Phosphodiesterase 8 (PDE8): Distribution and Cellular Expression and Association with Alzheimer's Disease.

Phosphodiesterase 8 (PDE8), as a member of PDE superfamily, specifically promotes the hydrolysis and degradation of intracellular cyclic adenosine monophosphate (cAMP), which may be associated with pathogenesis of Alzheimer's disease (AD). However, little is currently known about potential role in the central nervous system (CNS). Here we investigated the distribution and expression of PDE8 in brain of mouse, which we believe can provide evidence for studying the role of PDE8 in CNS and the relationship between PDE8 and AD. Here, C57BL/6J mice were used to observe the distribution patterns of two subtypes of PDE8, PDE8A and PDE8B, in different sexes in vivo by western blot (WB). Meanwhile, C57BL/6J mice were also used to demonstrate the distribution pattern of PDE8 in selected brain regions and localization in neural cells by WB and multiplex immunofluorescence staining. Furthermore, the triple transgenic (3×Tg-AD) mice and wild type (WT) mice of different ages were used to investigate the changes of PDE8 expression in the hippocampus and cerebral cortex during the progression of AD. PDE8 was found to be widely expressed in multiple tissues and organs including heart, kidney, stomach, brain, and liver, spleen, intestines, and uterus, with differences in expression levels between the two subtypes of PDE8A and PDE8B, as well as two sexes. Meanwhile, PDE8 was widely distributed in the brain, especially in areas closely related to cognitive function such as cerebellum, striatum, amygdala, cerebral cortex, and hippocampus, without differences between sexes. Furthermore, PDE8A was found to be expressed in neuronal cells, microglia and astrocytes, while PDE8B is only expressed in neuronal cells and microglia. PDE8A expression in the hippocampus of both female and male 3×Tg-AD mice was gradually increased with ages and PDE8B expression was upregulated only in cerebral cortex of female 3×Tg-AD mice with ages. However, the expression of PDE8A and PDE8B was apparently increased in both cerebral cortex and hippocampus in both female and male 10-month-old 3×Tg-AD mice compared WT mice. These results suggest that PDE8 may be associated with the progression of AD and is a potential target for its prevention and treatment in the future.

The Construction and Application of a New Screening Method for Phosphodiesterase Inhibitors.

Phosphodiesterases (PDEs), a superfamily of enzymes that hydrolyze cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), are recognized as a therapeutic target for various diseases. However, the current screening methods for PDE inhibitors usually experience problems due to complex operations and/or high costs, which are not conducive to drug development in respect of this target. In this study, a new method for screening PDE inhibitors based on GloSensor technology was successfully established and applied, resulting in the discovery of several novel compounds of different structural types with PDE inhibitory activity. Compared with traditional screening methods, this method is low-cost, capable of dynamically detecting changes in substrate concentration in live cells, and can be used to preliminarily determine the type of PDEs affected by the detected active compounds, making it more suitable for high-throughput screening for PDE inhibitors.

cGAS/STING signaling pathway-mediated microglial activation in the PFC underlies chronic ethanol exposure-induced anxiety-like behaviors in mice.

Chronic ethanol consumption is a prevalent condition in contemporary society and exacerbates anxiety symptoms in healthy individuals. The activation of microglia, leading to neuroinflammatory responses, may serve as a significant precipitating factor; however, the precise molecular mechanisms underlying this phenomenon remain elusive. In this study, we initially confirmed that chronic ethanol exposure (CEE) induces anxiety-like behaviors in mice through open field test and elevated plus maze test. The cGAS/STING signaling pathway has been confirmed to exhibits a significant association with inflammatory signaling responses in both peripheral and central systems. Western blot analysis confirmed alterations in the cGAS/STING signaling pathway during CEE, including the upregulation of p-TBK1 and p-IRF3 proteins. Moreover, we observed microglial activation in the prefrontal cortex (PFC) of CEE mice, characterized by significant alterations in branching morphology and an increase in cell body size. Additionally, we observed that administration of CEE resulted in mitochondrial dysfunction within the PFC of mice, accompanied by a significant elevation in cytosolic mitochondrial DNA (mtDNA) levels. Furthermore, our findings revealed that the inhibition of STING by H-151 effectively alleviated anxiety-like behavior and suppressed microglial activation induced by CEE. Our study unveiled a significant association between anxiety-like behavior, microglial activation, inflammation, and mitochondria dysfunction during CEE.

Discovery of novel positive allosteric modulators targeting GluN1/2A NMDARs as anti-stroke therapeutic agents.

Excitotoxicity due to excessive activation of NMDARs is one of the main mechanisms of neuronal death during ischemic stroke. Previous studies have suggested that activation of either synaptic or extrasynaptic GluN2B-containing NMDARs results in neuronal damage, whereas activation of GluN2A-containing NMDARs promotes neuronal survival against ischemic insults. This study applied a systematic in silico, in vitro, and in vivo approach to the discovery of novel and potential GluN1/2A NMDAR positive allosteric modulators (PAMs). Ten compounds were obtained and identified as potential GluN1/2A PAMs by structure-based virtual screening and calcium imaging. The neuroprotective activity of the candidate compounds was demonstrated in vitro. Subsequently, compound 15 (aegeline) was tested further in the model of transient middle cerebral artery occlusion (tMCAO) in vivo, which significantly decreased cerebral infarction. The mechanism by which aegeline exerts its effect on allosteric modulation was revealed using molecular dynamics simulations. Finally, we found that the neuroprotective effect of aegeline was significantly correlated with the enhanced phosphorylation of cAMP response element-binding protein (CREB). Our study discovered the neuroprotective effect of aegeline as a novel PAM targeting GluN1/2A NMDAR, which provides a potential opportunity for the development of therapeutic agents for ischemic stroke.

Chronic pain exacerbates memory impairment and pathology of Aß and tau by upregulating IL-1ß and p-65 signaling in a mouse model of Alzheimer's disease.

BACKGROUND: Chronic pain is linked to cognitive impairment; however, the underlying mechanisms remain unclear. In the present study, we examined these mechanisms in a well-established mouse model of Alzheimer's disease (AD). METHODS: Neuropathic pain was modeled in 5-month-old transgenic APPswe/PS1dE9 (APP/PS1) mice by partial ligation of the sciatic nerve on the left side, and chronic inflammatory pain was modeled in another group of APP/PS1 mice by injecting them with complete Freund's adjuvant on the plantar surface of the left hind paw. Six weeks after molding, the animals were tested to assess pain threshold (von Frey filament), learning, memory (novel object recognition, Morris water maze, Y-maze, and passive avoidance), and depression-like symptoms (sucrose preference, tail suspension, and forced swimming). After behavioral testing, mice were sacrificed and the levels of p65, amyloid-ß (residues 1-42) and phospho-tau in the hippocampus and cerebral cortex were assayed using western blotting, while interleukin (IL)-1ß levels were measured by enzyme-linked immunosorbent assay. RESULTS: Animals subjected to either type of chronic pain showed lower pain thresholds, more severe deficits in learning and memory, and stronger depression-like symptoms than the corresponding control animals. Either type of chronic pain was associated with upregulation of p65, amyloid-ß (1-42), and IL-1ß in the hippocampus and cerebral cortex, as well as higher levels of phosphorylated tau. CONCLUSIONS: Chronic pain may exacerbate cognitive deficits and depression-like symptoms in APP/PS1 mice by worsening pathology related to amyloid-ß and tau and by upregulating signaling involving IL-1ß and p65.

Rolipram Ameliorates Memory Deficits and Depression-Like Behavior in APP/PS1/tau Triple Transgenic Mice: Involvement of Neuroinflammation and Apoptosis via cAMP Signaling.

BACKGROUND: Alzheimer disease (AD) and depression often cooccur, and inhibition of phosphodiesterase-4 (PDE4) has been shown to ameliorate neurodegenerative illness. Therefore, we explored whether PDE4 inhibitor rolipram might also improve the symptoms of comorbid AD and depression. METHODS: APP/PS1/tau mice (10 months old) were treated with or without daily i.p. injections of rolipram for 10 days. The animal groups were compared in behavioral tests related to learning, memory, anxiety, and depression. Neurochemical measures were conducted to explore the underlying mechanism of rolipram. RESULTS: Rolipram attenuated cognitive decline as well as anxiety- and depression-like behaviors. These benefits were attributed at least partly to the downregulation of amyloid-ß, Amyloid precursor protein (APP), and Presenilin 1 (PS1); lower tau phosphorylation; greater neuronal survival; and normalized glial cell function following rolipram treatment. In addition, rolipram upregulated B-cell lymphoma-2 (Bcl-2) and downregulated Bcl-2-associated X protein (Bax) to reduce apoptosis; it also downregulated interleukin-1ß, interleukin-6, and tumor necrosis factor-α to restrain neuroinflammation. Furthermore, rolipram increased cAMP, PKA, 26S proteasome, EPAC2, and phosphorylation of ERK1/2 while decreasing EPAC1. CONCLUSIONS: Rolipram may mitigate cognitive deficits and depression-like behavior by reducing amyloid-ß pathology, tau phosphorylation, neuroinflammation, and apoptosis. These effects may be mediated by stimulating cAMP/PKA/26S and cAMP/exchange protein directly activated by cAMP (EPAC)/ERK signaling pathways. This study suggests that PDE4 inhibitor rolipram can be an effective target for treatment of comorbid AD and depression.

Imbalance of multiple neurotransmitter pathways leading to depression-like behavior and cognitive dysfunction in the triple transgenic mouse model of Alzheimer disease.

Depression is among the most frequent psychiatric comorbid conditions in Alzheimer disease (AD). However, pharmacotherapy for depressive disorders in AD is still a big challenge, and the data on the efffcacy of current antidepressants used clinically for depressive symptoms in patients with AD remain inconclusive. Here we investigated the mechanism of the interactions between depression and AD, which we believe would aid in the development of pharmacological therapeutics for the comorbidity of depression and AD. Female APP/PS1/Tau triple transgenic (3×Tg-AD) mice at 24 months of age and age- and sex-matched wild-type (WT) mice were used. The shuttle-box passive avoidance test (PAT) were implemented to assess the abilities of learning and memory, and the open field test (OFT) and the tail suspension test (TST) were used to assess depression-like behavior. High-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) was used to detect the level of neurotransmitters related to depression in the hippocampus of mice. The data was identified by orthogonal projections to latent structures discriminant analysis (OPLS-DA). Most neurotransmitters exert their effects by binding to the corresponding receptor, so the expression of relative receptors in the hippocampus of mice was detected using Western blot. Compared to WT mice, 3×Tg-AD mice displayed significant cognitive impairment in the PAT and depression-like behavior in the OFT and TST. They also showed significant decreases in the levels of L-tyrosine, norepinephrine, vanillylmandelic acid, 5-hydroxytryptamine, and acetylcholine, in contrast to significant increases in 5-hydroxyindoleacetic acid, L-histidine, L-glutamine, and L-arginine in the hippocampus. Moreover, the expression of the alpha 1a adrenergic receptor (ADRA1A), serotonin 1 A receptor (5HT1A), and γ-aminobutyric acid A receptor subunit alpha-2 (GABRA2) was significantly downregulated in the hippocampus of 3×Tg-AD mice, while histamine H3 receptor (H3R) expression was significantly upregulated. In addition, the ratio of phosphorylated cAMP-response element-binding protein (pCREB) and CREB was significantly decreased in the hippocampus of 3×Tg-AD mice than WT mice. We demonstrated in the present study that aged female 3×Tg-AD mice showed depression-like behavior accompanied with cognitive dysfunction. The complex and diverse mechanism appears not only relevant to the imbalance of multiple neurotransmitter pathways, including the transmitters and receptors of the monoaminergic, GABAergic, histaminergic, and cholinergic systems, but also related to the changes in L-arginine and CREB signaling molecules.

Jin-Zhen oral liquid for pediatric coronavirus disease (COVID-19): A randomly controlled, open-label, and non-inferiority trial at multiple clinical centers.

Background: As the coronavirus disease 2019 (COVID-19) pandemic progressed, especially with the emergence of the Omicron variant, the proportion of infected children and adolescents increased significantly. Some treatment such as Chinese herbal medicine has been administered for COVID-19 as a therapeutic option. Jin-Zhen Oral Liquid is widely used for pediatric acute bronchitis, while the efficacy and safety in the treatment of pediatric COVID-19 are unclear. Methods: We conducted a randomized controlled, open-label, multicenter, non-inferiority clinical study involving hospitalized children with mild to moderate COVID-19. Children eligible for enrollment were randomly assigned in a 1:1 ratio to Jin-Zhen Oral Liquid (the treatment group) and Jinhua Qinggan Granules (the positive control group) and received the respective agent for 14 days, followed by a 14-day follow-up after discontinuation of the treatment. The primary efficacy endpoint was the time to first negative viral testing. The secondary endpoints were the time and rate of major symptoms disappearance, duration of hospitalization, and the proportion of symptoms changed from asymptomatic or mild to moderate or severe/critical illness. In addition, the safety end points of any adverse events were observed. Results: A total of 240 child patients were assigned randomly into the Jin-Zhen Oral Liquid (117 patients) and Jinhua Qinggan Granules (123 patients) groups. There was no significant difference of the baselines in terms of the clinical characteristics and initial symptoms between the two groups. After 14-day administration, the time to first negative viral testing in the Jin-Zhen group (median 6.0 days, 95% CI 5.0-6.0) was significantly shorter compared with the positive control Jinhua Qinggan Granules group (median 7.0 days, 95% CI 7.0-8.0). The time and rate of major clinical symptoms disappearance were comparable to the positive control. The symptom disappearance time of pharyngalgia and hospitalization duration were significantly shortened in the Jin-zhen Oral Liquid group. No participants in either group experienced post-treatment exacerbation to severe or critical illness. No adverse events were observed in the Jin-Zhen Oral Liquid treatment group (0.0%) while 1 patient with adverse events occurred in the positive control Jinhua Qinggan granules group (0.8%). No serious adverse events were observed during the study period in both groups. Conclusion: Jin-Zhen Oral Liquid is safe and effective in the treatment of mild to medium COVID-19 in children. It is non-inferior to Jinhua Qinggan granules in shortening the time to first negative viral testing, the time and rate of major clinical symptoms disappearance, and the hospitalization duration. The results suggest that Jin-Zhen Oral Liquid can be a recommended drug for treatment of pediatric COVID-19 patients.

ß-Glucan attenuates cognitive impairment of APP/PS1 mice via regulating intestinal flora and its metabolites.

BACKGROUND: The intestinal flora has been shown to be involved in the progression of Alzheimer's disease (AD) and can be improved by ß-glucan, a polysaccharide derived from Saccharomyces cerevisiae, which affects cognitive function through the intestinal flora. However, it is not known if this effect of ß-glucan is involved in AD. METHOD: This study used behavioral testing to measure cognitive function. After that, high-throughput 16 S rRNA gene sequencing and GC-MS were used to analyze the intestinal microbiota and metabolite SCFAs of AD model mice, and further explore the relationship between intestinal flora and neuroinflammation. Finally, the expressions of inflammatory factors in the mouse brain were detected by Western blot and Elisa methods. RESULTS: We found that appropriate supplementation of ß-glucan during the progression of AD can improve cognitive impairment and reduce A ß plaque deposition. In addition, supplementation of ß-glucan can also promote changes in the composition of the intestinal flora, thereby changing the flora metabolites in the intestinal content and reduce the activation of inflammatory factors and microglia in the cerebral cortex and hippocampus through the brain-gut axis. While reducing the expression of inflammatory factors in the hippocampus and cerebral cortex, thereby controlling neuroinflammation. CONCLUSION: The imbalance of the gut microbiota and metabolites plays a role in the progression of AD; ß-glucan blocks the development of AD by improving the gut microbiota and its metabolites and reducing neuroinflammation. ß-Glucan is a potential strategy for the treatment of AD by reshaping the gut microbiota and improving its metabolites.

Cyclic Nucleotide Phosphodiesterases in Alcohol Use Disorders: Involving Gut Microbiota.

Alcohol abuse is 1 of the most significant public health problems in the world. Chronic, excessive alcohol consumption not only causes alcohol use disorder (AUD) but also changes the gut and lung microbiota, including bacterial and nonbacterial types. Both types of microbiota can release toxins, further damaging the gastrointestinal and respiratory tracts; causing inflammation; and impairing the functions of the liver, lung, and brain, which in turn deteriorate AUD. Phosphodiesterases (PDEs) are critical in the control of intracellular cyclic nucleotides, including cyclic adenosine monophosphate and cyclic guanosine monophosphate. Inhibition of certain host PDEs reduces alcohol consumption and attenuates alcohol-related impairment. These PDEs are also expressed in the microbiota and may play a role in controlling microbiota-associated inflammation. Here, we summarize the influences of alcohol on gut/lung bacterial and nonbacterial microbiota as well as on the gut-liver/brain/lung axis. We then discuss the relationship between gut and lung microbiota-mediated PDE signaling and AUD consequences in addition to highlighting PDEs as potential targets for treatment of AUD.

Transcriptome analysis of fasudil treatment in the APPswe/PSEN1dE9 transgenic (APP/PS1) mice model of Alzheimer's disease.

Alzheimer's disease (AD) is the most common cause of progressive dementia. In the present study, we showed hippocampal tissue transcriptome analysis in APPswe/PSEN1dE9 (APP/PS1, AD model) mice treated with fasudil (ADF) and compared with AD mice treated with saline (ADNS) and wild type mice (WT). The competing endogenous RNA (ceRNA) network was constructed and validated the differential expression of mRNA, lncRNA, miRNA, and circRNA. Our study showed differentially expressed mRNAs (DEMs) between WT and ADNS, while enriched in cell growth and death and nervous system pathways. DEMs between ADNS-ADF were enriched in the nervous system, glycosaminoglycan biosynthesis-keratan sulfate (KS) and Quorum sensing pathways. We validated four genes with RT-PCR, whereas enrichment of Acyl-CoA Synthetase Long Chain Family Member 4 (Acsl4, ENSMUST00000112903) in Quorum sensing pathways, and BTG anti-proliferation factor 1 (Btg1, ENSMUST00000038377) in RNA degradation pathways were conducted. Expression of these two genes were higher in ADNS, but were significantly reduced in ADF. Histone H4 transcription factor (Hinfp, ENSMUST00000216508) orchestrate G1/S transition of mitotic cell cycle and co-expressed with mmu-miR-26a-2-3p-mediated ceRNA and mmu-miR-3065-5p-mediated ceRNA; Wnt family member 4 (Wnt4, ENSMUST00000045747) was enriched in mTOR, Hippo and Wnt signaling pathway. Expression of these two genes were significantly lower in ADNS, and fasudil treatment reverse it. The present studies demonstrated four genes: Acsl4, Btg1, Hinfp, Wnt4 could be potential biomarkers of AD and the targets of fasudil treatment. These results will pave a novel direction for future clinic studies for AD and fasudil treatment.

Synergistic effects of two naturally occurring iridoids in eliciting a rapid antidepressant action by up-regulating hippocampal PACAP signalling.

BACKGROUND AND PURPOSE: Current mainstream antidepressants have limited efficacy with a delayed onset of action. Yueju, a herbal medicine, has a rapid antidepressant action. Identification of the active ingredients in Yueju and the mechanism/s involved was carried out. EXPERIMENTAL APPROACH: Key molecule/s and compounds involved in this antidepressant action was identified by transcriptomic and HPLC analysis, respectively. Antidepressant effects were evaluated using various behavioural experiments. The signalling involved was assessed using site-directed pharmacological intervention or optogenetic manipulation. KEY RESULTS: Transcriptomic analysis showed that Yueju up-regulated pituitary adenylate cyclase activating polypeptide (PACAP) expression in the hippocampus. Two iridoids, geniposide and shanzhiside methyl ester, were identified and quantified from Yueju. Only co-treatment with both, at an equivalent concentrations found in Yueju, increased PACAP expression and elicited a rapid antidepressant action, which were blocked by intra-dentate gyrus infusion of a PACAP antagonist or optogenetic inactivation of PACAP expressing neurons. Geniposide and shanzhiside methyl ester co-treatment rapidly inhibited CaMKII phosphorylation and enhanced mTOR/4EBP1/P70S6k/BDNF ignalling, while intra-dentate gyrus infusions of a CaMKII activator blunted the rapid antidepressant action and BDNF expression up-regulation induced by the co-treatment. A single co-treatment of them rapidly improved depression-like behaviours and up-regulated hippocampal PACAP signalling in the repeated corticosterone-induced depression model, further confirming the involvement of PACAP. CONCLUSION AND IMPLICATIONS: Geniposide and shanzhiside methyl ester co-treatment had a synergistic rapid onset antidepressant action by triggering hippocampal PACAP activity and associated CaMKII-BDNF signalling. This mechanism could be targeted for development of fast onset antidepressants.

Biochanin A alleviates cognitive impairment and hippocampal mitochondrial damage in ovariectomized APP/PS1 mice.

BACKGROUND: Estrogen deficiency leads to mitochondrial defects that precede Alzheimer's disease (AD)-associated pathological changes in a postmenopausal mouse model. Biochanin A (BCA) is a phytoestrogen isolated from Trifolium pratense L. used to relieve postmenopausal problems in women. In previous work, we observed that oral BCA treatment led to neuroprotection in an ovariectomized rat model. The objective of this study was to investigate whether and how BCA protects against hippocampal mitochondrial damage in a postmenopausal model of AD. METHOD: APP/PS1 mice underwent bilateral ovariectomy and then, seven days later, received oral BCA at 20 or 40 mg/kg, or oral estradiol at 0.5 mg/kg, daily for 90 days. Sham animals were not ovariectomized and received no additional treatments. Cognitive function was examined using the passive avoidance task, novel object recognition test, and Morris water maze test. The level of circulating estrogen in vivo was assessed indirectly by measuring the wet weight of the uterus. We detected Aß deposition and PGC-1α in brain by immunohistochemistry; p62, by immunofluorescence; and ERα, ERß, PGC-1α, NRF1, mtTFA, Drp1, OPA1, Mfn2, Beclin1, LC3B, Pink1, and Parkin by immunoblotting. RESULTS: BCA treatment rescued cognitive decline and reduced Aß deposition and BACE1 expression in the hippocampus of ovariectomized APP/PS1 mice. BCA reversed the imbalance of mitochondrial dynamics caused by ovariectomy by increasing the expression of phospho-Drp1 (ser637), OPA1, and Mfn2. BCA reversed abnormal mitophagy induced by ovariectomy by increasing the expression of Beclin1, LC3B, Pink1, and Parkin, as well as by reducing the expression of p62. CONCLUSIONS: BCA treatment enhances learning and memory abilities and alleviates AD symptoms in a postmenopausal model of AD. A possible mechanism is that BCA rescues the reduction of mitochondrial biogenesis, imbalance of mitochondrial dynamics, and abnormal mitophagy caused by ovariectomy. This study supports further research on BCA to develop treatments for postmenopausal women with AD.

Baicalin attenuates amyloid ß oligomers induced memory deficits and mitochondria fragmentation through regulation of PDE-PKA-Drp1 signalling.

RATIONALE: Mitochondrial fragmentation contributes to the initiation of Alzheimer's disease (AD) pathology. Baicalin plays a significant role in rescuing mitochondrial dysfunction. However, the effect of baicalin treatment on the modulation of mitochondrial fragmentation has not yet been assessed. OBJECTIVES: The present study was designed to evaluate the effect of baicalin on memory and understand its mechanism of action. RESULTS: Baicalin treatment significantly reversed the altered learning and memory behaviours in AD mouse model. We found that baicalin treatment significantly improved the levels of microtubule association protein-2 and enhanced the expression of synaptophysin and postsynaptic density protein 95 (PSD95). Moreover, treatment with baicalin reversed amyloid-ß oligomer (AßO)-induced abnormalities in the succinate dehydrogenase complex iron sulphur subunit B (SDHB) and cytochrome c oxidase components I (COXI) and mitochondrial fragmentation in the hippocampus. Further, we found that baicalin decreased the PDE4 levels and upregulated the levels of phosphorylated Ser157 site of vasodilator-stimulated phosphoprotein (pVASPs157) and phosphorylated Ser637 site of mitochondrial dynamin-related protein 1 (pDrp1S637). Moreover, in AßO-treated HT-22 cells, H89 inhibited the effect of baicalin on PSD95, mitochondrial fragmentation, SDHB and COXI, PDE4, pVASPs157, and pDrp1S637. CONCLUSION: The effect of baicalin on memory improvement may be due to improved synaptic plasticity, mitochondrial fragmentation, and rescue of dysfunction via the inhibition of PDE4, which leads to activation of pDrp1S637 in the AßO-induced model.

Inhibition of phosphodiesterase-4 in the spinal dorsal horn ameliorates neuropathic pain via cAMP-cytokine-Cx43 signaling in mice.

BACKGROUND: The spinal phosphodiesterase-4 (PDE4) plays an important role in chronic pain. Inhibition of PDE4, an enzyme catalyzing the hydrolysis of cyclic adenosine monophosphate AMP (cAMP), produces potent antinociceptive activity. However, the antinociceptive mechanism remains largely unknown. Connexin43 (Cx43), a gap junction protein, has been shown to be involved in controlling pain transduction at the spinal level; restoration of Cx43 expression in spinal astrocytes to the normal levels reduces nerve injury-induced pain. Here, we evaluate the novel mechanisms involving spinal cAMP-Cx43 signaling by which PDE4 inhibitors produce antinociceptive activity. METHODS: First, we determined the effect of PDE4 inhibitors rolipram and roflumilast on partial sciatic nerve ligation (PSNL)-induced mechanical hypersensitivity. Next, we observed the role of cAMP-Cx43 signaling in the effect of PDE4 inhibitors on PSNL-induced mechanical hypersensitivity. RESULTS: Single or repeated, intraperitoneal or intrathecal administration of rolipram or roflumilast significantly reduced mechanical hypersensitivity in mice following PSNL. In addition, repeated intrathecal treatment with either of PDE4 inhibitors reduced PSNL-induced downregulation of cAMP and Cx43, and upregulation of proinflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1ß. Furthermore, the antinociceptive effects of PDE4 inhibitors were attenuated by the protein kinase A (PKA) inhibitor H89, TNF-α, or Cx43 antagonist carbenoxolone. Finally, PSNL-induced upregulation of PDE4B and PDE4D, especially the PDE4B subtype, was reduced by treatment with either of the PDE4 inhibitors. CONCLUSIONS: The results suggest that the antinociceptive effect of PDE4 inhibitors is contributed by increasing Cx43 expression via cAMP-PKA-cytokine signaling in the spinal dorsal horn.

Inhibition of Rho Kinase by Fasudil Ameliorates Cognition Impairment in APP/PS1 Transgenic Mice via Modulation of Gut Microbiota and Metabolites.

Background: Fasudil, a Rho kinase inhibitor, exerts therapeutic effects in a mouse model of Alzheimer's disease (AD), a chronic neurodegenerative disease with progressive loss of memory. However, the mechanisms remain unclear. In addition, the gut microbiota and its metabolites have been implicated in AD. Methods: We examined the effect of fasudil on learning and memory using the Morris water-maze (MWM) test in APPswe/PSEN1dE9 transgenic (APP/PS1) mice (8 months old) treated (i.p.) with fasudil (25 mg/kg/day; ADF) or saline (ADNS) and in age- and gender-matched wild-type (WT) mice. Fecal metagenomics and metabolites were performed to identify novel biomarkers of AD and elucidate the mechanisms of fasudil induced beneficial effects in AD mice. Results: The MWM test showed significant improvement of spatial memory in APP/PS1 mice treated with fasudil as compared to ADNS. The metagenomic analysis revealed the abundance of the dominant phyla in all the three groups, including Bacteroidetes (23.7-44%) and Firmicutes (6.4-26.6%), and the increased relative abundance ratio of Firmicutes/Bacteroidetes in ADNS (59.1%) compared to WT (31.7%). In contrast, the Firmicutes/Bacteroidetes ratio was decreased to the WT level in ADF (32.8%). Lefse analysis of metagenomics identified s_Prevotella_sp_CAG873 as an ADF potential biomarker, while s_Helicobacter_typhlonius and s_Helicobacter_sp_MIT_03-1616 as ADNS potential biomarkers. Metabolite analysis revealed the increment of various metabolites, including glutamate, hypoxanthine, thymine, hexanoyl-CoA, and leukotriene, which were relative to ADNS or ADF microbiota potential biomarkers and mainly involved in the metabolism of nucleotide, lipids and sugars, and the inflammatory pathway. Conclusions: Memory deficit in APP/PS1 mice was correlated with the gut microbiome and metabolite status. Fasudil reversed the abnormal gut microbiota and subsequently regulated the related metabolisms to normal in the AD mice. It is believed that fasudil can be a novel strategy for the treatment of AD via remodeling of the gut microbiota and metabolites. The novel results also provide valuable references for the use of gut microbiota and metabolites as diagnostic biomarkers and/or therapeutic targets in clinical studies of AD.

Phosphodiesterase 7(PDE7): A unique drug target for central nervous system diseases.

Phosphodiesterase 7 (PDE7), one of the 11 phosphodiesterase (PDE) families, specifically hydrolyzes cyclic 3', 5'-adenosine monophosphate (cAMP). PDE7 is involved in many important functional processes in physiology and pathology by regulating intracellular cAMP signaling. Studies have demonstrated that PDE7 is widely expressed in the central nervous system (CNS) and potentially related to pathogenesis of many CNS diseases. Here, we summarized the classification and distribution of PDE7 in the brain and its functional roles in the mediation of CNS diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), and schizophrenia. It is expected that the findings collected here will not only lead to a better understanding of the mechanisms by which PDE7 mediates CNS function and diseases, but also aid in the development of novel drugs targeting PDE7 for treatment of CNS diseases.

Advances in Cyclic Nucleotide Phosphodiesterase-Targeted PET Imaging and Drug Discovery.

Cyclic nucleotide phosphodiesterases (PDEs) control the intracellular concentrations of cAMP and cGMP in virtually all mammalian cells. Accordingly, the PDE family regulates a myriad of physiological functions, including cell proliferation, differentiation and apoptosis, gene expression, central nervous system function, and muscle contraction. Along this line, dysfunction of PDEs has been implicated in neurodegenerative disorders, coronary artery diseases, chronic obstructive pulmonary disease, and cancer development. To date, 11 PDE families have been identified; however, their distinct roles in the various pathologies are largely unexplored and subject to contemporary research efforts. Indeed, there is growing interest for the development of isoform-selective PDE inhibitors as potential therapeutic agents. Similarly, the evolving knowledge on the various PDE isoforms has channeled the identification of new PET probes, allowing isoform-selective imaging. This review highlights recent advances in PDE-targeted PET tracer development, thereby focusing on efforts to assess disease-related PDE pathophysiology and to support isoform-selective drug discovery.

Biochanin A Attenuates Ovariectomy-Induced Cognition Deficit via Antioxidant Effects in Female Rats.

Background: Impairment of memory and cognition is one of the major symptoms in women with postmenopausal disorders due to estrogen deficiency, which accounts for the much higher prevalence of Alzheimer's disease in females. Biochanin A (BCA), a natural phytoestrogen, has been reported to protect neurons against ischemic brain injury. However, the neuroprotective effects of BCA in the postmenopausal-like model of ovariectomized (OVX) rats remain to be investigated. Methods: All the rats except for the sham group underwent the resection of bilateral ovaries. Seven days after the OVX surgery, rats were randomly divided into six groups: sham, OVX, OVX + BCA (5 mg/kg), OVX + BCA (20 mg/kg), OVX + BCA (60 mg/kg), and OVX + estradiol (E2; 0.35 mg/kg), which were administrated daily by gavage for 12 weeks. Learning and memory were examined using the Morris water-maze test before the end of the experiment. Morphological changes of the rat hippocampus were observed by HE staining and electron microscopy. Malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in the hippocampus were measured. The effect of BCA on cell viability was measured in the presence of hydrogen peroxide (H2O2) using CCK8. Flow cytometry was used to measure neuronal apoptosis and reactive oxygen species (ROS) induced by H2O2. Expression of Bcl-2, Bax, and Caspase-3 was determined by Western blotting using hippocampal tissues and primary cultures of hippocampal neurons. Results: Chronic treatment with BCA mimicked the ability of E2 to reverse the deficit of learning and memory in the Morris water-maze test in OVX rats. BCA normalized OVX-induced morphological changes as revealed by HE staining and electron microscopy. In addition, BCA significantly decreased the levels of MDA, the biomarker of oxidative damage, and increased the activity of the intracellular antioxidant enzymes SOD and GSH-Px in OVX rats. Further, in primary cultures of hippocampal neurons, BCA reversed H2O2-induced decreases in cell viability and accumulation of ROS. Finally, BCA reversed OVX- or H2O2-induced increases in Bax and Caspase-3 and decreases in Bcl-2 in the hippocampus and primary cultures of hippocampal neurons. Conclusion: These results suggest that BCA improves memory through its neuroprotective properties in the brain under the circumstance of estrogen deficiency and can be used for treatment of memory loss in postmenopausal women.

Ischemic stroke/transient ischemic attack in adults with primary immune thrombocytopenia: a meta-analysis.

OBJECTIVE: To carry out a systematic review to help resolve the controversy of ischemic stroke (IS)/transient ischemic attack (TIA) in patients with primary immune thrombocytopenia (ITP). METHODS: A database search of PubMed and Ovid Embase was conducted for epidemiologic studies published up to December 17, 2019. The effective size was estimated by pooled prevalence, annualized incidence/risk, relative risk (RR), and their corresponding 95% confidence intervals (CIs). RESULTS: The systematic review included 14 eligible studies from 11 publications. The pooled annualized cumulative incidence was 0.15% (95% CI, 0.03-0.26%) per person-years. And the pooled annualized cumulative risk of IS/TIA of ITP was 0.86% (95% CI, 0.33-1.39%) per year based on 3 population-based cohort studies. There was a higher risk of incident IS/TIA in ITP patients than ITP-free subjects (pooled unadjusted or adjusted RR with 95% CI, 1.46 [1.22-1.74] or 1.50 [1.29-1.73]). CONCLUSIONS: IS/TIA was not uncommon in patients with primary ITP. ITP patients have a higher risk of IS/TIA compared with the reference cohorts. Healthcare professionals should take into account the risk of IS/TIA when treating ITP patients with or without a history of IS/TIA.