Hz Mice Research Articles

Effect of 40 Hz light flicker on behaviors of adult C57BL/6J mice

40 Hz light flicker can activate multiple brain regions of wild-type mice. However, there are no systematic studies on the behavioral effects of 40 Hz light flicker on wild-type mice. Adult wild-type C57BL/6J mice were treated with 40 Hz light flicker (200 lx, 40 Hz, 1 h/day for 3 weeks) to evaluate its effects on several behaviors, including mood, locomotor activity, memory, social interaction, mechanical pain, and sense of smell. In the open field test, the elevated zero-maze test, forced swimming test, and tail suspension test, 40 Hz mice showed no anxiety and depression-like behaviors. In the rotarod test, no differences were found between the anti-fatigue ability and motor coordination ability. In memory-related tests, 40 Hz mice showed the short-term cognitive enhancement in the novel object recognition test. Interestingly, 40 Hz mice showed no enhanced the long-term memory performance in the contextual fear conditioning test, and tone-cued fear conditioning test. Besides, 40 Hz mice increased their exploration of social cues that were unfamiliar to them and differed significantly from their own experiences. In terms of sensory abilities, 40 Hz mice had unchanged pain sensitivity in the von Frey fiber test and significant enhancement in the olfactory ability in the food-seeking test. In conclusion, this 40 Hz light stimulation paradigm has high safety and can improve the specific behavioral ability, which provides a theoretical basis for the future use of 40 Hz light flicker as a disease prevention or treatment method.

A facile synthesis of 1,3,4-oxadiazole-based carbamothioate molecules: Antiseizure potential, EEG evaluation and in-silico docking studies

In present work, a series of novel structural hybrids of 1,3,4-oxadiazole and carbamothioate was designed by chemical modification of 2-(4-isobutylphenyl)propanoic acid. Target compounds (7a-f) were synthesized in significant yields (84–88 %) by coupling compound (4) with different electrophiles under different reaction conditions. The structures of oxadiazole based carbamothionate derivatives were confirmed by spectroscopic (FTIR, 1H NMR, 13C NMR) and physiochemical methods. During in-vivo experimentation, all synthesized compounds were tested through 6 Hz (32 mA) and PTZ (80 mg/kg) mouse seizure models. The 7b and 7c showed significant outcomes (P < 0.05) in terms of seizure severity, protection and mortality. The behavioural outcomes of PTZ tests were further strengthened with video-electroencephalogram (vEEG) findings in which EEGs were analyzed for epileptic spikes to understand the impact of 7b and 7c treatment on these ictal activities. The 7b was found most efficient in reducing the seizure spiking activity in brains of PTZ-treated mice while both 7b and 7c significantly reduced overall PTZ-induced seizure severity. The molecular docking studies also predicted the BBB permeability, reduced binding energies and good compound interaction with GABAA receptors and SV2A protein. Therefore, the observed pharmacological outcomes might be attributed to the GABAA agonistic and SV2A modulating potential of these oxadiazole-carbamothioate hybrid compounds.

The sulfonadyns: a class of aryl sulfonamides inhibiting dynamin I GTPase and clathrin mediated endocytosis are anti-seizure in animal models.

We show that dansylcadaverine (1) a known in-cell inhibitor of clathrin mediated endocytosis (CME), moderately inhibits dynamin I (dynI) GTPase activity (IC50 45 μM) and transferrin (Tfn) endocytosis in U2OS cells (IC50 205 μM). Synthesis gave a new class of GTP-competitive dynamin inhibitors, the Sulfonadyns™. The introduction of a terminal cinnamyl moiety greatly enhanced dynI inhibition. Rigid diamine or amide links between the dansyl and cinnamyl moieties were detrimental to dynI inhibition. Compounds with in vitro inhibition of dynI activity <10 μM were tested in-cell for inhibition of CME. These data unveiled a number of compounds, e.g. analogues 33 ((E)-N-(6-{[(3-(4-bromophenyl)-2-propen-1-yl]amino}hexyl)-5-isoquinolinesulfonamide)) and 47 ((E)-N-(3-{[3-(4-bromophenyl)-2-propen-1-yl]amino}propyl)-1-naphthalenesulfonamide)isomers that showed dyn IC50 <4 μM, IC50(CME) <30 μM and IC50(SVE) from 12-265 μM. Both analogues (33 and 47) are at least 10 times more potent that the initial lead, dansylcadaverine (1). Enzyme kinetics revealed these sulfonamide analogues as being GTP competitive inhibitors of dynI. Sulfonadyn-47, the most potent SVE inhibitor observed (IC50(SVE) = 12.3 μM), significantly increased seizure threshold in a 6 Hz mouse psychomotor seizure test at 30 (p = 0.003) and 100 mg kg-1 ip (p < 0.0001), with similar anti-seizure efficacy to the established anti-seizure medication, sodium valproate (400 mg kg-1). The Sulfonadyn™ class of drugs target dynamin and show promise as novel leads for future anti-seizure medications.

Pancreatic β-Cell O-GlcNAc Transferase Overexpression Increases Susceptibility to Metabolic Stressors in Female Mice.

The nutrient-sensor O-GlcNAc transferase (Ogt), the sole enzyme that adds an O-GlcNAc-modification onto proteins, plays a critical role for pancreatic β-cell survival and insulin secretion. We hypothesized that β-cell Ogt overexpression would confer protection from β-cell failure in response to metabolic stressors, such as high-fat diet (HFD) and streptozocin (STZ). Here, we generated a β-cell-specific Ogt in overexpressing (βOgtOE) mice, where a significant increase in Ogt protein level and O-GlcNAc-modification of proteins were observed in islets under a normal chow diet. We uncovered that βOgtOE mice show normal peripheral insulin sensitivity and glucose tolerance with a regular chow diet. However, when challenged with an HFD, only female βOgtOE (homozygous) Hz mice developed a mild glucose intolerance, despite increased insulin secretion and normal β-cell mass. While female mice are normally resistant to low-dose STZ treatments, the βOgtOE Hz mice developed hyperglycemia and glucose intolerance post-STZ treatment. Transcriptome analysis between islets with loss or gain of Ogt by RNA sequencing shows common altered pathways involving pro-survival Erk and Akt and inflammatory regulators IL1β and NFkβ. Together, these data show a possible gene dosage effect of Ogt and the importance O-GlcNAc cycling in β-cell survival and function to regulate glucose homeostasis.

Presence of Systemic Amyloidosis in Mice with Partial Deficiency in Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) in Aging

Pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide with widespread expression and general cytoprotective effects, is also involved in aging. Previously, we observed accelerated systemic senile amyloidosis in PACAP knockout (KO) mice. As mice partially lacking PACAP (heterozygous-HZ) show variable symptoms, here we investigated whether HZ mice have accelerated aging, completed with observations in PAC1 receptor KO mice. As we have limited data on qualitative or quantitative changes in the blood of PACAP-deficient mice, we investigated whether these changes could be in the background of the amyloidosis. Routine histological staining was used to examine amyloid deposits, rated on a severity scale 0–3. Blood was collected from PACAP wild type/HZ mice for complete blood analysis. In contrast to receptor KO mice showing no amyloidosis, histopathological analysis revealed severe deposits in PACAP HZ mice, with kidney, spleen, skin, and intestines being most affected. Increased cholesterol, lipoprotein levels, and differences in several blood count parameters were found in HZ mice. In summary, amyloidosis also develops in partial absence of PACAP, in contrast to the lack of its PAC1 receptor. In addition to the earlier identified inflammatory and degenerative disturbances, the alteration in lipid metabolism and bone marrow activity can also be additional factors leading to systemic degenerative processes.

Synthesis, in vivo anticonvulsant testing, and molecular modeling studies of new nafimidone derivatives.

An estimated 50 million people suffer epilepsy worldwide and 30% of the cases do not respond to current antiepileptic drugs (AEDs). Here, we report synthesis and anticonvulsant screening of new derivatives of nafimidone, a well-known member of (arylakyl)azole anticonvulsants. The compounds showed promising protection against maximal electroshock (MES)-induced seizures in mice and rats when administered via intraperitoneal (ip) and oral route. Especially, 5b, 5c, and 5i displayed outstanding activity in rats in MES test when given ip (ED50 : 16.0, 15.8, and 11.8 mg/kg, respectively). Additionally, 5l was active against 6 Hz and corneal-kindled mice models. Behavioral toxicity of the compounds was very low and their therapeutic indexes were high compared to some currently available AEDs. A number of pharmaceutically relevant descriptors and properties were predicted for the compounds in silico in comparison with a set of known drugs. Favorable results were obtained such as good blood-brain barrier permeability and high oral absorption, as well as drug-likeness. 5l was found to show affinity to the benzodiazepine binding site of A-type GABA receptor via molecular docking simulations.

Brain hyperserotonemia causes autism-relevant social deficits in mice

BackgroundHyperserotonemia in the brain is suspected to be an endophenotype of autism spectrum disorder (ASD). Reducing serotonin levels in the brain through modulation of serotonin transporter function may improve ASD symptoms.MethodsWe analyzed behavior and gene expression to unveil the causal mechanism of ASD-relevant social deficits using serotonin transporter (Sert) knockout mice.ResultsSocial deficits were observed in both heterozygous knockout mice (HZ) and homozygous knockout mice (KO), but increases in general anxiety were only observed in KO mice. Two weeks of dietary restriction of the serotonin precursor tryptophan ameliorated both brain hyperserotonemia and ASD-relevant social deficits in Sert HZ and KO mice. The expression of rather distinct sets of genes was altered in Sert HZ and KO mice, and a substantial portion of these genes was also affected by tryptophan depletion. Tryptophan depletion in Sert HZ and KO mice was associated with alterations in the expression of genes involved in signal transduction pathways initiated by changes in extracellular serotonin or melatonin, a derivative of serotonin. Only expression of the AU015836 gene was altered in both Sert HZ and KO mice. AU015836 expression and ASD-relevant social deficits normalized after dietary tryptophan restriction.ConclusionsThese findings reveal a Sert gene dose-dependent effect on brain hyperserotonemia and related behavioral sequelae in ASD and a possible therapeutic target to normalize brain hyperserotonemia and ASD-relevant social deficits.

F40. NEUREXIN-1α (NRNX1α) HYPOFUNCTION INDUCES SCHIZOPHRENIA-RELEVANT DEFICITS IN CEREBRAL METABOLISM, COGNITIVE PROCESSING SPEED AND COGNITIVE FLEXIBILITY

BackgroundHeterozygous deletions in NEUREXIN-1 (NRXN1) substantially increase the risk of developing schizophrenia (SZ) (Rujescu et al., 2009. Hum Mol Genet 18(5):988–96). We currently have little understanding into the mechanisms by which NRXN1 impacts on the brain to increase the risk of developing the disorder, and to which symptom domains NRXN1 may contribute. Patients with schizophrenia show deficits in cognitive processing speed and cognitive flexibility (Sanchez et al., 2009. J Clin Psychiat. 70(6):888–896, Dieci et al., 1997. Schizophr Res. 25(1):33–42). In addition, patients show characteristic alterations in brain function including “hypofrontality”; prefrontal cortex hypometabolism (Hill et al., 2004. Acta Psychiatr Scand. 110(4):243–56). Here we characterise, in a transgenic mouse model, the impact of Nrxn1α hypofunction on cognitive flexibility, processing speed and cerebral metabolism to determine the potential translational relevance of the model to SZ.MethodsNrxn1α heterozygous (Hz) mice and their wild-type (Wt) littermates, of both sexes, were tested at 3, 6, 9 and 12 months old using a between-groups design. Associative learning and cognitive flexibility (reversal learning and set shifting) were assessed in a two choice odour based set shifting task (adapted from Young et al., 2010. Cog Affect Behav Neurosci. 10(2):243–251). Mice completed a series of testing phases that included two odour discrimination phases (OD1 and OD2), one reversal learning phase (OD2R) and an extra-dimensional shift (EDS), with animals shifting attentional set from odour to location. The criterion to successfully complete each phase was set at 6 consecutive correct choices. The number of trials to reach criterion, percentage correct and average latency for correct choices were recorded. After behavioural testing cerebral metabolism was determined in 49 brain regions using 14C-2-deoxyglucose functional brain imaging (Dawson et al., 2015. Transl Psychiatry. 5(5):e569). Data were analysed using ANOVA and t-test with Bonferroni correction. Significance was set at p<0.05.ResultsIn the associative learning phases of the task (OD1 and OD2) Nrxn1α Hz mice took a similar number of trials as Wt controls to reach criteria. Nrxn1α Hz mice also completed a similar percentage of correct trials during these phases. This suggests that associative learning is not impaired in Nrxn1α Hz mice. However, Nrxn1α Hz mice showed a significant increase in the latency of correct choices in comparison to Wt animals during these phases, supporting significantly decreased processing speed in these animals. We also found that reversal learning (CDR2) was impaired in Nrxn1α Hz mice, evidenced by a significant increase in trials to criterion relative to Wt controls. In the brain imaging study, we found that Nrxn1α Hz mice show significant hypofrontality, with a reduced rate of metabolism in the anterior and medial prelimbic cortex (aPrL, mPrL). By contrast, Nrxn1α heterozygous mice show significant hypermetabolism in the dorsal raphe (DR), ventral tegmental area (VTA) and retrosplenial cortex (RSC).DiscussionNrxn1α heterozygosity induces SZ-like impairments in cognitive processing speed, cognitive flexibility (reversal learning) and cerebral metabolism, including the induction of hypofrontality. Nrxn1α heterozygosity also alters metabolism in neuromodulatory brain regions, including the serotonergic DR and dopaminergic VTA, which may also contribute to its impact on cognition. These data give new insight into the mechanisms by which NRXN1 heterozygosity increases the risk of developing SZ and suggest that Nrxn1α Hz mice provide a translational tool for drug discovery in relation to the cognitive deficits seen in the disorder.

Construct and face validity of a new model for the three-hit theory of depression using PACAP mutant mice on CD1 background

Major depression is a common cause of chronic disability. Despite decades of efforts, no equivocally accepted animal model is available for studying depression. We tested the validity of a new model based on the three-hit concept of vulnerability and resilience. Genetic predisposition (hit 1, mutation of pituitary adenylate cyclase-activating polypeptide, PACAP gene), early-life adversity (hit 2, 180-min maternal deprivation, MD180) and chronic variable mild stress (hit 3, CVMS) were combined. Physical, endocrinological, behavioral and functional morphological tools were used to validate the model. Body- and adrenal weight changes as well as corticosterone titers proved that CVMS was effective. Forced swim test indicated increased depression in CVMS PACAP heterozygous (Hz) mice with MD180 history, accompanied by elevated anxiety level in marble burying test. Corticotropin-releasing factor neurons in the oval division of the bed nucleus of the stria terminalis showed increased FosB expression, which was refractive to CVMS exposure in wild-type and Hz mice. Urocortin1 neurons became over-active in CMVS-exposed PACAP knock out (KO) mice with MD180 history, suggesting the contribution of centrally projecting Edinger–Westphal nucleus to the reduced depression and anxiety level of stressed KO mice. Serotoninergic neurons of the dorsal raphe nucleus lost their adaptation ability to CVMS in MD180 mice. In conclusion, the construct and face validity criteria suggest that MD180 PACAP HZ mice on CD1 background upon CVMS may be used as a reliable model for the three-hit theory.

IGF-1 modulates gene expression of proteins involved in inflammation, cytoskeleton, and liver architecture

Even though the liver synthesizes most of circulating IGF-1, it lacks its receptor under physiological conditions. However, according to previous studies, a damaged liver expresses the receptor. For this reason, herein, we examine hepatic histology and expression of genes encoding proteins of the cytoskeleton, extracellular matrix, and cell-cell molecules and inflammation-related proteins. A partial IGF-1 deficiency murine model was used to investigate IGF-1’s effects on liver by comparing wild-type controls, heterozygous igf1+/−, and heterozygous mice treated with IGF-1 for 10 days. Histology, microarray for mRNA gene expression, RT-qPCR, and lipid peroxidation were assessed. Microarray analyses revealed significant underexpression of igf1 in heterozygous mice compared to control mice, restoring normal liver expression after treatment, which then normalized its circulating levels. IGF-1 receptor mRNA was overexpressed in Hz mice liver, while treated mice displayed a similar expression to that of the controls. Heterozygous mice showed overexpression of several genes encoding proteins related to inflammatory and acute-phase proteins and underexpression or overexpression of genes which coded for extracellular matrix, cytoskeleton, and cell junction components. Histology revealed an altered hepatic architecture. In addition, liver oxidative damage was found increased in the heterozygous group. The mere IGF-1 partial deficiency is associated with relevant alterations of the hepatic architecture and expression of genes involved in cytoskeleton, hepatocyte polarity, cell junctions, and extracellular matrix proteins. Moreover, it induces hepatic expression of the IGF-1 receptor and elevated acute-phase and inflammation mediators, which all resulted in liver oxidative damage.

Partial IGF-1 deficiency induces brain oxidative damage and edema, which are ameliorated by replacement therapy.

Insulin-like growth factor 1 (IGF-1) induces multiple cytoprotective effects on every tissue, including the brain. Since the mechanisms by which IGF-1 produces neuroprotection are not fully understood, the aim of this work was to delve into the underlying mechanisms. IGF-1 deficient mice (Hz) were compared with wild type (WT) and Hz mice treated with low doses of IGF-1 (2 µg/100 g body weight/day) for 10 days (Hz + IGF). Gene expression, quantitative PCR, histology, and magnetic resonance imaging were performed in the three groups. IGF-1 deficiency induced increased oxidative damage determined by markers of lipid peroxidation and hypoxia, as well as gene expression of heat shock proteins, antioxidant enzymes, and molecules involved in inflammation, apoptosis, and mitochondrial protection. These changes correlated with edema and learning impairment in Hz mice. IGF-1 therapy improved all these alterations. In conclusion, IGF-1 deficiency is responsible for increased brain oxidative damage, edema, and impaired learning and memory capabilities which are rescued by IGF-1 replacement therapy.

The role of connexin43 hemichannels in limbic seizures

Event Abstract Back to Event The role of connexin43 hemichannels in limbic seizures Laura Walrave1*, Mathieu Vinken2, Luc Leybaert3 and Ilse J. Smolders1 1 Vrije Universiteit Brussel, FASC, Belgium 2 Vrije Universiteit Brussel, FAFY, Belgium 3 Universiteit Gent, Basic Medical Sciences, Belgium Nowadays, the contribution of astrocytic connexin43 hemichannels (Cx43-HCs) to brain functioning and dysfunctioning hasn’t been fully elucidated. In this study, we want to screen Cx43-HCs as novel antiepileptic drug targets through the in vivo screening of a newly developed and selective Cx43-HC-inhibitor (TAT-Gap19) in different acute models of seizures. In the acute pilocarpine rat model, we found that an intrahippocampal perfusion of 12.5 µM TAT-Gap19 was able to significantly reduce the seizure-related behavioural movements (based on Racine’s scale) induced by pilocarpine. In the acute pilocarpine mouse model, ECoG recordings were used to compare seizure severity because of the unclear behaviour in these animals. We found that an intrahippocampal perfusion of 25 µM TAT-Gap19 significantly reduced the total seizure duration (sum of duration of all individual seizures displayed on ECoG recordings). We will also determine the concentration of glutamate and D-serine in the dialysate samples which were collected during this experiment in view of the hypothesis that Cx43-HCs might release these gliotransmitters in vivo. In the six Hertz (6 Hz) mouse model, an electrical model of therapy-resistant seizures, we found that an intracerebroventricular injection of 1 nmol TAT-Gap19 and an intraperitoneal injection of 25 mg/kg TAT-Gap19 leads to a significant decrease in the total seizure duration. These results suggest that Cx43-HCs play a role in seizure generation. Additionally, it is of very high importance to screen TAT-Gap19 in chronic models of epilepsy in order to unravel the role these channels play in epilepsy and epileptogenesis. Keywords: connexin43 hemichannels, Epilepsy, Temporal Lobe, Animal Models, Seizures, Peptides Conference: 11th National Congress of the Belgian Society for Neuroscience, Mons, Belgium, 22 May - 22 May, 2015. Presentation Type: Poster presentation Topic: Neuroscience Citation: Walrave L, Vinken M, Leybaert L and Smolders IJ (2015). The role of connexin43 hemichannels in limbic seizures. Front. Neurosci. Conference Abstract: 11th National Congress of the Belgian Society for Neuroscience. doi: 10.3389/conf.fnins.2015.89.00031 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 05 May 2015; Published Online: 05 May 2015. * Correspondence: Miss. Laura Walrave, Vrije Universiteit Brussel, FASC, Jette, Vlaams-Brabant, 1090, Belgium, laura.walrave@vub.ac.be Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Laura Walrave Mathieu Vinken Luc Leybaert Ilse J Smolders Google Laura Walrave Mathieu Vinken Luc Leybaert Ilse J Smolders Google Scholar Laura Walrave Mathieu Vinken Luc Leybaert Ilse J Smolders PubMed Laura Walrave Mathieu Vinken Luc Leybaert Ilse J Smolders Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Vibrating Frequency Thresholds in Mice and Rats: Implications for the Effects of Vibrations on Animal Health

Vibrations in research facilities can cause complex animal behavioral and physiological responses that can affect animal health and research outcomes. The goal of this study was to determine the range of frequency values, where animals are unable to attenuate vibrations, and therefore may be most susceptible to their effects. Anesthetized and euthanized adult rats and mice were exposed to vibration frequencies over a wide range (0-600 Hz) and at a constant magnitude of 0.3 m/s(2). Euthanized animals were additionally exposed to vibrations at an acceleration of 1 m/s(2). The data showed that at most frequencies rodents were able to attenuate vibration magnitudes, with values for the back-mounted accelerometer being substantially less than that of the table. At frequencies of 41-60 Hz mice did not attenuate vibration magnitude, but instead the magnitude of the table and animal were equal or amplified. Rats experienced the same pattern of non-attenuation between 31 and 50 Hz. Once euthanized, the mice vibrated at a slightly more elevated frequency (up to 100 Hz). Based on these results, it may be prudent that in laboratory settings, vibrations in the ranges reported here should be accounted for as possible contributors to animal stress and/or biomechanical changes.

Accelerated protein damage in brains of PIMT+/− mice; a possible model for the variability of cognitive decline in human aging

Isoaspartate formation is a common type of protein damage normally kept in check by the repair enzyme protein-L-isoaspartyl methyltransferase (PIMT). Mice with a knockout of the gene (Pcmt1) for this enzyme (KO, −/−) exhibit a pronounced neuropathology with fatal epileptic seizures at 30–60 days. Heterozygous (HZ, +/−) mice have 50% of the PIMT activity found in wild-type (WT, +/+) mice, but appear normal. To see if HZ mice exhibit accelerated aging at the molecular level, we compared brain extracts from HZ and WT mice at 8 months and 2 years with regard to PIMT activity, isoaspartate levels, and activity of an endogenous PIMT substrate, creatine kinase B. PIMT activity declined modestly with age in both genotypes. Isoaspartate was significantly higher in HZ than WT mice at 8 months and more so at 2 years, rising 5× faster in HZ males and 3× faster in females. Creatine kinase activity decreased with age and was always lower in the HZ mice. These findings suggest the individual variation of human PIMT levels may significantly influence the course of age-related central nervous system dysfunction.

Glutaminase1 heterozygous mice show enhanced trace fear conditioning and Arc/Arg3.1 expression in hippocampus and cingulate cortex

Mice heterozygous for a mutation in the glutaminase (GLS1) gene (GLS1 HZ mice), with reduced glutamate recycling and release, display reduced hippocampal function as well as memory of contextual cues in a delay fear conditioning (FC) paradigm. Here, we asked whether this deficit reflects an inability to process contextual information or a selective alteration in salience attribution. In addition, we asked whether baseline and activity-induced hippocampal activity were diminished in GLS1 HZ mice. For this purpose, we manipulated the relative salience of the conditioned stimulus (CS) and contextual cues in FC tasks, and examined gene expression of the immediate early gene Arc (Arc/Arg3.1) in hippocampus and anterior cingulate cortex (ACC) following trace FC (tFC). The results indicate that GLS1 HZ mice succeed in processing contextual information when the salient CS is absent or less predictive. In addition, in the hippocampus-dependent tFC paradigm GLS1 HZ mice display enhanced CS learning. Furthermore, while baseline arc activation was reduced in GLS1 HZ mice in the hippocampus, in line with previous fMRI findings, it was enhanced in the hippocampus and anterior cingulate cortex following tFC. These findings suggest that GLS1 HZ mice have a pro-cognitive profile in the tFC paradigm, and this phenotype involves activation of both hippocampus and ACC.Taken together with previous work on the GLS1 HZ mouse, this study sheds light on the importance of glutamate transmission to memory processes that require the allocation of attentional resources, and extends our understanding of the underpinnings of attention deficits in SZ.

Synthesis of a FTO inhibitor with anticonvulsant activity.

We describe the rationale for and the synthesis of a new class of compounds utilizing a modular approach that are designed to mimic ascorbic acid and to inhibit 2-oxoglutarate-dependent hydroxylases. Preliminary characterization of one of these compounds indicates in vivo anticonvulsant activity (6 Hz mouse model) at nontoxic doses, inhibition of the 2-oxoglutarate-dependent hydroxylase FTO, and expected increase in cellular N(6)-methyladenosine. This compound is also able to modulate various microRNA, an interesting result in light of the recent view that modulation of microRNAs may be useful for the treatment of CNS disease.

An experimental model of partial insulin-like growth factor-1 deficiency in mice

Insulin-like growth factor-1 (IGF-1) is responsible for many systemic growth hormone (GH) functions although it has an extensive number of inherent activities (anabolic, cytoprotective, and anti-inflammatory). The potential options for IGF-1 therapy arise as a promising strategy in a wide list of human diseases. However, deeper studies are needed from a suitable animal model. All human conditions of IGF-1 deficiency consist in partially decreased IGF-1 levels since total absence of this hormone is hardly compatible with life. The aim of this work was to confirm that heterozygous Igf-1 (+/-) mice (Hz) may be considered as an appropriate animal model to study conditions of IGF-1 deficiency, focusing on early ages. Heterozygous Igf-1 (+/-) mice were compared to homozygous Igf-1 (+/+) by assessing gene expression by quantitative PCR, serum circulating levels by ELISA, and tissue staining. Compared to controls, Hz mice (25 days old) showed a partial but significant reduction of IGF-1 circulating levels, correlating with a reduced body weight and diminished serum IGFBP-3 levels. Hz mice presented a significant decrease of IGF-1 gene expression in related organs (liver, bone, testicles, and brain) while IGF-1 receptor showed a normal expression. However, gene expression of growth hormone receptor (GHR) was increased in the liver but reduced in the bone, testicles, and brain. In addition, a significant reduction of cortical bone thickness and histopathological alterations in the testicles were found in Hz mice when compared to controls. Finally, the lifelong evolution of IGF-1 serum levels showed significant differences throughout life until aging in mice. Results in this paper provide evidence for considering heterozygous mice as a suitable experimental model, from early stages, to get more insight into the mechanisms of the beneficial actions induced by IGF-1 replacement therapy.

Mice heterozygous for AChE are more sensitive to AChE inhibitors but do not respond to BuChE inhibition

An impaired central cholinergic system is at least partly involved in Alzheimer's disease (AD) pathogenesis, with cholinergic markers such as acetylcholinesterase (AChE) activity and protein levels decreasing as cognitive decline progresses. AD patients receive AChE inhibitor drugs to enhance cholinergic responses in the brain. The present study characterises the cholinergic system of mice heterozygous for AChE (HZ) as a suitable in vivo model for permanently reduced AChE activity. In comparison to homozygous, wild type (WT) mice, HZ mice show a 40% reduction of AChE activity in the brain, while their hippocampal ACh levels are increased by 56% as measured by microdialysis; choline acetyltransferase levels remain unaltered, and choline uptake increases 2-fold. We demonstrate that HZ mice are significantly more sensitive to local AChE inhibition (BW284c51), but remain insensitive to butyrylcholinesterase (BuChE) inhibition (bambuterol). HZ mice are also more sensitive to the peripheral application of the selective AChE inhibitor donepezil or the mixed inhibitor physostigmine; extracellular ACh levels rise significantly after administration of both drugs; also glucose levels are moderately increased indicating potentially non-cholinergic effects of donepezil. Behavioural tests show comparable cognitive function in both mouse strains. Our results are discussed in relation to the use of AChE/BuChE inhibitors in AD patients.

Spontaneous Kisspeptin Neuron Firing in the Adult Mouse Reveals Marked Sex and Brain Region Differences but No Support for a Direct Role in Negative Feedback

Kisspeptin-Gpr54 signaling is critical for the GnRH neuronal network controlling fertility. The present study reports on a kisspeptin (Kiss)-green fluorescent protein (GFP) mouse model enabling brain slice electrophysiological recordings to be made from Kiss neurons in the arcuate nucleus (ARN) and rostral periventricular region of the third ventricle (RP3V). Using dual immunofluorescence, approximately 90% of GFP cells in the RP3V of females, and ARN in both sexes, are shown to be authentic Kiss-synthesizing neurons in adult mice. Cell-attached recordings of ARN Kiss-GFP cells revealed a marked sex difference in their mean firing rates; 90% of Kiss-GFP cells in males exhibited slow irregular firing (0.17 ± 0.04 Hz) whereas neurons from diestrous (0.01 ± 0.01 Hz) and ovariectomized (0 Hz) mice were mostly or completely silent. In contrast, RP3V Kiss-GFP cells were all spontaneously active, exhibiting tonic, irregular, and bursting firing patterns. Mean firing rates were significantly (P < 0.05) higher in diestrus (2.1 ± 0.3 Hz) compared with ovariectomized (1.0 ± 0.2 Hz) mice without any changes in firing pattern. Recordings from RP3V Kiss-GFP neurons at the time of the proestrous GnRH surge revealed a significant decline in firing rate after the surge. Together, these observations demonstrate unexpected sex differences in the electrical activity of ARN Kiss neurons and markedly different patterns of firing by Kiss neurons in the ARN and RP3V. Although data supported a positive influence of gonadal steroids on RP3V Kiss neuron firing, no direct evidence was found to support the previously postulated role of ARN Kiss neurons in the estrogen-negative feedback mechanism.

Structural sweet spot for A1 adenosine receptor activation by truncated (N)-methanocarba nucleosides: receptor docking and potent anticonvulsant activity.

A(1) adenosine receptor (AR) agonists display antiischemic and antiepileptic neuroprotective activity, but peripheral cardiovascular side effects impeded their development. SAR study of N(6)-cycloalkylmethyl 4'-truncated (N)-methanocarba-adenosines identified 10 (MRS5474, N(6)-dicyclopropylmethyl, K(i) = 47.9 nM) as a moderately A(1)AR-selective full agonist. Two stereochemically defined N(6)-methynyl group substituents displayed narrow SAR; groups larger than cyclobutyl greatly reduced AR affinity, and those larger or smaller than cyclopropyl reduced A(1)AR selectivity. Nucleoside docking to A(1)AR homology model characterized distinct hydrophobic cyclopropyl subpockets, the larger "A" forming contacts with Thr270 (7.35), Tyr271 (7.36), Ile274 (7.39), and carbon chains of glutamates (EL2) and the smaller subpocket "B" forming contacts between TM6 and TM7. 10 suppressed minimal clonic seizures (6 Hz mouse model) without typical rotarod impairment of A(1)AR agonists. Truncated nucleosides, an appealing preclinical approach, have more druglike physicochemical properties than other A(1)AR agonists. Thus, we identified highly restricted regions for substitution around N(6) suitable for an A(1)AR agonist with anticonvulsant activity.