"When Will All of This End?": A 65-Year-Old Man With Amyotrophic Lateral Sclerosis and Psychiatric Distress.

Patients with amyotrophic lateral sclerosis (ALS) are impacted both physically and psychiatrically during their illness. Emotional distress (ie, anxiety, depression, stress) is common in patients diagnosed with ALS, as prognosis is poor and there are very few effective treatments. The progression of symptoms is unpredictable, and all cases are terminal. Neuropsychiatric symptoms are also increasingly recognized as part of ALS symptomatology. There are currently no empirically supported interventions or best practices for adjustment to ALS. This case presents both the psychological and pharmacologic aspects of caring for a patient with ALS. Psychotherapy utilized a cognitive behavioral therapy-informed approach, and pharmacotherapy was tailored to the specific needs of the patient. We explore how these approaches impacted our patient, as well as how ALS-specific challenges presented throughout the course of treatment.

Resilient together-ALS: leveraging the NDD transdiagnostic framework to develop an early dyadic intervention for people with amyotrophic lateral sclerosis and their informal care-partners.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive weakness and eventual death, usually within 3-5 years. An ALS diagnosis is associated with substantial emotional distress for both the affected person and their family care-partners which impairs the ability to engage in important conversations about long term care planning, negatively impacts ALS symptoms for the patient, and quality of life for both patient and care-partner. Here we 1) discuss published works identified by the authors about psychosocial interventions for the ALS population, 2) identify a lack of early, dyadic interventions to support psychosocial needs of people with ALS and care-partners; 3) describe the Neurodegenerative Diseases (NDD) framework for early dyadic intervention development and 4) propose an adaptation of an evidence-based early dyadic psychosocial intervention, Recovering Together, for the unique needs of people with ALS and their care-partners (Resilient Together-ALS; RT-ALS) using the NDD framework. Future work will use stakeholder feedback to optimize the intervention for subsequent efficacy testing.

REL-1017 (Esmethadone) as Adjunctive Treatment in Patients With Major Depressive Disorder: A Phase 2a Randomized Double-Blind Trial.

Objective: The purpose of this study was to examine the effects of REL-1017 (esmethadone), a novel N-methyl-d-aspartate receptor (NMDAR) channel blocker, in patients with major depressive disorder who failed to benefit from one to three standard antidepressant treatments in their current major depressive episode. Methods: A 7-day phase 2 multicenter randomized double-blind placebo-controlled trial, comprising three arms, was conducted to assess the safety, tolerability, pharmacokinetics, and efficacy of two dosages of REL-1017 (25 mg or 50 mg orally once a day). Patients were randomly assigned in a 1:1:1 ratio to placebo (N=22), REL-1017 25 mg/day (N=19), or REL-1017 50 mg/day (N=21). Safety scales included the 4-item Positive Symptom Rating Scale for psychotomimetic symptoms, the Clinician-Administered Dissociative States Scale for dissociative symptoms, the Clinical Opiate Withdrawal Scale for withdrawal signs and symptoms, and the Columbia-Suicide Severity Rating Scale for suicidality. The primary efficacy endpoint was the Montgomery-Åsberg Depression Scale (MADRS) score. All 62 randomly assigned patients were included in the full analysis set population analysis. Results: Patients experienced mild or moderate transient adverse events and no evidence of dissociative or psychotomimetic effects, opioid effects, or withdrawal signs and symptoms. The improvement in MADRS score shown on day 4 in both of the REL-1017 dosage groups was sustained through day 7 (last dose) and day 14 (7 days after the last dose), with effect sizes from 0.7 to 1.0. Conclusions: This trial showed favorable safety, tolerability, and pharmacokinetic profiles and suggests that REL-1017 may have rapid and sustained antidepressant effects compared with placebo in patients with inadequate responses to antidepressant treatments. These results will need confirmation in larger and longer trials.

When real life conditions do not follow textbook diagnosis: A diagnostic challenge from a neuropsychiatric clinic.

We present the case of a 61-year-old retired catholic priest, who was adopted at a very young age, with psychiatric history of anxiety and depression presenting for evaluation of at least 4 year memory loss and word finding difficulties. Over the preceding couple of years his cognitive functions had rapidly declined. As a result, he became dependent on his elderly parents for most of his instrumental activities of daily living including administration of medication, financial management, and driving. He continues to be independent in his personal care. His presentation offered diagnostic challenges due to the interplay of anxiety and cognitive disorders involving both memory and language domains. In addition, he resisted to repeat formal neuropsychological evaluation. At the bedside, his poor effort on testing was often blamed on his severe anxiety confounding the clinical picture. Lack of knowledge of his family history and his childhood development, and unclear premorbid functioning complicated the diagnostic formulation. A differential diagnosis ranging from possible functional cognitive disorder to neurodevelopmental disorder and neurodegenerative disorders will be discussed.

The N-methyl-D-aspartate receptor antagonist d-methadone acutely improves depressive-like behavior in the forced swim test performance of rats.

d-Methadone (dextromethadone) is a noncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonist that binds to the dizocilpine (MK-801)-binding site of the receptor with an affinity comparable with that of well-established NMDAR antagonists. Considering the similar NMDAR activity of ketamine and d-methadone and the rapid and robust antidepressant effects of ketamine, we compared these 2 drugs in the forced swim test in Sprague-Dawley rats, which has been shown to be predictive of antidepressant activity for drugs with different mechanisms of action including ketamine. This study evaluated the antidepressant-like effect of d-methadone (10, 20, and 40 mg/kg) in the forced swim test 24 hr following a single-dose administration. At all doses, d-methadone significantly (p < .05) decreased immobility of rats compared with vehicle, suggesting antidepressant-like activity. In addition, the effect of d-methadone (20 and 40 mg/kg) on immobility was greater than the effect seen with ketamine (10 mg/kg). Importantly, there were no changes in locomotor activity of rats that could have confounded the immobility effects at all doses (10, 20, and 40 mg/kg) of d-methadone. This is the first demonstration that the NMDAR antagonist, d-methadone, exerts antidepressant-like activity in a preclinical animal model and that its efficacy is similar to or even stronger than that of ketamine, an antidepressant that demonstrates a rapid onset activity and robust efficacy in patients with treatment-resistant depression. d-Methadone is currently being evaluated in a Phase 2a clinical study for patients with treatment-resistant depression and could potentially represent a new effective antidepressant in the growing class of NMDAR antagonists. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

N-Methyl-D-aspartate receptor antagonist d-methadone produces rapid, mTORC1-dependent antidepressant effects.

Currently available antidepressants have a delayed onset and limited efficacy, highlighting the need for new, rapid and more efficacious agents. Ketamine, an NMDA receptor antagonist, has emerged as a new rapid-acting antidepressant, effective even in treatment resistant patients. However, ketamine induces undesired psychotomimetic and dissociative side effects that limit its clinical use. The d-stereoisomer of methadone (dextromethadone; REL-1017) is a noncompetitive NMDA receptor antagonist with an apparently favorable safety and tolerability profile. The current study examined the rapid and sustained antidepressant actions of d-methadone in several behavioral paradigms, as well as on mTORC1 signaling and synaptic changes in the medial prefrontal cortex (mPFC). A single dose of d-methadone promoted rapid and sustained antidepressant responses in the novelty-suppressed feeding test (NSFT), a measure of anxiety, and in the female urine sniffing test (FUST), a measure of motivation and reward. D-methadone also produced a rapid reversal of the sucrose preference deficit, a measure of anhedonia, in rats exposed to chronic unpredictable stress. D-methadone increased phospho-p70S6 kinase, a downstream target of mTORC1 in the mPFC, and intra-mPFC infusion of the selective mTORC1 inhibitor rapamycin blocked the antidepressant actions of d-methadone in the FUST and NSFT. D-methadone administration also increased levels of the synaptic proteins, PSD95, GluA1, and Synapsin 1 and enhanced synaptic function in the mPFC. Studies in primary cortical cultures show that d-methadone also increases BDNF release, as well as phospho-p70S6 kinase. These findings indicate that d-methadone induces rapid antidepressant actions through mTORC1-mediated synaptic plasticity in the mPFC similar to ketamine.

Characterization of the Safety and Pharmacokinetic Profile of D-Methadone, a Novel N-Methyl-D-Aspartate Receptor Antagonist in Healthy, Opioid-Naive Subjects: Results of Two Phase 1 Studies.

PURPOSE/BACKGROUND: N-methyl-D-aspartate (NMDA) receptor (NMDAR) antagonists are potential agents for the treatment of several central nervous system disorders including major depressive disorder. Racemic methadone, L-methadone, and D-methadone all bind the NMDAR with an affinity similar to that of established NMDAR antagonists, whereas only L-methadone and racemic methadone bind to opioid receptors with high affinity. Therefore, D-methadone is expected to have no clinically significant opioid effects at therapeutic doses mediated by its NMDAR antagonism. METHODS: We conducted 2 phase 1, double-blind, randomized, placebo-controlled, single- and multiple-ascending-dose studies to investigate the safety and tolerability of oral D-methadone and to characterize its pharmacokinetic profile in healthy opioid-naive volunteers. RESULTS: D-Methadone exhibits linear pharmacokinetics with dose proportionality for most single-dose and multiple-dose parameters. Single doses up to 150 mg and daily doses up to 75 mg for 10 days were well tolerated with mostly mild treatment-emergent adverse events and no severe or serious adverse events. Dose-related somnolence and nausea occurred and were mostly present at the higher dose level. There was no evidence of respiratory depression, dissociative and psychotomimetic effects, or withdrawal signs and symptoms upon abrupt discontinuation. An overall dose-response effect was observed, with higher doses resulting in larger QTcF (QT interval corrected using Fridericia formula) changes from baseline, but none of the changes were considered clinically significant by the investigators. Mild, dose-dependent pupillary constriction of brief duration occurred particularly at the 60-mg dose or above in the single-ascending-dose study and at the dose of 75 mg in the multiple-ascending-dose study. No detectable conversion of D-methadone to L-methadone occurred in vivo. CONCLUSIONS: These results support the safety and continued clinical development of D-methadone as an NMDAR antagonist for the treatment of depression and other central nervous system disorders.

In vivo measurement of PDE10A enzyme occupancy by positron emission tomography (PET) following single oral dose administration of PF-02545920 in healthy male subjects.

Phosphodiesterase 10A (PDE10A) is an enzyme highly enriched in the striatal medium spiny neurons. It is involved in the regulation of cytoplasmic levels of cAMP and cGMP and signaling within the basal ganglia. This study with PDE10A radioligand [18F]MNI-659 was designed to measure the enzyme occupancy of PF-02545920 in 8 healthy male volunteers (48 ± 4 years) after a single oral dose (10 mg or 20 mg) and to evaluate safety and tolerability. Arterial blood sampling was performed to obtain a metabolite-corrected plasma input function for the quantification of [18F]MNI-659 binding to PDE10A. The occupancy of PF-02545920 was calculated with two different methods: In Method 1, [18F]MNI-659 enzyme occupancy was calculated from the estimates of binding potential, using the cerebellum as a reference region; in Method 2, occupancy was estimated from the slope of the revised Lassen's plot. Serum concentrations of PF-02545920 were measured to determine the relationship between concentration and occupancy. Based on Method 1, striatal PDE10A occupancy increased with increasing PF-02545920 dose: 14-27% at 10 mg dose (N = 4) and 45-63% at 20 mg dose (N = 3). Comparable occupancies were observed using Lassen's plot Method 2: 10 mg: 14-37%; 20 mg: 46-55%. The relationship between exposure and occupancy was best described using an Emax model. The serum concentration associated with 50% occupancy was estimated to be 93.2 ng/mL. Single oral doses of 10 mg or 20 mg of PF-02545920 were safe and well tolerated in healthy male volunteers [NCT# 01918202].

Challenges, solutions, and recommendations for Alzheimer's disease combination therapy.

Given the complex neuropathology Alzheimer's disease (AD), combination therapy may be necessary for effective treatment. However, scientific, pragmatic, regulatory, and business challenges need to be addressed before combination therapy for AD can become a reality. Leaders from academia and industry, along with a former member of the Food and Drug Administration and the Alzheimer's Association, have explored these challenges and here propose a strategy to facilitate proof-of-concept combination therapy trials in the near future. First, a more integrated understanding of the complex pathophysiology and progression of AD is needed to identify the appropriate pathways and the disease stage to target. Once drug candidates are identified, novel clinical trial designs and selection of appropriate outcome assessments will be needed to enable definition and evaluation of the appropriate dose and dosing regimen and determination of efficacy. Success in addressing this urgent problem will only be achieved through collaboration among multiple stakeholders.

Efficacy and safety of a form of cranial electrical stimulation (CES) as an add-on intervention for treatment-resistant major depressive disorder: A three week double blind pilot study.

We examined efficacy and safety of one specific cranial electrical stimulator (CES) device at a fixed setting in subjects with treatment-resistant major depressive disorder (MDD). Thirty subjects (57% female, mean age 48.1 ± 12.3 years) with MDD and inadequate response to standard antidepressants were randomized to 3 weeks of treatment with CES (15/500/15,000 Hz, symmetrical rectangular biphasic current of 1-4 mAmp, 40 V) or sham CES (device off) for 20 min, 5 days per week. The primary outcome measure was improvement in the 17-item Hamilton Depression Rating Scale (HAM-D-17). Adverse effects (AEs) were assessed using the Patient Related Inventory of Side Effects (PRISE). Completion rates were 88% for CES, 100% for sham. Both treatment groups demonstrated improvement of about 3-5 points in HAM-D-17 scores (p < 0.05 for both), and no significant differences were observed between groups. Remission rates were 12% for CES, and 15% for sham, a nonsignificant difference. CES was deemed safe, with good tolerability; poor concentration and malaise were the only distressing AEs that differed significantly between CES and sham (p = 0.019 and p = 0.043, respectively). Limitations include a small sample and lack of an active comparator therapy. Although both treatment groups improved significantly, this CES at the setting chosen did not separate from sham in this sample. Thus we cannot rule out that the benefit from this setting used in this particular form of CES was due to placebo effects. Since this form of CES has other settings, future studies should test these settings and compare it against other CES devices. Clinicaltrials.gov ID: NCT01325532.

S-adenosyl methionine (SAMe) versus escitalopram and placebo in major depression RCT: efficacy and effects of histamine and carnitine as moderators of response.

OBJECTIVE: To assess the antidepressant efficacy of S-adenosyl methionine (SAMe), a naturally occurring methyl donor, versus the selective serotonin reuptake inhibitor (SSRI) escitalopram and a placebo control; and to determine whether serum histamine or carnitine levels modified treatment response. METHODS: We examined a subsample (n=144) from one site of a two-site study of adults with diagnosed Major Depressive Disorder (MDD), recruited from 4/13/05 to 12/22/09, who consented to the additional blood draw for serum histamine and carnitine levels. After washout, eligible subjects were randomized to SAMe (1600-3200mg/daily), escitalopram (10-20mg/daily), or matching placebo for 12 weeks of double-blind treatment (titration at week 6 in non-response). RESULTS: On the primary outcome of the Hamilton Depression Rating Scale (HAMD-17), a significant difference in improvement was observed between groups from baseline to week 12 (p=0.039). The effect size from baseline to endpoint was moderate to large for SAMe versus placebo (d=0.74). SAMe was superior to placebo from week 1, and to escitalopram during weeks 2, 4, and 6. No significant effect was found between escitalopram and placebo or SAMe. Response rates (HAMD-17≥50% reduction) at endpoint were 45%, 31%, and 26% for SAMe, escitalopram, and placebo, respectively; while remission rates (HAM-D≤7) were 34% for SAMe (p=0.003), 23% for escitalopram (p=0.023), and 6% for placebo. No correlation between baseline histamine level and reduction of HAMD-17 score was found for either the SAMe or escitalopram groups. Baseline carnitine levels were also not found to moderate response to either treatment. LIMITATIONS: While SAMe appears to be an effective antidepressant agent, the overall findings from the parent study (which showed no significant difference between groups due to site differences) must be taken into consideration. CONCLUSIONS: These preliminary results provide encouraging evidence for the use of SAMe in the treatment of MDD. Histamine and carnitine serum level may not necessarily moderate response to SAMe.

Relationship between sleep disturbance and depression, anxiety, and functioning in college students.

BACKGROUND: Sleep disturbance (SD) has complex associations with depression, both preceding and following the onset and recurrence of depression. We hypothesized that students with depressive symptoms with SD would demonstrate a greater burden of comorbid psychiatric symptoms and functional impairment compared to students with depressive symptoms without SD. METHODS: During a mental health screening, 287 undergraduate students endorsed symptoms of depression (Beck Depression Inventory [BDI] ≥ 13) and filled out the following self-report measures: demographic questionnaire, BDI, Anxiety Symptom Questionnaire-intensity and frequency (ASQ), Beck Hopelessness Scale (BHS), Beck Anxiety Inventory (BAI), Quality of Life Enjoyment and Satisfaction Questionnaire (QLESQ), and the Massachusetts General Hospital Cognitive and Physical Functioning Questionnaire (CPFQ). SD was measured using the BDI sleep item #16 dichotomized (score 0: no SD; or score > 0: some SD). RESULTS: Students with depressive symptoms and SD (n = 220), compared to those without SD (n = 67), endorsed significantly more intense and frequent anxiety and poorer cognitive and physical functioning. Students with depressive symptoms with and without SD did not significantly differ in depressive severity, hopelessness, or quality of life. CONCLUSIONS: College students with depressive symptoms with SD may experience a greater burden of comorbid anxiety symptoms and hyperarousal, and may have impairments in functioning, compared to students with depressive symptoms without SD. These findings require replication.

The effect of sildenafil on quality of life.

BACKGROUND: Antidepressant-induced sexual dysfunction affects approximately 50% of patients taking antidepressants. Previous research has explored sildenafil's effectiveness in treating various forms of erectile dysfunction, but there is no research supporting sildenafil's use for improving the quality of life for patients with sexual dysfunction linked to antidepressant use. The authors of this article aimed to assess the improvements in quality of life in patients taking sildenafil to treat antidepressant-induced sexual dysfunction. METHODS: One hundred and two out of 2,239 male and female patients in the follow-up phase of the Sequenced Treatment Alternatives to Relieve Depression antidepressant trials who complained of sexual dysfunction were given sildenafil, 50 to 100 mg, as needed. After 12 months, we measured patients' change in libido, sexual drive, family relationships, overall well-being, satisfaction with treatment, and overall contentment with items on the 17-item Hamilton Depression Rating Scale, Quality of Life Enjoyment and Satisfaction Questionnaire, 30-item Inventory of Depressive Symptoms, and 12-item Short Form Health Survey. RESULTS: There was a significant association between sildenafil use and improvement in libido and sexual drive by month 6. There was no significant improvement in the quality-of-life scores we examined, but treatment satisfaction and overall contentment increased over time. CONCLUSIONS: Despite no direct association with sildenafil use and quality-of-life scores, sildenafil may be a beneficial treatment for antidepressant-induced sexual dysfunction. A double-blind, placebo-controlled study of sildenafil in antidepressant-induced sexual dysfunction is needed to further explore its potential benefits.

A 12-week, randomized, double-blind, placebo-controlled, sequential parallel comparison trial of ziprasidone as monotherapy for major depressive disorder.

OBJECTIVE: To study ziprasidone monotherapy for major depressive disorder, defined according to the DSM-IV. METHOD: One hundred twenty outpatients were enrolled between June 2008 and September 2010 in a 12-week study that was divided into two 6-week periods according to the sequential parallel comparison design. Patients were randomized in a 2:3:3 fashion to receive ziprasidone for 12 weeks, placebo for 6 weeks followed by ziprasidone for 6 weeks, or placebo for 12 weeks. The main outcome measure was the 17-item Hamilton Depression Rating Scale (HDRS-17), with the Quick Inventory of Depressive Symptomatology, Self-Rated (QIDS-SR), and Clinical Global Impressions-Severity of Illness scale (CGI-S) serving as the study secondary measures. RESULTS: One hundred twenty patients (53 women [44.1%]) were randomized to treatment. The mean (SD) age of these patients was 43.7 (11.0) years. Mean (SD) baseline HDRS-17, CGI-S, and QIDS-SR scores were 19.9 (5.0), 4.3 (0.6), and 15.6 (3.0), respectively. There was no statistically significant difference in reduction of depressive symptoms, response rates, or remission rates between ziprasidone- or placebo-treated patients. This was true for both the study primary as well as secondary outcome scales. CONCLUSIONS: In conclusion, treatment with ziprasidone monotherapy was not associated with any statistically significant advantage in efficacy over placebo. Although studies involving larger sample size would be required to have adequate statistical power to detect treatment differences smaller than 2.5 points on the HDRS-17, such differences would be of questionable clinical relevance. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00555997.

Functional alterations in memory networks in early Alzheimer's disease.

The hallmark clinical symptom of early Alzheimer's disease (AD) is episodic memory impairment. Recent functional imaging studies suggest that memory function is subserved by a set of distributed networks, which include both the medial temporal lobe (MTL) system and the set of cortical regions collectively referred to as the default network. Specific regions of the default network, in particular, the posteromedial cortices, including the precuneus and posterior cingulate, are selectively vulnerable to early amyloid deposition in AD. These regions are also thought to play a key role in both memory encoding and retrieval, and are strongly functionally connected to the MTL. Multiple functional magnetic resonance imaging (fMRI) studies during memory tasks have revealed alterations in these networks in patients with clinical AD. Similar functional abnormalities have been detected in subjects at-risk for AD, including those with genetic risk and older individuals with mild cognitive impairment. Recently, we and other groups have found evidence of functional alterations in these memory networks even among cognitively intact older individuals with occult amyloid pathology, detected by PET amyloid imaging. Taken together, these findings suggest that the pathophysiological process of AD exerts specific deleterious effects on these distributed memory circuits, even prior to clinical manifestations of significant memory impairment. Interestingly, some of the functional alterations seen in prodromal AD subjects have taken the form of increases in activity relative to baseline, rather than a loss of activity. It remains unclear whether these increases in fMRI activity may be compensatory to maintain memory performance in the setting of early AD pathology or instead, represent evidence of excitotoxicity and impending neuronal failure. Recent studies have also revealed disruption of the intrinsic connectivity of these networks observable even during the resting state in early AD and asymptomatic individuals with high amyloid burden. Research is ongoing to determine if these early network alterations will serve as sensitive predictors of clinical decline, and eventually, as markers of pharmacological response to potential disease-modifying treatments for AD.

Protection against beta-amyloid induced abnormal synaptic function and cell death by Ginkgolide J.

A new Ginkgo biloba extract P8A (TTL), 70% enriched with terpene trilactones, prevents A beta(1-42) induced inhibition of long-term potentiation in the CA1 region of mouse hippocampal slices. This neuroprotective effect is attributed in large part to ginkgolide J that completely replicates the effect of the extract. Ginkgolide J is also capable of inhibiting cell death of rodent hippocampal neurons caused by A beta(1-42). This beneficial and multi-faceted mode of action of the ginkgolide makes it a new and promising lead in designing therapies against Alzheimer's disease.

Amyloid beta peptide adversely affects spine number and motility in hippocampal neurons.

Elevated levels of amyloid-beta peptide (Abeta) are found in Down's syndrome patients and alter synaptic function during the early stages of Alzheimer's disease. Dendritic spines, sites of most excitatory synaptic contacts, are considered to be an important locus for encoding synaptic plasticity. We used time-lapse two-photon imaging of hippocampal pyramidal neurons in organotypic slices to study the effects of Abeta on the development of dendritic spines. We report that exposure of hippocampal neurons to sub-lethal levels of Abeta decreased spine density, increased spine length and subdued spine motility. The effect of Abeta on spine density was reversible. Moreover, Abeta's effect on dendritic spine density was blocked by rolipram, a phosphodiesterase type IV inhibitor, suggesting the involvement of a cAMP dependent pathway. These findings raise the possibility that Abeta-induced spine alterations could underlie the cognitive defects in Alzheimer's disease and Down syndrome.

Ubiquitin hydrolase Uch-L1 rescues beta-amyloid-induced decreases in synaptic function and contextual memory.

The neuronal ubiquitin/proteasomal pathway has been implicated in the pathogenesis of Alzheimer's disease (AD). We now show that a component of the pathway, ubiquitin C-terminal hydrolase L1 (Uch-L1), is required for normal synaptic and cognitive function. Transduction of Uch-L1 protein fused to the transduction domain of HIV-transactivator protein (TAT) restores normal enzymatic activity and synaptic function both in hippocampal slices treated with oligomeric Abeta and in the APP/PS1 mouse model of AD. Moreover, intraperitoneal injections with the fusion protein improve the retention of contextual learning in APP/PS1 mice over time. The beneficial effect of the Uch-L1 fusion protein is associated with restoration of normal levels of the PKA-regulatory subunit IIalpha, PKA activity, and CREB phosphorylation.

Amyloid-beta peptide inhibits activation of the nitric oxide/cGMP/cAMP-responsive element-binding protein pathway during hippocampal synaptic plasticity.

Amyloid-beta (Abeta), a peptide thought to play a crucial role in Alzheimer's disease (AD), has many targets that, in turn, activate different second-messenger cascades. Interestingly, Abeta has been found to markedly impair hippocampal long-term potentiation (LTP). To identify a new pathway that might be responsible for such impairment, we analyzed the role of the nitric oxide (NO)/soluble guanylyl cyclase (sGC)/cGMP/cGMP-dependent protein kinase (cGK)/cAMP-responsive element-binding protein (CREB) cascade because of its involvement in LTP. The use of the NO donor 2-(N,N-dethylamino)-diazenolate-2-oxide diethylammonium salt (DEA/NO), the sGC stimulator 3-(4-amino-5-cyclopropylpyrimidine-2-yl)-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine, or the cGMP-analogs 8-bromo-cGMP and 8-(4-chlorophenylthio)-cGMP reversed the Abeta-induced impairment of CA1-LTP through cGK activation. Furthermore, these compounds reestablished the enhancement of CREB phosphorylation occurring during LTP in slices exposed to Abeta. We also found that Abeta blocks the increase in cGMP immunoreactivity occurring immediately after LTP and that DEA/NO counteracts the effect of Abeta. These results strongly suggest that, when modulating hippocampal synaptic plasticity, Abeta downregulates the NO/cGMP/cGK/CREB pathway; thus, enhancement of the NO/cGMP signaling may provide a novel approach to the treatment of AD and other neurodegenerative diseases with elevated production of Abeta.