Protective effects of phosphodiesterase 2 inhibitor against Aß1-42 induced neuronal toxicity.

Our previous study suggested that inhibition of Phosphodiesterase 2 ameliorates memory loss upon exposure to oxidative stress. While whether memory enhancing effects of PDE2 inhibition on Alzheimer's disease mouse model are involved in antioxidant defense and neuronal remodeling, are largely unexplored. The present study addressed whether and how PDE2 inhibitor Bay 60-7550 rescued Aß oligomers (Aßo)-induced neuronal damage and memory impairment. The results suggested that exposure of primary cortical neurons to Aßo induced neuronal cells damage and increased PDE2 expression, which were paralleled to an increase in the oxidative parameter malondialdehyde (MDA) level and cellular apoptosis. However, this Aßo-induced oxidative damage was blocked by pre-treatment with protein kinase A or G (PKA or PKG) inhibitor, suggesting the involvement of cAMP/cGMP signaling. Moreover, microinjection of Aßo into the prefrontal cortex of mice increased the MDA level; while Bay 60-7550 reversed this effect and increased antioxidant and anti-apoptotic factors, i.e. increased trolox-equivalent-antioxidant capacity and Bcl-2/Bax ratio. Bay 60-7550 also rescued Aßo-induced synaptic atrophy and memory deficits, as evidenced by the increased synaptic proteins' levels and spine density in the prefrontal cortex, and improved cognitive behaviors by decreased working memory errors in the eight-arm maze and increased discrimination index in the novel object recognition test. These findings suggest that inhibition of PDE2 contributes to antioxidant defense and neuronal remodeling by regulation of cAMP/cGMP signaling, which provide a theoretical basis for the future use of PDE2 inhibitors as the anti-AD drugs.

METTL3-dependent RNA m6A dysregulation contributes to neurodegeneration in Alzheimer's disease through aberrant cell cycle events.

BACKGROUND: N6-methyladenosine (m6A) modification of RNA influences fundamental aspects of RNA metabolism and m6A dysregulation is implicated in various human diseases. In this study, we explored the potential role of RNA m6A modification in the pathogenesis of Alzheimer disease (AD). METHODS: We investigated the m6A modification and the expression of m6A regulators in the brain tissues of AD patients and determined the impact and underlying mechanism of manipulated expression of m6A levels on AD-related deficits both in vitro and in vivo. RESULTS: We found decreased neuronal m6A levels along with significantly reduced expression of m6A methyltransferase like 3 (METTL3) in AD brains. Interestingly, reduced neuronal m6A modification in the hippocampus caused by METTL3 knockdown led to significant memory deficits, accompanied by extensive synaptic loss and neuronal death along with multiple AD-related cellular alterations including oxidative stress and aberrant cell cycle events in vivo. Inhibition of oxidative stress or cell cycle alleviated shMettl3-induced apoptotic activation and neuronal damage in primary neurons. Restored m6A modification by inhibiting its demethylation in vitro rescued abnormal cell cycle events, neuronal deficits and death induced by METTL3 knockdown. Soluble Aß oligomers caused reduced METTL3 expression and METTL3 knockdown exacerbated while METTL3 overexpression rescued Aß-induced synaptic PSD95 loss in vitro. Importantly, METTL3 overexpression rescued Aß-induced synaptic damage and cognitive impairment in vivo. CONCLUSIONS: Collectively, these data suggested that METTL3 reduction-mediated m6A dysregulation likely contributes to neurodegeneration in AD which may be a therapeutic target for AD.

A Novel PDE4D Inhibitor BPN14770 Reverses Scopolamine-Induced Cognitive Deficits via cAMP/SIRT1/Akt/Bcl-2 Pathway.

A global, quantitative proteomics/systems-biology analysis of the selective pharmacological inhibition of phosphodiesterase-4D (PDE4D) revealed the differential regulation of pathways associated with neuroplasticity in memory-associated brain regions. Subtype selective inhibitors of PDE4D bind in an allosteric site that differs between mice and humans in a single amino acid (tyrosine vs. phenylalanine, respectively). Therefore to study selective inhibition of PDE4D by BPN14770, a subtype selective allosteric inhibitor of PDE4D, we utilized a line of mice in which the PDE4D gene had been humanized by mutating the critical tyrosine to phenylalanine. Relatively low doses of BPN14770 were effective at reversing scopolamine-induced memory and cognitive deficits in humanized PDE4D mice. Inhibition of PDE4D alters the expression of protein kinase A (PKA), Sirt1, Akt, and Bcl-2/Bax which are components of signaling pathways for regulating endocrine response, stress resistance, neuronal autophagy, and apoptosis. Treatment with a series of antagonists, such as H89, sirtinol, and MK-2206, reversed the effect of BPN14770 as shown by behavioral tests and immunoblot analysis. These findings suggest that inhibition of PDE4D enhances signaling through the cAMP-PKA-SIRT1-Akt -Bcl-2/Bax pathway and thereby may provide therapeutic benefit in neurocognitive disorders.

Phosphodiesterase 2 inhibitor Hcyb1 reverses corticosterone-induced neurotoxicity and depression-like behavior.

RATIONALE: Currently available PDE2 inhibitors have poor brain penetration that limits their therapeutic utility in the treatment of depression. Hcyb1 is a novel selective PDE2 inhibitor that was introduced more lipophilic groups with polar functionality to the scaffold pyrazolopyrimidinone to improve the blood-brain barrier (BBB) penetration. Our previous study suggested that Hcyb1 increased the neuronal cell viability and exhibited antidepressant-like effects, which were parallel to the currently available PDE2 inhibitor Bay 60-7550. OBJECTIVES: The present study investigated whether Hcyb1 protected HT-22 cells against corticosterone-induced neurotoxicity and produced antidepressant-like effects in behavioral tests in stressed mice. METHODS: The neuroprotective effects of Hcyb1 against corticosterone-induced cell lesion were examined by cell viability (MTS) assay. The enzyme-linked immunosorbent assay (ELISA) and immunoblot analysis were used to determine the levels of cAMP or cGMP and expression of pCREB or BDNF, respectively, in the corticosterone-treated HT-22 cells. The antidepressant-like effects of Hcyb1 were determined in the tail suspension and novelty suppressed feeding tests in stressed mice. RESULTS: In the cell-based assay, Hcyb1 significantly increased cell viability of HT-22 cells against corticosterone-induced neurotoxicity in a time- and dose-dependent manner. Hcyb1 also rescued corticosterone-induced decreases in both cGMP and cAMP levels, pCREB/CREB and BDNF expression. These protective effects of Hcyb1 were prevented by pretreatment with either the PKA inhibitor H89 or the PKG inhibitor KT5823. Moreover, Hcyb1 reversed acute stress-induced increases in immobility time and the latency to feed in the tail suspension and novelty suppressed feeding tests, respectively, which were prevented by pretreatment with H89 or KT5823. CONCLUSION: These findings provide evidence that the neuroprotective effects of Hcyb1 are mediated by PDE2-dependent cAMP/cGMP signaling.

Single housing-induced effects on cognitive impairment and depression-like behavior in male and female mice involve neuroplasticity-related signaling.

Single-housed stress elicits a range of social isolation-related behavioral and neurobiological abnormalities. To investigate single housing-induced behavioral changes and sex differences on stress outcomes, we examined single-housed stress-induced learning and memory impairment, depression-like behaviors, neuroplasticity abnormalities and underlying mechanism. The results showed that male and female mice socially isolated for 8 weeks had significantly decreased memory acquisition, as demonstrated in the learning curve of the Morris water maze task. Memory consolidation and retrieval were also decreased in both the single-housed male and female mice. These findings were corroborated further by the two classical animal models, Y-maze and novel object recognition tests, as demonstrated by reduced spontaneous alternation and recognition index in both sexes of single-housed mice. Subsequent studies suggested that single-housed male mice exhibited increased immobility time in both the forced swim and tail suspension tests, while the female mice only exhibited increased immobility time in the tail suspension test. Moreover, single-housed stress significantly decreased the apical and basal branch points, dendritic length, and spine density in the CA1 of hippocampal neurons in both male and female mice. These effects were consistent with decreased neuroplasticity and neuroprotective-related molecules such as synaptophysin, PSD95, PKA, pCREB and BDNF expression. These findings suggest that loss of neuronal remodeling and neuroprotective mechanisms due to single housing are involved in behavioral changes in both male and female mice. The results provide further evidence that neuroplasticity-related signaling plays a crucial role in isolation-induced effects on neuropsychiatric behavioral deficits in both sexes.

Protection from Amyloid ß Peptide-Induced Memory, Biochemical, and Morphological Deficits by a Phosphodiesterase-4D Allosteric Inhibitor.

Recent imaging studies of amyloid and tau in cognitively normal elderly subjects imply that Alzheimer's pathology can be tolerated by the brain to some extent due to compensatory mechanisms operating at the cellular and synaptic levels. The present study investigated the effects of an allosteric inhibitor of phosphodiesterase-4D (PDE4D), known as BPN14770 (2-(4-((2-(3-Chlorophenyl)-6-(trifluoromethyl)pyridin-4-yl)methyl)phenyl)acetic Acid), on impairment of memory, dendritic structure, and synaptic proteins induced by bilateral microinjection of oligomeric amyloid beta (Aß 1-42 into the hippocampus of humanized PDE4D (hPDE4D) mice. The hPDE4D mice provide a unique and powerful genetic tool for assessing PDE4D target engagement. Behavioral studies showed that treatment with BPN14770 significantly improved memory acquisition and retrieval in the Morris water maze test and the percentage of alternations in the Y-maze test in the model of Aß impairment. Microinjection of oligomeric Aß 1-42 caused decreases in the number of dendrites, dendritic length, and spine density of pyramid neurons in the hippocampus. These changes were prevented by BPN14770 in a dose-dependent manner. Furthermore, molecular studies showed that BPN14770 prevented Aß-induced decreases in synaptophysin, postsynaptic density protein 95, phosphorylated cAMP-response element binding protein (CREB)/CREB, brain-derived neurotrophic factor, and nerve growth factor inducible protein levels in the hippocampus. The protective effects of BPN14770 against Aß-induced memory deficits, synaptic damage, and the alteration in the cAMP-meditated cell signaling cascade were blocked by H-89 (N-[2-(p-Bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride), an inhibitor of protein kinase A. These results suggest that BPN14770 may activate compensatory mechanisms that support synaptic health even with the onset of amyloid pathology in Alzheimer's disease. SIGNIFICANCE STATEMENT: This study demonstrates that a phosphodiesterase-4D allosteric inhibitor, BPN14770, protects against memory loss and neuronal atrophy induced by oligomeric Aß 1-42. The study provides useful insight into the potential role of compensatory mechanisms in Alzheimer's disease in a model of oligomeric Aß 1-42 neurotoxicity.

The antidepressant- and anxiolytic-like effects of resveratrol: Involvement of phosphodiesterase-4D inhibition.

Resveratrol is a natural non-flavonoid polyphenol found in red wine, which has numerous pharmacological properties including anti-stress and antidepressant-like abilities. However, whether the antidepressant- and anxiolytic-like effects of resveratrol are related to the inhibition of phosphodiesterase 4 (PDE4) and its subtypes remains unknown. The same holds true for the subsequent cAMP-dependent pathway. The first set of studies investigated whether resveratrol exhibited neuroprotective effects against corticosterone-induced cell lesion as well as its underlying mechanism. We found that 100 µM corticosterone induced PDE2A, PDE3B, PDE4A, PDE4D, PDE10 and PDE11 expression in HT-22 cells, which results in significant cell lesion. However, treatment with resveratrol increased cell viability in a dose- and time-dependent manner. These effects seem related to the inhibition of PDE4D, as evidenced by resveratrol dose-dependently decreasing PDE4D expression. In addition, the PKA inhibitor H89 reversed resveratrol's effects on cell viability. Resveratrol prevented corticosterone-induced reduction in cAMP, pVASP(s157), pCREB, and BDNF levels, indicating that cAMP signaling is involved in resveratrol-induced neuroprotective effects. Not to mention, PDE4D knockdown by PDE4D siRNA potentiated the effect of low dose of resveratrol on cAMP, pVASP, pCREB, and BDNF expression, while PDE4D overexpression reversed the effect of high dose of resveratrol on the expression of the above proteins. Finally, the subsequent in vivo data supports the in vitro findings, suggesting that resveratrol-induced antidepressant- and anxiolytic-like effects are mediated by PDE4D. Overall, these findings support the hypothesis that PDE4D-mediated cAMP signaling plays an important role in resveratrol's protective effects on stress-induced depression- and anxiety-like behavior.

Design and Synthesis of Selective Phosphodiesterase 4D (PDE4D) Allosteric Inhibitors for the Treatment of Fragile X Syndrome and Other Brain Disorders.

Novel pyridine- and pyrimidine-based allosteric inhibitors are reported that achieve PDE4D subtype selectivity through recognition of a single amino acid difference on a key regulatory domain, known as UCR2, that opens and closes over the catalytic site for cAMP hydrolysis. The design and optimization of lead compounds was based on iterative analysis of X-ray crystal structures combined with metabolite identification. Selectivity for the activated, dimeric form of PDE4D provided potent memory enhancing effects in a mouse model of novel object recognition with improved tolerability and reduced vascular toxicity over earlier PDE4 inhibitors that lack subtype selectivity. The lead compound, 28 (BPN14770), has entered midstage, human phase 2 clinical trials for the treatment of Fragile X Syndrome.

Reduced phosphodiesterase-2 activity in the amygdala results in anxiolytic-like effects on behavior in mice.

BACKGROUND: Phosphodiesterase-2 (PDE2) is a cyclic nucleotide phosphodiesterase and is highly expressed in the amygdala, which suggests its important role in anxiety-like behavior. AIMS: The present study examined whether reduced PDE2A expression in the central nucleus of the amygdala (CeA) produces anxiolytic-like effects in mice. METHODS: PDE2A knockdown in amygdaloid (AR5) cells or the CeA was established using a lentiviral vector-based siRNA system. The anxiety-like behaviors were detected by the elevated plus maze (EPM) and hole-board tests in mice. The related proteins involved in cAMP/cGMP-dependent signaling, such as specific marker VASPser239, CREBser133 and BDNF were detected by immunoblot analysis. RESULTS: PDE2A inhibition in AR-5 cells resulted in increases in cAMP/cGMP-related pVASPser239 and pCREBser133. Behavioral tests showed that PDE2A knockdown in the CeA induced anxiolytic-like effects as evidenced by the increases in percentages of open-arm entries and time spent in the open arms in the EPM test, and the increases in head dips and time spent in head dipping in the hole-board test. However, these anxiolytic-like effects were antagonized by pre-treatment of soluble guanylyl cyclase inhibitor ODQ or adenylate cyclase inhibitor SQ. Furthermore, PDE2A knockdown significantly increased pVASPSer239, pCREBSer133 and decreased BDNF expression in the amygdala. Pre-intra-CeA of ODQ or SQ reversed or partially prevented the effects of PDE2A knockdown on these proteins. CONCLUSIONS: The results suggest that PDE2A plays a crucial role in the regulation of anxiety by the cGMP/cAMP-dependent pVASP-pCREB-BDNF signaling pathway.

Report of the 2018-2019 Research and Graduate Affairs Committee.

The 2018-2019 Research and Graduate Affairs Committee (RGAC) was charged with critically evaluating the leadership development support necessary for pharmacy researchers, including postdoctoral trainees, to develop the skills needed to build and sustain successful research programs and analyzing how well those needs are being met by existing programs both within AACP and at other organizations. The RGAC identified a set of skills that could reasonably be expected to provide the necessary foundation to successfully lead a research team and mapped these skills to the six domains of graduate education in the pharmaceutical sciences established by the 2016-2017 RGAC (Table 1). In addition, the RGAC identified competency in team science and the bench-to-bedside-to-beyond translational spectrum as being critical elements of research leadership. The universality of these skills and their value prompted the RGAC to make two related recommendations to AACP: [Table: see text] Recommendation 1: AACP should promote the development and use of strategies to ensure intentional and ongoing professional development, such as Individual Development Plans. Recommendation 2: AACP should explore collaborative research leadership development opportunities between faculty at research-intensive institutions and faculty at non-research-intensive institutions. The RGAC also examined programs available at AACP and other national organizations that could help pharmacy faculty develop foundational skills for research leadership (Table 2). The RGAC administered two surveys, one to administrators responsible for research at colleges and schools of pharmacy and one to faculty members at pharmacy schools, to gather information about training needs, programming and support available for research leadership development. Administrators and faculty agreed that research is important for career advancement for faculty, and almost all administrators reported their schools provide funds, release time and mentoring for participation in research career development. However, a lack of faculty awareness regarding programs and available support may be a barrier to participation. The RGAC therefore makes two recommendations and one suggestion related to AACP programming: [Table: see text] Recommendation 3: AACP should expand research leadership development opportunities building from existing programs such as ALFP and AACP Catalyst, with consideration placed on developing programs that promote collaborative research. Recommendation 4: AACP should collaborate with other professional organizations to expand research leadership development opportunities across the academy. Suggestion 1: Colleges and schools of pharmacy should take a proactive role in promoting and facilitating research leadership development for faculty. The RGAC separately examined the research leadership development needs of postdoctoral trainees, recognizing the distinct needs of trainees along the PhD or PhD/PharmD, PharmD/fellowship, and PharmD/residency paths. A review of organizational resources and opportunities for post-doctoral trainees available from national organizations, including AACP, was undertaken (Table 5). The RGAC sees an opportunity for AACP to foster research development of those trainees whose career track will likely be in clinical practice and makes one recommendation and one suggestion related to postdoctoral trainees: Recommendation 5: AACP should support and/or develop programs and activities for pharmacy residents seeking to transition into faculty positions to acquire the skills necessary to develop and lead research programs. Suggestion 2: Colleges and schools of pharmacy should include postdoctoral trainees with academic interests in research leadership development opportunities available to junior faculty. In addition, the RGAC proposed one policy statement that was adopted July 2019 by the AACP House of Delegates: Policy Statement: AACP recognizes the positive role that research leadership development can play in the success of early and mid-career faculty.

Breaking Down Barriers to Pharmacy Graduate Education: The Report of the 2017-2018 Research and Graduate Affairs Committee.

EXECUTIVE SUMMARY The 2017-2018 Research and Graduate Affairs Committee (RGAC) was given three charges aimed at helping academic pharmacy address barriers that must be overcome by both students and schools to attract, retain, and support the development of a diverse, well-rounded, and successful graduate student population. These charges were (1) identifying teaching methodologies, tools and opportunities that graduate programs can introduce into curriculum to overcome barriers to success of today's and tomorrow's learners; (2) developing a strategy for achieving member support of the 2016-2017 recommended graduate competencies by identifying gaps in and existing examples of courses or opportunities that achieve competency-based pharmacy graduate education; and (3) identifying potential strategies to address identified barriers to pursuing graduate education, especially among under-represented student populations. This report describes attitudes toward and opportunities related to competency-based education in graduation education in colleges and schools of pharmacy, identifies types of tools schools could use to enhance training towards the competency framework developed by the 2016-2017 RGAC, particularly with regards to the so-called power skills, and outlines a role for AACP in facilitating this training. This report also considers a number of barriers, both perceived and real, that potential students encounter when considering graduate training and suggests strategies to understand the impact of and mitigate these barriers. To strengthen competency-based graduate education, the RGAC puts forth two recommendations that AACP develop a toolkit supporting the training of power skills and that AACP should develop or curate programs or tools to support the use of individual development plans (IDPs). The RGAC also puts forth a suggestion to schools that IDPs be implemented for all students. In considering the barriers to pursuing graduate education, the Committee proposes one policy statement that AACP supports the training and development of an increasingly diverse population of researchers at pharmacy schools through active efforts to promote M.S. and Ph.D. education along with Pharm.D. education. Additionally, the Committee provides recommendations that AACP should expand its efforts in career tracking of graduate students to include collection and/or analysis of data that could inform the Academy's understanding of barriers to pursuing graduate education in pharmacy schools, the AACP Office of Institutional Research and Effectiveness should expand upon graduate program data described in the annual Profile of Pharmacy Students report, and finally that AACP should include graduate programs in efforts to increase diversity of students at pharmacy schools.

Inhibition of phosphodiesterase 2 reverses gp91phox oxidase-mediated depression- and anxiety-like behavior.

Phosphodiesterase 2 (PDE2) plays an important role in treatment of stress-related depression through regulation of antioxidant defense and neuroprotective mechanisms. However, the causal relationship between PDE2 and the prevalence of depression and anxiety upon exposure to oxidative stress has not been investigated. The present study examined whether the effects of PDE2 inhibition on oxidative stress were directly involved in reduced ROS by regulating NADPH subunits gp91phox oxidase. The results suggested that the PDE2 inhibitor Bay 60-7550 reversed oxidative stress-induced behavioral signature, i.e. depression and anxiety. Pretreatment with the oxidizing agent DTNB completely blocked, while the reducing agent DTT and the NADPH oxidase inhibitor apocynin potentiated the effects of Bay 60-7550 on behavioral abnormalities, demonstrating the relationship between PDE2 and oxidative stress. Consistently, an in vitro test revealed the positive correlation between ROS and PDE2 levels. Moreover, Bay 60-7550 decreased corticosterone-induced gp91phox expression, which is the source of ROS. The subsequent study suggested that Bay 60-7550 induced decrease in ROS and increase in cAMP/cGMP, pVASP, pCREB, and the neurotrophic factor BDNF levels, which were completely blocked by CRISPR/Cas9-mediated gp91phox overexpression and potentiated by gp91phox siRNA-based antioxidant strategies. The in vivo test in stressed mice further suggested that gp91phox overexpression completely blocked the antidepressant- and anxiolytic-like effects of Bay 60-7550, while gp91phox knockdown enhanced such effects. These results provide solid evidence that the antidepressant- and anxiolytic-like effects of Bay 60-7550 against stress are causally related to down-regulation of gp91phox and activation of the cAMP/cGMP-pVASP-CREB-BDNF signaling pathway.

Memory enhancing effects of BPN14770, an allosteric inhibitor of phosphodiesterase-4D, in wild-type and humanized mice.

Inhibitors of phosphodiesterase-4 (PDE4) have beneficial effects on memory in preclinical and clinical studies. Development of these drugs has stalled due to dose-limiting side effects of nausea and emesis. While use of subtype-selective inhibitors (i.e., for PDE4A, B, or D) could overcome this issue, conservation of the catalytic region, to which classical inhibitors bind, limits this approach. The present study examined the effects of BPN14770, an allosteric inhibitor of PDE4D, which binds to a primate-specific, N-terminal region. In mice engineered to express PDE4D with this primate-specific sequence, BPN14770 was 100-fold more potent for improving memory than in wild-type mice; meanwhile, it exhibited low potency in a mouse surrogate model for emesis. BPN14770 also antagonized the amnesic effects of scopolamine, increased cAMP signaling in brain, and increased BDNF and markers of neuronal plasticity associated with memory. These data establish a relationship between PDE4D target engagement and effects on memory for BPN14770 and suggest clinical potential for PDE4D-selective inhibitors.

Inhibition of phosphodiesterase 2 by Bay 60-7550 decreases ethanol intake and preference in mice.

RATIONALE: Alcohol use disorder (AUD) is a chronically relapsing condition, which affects nearly 11% of population worldwide. Currently, there are only three FDA-approved medications for treatment of AUD, and normally, satisfactory effects are hard to be achieved. Cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) signaling has been implicated in regulation of ethanol intake. Phosphodiesterase 2 (PDE), a dual substrate PDE that hydrolyzes both cAMP and cGMP, may play a crucial role in regulating ethanol consumption. METHODS: The present study determined whether PDE2 was involved in the regulation of ethanol intake and preference. The two-bottle choice procedure was used to examine the effects of the selective PDE2 inhibitor Bay 60-7550 on ethanol intake. The sucrose and quinine intake (taste preference) and locomotor activity (sedative effects) were also measured to exclude the false positive effects of Bay 60-7550. RESULTS: Treatment with Bay 60-7550 (1 and 3 mg/kg, i.p.) decreased ethanol intake and preference, without changing total fluid intake. In addition, Bay 60-7550 at doses that reduced ethanol intake did not affect sucrose and quinine intake and preference, which excluded the potential influence of taste preference and sedative effects on ethanol drinking behavior. Moreover, Bay 60-7550 at 3 mg/kg did not alter locomotor activity or ethanol metabolism, further supporting the specific effect of Bay 60-7550 on ethanol drinking behavior. CONCLUSIONS: The results suggest that PDE2 plays a role in the regulation of ethanol consumption and that PDE2 inhibitors may be a novel class of drugs for treatment of alcoholism.

A novel PDE9 inhibitor WYQ-C36D ameliorates corticosterone-induced neurotoxicity and depression-like behaviors by cGMP-CREB-related signaling.

BACKGROUND: Major depressive disorder (MDD) is a mental disease characterized by depressed mood, lifetime anxiety, and deficits of learning and memory. Inhibition of phosphodiesterase 9 (PDE9) has been reported to improve rodent cognitive and memory function. However, the role of PDE9 in MDD, in particular its manifestations of depression and anxiety, has not been investigated. METHODS: We examined the protective effects of WYQ-C36D (C36D), a novel PDE9 inhibitor, against corticosterone-induced cytotoxicity, pCREB/CREB and BDNF expression by cell viability, and immunoblot assays in HT-22 cells. The potential effects of C36D at doses of 0.1, 0.5, and 1 mg/kg on stress-induced depression- and anxiety-like behaviors and memory deficits were also examined in mice. RESULTS: C36D significantly protected HT-22 cells against corticosterone-induced cytotoxicity and rescued corticosterone-induced decreases in cGMP, CREB phosphorylation, and BDNF expression. All these effects were otherwise blocked by the PKG inhibitor Rp-8-Br-PET-cGMPS (Rp8). In addition, when tested in vivo in stressed mice, C36D produced antidepressant-like effects on behavior, as shown by decreased immobility time both in the forced swimming and tail suspension tests. C36D also showed anxiolytic-like and memory-enhancing effects in the elevated plus-maze and novel object recognition tests. CONCLUSION: Our results show that inhibition of PDE9 by C36D produces antidepressant- and anxiolytic-like behavioral effects and memory enhancement by activating cGMP/PKG signaling pathway. PDE9 inhibitors may have the potential as a novel class of drug to treat MDD.

The neuroprotective and antidepressant-like effects of Hcyb1, a novel selective PDE2 inhibitor.

AIMS: Depression is currently the most common mood disorder. Regulation of intracellular cyclic adenosine monophosphate (cAMP) and/or cyclic guanosine monophosphate (cGMP) signaling by phosphodiesterase (PDE) inhibition has been paid much attention for treatment of depression. This study aimed to investigate the neuroprotective effects of Hcyb1, a novel PDE2 inhibitor, in HT-22 cells and antidepressant-like effects in mouse models of depression. METHODS: Hcyb1 was synthesized and its selectivity upon PDE2 was tested. Moreover, HT-22 hippocampal cells were used to determine the effects of Hcyb1 on cell viability, cyclic nucleotide levels, and the downstream molecules related to cAMP/cGMP signaling by neurochemical, enzyme-linked immunosorbent, and immunoblot assays in vitro. The antidepressant-like effects of Hcyb1 were also determined in the forced swimming and tail suspension tests in mice. RESULTS: Hcyb1 had a highly selective inhibition of PDE2A (IC50  = 0.57 ± 0.03 µmol/L) and over 250-fold selectivity against other recombinant PDE family members. Hcyb1 at concentrations of 10-10 and 10-9  mol/L significantly increased cell viability after treatment for 24 hours. At concentrations of 10-9 ~10-7  mol/L, Hcyb1 also increased cGMP levels by 1.7~2.3 folds after 10-minute treatment. Furthermore, Hcyb1 at the concentrations of 10-9  mol/L increased both cGMP and cAMP levels 24 hours after treatment. The levels of phosphorylation of CREB and BDNF were also increased by Hcyb1 treatment in HT-22 cells for 24 hours. Finally, in the in vivo tests, Hcyb1 (0.5, 1, and 2 mg/kg, i.g.) decreased the immobility time in both forced swimming and tail suspension tests, without altering locomotor activity. CONCLUSION: These results suggest that the novel PDE2 inhibitor Hcyb1 produced neuroprotective and antidepressant-like effects most likely mediated by cAMP/cGMP-CREB-BDNF signaling.

Competency, Programming, and Emerging Innovation in Graduate Education within Schools of Pharmacy: The Report of the 2016-2017 Research and Graduate Affairs Committee.

Graduate education in the pharmaceutical sciences is a cornerstone of research within pharmacy schools. Pharmaceutical scientists are critical contributors to addressing the challenges of new drug discovery, delivery, and optimal care in order to ensure improved therapeutic outcomes in populations of patients. The American Association of Colleges of Pharmacy (AACP) charged the 2016-2017 Research and Graduate Affairs Committee (RGAC) to define the competencies necessary for graduate education in the pharmaceutical sciences (Charge 1), recommend collaborative curricular development across schools of pharmacy (Charge 2), recommend AACP programing for graduate education (Charge 3), and provide guidance on emerging areas for innovation in graduate education (Charge 4). With respect to Charges 1 and 2, the RGAC committee developed six domains of core competencies for graduate education in the pharmaceutical sciences as well as recommendations for shared programming. For Charge 3, the committee made 3 specific programming recommendations that include AACP sponsored regional research symposia, a professional development forum at the AACP INterim Meeting, and the addition of a graduate research and education poster session at the AACP Annual Meeting. For Charge 4, the committee recommended that AACP develop a standing committee of graduate program deans and directors to provide guidance to member schools in support of graduate program representation at AACP meetings, develop skills for interprofessional teamwork and augment research through integration of Pharm.D., Ph.D., postdoctoral associates, resident, and fellow experiences. Two proposed policy statements by the committee are that AACP believes core competencies are essential components of graduate education and AACP supports the inclusion of research and graduate education focuses in its portfolio of meetings and programs.

The Role of Phosphodiesterase-2 in Psychiatric and Neurodegenerative Disorders.

Cyclic nucleotide PDEs are a super-family of enzymes responsible for regulating intracellular levels of the second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Through their catalysis, PDEs are able to exert tight regulation over these important intracellular signaling cascades. Previously, PDEs have been implicated in learning and memory, as well as in mood disorders, such as anxiety and depression. PDE2 is of special interest due to its high level of expression in the forebrain, specifically in the isocortex, entorhinal cortex, striatum, hippocampus, amygdala, and medial habenula. Many of these brain regions are considered participants of the limbic system, which is known as the emotional regulatory center of the brain, and is important for modulating emotion and long-term memory. Therefore, PDE2s coincidental expression in these areas suggests an important role for PDE2 in these behaviors, and researchers are continuing to uncover the complex connections. It was shown that PDE2 inhibitors have pro-cognitive effects in tests of memory, including the object recognition test. PDE2 inhibitors are also protective against cognitive deficits in various models of cognitive impairment. Additionally, PDE2 inhibitors are protective against many different forms of stress-induced anxiety-like and depression-like behaviors. Currently, there is a great need for novel therapeutics for the treatment of mood and cognitive disorders, especially anxiety and depression, and other neurodegenerative diseases, such as Alzheimer's disease, and PDE2 is emerging as a viable target for future drug development for many of these diseases.

Alteration of Neuronal Excitability and Short-Term Synaptic Plasticity in the Prefrontal Cortex of a Mouse Model of Mental Illness.

Using a genetic mouse model that faithfully recapitulates a DISC1 genetic alteration strongly associated with schizophrenia and other psychiatric disorders, we examined the impact of this mutation within the prefrontal cortex. Although cortical layering, cytoarchitecture, and proteome were found to be largely unaffected, electrophysiological examination of the mPFC revealed both neuronal hyperexcitability and alterations in short-term synaptic plasticity consistent with enhanced neurotransmitter release. Increased excitability of layer II/III pyramidal neurons was accompanied by consistent reductions in voltage-activated potassium currents near the action potential threshold as well as by enhanced recruitment of inputs arising from superficial layers to layer V. We further observed reductions in both the paired-pulse ratios and the enhanced short-term depression of layer V synapses arising from superficial layers consistent with enhanced neurotransmitter release at these synapses. Recordings from layer II/III pyramidal neurons revealed action potential widening that could account for enhanced neurotransmitter release. Significantly, we found that reduced functional expression of the voltage-dependent potassium channel subunit Kv1.1 substantially contributes to both the excitability and short-term plasticity alterations that we observed. The underlying dysregulation of Kv1.1 expression was attributable to cAMP elevations in the PFC secondary to reduced phosphodiesterase 4 activity present in Disc1 deficiency and was rescued by pharmacological blockade of adenylate cyclase. Our results demonstrate a potentially devastating impact of Disc1 deficiency on neural circuit function, partly due to Kv1.1 dysregulation that leads to a dual dysfunction consisting of enhanced neuronal excitability and altered short-term synaptic plasticity.SIGNIFICANCE STATEMENT Schizophrenia is a profoundly disabling psychiatric illness with a devastating impact not only upon the afflicted but also upon their families and the broader society. Although the underlying causes of schizophrenia remain poorly understood, a growing body of studies has identified and strongly implicated various specific risk genes in schizophrenia pathogenesis. Here, using a genetic mouse model, we explored the impact of one of the most highly penetrant schizophrenia risk genes, DISC1, upon the medial prefrontal cortex, the region believed to be most prominently dysfunctional in schizophrenia. We found substantial derangements in both neuronal excitability and short-term synaptic plasticity-parameters that critically govern neural circuit information processing-suggesting that similar changes may critically, and more broadly, underlie the neural computational dysfunction prototypical of schizophrenia.

Comparison of the Pharmacological Profiles of Selective PDE4B and PDE4D Inhibitors in the Central Nervous System.

Inhibition of cyclic AMP (cAMP)-specific phosphodiesterase 4 (PDE4) has been proposed as a potential treatment for a series of neuropsychological conditions such as depression, anxiety and memory loss. However, the specific involvement of each of the PDE4 subtypes (PDE4A, 4B and 4C) in different categories of behavior has yet to be elucidated. In the present study, we compared the possible pharmacological effects of PDE4B and PDE4D selective inhibitors, A-33 and D159687, in mediating neurological function in mice. Both compounds were equally potent in stimulating cAMP signaling in the mouse hippocampal cell line HT-22 leading to an increase in CREB phosphorylation. In contrast, A-33 and D159687 displayed distinct neuropharmacological effects in mouse behavioral tests. A-33 has an antidepressant-like profile as indicated by reduced immobility time in the forced swim and tail suspension tasks, as well as reduced latency to feed in the novelty suppressed feeding test. D159687, on the other hand, had a procognitive profile as it improved memory in the novel object recognition test but had no antidepressant or anxiolytic benefit. The present data suggests that inhibitors targeting specific subtypes of PDE4 may exhibit differential pharmacological effects and aid a more efficient pharmacotherapy towards neuropsychological conditions.