,more than 60 different PDE isoenzymes derived from 22 genes are identified and grouped into 11 broad families(PDE1-PDE11). PDEs are expressed in a cell/tissue-specific manner and only a few enzymes are expressed in any single cell type. Through systematic assessment of the expression levels of all known PDE isoforms in contractile versus synthetic SMCs,we found that the expression levels of a number of PDE are significantly altered between two SMC phenotypes. We then explored the functional roles and underlying mechanisms of these altered PDEs in vascular SMCs pathogenesis and vascular remodeling in vitro and in vivo using a variety of gain-of-or loss-of-function approaches. For example,we found that Ca^(2+)/calmodulinstimulated cAMP/cGMP-hydrolyzing PDE 1C is selectively expressed in synthetic SMCs in vitro and in various vascular disease models in vivo. PDE 1C upregulation contributes to a number of pathogenic functions of synthetic SMCs,such as cell proliferation,migration,and matrix protein metabolism.PDE 1C deficiency markedly attenuates intimal hyperplasia,atherosclerosis,and aortic aneurysm in experimental mouse disease models. These findings suggest that PDE 1C functions as a key regulator of the synthetic SMC pathology in vascular remodeling. Inhibiting PDE 1C function may represent a novel therapeutic strategy for protecting against the pathogenesis of vascular diseases.

Phosphodiesterases:novel targets for treatment of alcoholism

OBJECTIVE Alcoholism is one of the most damaging psychiatric disorders and causes serious social and health problems in the world. However,there are no ideal treatments for this disease in clinic.Phosphodiesterases(PDEs) are a superfamily of enzymes consisting of 11 PDE families that hydrolyze cyclicAMP(cA MP) and/or cyclicGMP(cGMP). Among them,PDE4 is critical in the control of intracellular cAMP levels and has been shown to play an important role in the regulation of ethanol consumption.However,the functional role of PDE4 in mediating alcoholism remains unclear. METHODS Ethanol drinking and preference were examined using the two-bottle choice and/or drinking-in-dark(DID) test in high alcohol preferring(HAP) animals,including C57,HAP,and PDE4-subtype knockout mice,and Fawn-Hooded(FH/Wjd) rats,treated with or without the PDE4 inhibitor rolipram or roflumilast. Ethanol withdrawal-induced anxiety-and depressive-like behaviors were examined using the elevated plusmaze,holeboard,forced-swim,and tail-suspension tests in C57 mice or FH rats in the presence of PDE4 inhibition. Levels of cAMP,CREB were determined in brain regions. RESULTS Treatment with rolipram or roflumilast decreased ethanol intake and preference in two-bottle choice and DID tests in C57 and HAP mice as well as FH rats. Mice deficient in PDE4 B,but not PDE4 D,displayed similar effects to general PDE4 inhibition. In addition,rolipram reversed ethanol withdrawal-induced anxietyand depressive-like behaviors 1 d and 14 d,respectively,following withdrawal from ethanol drinking in the two-bottle choice in C57 mice or FH rats. Locomotor activity was not changed in either mice or rats treated with the PDE4 inhibitors. Levels of cAMP,p CREB in the brain were increased by rolipram.CONCLUSION The results provide solid evidence for the important role of PDE4 in ethanol consumptionand ethanol withdrawal-induced symptoms. Inhibitors of PDE4,in particular the PDE4 B isoform,can be a novel class of treatment for alcoholism.

环核苷酸磷酸二酯酶:神经精神疾病的药物作用靶标(英文)

OBJECTIVE To investigate the relationship between the neurochemical and behavioral effects of inhibitors of cyclic nucleotide phosphodiesterases 2(PDE2) and PDE4 in the hope of identifying promising therapeutic targets and indications. METHODS Depression-and anxiety-like behaviors were evaluated by forced swimming,tail suspending and elevated plus maze tests. The memory enhancing effects were evaluated by Morris water maze test. RESULTS Inhibition of PDE4 results in antidepressant-like and memory-enhancing effects,in part due to increased cyclicAMP signaling.While targeting PDE4 subtypes(PDE4A-D) pharmacologically has proven challenging due to a highly conserved inhibitor-binding site in the catalytic region of the enzyme,some promise is offered by recently identified negative allosteric modulators of PDE4,which can act in a subtype-specific manner.While PDE2 has not been studied as extensively,it has been shown to be coded for by a single mammalian gene and to be highly expressed in the brain. Its inhibition results in anxiolytic-and antidepressant-like effects as wells as reducing oxidative stress and affording some degree of neuroprotection;these actions appear to be due to increased cyclicGMP signaling,even though PDE2 catalyzes the hydrolysis of both cyclicAMP and cyclicGMP. CONCLUSION Inhibitors targeting specific family of PDE may exhibit differential pharmacological effects and aid a more efficient pharmacotherapy towards neuropsychological conditions,while drug discovery efforts focusing on PDE2 are not as advanced as those for PDE4,some selective inhibitors are being developed and evaluated.

行气调神针刺疗法对缺血性卒中后抑郁大鼠左前皮质及海马CREB和PDE4mRNA表达的影响

目的观察cAMP反应元件结合蛋白(cAMP response element binding protein,CREB)和磷酸二酯酶4(phosphodiesterase 4,PDE4)在缺血性卒中后抑郁(post stroke depression,PSD)发病中的作用及行气调神针刺疗法对其的影响。方法将SD大鼠随机分为正常组、模型组、行气调神针刺组、西药组,每组各20只。采用大脑中动脉电凝结合应激和孤养的方法复制PSD模型。针刺组取"人中"、双侧"合谷"和双侧"太冲",针刺治疗6周,西药组予以盐酸氟西汀灌胃治疗6周。采用RT-PCR检测左前皮质及海马CREB mRNA和PDE4mRNA的表达水平。结果最终各组样本量为11。与正常组比较,模型组大鼠左前皮质及海马CREB mRNA表达水平显著下调(P<0.01),PDE4mRNA表达水平显著上调(P<0.01);与模型组比较,西药组及针刺组大鼠左前皮质及海马CREB mRNA表达水平显著上调(P<0.01),PDE4mRNA表达水平显著下调(P<0.01)。结论行气调神针刺疗法治疗PSD的机制与上调脑组织CREB mRNA的表达和下调PDE4mRNA的表达有关。

Identification of two glycerophosphodiester phosphodiesterase genes in maize leaf phosphorus remobilization

Phosphate deficiency is one of the leading causes of crop productivity loss.Phospholipid degradation liberates phosphate to cope with phosphate deficiency.Glycerophosphodiester phosphodiesterases(GPX-PDEs)hydrolyse the intermediate products of phospholipid catabolism glycerophosphodiesters into glycerol-3-phosphate,a precursor of phosphate.However,the function of GPX-PDEs in phosphate remobilization in maize remains unclear.In the present study,we characterized two phosphate deficiency-inducible GPX-PDE genes,ZmGPX-PDE1 and ZmGPX-PDE5,in maize leaves.ZmGPX-PDE1 and ZmGPX-PDE5 were transcriptionally regulated by ZmPHR1,a well-described phosphate starvation-responsive transcription factor of the MYB family.Complementation of the yeast GPX-PDE mutant gde1Δindicated that ZmGPX-PDE1 and ZmGPX-PDE5 functioned as GPX-PDEs,suggesting their roles in phosphate recycling from glycerophosphodiesters.In vitro enzyme assays showed that ZmGPX-PDE1 and ZmGPX-PDE5 catalysed glycerophosphodiester degradation with different substrate preferences for glycerophosphoinositol and glycerophosphocholine,respectively.ZmGPX-PDE1 was upregulated during leaf senescence,and more remarkably,loss of ZmGPXPDE1 inmaize compromised the remobilization of phosphorus fromsenescing leaves to young leaves,resulting in a stay-green phenotype under phosphate starvation.These results suggest that ZmGPX-PDE1 catalyses the degradation of glycerophosphodiesters in maize,promoting phosphate recycling from senescing leaves to new leaves.This mechanism is crucial for improving phosphorus utilization efficiency in crops.

Regulation by phosphodiesterase of anxiety-and depressive-like behavior induced by alcohol withdrawal in mice

OBJECTIVE Alcohol dependence is not only the most common public health prob⁃lem worldwide,but also the cause of many alco⁃hol-related diseases,such as anxiety and depres⁃sion.However,the mechanism of these comor⁃bidities is not clear.Recently,the role of phos⁃phodiesterases(PDEs)in anxiety-and depres⁃sion-like behavior induced by alcohol withdrawal has received increasing attentions.PDEs are a superfamily of enzymes that catalyze the hydroly⁃sis of intracellular cyclic AMP(cAMP)and(or)cyclic GMP(cGMP).There are 11 families(PDE1-PDE11),each of which has 1 to 4 sub⁃types encoded by different genes.In the present study,we identified the key PDEs involved in anxiety-and depression-like behavior induced by alcohol withdrawal.METHODS After withdrawal from short-term or chronic intermittent ethanol vapor exposure(STEVE and CIEVE,respectively),adult male C57BL/6J(B6)mice were tested for anxiety-and depression-like behavior using the sucrose preference,open field,elevated plus-maze,tail suspension,forced swimming,hole board and light-dark tests.In addition,the expression of PDE subtypes(PDE2,PDE4,and PDE7)in the hippocampus,amygdala,and stria⁃tum,which are considered as anxiety-and(or)depression-related brain regions,was detected by Western blotting.RESULTS①Differences in anxiety-and depression-like behaviors between STEVE and CIEVE mice.Compared to STEVE mice,CIEVE mice showed greater anxiety-and depression-like behavior in the tests described above.②The expression of PDE2,PDE4 and PDE7 in the anxiety-and depression-related brain regions of CIEVE mice.Compared to the STEVE mice,CIEVE mice showed significant higher expression of PDE4A and PDE7A in the hippo⁃campus(P<0.05)and PDE4D and PDE7A in the amygdala(P<0.05).However,the expres⁃sion of PDE2A,PDE4B,PDE4D and PDE7B in the hippocampus,PDE2A,PDE4A,PDE4B and PDE7B in the amygdala,PDE2A,PDE4A,PDE4B,PDE4D,PDE7A and PDE7B in the striatum was not significantly changed.CONCLUSION The model of CIEVE showed significant anxiety-and depression-like behavior,with concurrent increases in the expression of PDE4A and PDE7A in the hippocampus and PDE4D and PDE7A in the amygdala.These results suggest that PDE4A,PDE4D,and DE7A may play an important role in the regulation of anxiety-and depression-like behavior induced by alcohol withdrawal.

Cyclic nucleotide phosphodiesterase 3B is connected to osteopontin and protein kinase CK2 in pancreatic <i>β</i>-cells

Islets from RIP-PDE3B mice, exhibiting β-cell specific overexpression of the cAMP/cGMP-degrading enzyme phosphodiesterase 3B (PDE3B) and dysregulated insulin secretion, were subjected to microarray analysis. We show that osteopontin (OPN) mRNA is increased in a dose-dependent manner in islets from RIP-PDE3B mice, as compared to wild-type islets. In addition, in silico analysis shows that PDE3B and OPN are interacting. Furthermore, OPN interacts with protein kinase CK2 ina distinct submodule of the protein-protein interaction network. We studied PDE3B and OPN proteins and, in some cases, also PDE1B and PDE4C, under conditions of relevance for insulin secretion. In the presence of forskolin, PDE inhibitors, insulin, or a protein kinase CK2 inhibitor, similar alterations in protein levels of PDE3B and OPN are shown. In summary, results from using a number of strategies demonstrate a connection between PDE3B and OPNas well as a role for protein kinase CK2 inpancreatic β-cells.

Improved spontaneous erectile function in men with mild-tomoderate arteriogenic erectile dysfunction treated with a nightly dose of sildenafil for one year： a randomized trial

Aim： To test the hypothesis that sildenafil （50 mg nightly for one year） can improve spontaneous erectile function （EF） in men with mild-to-moderate arteriogenic erectile dysfunction （ED） responsive to erectogenic treatment. Methods： In a prospective open-label trial, 112 men with ED were randomized to sildenafil 50 mg nightly or sildenafil 50 or 100 mg as needed for 12 months, followed by one-month and 6-month non-medicated periods. Non-randomized, non-medicated men with ED were also assessed. The EF domain of the International Index of Erectile Function （IIEF EF） and the peak systolic velocity （PSV） of penile cavernous arteries were used to measure the efficacy. Results： After sildenafil treatment and a subsequent non-medicated month, IIEF EF was normal in 29 of 48 （60.4%, 95% confidence interval [CI]： 45.3-74.2%） of the nightly group vs. 4 of 49 （8.2%, 95% CI： 2.3-19.6%） of the as-needed group. PSV improved by 11.2 cm/s （95% CI： 4.7-21.4; P = 0.012） in the nightly group but only by 3.4 cm/s （-5.1- 14.7; P = 0.435） in the as-needed group. IIEF EF normalized in 1 of 18 （5.6%, 95% CI： 0.1-27.3%） non-medicated men and the PSV declined slightly. Six months after treatment, the IIEF EF remained normal and PSV was stabilized in most （28/29, 97%） nightly group men who had initially normalized. Conclusion： Sildenafil nightly for one year resulted in ED regression that persisted well beyond the end of treatment, so that spontaneous EF was characterized as normal on the IIEF in most men. The results from this open-label, randomized trial warrant verification under double-blind, placebo-controlled conditions.

Prevalence and medical management of erectile ：lysfunction in Asia

Erectile dysfunction （ED） is an important worldwide health issue that has a significant negative impact on the quality of life and life satisfaction of both the affected individual and his partner. Here we review the prevalence of ED in Asia, associated factors that may influence sexual attitudes and sexual behaviours, and randomized clinical trials （RCTs） of phosphodiesterase-5 （PDE-5） inhibitors to evaluate the clinical efficacy and safety of PDE-5 inhibitors in Asian men. We searched for English-language articles in MEDLINE and PubMed from January 2000 to September 2010. Our results showed that the overall reported prevalence rate of ED in Asia ranged widely, from 2% to 88%. This finding indicates that ED is a common and major health problem in this region. However, sociocultural and economic factors in Asia prevent people from seeking and obtaining appropriate medical care. We found reports on five kinds of PDE-5 inhibitors for the management of ED.＇ sildenafil, vardenafil, tadalafil, udenafil and mirodenafih The results of RCTs showed that these five PDE-5 inhibitors are more effective than placebo in improving erectile function in Asian men with ED and that these drugs have similar efficacy and safety profiles.

Effects of phosphodiesterase 5 inhibitors on sperm parameters and fertilizing capacity

The aim of this review study is to elucidate the effects that phosphodiesterase 5 （PDE5） inhibitors exert on spermatozoa motility, capacitation process and on their ability to fertilize the oocyte. Second messenger systems such as the cAMP/adenylate cyclase （AC） system and the cGMP/guanylate cyclase （GC） system appear to regulate sperm functions. Increased levels of intracytosolic cAMP result in an enhancement of sperm motility and viability. The stimulation of GC by low doses of nitric oxide （NO） leads to an improvement or maintenance of sperm motility, whereas higher concentrations have an adverse effect on sperm parameters. Several in vivo and in vitro studies have been carried out in order to examine whether PDE5 inhibitors affect positively or negatively sperm parameters and sperm fertilizing capacity. The results of these studies are controversial. Some of these studies demonstrate no significant effects of PDE5 inhibitors on the motility, viability, and morphology of spermatozoa collected from men that have been treated with PDE5 inhibitors. On the other hand, several studies demonstrate a positive effect of PDE5 inhibitors on sperm motility both in vivo and in vitro. In vitro studies of sildenafil citrate demonstrate a stimulatory effect on sperm motility with an increase in intracellular cAMP suggesting an inhibitory action of sildenafil citrate on a PDE isoform other than the PDE5. On the other hand, tadalafil＇s actions appear to be associated with the inhibitory effect of this compound on PDE11. In vivo studies in men treated with vardenafil in a daily basis demonstrated a significantly larger total number of spermatozoa per ejaculate, quantitative sperm motility, and qualitative sperm motility; it has been suggested that vardenafil administration enhances the secretory function of the prostate and subsequently increases the qualitative and quantitative motility of spermatozoa. The effect that PDE5 inhibitors exert on sperm parameters may lead to the improvement of the outcome of assisted reproductive technology （ART） programs. In the future PDE5 inhibitors might serve as adjunct therapeutical agents for the alleviation of male infertility.

Inhibition of phosphodiesterase 4 by FCPR16 protects SH-SY5Y cells against MPP^+ -induced decline of mitochondrial membrane potential and oxidative stress

Parkinson disease(PD) is a chronic neurodegenerative disorder caused by progressive dopaminergic neuronal death in the substantia nigra pars compacta within the midbrain.There still is no cure,effective treatments for PD,available therapies are only capable of offering temporary and symptomatic relief to the patients.There are certain patents that claim phosphodiesterase(PDE) inhibitors as possible anti-PD drugs,PDE4 is a promising target for the treatment of PD and the underlying mechanism has not yet been well elucidated.PDE4 is an enzyme that specifically hydrolyzes intracellular cyclic adenosine monophosphate(cAMP)throughout the body,including the brain.Most of the available PDE4 inhibitors exert unpleasant and serious side effects,such as emesis and nausea,which hinder its clinical application.Therefore,more efforts are needed before PDE4 inhibitors with high therapeutic indices are available for treatment of PD.FCPR16 is a novel PDE4 inhibitor with little emetic potential,which exhibits excellent enzyme inhibition activity(IC50=90 nmol·L^(-1)).METHODS SH-SY5 Y cell was induced with 1-methyl-4-phenylpyridinium(MPP+)to mimic PD cell injury in vitro,and CCK-8 assay was used to investigate the viability effects of different concentration of FCPR16(3.1-50 μmol·L^(-1)) on MPP+-injured SH-SY5 Y cells.Detection of apoptosis was performed by flow cytometry.The level of ntracellular reactive oxygen species was detected with the fluorescent probe DCFH-DA,and the mitochondrial membrane potential of cells in different experimental groups was detected with the JC-1 fluorescent probe.AO staining and Lysotracker Red staining were used to detect the intracellular antophagy changes.The expression of apoptosis related proteins,autophagy and other related signal molecules were demonstrated by Western blotting.Different cellular signaling pathway inhibitors were used to invesitigate the specific cellular mechanisms of FCPR16 protecting MPP+-induced cell injury.RESULTS FCPR16(12.5-50 μmol·L^(-1)) dose-dependently reduced MPP+-induced decline of cell viability,accompanied by reductions in nuclear condensation and lactate dehydrogenase release.The level of cleaved caspase 3 and the ratio of Bax/Bcl-2 were also decreased after treatment with FCPR16 in MPP+-treated cells.Furthermore,FCPR16(25 μmol·L^(-1)) significantly suppressed the accumulation of reactive oxygen species(ROS),prevented the decline of mitochondrial membrane potential(Δψm) and attenuated the expression of malonaldehyde level.Further studies disclosed that FCPR16 enhanced the levels of cA MP and the exchange protein directly activated by cA MP(Epac) in SHSY5 Y cel s.Western blotting analysis revealed that FCPR16 increased the phosphorylation of c AMP response element-binding protein(CREB) and protein kinase B(Akt)down-regulated by MPP+in SHSY5 Y cells.Moreover,the inhibitory effects of FCPR16 on the production of ROS and Δψm loss could be blocked by PKA inhibitor H-89 and Akt inhibitor KRX-0401.CONCLUSION The novel PDE4 inhibitor FCPR16 can protect against damaging pathways including oxidative stress,mitochondrial dysfunction and apoptosis in SH-SY5 Y cells.FCPR16 preventes MPP+-induced neurotoxicity through activation of cAMP/PKA/CREB and Epac/Akt signaling pathways.These may lead to develop mechanism based therapeutics and improved pharmacotherapy for PD.It is reasonable to assume that FCPR16 is a potential candidate for the prevention and treatment of PD.

Luteolin prevents f MLP-induced neutrophils adhesion via suppression of LFA-1 and phosphodiesterase 4 activity

Luteolin is an active ingredient found early from Fofium perillae and Flos Ionicerae, and has a specific inhibition on phosphodiesterase 4 （PDE4） activity in vitro. Researches show luteolin has pharmacological effects of anti-inflammation, anti-anaphylaxis, antitumor, antioxidant, protection of nervous system and so on, and has mainly been used for the treatment of respiratory inflammatory diseases, cancer and cardiovascular disease in clinic. PDE4, specific to hydrolyze cyclic AMP （cAMP）, is considered to be a new anti-inflammatory target due to the decisive role on cAMP signal in inflammatory cells such as neutrophils. In order to explore the anti-inflammatory mechanism, we further studied the effects of luteolin on the activity and expression of PDE4, the expression of lymphocyte function-associated antigen-1 （LFA-1） and macrophage-1 （MAC-l） in neutrophils, and the adhesion of neutrophils and endothelial cells. The results showed that luteolin had a dose-dependent inhibition on both bare PDE4 activity and PDE4 in cultured neutrophils, and had an obviously promotive effect on gene expressions of PDE4A, 4B and 4D in later period. Luteolin had a significant inhibitory effect on neutrophils adhesion and LFA-1 expression in early stage, and had no obvious effect on MAC-1 expression. Therefore, luteolin can inhibit LFA-1 expression of neutrophils, then inhibit the adhesion of neutrophils and endothelial cells, and the mechanism is at least related with the inhibition of PDE4 activity.

Efficacy and safety of on demand tadalafil in the treatment of East and Southeast Asian men with erectile dysfunction:a randomized double-blind,parallel,placebo-controlled clinical study

Aim： To assess the efficacy and safety of tadalafil in comparison to a placebo, when taken on demand for 12 weeks by East/Southeast Asian men with erectile dysfunction （ED）, Methods： This multicenter, randomized, double-blind, parallel group, placebo-controlled study was conducted at 17 centers across East and Southeast Asia between August 2002 and February 2003. Men more than 18 years of age with mild to severe ED of various etiologies were randomized to receive a placebo or 20 mg of tadalafil taken as needed （maximum once daily）. Efficacy assessments included the International Index of Erectile Function, the Sexual Encounter Profile diary and Global Assessment Questions. Results： Tadalafil significantly improved erectile function as compared to the placebo （P 〈 0.001）. At the endpoint, the patients receiving 20 mg of tadalafil reported a greater mean per patient percentage of successful intercourse attempts （Sexual Encounter Profile question 3： 70.9% compared to 33.5% in the placebo） and a greater proportion of improved erections （Global Assessment Question： 86.2% compared to 30.1%）. Most （≥3%） treatment emergent adverse events were mild or moderate. The most common treatment emergent adverse events were headache, back pain, dizziness and dyspepsia. Conclusion： Tadalafil was an effective and well-tolerated treatment for ED in East and Southeast Asian men.

Recent insights into androgen action on the anatomical and physiological substrate of penile erection

Erectile response is centrally and peripherally regulated by androgens. The original insights into the mechanisms of action of androgens were that androgens particularly exert effects on libido and that erections in response to erotic stimuli were relatively androgen-independent. It was shown that sexual functions in men required androgen levels at the low end of reference values of testosterone. So it seemed that testosterone was not useful treatment for men with erectile difficulties, particularly following the advent of the phosphodiesterase type 5 （PDE5） inhibitors. However, approximately 50% of those treated with PDE5 inhibitors discontinue their treatment. A number of recent developments shed new light on testosterone treatment of erectile dysfunction （ED） in aging men. （1） A recent insight is that, in contrast to younger men, elderly men might require higher levels of testosterone for normal sexual functioning. （2） Several studies have indicated that PDE5 inhibitors are not always sufficient to restore erectile potency in men, and that testosterone improves the therapeutical response to PDE5 inhibitors considerably. （3） There is growing insight that testosterone has profound effects on tissues of the penis involved in the mechanism of erection and that testosterone deficiency impairs the anatomical and physiological substrate of erectile capacity, reversible upon androgen replacement. The synthesis of PDE5 is upregulated by androgens, and the arterial inflow into the penis is improved by giving androgen. The above invites a re-examination of the merits of giving testosterone to aging men with ED. The beneficial effects of PDE5 inhibitors may only be optimally expressed in a eugonadal environment. （Asian J Androl 2006 Jan; 8： 3-9）

Influence of gallic acid on porcine neutrophils phosphodiesterase 4,IL-6,TNF-α and rat arthritis model

Our previous studies showed that the anti-inflammatory effects of Paeonia lactiflora roots extract may be mediated, at least in part, through its gallic acid content, and this effect may be regulated in part by an inhibition on c AMP-phosphodiesterase（PDE）. To explore the anti-inflammatory effect and mechanism, the influence of gallic acid on neutrophils PDE4 activity and expression, TNF-α and IL-6 content and rat arthritis model were further studied. PDE4 activity and gene express were calculated respectively by substrate c AMP change examined with HPLC and real-time RT-PCR. The concentration of IL-6 and TNF-α in supernatant were assayed by ELISA method. Model of rat arthritis was caused by complete Freund＇s adjuvant. Results showed that gallic acid had a dose-dependent restraint on PDE4 activity of neutrophils in vitro, promoted significantly PDE4 A expression（P〈0.01）, and had no influence on the expressions of PDE4 B and 4D. However, PDE4 C expression was not detected. Gallic acid could promote IL-6 release（P〈0.05）, and inhibit TNF-α release of neutrophils（P〈0.05）. The experiment in vivo showed that gallic acid had obvious restraint on local inflammation of animal model（P〈0.05）. Therefore, the anti-inflammatory effect of gallic acid may be mediated in part through an inhibition on PDE4 activity and further an increase of IL-6 and a decrease of TNF-α of neutrophils, and this effect seemed to have no relationship with PDE4 expression.

Counter-regulatory phosphatases TNAP and NPP1 temporally regulate tooth root cementogenesis

Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate （Pi） to mineral inhibitor pyrophosphate （PPi）, where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase （TNAP） and ectonucleotide pyrophosphatase/phosphodiesterase 1 （NPP1）. The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enppl null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enppl gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected.

New oral agents for erectile dysfunction: what is changing in our practice?

Erectile dysfunction (ED) is a highly prevalent disorder affecting an estimated 152 million men worldwide and isassociated with a variety of behavioral risk factors, such as cigarette smoking and excessive alcohol consumption, aswell as numerous age - related medical conditions, notably type-2 diabetes mellitus and cardiovascular disease. A ratio-nal step - wise approach which includes comprehensive medical and sexual history, a focused physical examination andessential laboratory tests such as fasting glucose, lipid profile and testosterone assay is to be preferred. Current diagnos-tic work - up does not recommend any of the specialized tests which were previously considered mandatory-i. e. penilepharmacotesting, Duplex ultrasound and nocturnal penile tumescence. Hormonal replacement therapy is appropriate onlyin the hypogonadal male with ED. Prior to direct intervention, the physician should consider altering modifiable riskfactors or causes, although frequently insufficient to reverse ED completely. When indicated, oral therapy with newmolecules (phosphodiesterase inhibitors or apomorphine) is the first - line treatment for the majority of patients becauseof potential benefits and lack of invasiveness. (Asian J Androl 2001 Sep; 3: 175-179 )

Diabetic nephropathy:Treatment with phosphodiesterase type 5 inhibitors

The importance of nitric oxide(NO) in vascular physiology is irrefutable;it stimulates the intracellular production of cyclic guanosine monophosphate(cGMP),initiating vascular smooth muscle relaxation.This biochemical process increases the diameter of small arteries,regulating blood flow distribution between arterioles and the microvasculature.The kidney is no exception,since NO predominantly dilates the glomerular afferent arterioles.It is now evident that the vascular production of cGMP can be augmented by inhibitors of phosphodiesterase type 5(PDE 5),the enzyme which breakdowns this cyclic nucleotide.This has clinical relevance,since diabetic nephropathy(DN) a major microvascular complication of diabetes mellitus and the most common cause of end-stage renal disease,increases intraglomerular capillary pressure,leading to glomerular hypertension.PDE 5 inhibitors may have,therefore,the potential to reduce glomerular hypertension.This review describes the use of PDE 5 inhibitors to improve the metabolic,haemodynamic and inflammatory pathways/responses,all of which are dysfunctional in DN.

Efficacy and safety of tadalafil taken as needed for the treatment of erectile dysfunction in Asian men： results of an integrated analysis

We evaluated the efficacy and safety of as-needed tadalafil in a diverse clinical population （with varying patient demographics, disease severity, and comorbid medical conditions） of Asian men with erectile dysfunction （ED）. An integrated analysis of five double-blind, placebo-controlled trials （N = 1 046） was performed. Patients were randomly assigned to receive 10 mg tadalafil （N = 185）, 20 mg tadalafil （N = 510）, or placebo （N = 351）. Efficacy assessments included the International Index of Erectile Function （IIEF）, Sexual Encounter Profile （SEP） diary and Global Assessment Question （GAQ）. Patients receiving 10 mg or 20 mg tadalafil showed significant improvement from baseline-to-end point on the Erectile Function domain of the International Index of Erectile Function （IIEF-EF） domain score in all clinical sub-populations analyzed, compared with patients receiving placebo （P 〈 0.001）. The 10-mg and 20-mg tadalafil groups showed a mean success rate of 64.1% and 70.5% for sexual intercourse attempts （SEP3, successful intercourse）, respectively, compared with 33.4% in the placebo group （P 〈 0.001）, and 85.5% and 85.4% reported improved erections at end point GAQ, respectively, versus 43.5% in the placebo group （P 〈 0.001）. Tadalafil was well tolerated across all groups studied. Headache and back pain were the most frequently reported adverse events. Overall, tadalafil was effective and well tolerated across a diverse clinical spectrum of Asian men with ED.