In vivo and in vitro ketamine exposure exhibits a dose-dependent induction of activity-dependent neuroprotective protein in rat neurons

Pre-adolescence repeat exposure to sub-anesthetic doses of ketamine induces long-lasting behaviors and cognition impairment in male and female rat adults

In pre-adolescence, repeated anesthesia may be required for therapeutic interventions. Adult cognitive and neurobehavioral problems may result from preadolescent exposure to anesthetics. This study examined the long-term morphological and functional effects of repeated sub-anesthetic doses of ketamine exposure on male and female rat adults during pre-adolescence. Weaned 48 pre-adolescent rats from eight mothers and were randomly divided into four equal groups: control group and the ketamine group of males and females (20 mg/kg daily for 14 days); then animals received care for 20-30 days. Repeated exposure to sub-anesthetic doses of ketamine on cognitive functions was assayed using Social discrimination and novel object tests. Besides, an elevated plus maze and fear conditioning apparatus were utilized to determine exploratory and anxiety-like behavior in adults. Toluidine blue stain was used to evaluate the number of dead neurons in the hippocampus, and the effects of ketamine on synaptic plasticity were compared in the perforant pathway of the CA1 of the hippocampus. Our study indicates that repeated exposure to sub-anesthetic doses of ketamine during pre-adolescence can result in neurobehavioral impairment in male and female rat adulthood but does not affect anxiety-like behavior. We found a significant quantifiable increase in dark neurons. Recorded electrophysiologically, repeat sub-anesthetic doses of ketamine resulted in hampering long-term potentiation and pair pulse in male adult animals. Our results showed that repeated exposure to sub-anesthetic doses of ketamine during pre-adolescence can induce hippocampus and neuroplasticity changes later in adulthood. This study opens up a new line of inquiry into potential adverse outcomes of repeated anesthesia exposure in pre-adolescent rats.

NAP (Davunetide): The Neuroprotective ADNP Drug Candidate Penetrates Cell Nuclei Explaining Pleiotropic Mechanisms

(1) Background: Recently, we showed aberrant nuclear/cytoplasmic boundaries/activity-dependent neuroprotective protein (ADNP) distribution in ADNP-mutated cells. This malformation was corrected upon neuronal differentiation by the ADNP-derived fragment drug candidate NAP (davunetide). Here, we investigated the mechanism of NAP nuclear protection. (2) Methods: CRISPR/Cas9 DNA-editing established N1E-115 neuroblastoma cell lines that express two different green fluorescent proteins (GFPs)-labeled mutated ADNP variants (p.Tyr718* and p.Ser403*). Cells were exposed to NAP conjugated to Cy5, followed by live imaging. Cells were further characterized using quantitative morphology/immunocytochemistry/RNA and protein quantifications. (3) Results: NAP rapidly distributed in the cytoplasm and was also seen in the nucleus. Furthermore, reduced microtubule content was observed in the ADNP-mutated cell lines. In parallel, disrupting microtubules by zinc or nocodazole intoxication mimicked ADNP mutation phenotypes and resulted in aberrant nuclear-cytoplasmic boundaries, which were rapidly corrected by NAP treatment. No NAP effects were noted on ADNP levels. Ketamine, used as a control, was ineffective, but both NAP and ketamine exhibited direct interactions with ADNP, as observed via in silico docking. (4) Conclusions: Through a microtubule-linked mechanism, NAP rapidly localized to the cytoplasmic and nuclear compartments, ameliorating mutated ADNP-related deficiencies. These novel findings explain previously published gene expression results and broaden NAP (davunetide) utilization in research and clinical development.

Chromatin remodeler Activity-Dependent Neuroprotective Protein (ADNP) contributes to syndromic autism

BACKGROUND

Individuals affected with autism often suffer additional co-morbidities such as intellectual disability. The genes contributing to autism cluster on a relatively limited number of cellular pathways, including chromatin remodeling. However, limited information is available on how mutations in single genes can result in such pleiotropic clinical features in affected individuals. In this review, we summarize available information on one of the most frequently mutated genes in syndromic autism the Activity-Dependent Neuroprotective Protein (ADNP).

RESULTS

Heterozygous and predicted loss-of-function ADNP mutations in individuals inevitably result in the clinical presentation with the Helsmoortel-Van der Aa syndrome, a frequent form of syndromic autism. ADNP, a zinc finger DNA-binding protein has a role in chromatin remodeling: The protein is associated with the pericentromeric protein HP1, the SWI/SNF core complex protein BRG1, and other members of this chromatin remodeling complex and, in murine stem cells, with the chromodomain helicase CHD4 in a ChAHP complex. ADNP has recently been shown to possess R-loop processing activity. In addition, many additional functions, for instance, in association with cytoskeletal proteins have been linked to ADNP.

CONCLUSIONS

We here present an integrated evaluation of all current aspects of gene function and evaluate how abnormalities in chromatin remodeling might relate to the pleiotropic clinical presentation in individual"s" with Helsmoortel-Van der Aa syndrome.

An open-label study evaluating the safety, behavioral, and electrophysiological outcomes of low-dose ketamine in children with ADNP syndrome

Activity-dependent neuroprotective protein (ADNP) syndrome is a rare genetic condition associated with intellectual disability and autism spectrum disorder. Preclinical evidence suggests that low-dose ketamine may induce expression of ADNP and that neuroprotective effects of ketamine may be mediated by ADNP. The goal of the proposed research was to evaluate the safety, tolerability, and behavioral outcomes of low-dose ketamine in children with ADNP syndrome. We also sought to explore the feasibility of using electrophysiological markers of auditory steady-state response and computerized eye tracking to assess biomarker sensitivity to treatment. This study utilized a single-dose (0.5 mg/kg), open-label design, with ketamine infused intravenously over 40 min. Ten children with ADNP syndrome ages 6 to 12 years were enrolled. Ketamine was generally well tolerated, and there were no serious adverse events. The most common adverse events were elation/silliness (50%), fatigue (40%), and increased aggression (40%). Using parent-report instruments to assess treatment effects, ketamine was associated with nominally significant improvement in a wide array of domains, including social behavior, attention deficit and hyperactivity, restricted and repetitive behaviors, and sensory sensitivities, a week after administration. Results derived from clinician-rated assessments aligned with findings from the parent reports. Overall, nominal improvement was evident based on the Clinical Global Impressions - Improvement scale, in addition to clinician-based scales reflecting key domains of social communication, attention deficit and hyperactivity, restricted and repetitive behaviors, speech, thinking, and learning, activities of daily living, and sensory sensitivities. Results also highlight the potential utility of electrophysiological measurement of auditory steady-state response and eye-tracking to index change with ketamine treatment. Findings are intended to be hypothesis generating and provide preliminary support for the safety and efficacy of ketamine in ADNP syndrome in addition to identifying useful endpoints for a ketamine clinical development program. However, results must be interpreted with caution given limitations of this study, most importantly the small sample size and absence of a placebo-control group.

Vineland Adaptive Behavior Scale in a Cohort of Four ADNP Syndrome Patients Implicates Age-Dependent Developmental Delays with Increased Impact of Activities of Daily Living

Activity-dependent neuroprotective protein (ADNP) is one of the lead genes in autism spectrum disorder/intellectual disability. Heterozygous, de novo ADNP mutations cause the ADNP syndrome. Here, to evaluate natural history of the syndrome, mothers of two ADNP syndrome boys aged 6 and a half and two adults aged 27 years (man and woman) were subjected to Vineland III questionnaire assessing adaptive behavior. The boys were assessed again about 2 years after the first measurements. The skill measures, presented as standard scores (SS) included domains of communication, daily living, socialization, motor skills and a sum of adaptive behavior composite. The age equivalent (AE) and growth scale values (GSV) encompassing 11 subdomains assess the age level at which the subject's raw score is found at a norm sample median and the individual temporal progression, respectively. The norm referenced standard scores age-matched, mean 100 ± 15 of the two children showed the lowest outcome in communication (SS: 20-30). Daily living skills presented SS of 50-60, with a possible potential loss of some activities as the child ages, especially in interpersonal relationships with people outside of the immediate family (boy A). In contrast, in socialization, both children were at the SS of 38, with some positive increase to SS of ~ 45 (interpersonal relations with family members and coping skills, depending on the particular individual), 2 years later. Interestingly, there was an apparent large difference in motor skills (gross and fine) at the young age, with subject B showing a relatively higher level of skills (SS: 70), decreasing to subject A level (SS: 40) 2 years later. Together, the adaptive behavior composite suggested a level of SS: 39-48 with B showing a potential increase (SS: 41-44) and A, a substantial decrease (SS: 48-39), suggesting a strong impact of daily living skills. Adults were at SS: 20, which is the lowest possible score. AE showed minor improvements for subject A and B, with all AE values being below 3 years. GSVs for subject A showed some improvement with age, especially in interpersonal, play and leisure, and gross motor subdomains. GSV for subject B showed minor improvements in the various subdomains. Notably, all subjects showed a percentile rank < 1 compared with age-matched norms except for subject B as to motor domain (2^nd percentile) at the age of 6 years. In summary, the results, especially comparing SS and AEs between childhood and adulthood, implied a continuous deterioration of activities compared to the general population, encompassing a slower developmental process coupled to possible neurodegeneration, strongly supporting a great need for disease modifying medicinal procedures.

Ketamine: Neuroprotective or Neurotoxic?

Ketamine, a non-competitive N-methyl-D-aspartate receptor (NMDAR) antagonist, has been employed clinically as an intravenous anesthetic since the 1970s. More recently, ketamine has received attention for its rapid antidepressant effects and is actively being explored as a treatment for a wide range of neuropsychiatric syndromes. In model systems, ketamine appears to display a combination of neurotoxic and neuroprotective properties that are context dependent. At anesthetic doses applied during neurodevelopmental windows, ketamine contributes to inflammation, autophagy, apoptosis, and enhances levels of reactive oxygen species. At the same time, subanesthetic dose ketamine is a powerful activator of multiple parallel neurotrophic signaling cascades with neuroprotective actions that are not always NMDAR-dependent. Here, we summarize results from an array of preclinical studies that highlight a complex landscape of intracellular signaling pathways modulated by ketamine and juxtapose the somewhat contrasting neuroprotective and neurotoxic features of this drug.

Reflections on the genetics-first approach to advancements in molecular genetic and neurobiological research on neurodevelopmental disorders

BACKGROUND

Neurodevelopmental disorders (NDDs), including autism spectrum disorder (ASD) and intellectual disability (ID), are common diagnoses with highly heterogeneous phenotypes and etiology. The genetics-first approach to research on NDDs has led to the identification of hundreds of genes conferring risk for ASD, ID, and related symptoms.

MAIN BODY

Although relatively few individuals with NDDs share likely gene-disruptive (LGD) mutations in the same gene, characterization of overlapping functions, protein networks, and temporospatial expression patterns among these genes has led to increased understanding of the neurobiological etiology of NDDs. This shift in focus away from single genes and toward broader gene-brain-behavior pathways has been accelerated by the development of publicly available transcriptomic databases, cell type-specific research methods, and sequencing of non-coding genomic regions.

CONCLUSIONS

The genetics-first approach to research on NDDs has advanced the identification of critical protein function pathways and temporospatial expression patterns, expanding the impact of this research beyond individuals with single-gene mutations to the broader population of patients with NDDs.

Effects of Ketamine on Learning and Memory in the Hippocampus of Rats through ERK, CREB, and Arc

Ketamine has become a popular recreational drug due to its neuronal anesthesia effect and low price. The process of learning and memory is part of the distinctive high-level neural activities in animals. We investigated the effects of subanesthetic and anesthetic doses of ketamine on the learning and memory-related signal transduction mechanisms. We used the Morris water maze test to execute rats' learning and memory ability and detected changes of Arc mRNA and Arc, cAMP-response element-binding protein (CREB), phospho-CREB (p-CREB), extracellular signal-regulated kinase (ERK), and phospho-ERK (p-ERK) protein expression in the hippocampus 10 min and 24 h after administration. Ten min after ketamine injection, the Arc gene and the protein expression levels increased in all groups; p-ERK only increased in the chronic subanesthetic dose group. After 24 h, the Arc gene and the protein expression levels of the subanesthetic dose group increased, but those of the chronic subanesthetic dose group and anesthetic dose group decreased. However, p-ERK increased in all groups. A chronic subanesthetic dose of ketamine could increase learning and memory ability through ERK, CREB, and Arc in a short time, and the high body temperature after the subanesthetic dose of ketamine injection was the main factor leading to changes in Arc. The subanesthetic dose of ketamine regulated learning and memory through ERK, CREB, and ARC 24 h after injection.

A Review of Nonanesthetic Uses of Ketamine

Ketamine, a nonselective NMDA receptor antagonist, is used widely in medicine as an anesthetic agent. However, ketamine's mechanisms of action lead to widespread physiological effects, some of which are now coming to the forefront of research for the treatment of diverse medical disorders. This paper aims at reviewing recent data on key nonanesthetic uses of ketamine in the current literature. MEDLINE, CINAHL, and Google Scholar databases were queried to find articles related to ketamine in the treatment of depression, pain syndromes including acute pain, chronic pain, and headache, neurologic applications including neuroprotection and seizures, and alcohol and substance use disorders. It can be concluded that ketamine has a potential role in the treatment of all of these conditions. However, research in this area is still in its early stages, and larger studies are required to evaluate ketamine's efficacy for nonanesthetic purposes in the general population.

Putative neuroprotective pharmacotherapies to target the staged progression of mental illness

AIM

Neuropsychiatric disorders including depression, bipolar and schizophrenia frequently exhibit a neuroprogressive course from prodrome to chronicity. There are a range of agents exhibiting capacity to attenuate biological mechanisms associated with neuroprogression. This review will update the evidence for putative neuroprotective agents including clinical efficacy, mechanisms of action and limitations in current assessment tools, and identify novel agents with neuroprotective potential.

METHOD

Data for this review were sourced from online databases PUBMED, Embase and Web of Science. Only data published since 2012 were included in this review, no data were excluded based on language or publication origin.

RESULTS

Each of the agents reviewed inhibit one or multiple pathways of neuroprogression including: inflammatory gene expression and cytokine release, oxidative and nitrosative stress, mitochondrial dysfunction, neurotrophin dysregulation and apoptotic signalling. Some demonstrate clinical efficacy in preventing neural damage or loss, relapse or cognitive/functional decline. Agents include: the psychotropic medications lithium, second generation antipsychotics and antidepressants; other pharmacological agents such as minocycline, aspirin, cyclooxygenase-2 inhibitors, statins, ketamine and alpha-2-delta ligands; and others such as erythropoietin, oestrogen, leptin, N-acetylcysteine, curcumin, melatonin and ebselen.

CONCLUSIONS

Signals of evidence of clinical neuroprotection are evident for a number of candidate agents. Adjunctive use of multiple agents may present a viable avenue to clinical realization of neuroprotection. Definitive prospective studies of neuroprotection with multimodal assessment tools are required.

VGF function in depression and antidepressant efficacy

Brain-derived neurotrophic factor (BDNF) is a critical effector of depression-like behaviors and antidepressant responses. Here, we show that VGF (non-acronymic), which is robustly regulated by BDNF/TrkB signaling, is downregulated in hippocampus (male/female) and upregulated in nucleus accumbens (NAc) (male) in depressed human subjects and in mice subjected to chronic social defeat stress (CSDS). Adeno-associated virus (AAV)-Cre-mediated Vgf ablation in floxed VGF mice, in dorsal hippocampus (dHc) or NAc, led to pro-depressant or antidepressant behaviors, respectively, while dHc- or NAc-AAV-VGF overexpression induced opposite outcomes. Mice with reduced VGF levels in the germ line (Vgf+/-) or in dHc (AAV-Cre-injected floxed mice) showed increased susceptibility to CSDS and impaired responses to ketamine treatment in the forced swim test. Floxed mice with conditional pan-neuronal (Synapsin-Cre) but not those with forebrain (αCaMKII-Cre) Vgf ablation displayed increased susceptibility to subthreshold social defeat stress, suggesting that neuronal VGF, expressed in part in inhibitory interneurons, regulates depression-like behavior. Acute antibody-mediated sequestration of VGF-derived C-terminal peptides AQEE-30 and TLQP-62 in dHc induced pro-depressant effects. Conversely, dHc TLQP-62 infusion had rapid antidepressant efficacy, which was reduced in BDNF floxed mice injected in dHc with AAV-Cre, and in NBQX- and rapamycin-pretreated wild-type mice, these compounds blocking α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor and mammalian target of rapamycin (mTOR) signaling, respectively. VGF is therefore a critical modulator of depression-like behaviors in dHc and NAc. In hippocampus, the antidepressant response to ketamine is associated with rapid VGF translation, is impaired by reduced VGF expression, and as previously reported, requires coincident, rapid BDNF translation and release.

Ketamine ameliorates oxidative stress-induced apoptosis in experimental traumatic brain injury via the Nrf2 pathway

Background

Ketamine can act as a multifunctional neuroprotective agent by inhibiting oxidative stress, cellular dysfunction, and apoptosis. Although it has been proven to be effective in various neurologic disorders, the mechanism of the treatment of traumatic brain injury (TBI) is not fully understood. The aim of this study was to investigate the neuroprotective function of ketamine in models of TBI and the potential role of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in this putative protective effect.

Materials and methods

Wild-type male mice were randomly assigned to five groups: Sham group, Sham + ketamine group, TBI group, TBI + vehicle group, and TBI + ketamine group. Marmarou’s weight drop model in mice was used to induce TBI, after which either ketamine or vehicle was administered via intraperitoneal injection. After 24 h, the brain samples were collected for analysis.

Results

Ketamine significantly ameliorated secondary brain injury induced by TBI, including neurological deficits, brain water content, and neuronal apoptosis. In addition, the levels of malondialdehyde (MDA), glutathione peroxidase (GPx), and superoxide dismutase (SOD) were restored by the ketamine treatment. Western blotting and immunohistochemistry showed that ketamine significantly increased the level of Nrf2. Furthermore, administration of ketamine also induced the expression of Nrf2 pathway-related downstream factors, including hemeoxygenase-1 and quinine oxidoreductase-1, at the pre- and post-transcriptional levels.

Conclusion

Ketamine exhibits neuroprotective effects by attenuating oxidative stress and apoptosis after TBI. Therefore, ketamine could be an effective therapeutic agent for the treatment of TBI.

Administration of Ketamine Causes Autophagy and Apoptosis in the Rat Fetal Hippocampus and in PC12 Cells

Drug abuse during pregnancy is a serious problem. Like alcohol, anticonvulsants, sedatives, and anesthetics, such as ketamine, can pass through the placental barrier and affect the growing fetus. However, the mechanism by which ketamine causes damage to fetal rats is not well understood. Therefore, in this study, we anesthetized pregnant rats with ketamine and evaluated the Total Antioxidant Capacity (T-AOC), Reactive Oxygen Species (ROS), and Malondialdehyde (MDA). Moreover, we determined changes in the levels of Cleaved-Caspase-3 (C-Caspase-3), Beclin-1, B-cell lymphoma-2 (Bcl-2), Bcl-2 Associated X Protein (Bax), Autophagy-related gene 4 (Atg4), Atg5, p62 (SQSTM1), and marker of autophagy Light Chain 3 (LC3). In addition, we cultured PC12 cells in vitro to determine the relationship between ROS, autophagy, and apoptosis following ketamine treatment. The results showed that ketamine induced changes in autophagy- and apoptosis-related proteins, reduced T-AOC, and generated excessive levels of ROS and MDA. In vitro experiments showed similar results, indicating that apoptosis levels can be inhibited by 3-MA. We also found that autophagy and apoptosis can be inhibited by N-acetyl-L-cysteine (Nac). Thus, anesthesia with ketamine in pregnant rats may increase the rate of autophagy and apoptosis in the fetal hippocampus and the mechanism may be through inhibition of antioxidant activity and ROS accumulation.

Ketamine induces hippocampal apoptosis through a mechanism associated with the caspase-1 dependent pyroptosis

Ketamine, a pediatric anesthetic, is widely used in clinical practice. There was growing evidence showing that ketamine can promote neuronal death in developing brains of both humans and animals. In this study, we used in vivo neonatal and juvenile mouse models to induce ketamine-related neurotoxicity in the hippocampus. Active caspase-3 and -9 proteins, which are responsible for the release of cytochrome C, and the mitochondrial translocation of p53, which is associated with mitochondrial apoptosis, were found to be significantly up-regulated in the ketamine-induced hippocampal neurotoxicity. Furthermore, we demonstrated that the levels of pyroptosis-related proteins, including caspase-1 and -11, NOD-like receptor family, pyrin domain containing 3 (NLRP3), and IL-1β and IL-18, significantly increased after multiple doses of ketamine administration. We speculated that ketamine triggered the formation of NLRP3 and caspase-1 complex and its translocation to the mitochondria. In consistent with this, ketamine treatment was found to induce pyroptosis in mouse primary hippocampal neurons, which was characterized by increased pore formation and elevated lactate dehydrogenase release in mitochondria. Silencing caspase-1 with lentivirus-mediated short hairpin RNA (shRNA) significantly decreased the levels of not only pyroptosis-related proteins but also mitochondrial apoptosis-associated proteins in mouse primary hippocampal neurons. We conclude that caspase-1-dependent pyroptosis is an important event which may be an essential pathway involved in the mitochondria-associated apoptosis in ketamine-induced hippocampal neurotoxicity.

ADNP Is a Therapeutically Inducible Repressor of WNT Signaling in Colorectal Cancer

Purpose: Constitutively active WNT signaling is a hallmark of colorectal cancers and a driver of malignant tumor progression. Therapeutic targeting of WNT signaling is difficult due to high pathway complexity and its role in tissue homeostasis. Here, we identify the transcription factor ADNP as a pharmacologically inducible repressor of WNT signaling in colon cancer.Experimental Design: We used transcriptomic, proteomic, and in situ analyses to identify ADNP expression in colorectal cancer and cell biology approaches to determine its function. We induced ADNP expression in colon cancer xenografts by low-dose ketamine in vivo Clinical associations were determined in a cohort of 221 human colorectal cancer cases.Results: ADNP was overexpressed in colon cancer cells with high WNT activity, where it acted as a WNT repressor. Silencing ADNP expression increased migration, invasion, and proliferation of colon cancer cells and accelerated tumor growth in xenografts in vivo Treatment with subnarcotic doses of ketamine induced ADNP expression, significantly inhibited tumor growth, and prolonged survival of tumor-bearing animals. In human patients with colon cancer, high ADNP expression was linked to good prognosis.Conclusions: Our findings indicate that ADNP is a tumor suppressor and promising prognostic marker, and that ketamine treatment with ADNP induction is a potential therapeutic approach that may add benefit to current treatment protocols for patients with colorectal cancer. Clin Cancer Res; 23(11); 2769-80. ©2016 AACR.