Crucial role of calbindin-D28k in the pathogenesis of Alzheimer's disease mouse model

Curcuminoid submicron particle ameliorates cognitive deficits and decreases amyloid pathology in Alzheimer's disease mouse model

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder and is triggered via abnormal accumulation of amyloid-β peptide (Aβ). Aggregated Aβ is responsible for disrupting calcium homeostasis, inducing neuroinflammation, and promoting neurodegeneration. In this study, we generated curcuminoid submicron particle (CSP), which reduce the average size to ~60 nm in diameter. CSP had elevated the bioavailability in vivo and better neuroprotective effect against oligomeric Aβ than un-nanosized curcuminoids in vitro. Two months of CSP consumption reversed spatial memory deficits and the loss of a calcium binding protein calbindin-D_28k in the hippocampus of AD mouse model. In addition, CSP consumption lowered amyloid plaques and astrogliosis in vivo and enhanced microglial Aβ phagocytosis in vitro, implying that the beneficial effects of CSP also mediated via modulating neuroinflammation and enhancing amyloid clearance. Taken together, our study demonstrated the protective effects of CSP toward ameliorating the memory impairment and pathological deficits in AD mouse model.

Towards a circuit-level understanding of hippocampal CA1 dysfunction in Alzheimer's disease across anatomical axes

The hippocampus has been a primary region of study with regards to synaptic and functional changes in Alzheimer’s disease (AD) due to its involvement in early stages, specifically area CA1. However, most work in this area has treated CA1 as a homogeneous structure comprised of uniform neural circuits. Yet, there is a plethora of evidence that CA1 varies in its structure and function across anatomical axes. Here I review the heterogeneity of the functional and circuit architecture of hippocampal area CA1 across three primary anatomical axes. I also summarize evidence that AD differentially affects these subregions, as well as hypotheses as to why this may occur.

Increased acetylation of Peroxiredoxin1 by HDAC6 inhibition leads to recovery of Aβ-induced impaired axonal transport

Background

Reduction or inhibition of histone deacetylase 6 (HDAC6) has been shown to rescue memory in mouse models of Alzheimer’s disease (AD) and is recently being considered a possible therapeutic strategy. However, the restoring mechanism of HDAC6 inhibition has not been fully understood.

Methods and results

Here, we found that an anti-oxidant protein Peroxdiredoxin1 (Prx1), a substrate of HDAC6, malfunctions in Aβ treated cells, the brains of 5xFAD AD model mice and AD patients. Malfunctioning Prx1, caused by reduced Prx1 acetylation levels, was recovered by HDAC6 inhibition. Increasing acetylation levels of Prx1 by HDAC6 inhibition recovered elevated reactive oxygen species (ROS) levels, elevated Ca²⁺ levels and impaired mitochondrial axonal transport, sequentially, even in the presence of Aβ. Prx1 mutant studies on the K197 site for an acetylation mimic or silencing mutation support the results showing that HDAC6 inhibitor restores Aβ-induced disruption of ROS, Ca²⁺ and axonal transport.

Conclusions

Taken together, increasing acetylation of Prx1 by HDAC6 inhibition has several beneficial effects in AD pathology. Here, we present the novel mechanism by which elevated acetylation of Prx1 rescues mitochondrial axonal transport impaired by Aβ. Therefore, our results suggest that modulation of Prx1 acetylation by HDAC6 inhibition has great therapeutic potential for AD and has further therapeutic possibilities for other neurodegenerative diseases as well.

Electronic supplementary material

The online version of this article (doi:10.1186/s13024-017-0164-1) contains supplementary material, which is available to authorized users.

ProNGF Drives Localized and Cell Selective Parvalbumin Interneuron and Perineuronal Net Depletion in the Dentate Gyrus of Transgenic Mice

ProNGF, the precursor of mature Nerve Growth Factor (NGF), is the most abundant NGF form in the brain and increases markedly in the cortex in Alzheimer's Disease (AD), relative to mature NGF. A large body of evidence shows that the actions of ProNGF and mature NGF are often conflicting, depending on the receptors expressed in target cells. TgproNGF#3 mice, expressing furin-cleavage resistant proNGF in CNS neurons, directly reveal consequences of increased proNGF levels on brain homeostasis. Their phenotype clearly indicates that proNGF can be a driver of neurodegeneration, including severe learning and memory behavioral deficits, cholinergic deficits, and diffuse immunoreactivity for A-beta and A-beta-oligomers. In aged TgproNGF#3 mice spontaneous epileptic-like events are detected in entorhinal cortex-hippocampal slices, suggesting occurrence of excitatory/inhibitory (E/I) imbalance. In this paper, we investigate the molecular events linking increased proNGF levels to the epileptiform activity detected in hippocampal slices. The occurrence of spontaneous epileptiform discharges in the hippocampal network in TgproNGF#3 mice suggests an impaired inhibitory interneuron homeostasis. In the present study, we detect the onset of hippocampal epileptiform events at 1-month of age. Later, we observe a regional- and cellular-selective Parvalbumin interneuron and perineuronal net (PNN) depletion in the dentate gyrus (DG), but not in other hippocampal regions of TgproNGF#3 mice. These results demonstrate that, in the hippocampus, the DG is selectively vulnerable to altered proNGF/NGF signaling. Parvalbumin interneuron depletion is also observed in the amygdala, a region strongly connected to the hippocampus and likewise receiving cholinergic afferences. Transcriptome analysis of TgproNGF#3 hippocampus reveals a proNGF signature with broad down-regulation of transcription. The most affected mRNAs modulated at early times belong to synaptic transmission and plasticity and extracellular matrix (ECM) gene families. Moreover, alterations in the expression of selected BDNF splice variants were observed. Our results provide further mechanistic insights into the vicious negative cycle linking proNGF and neurodegeneration, confirming the regulation of E/I homeostasis as a crucial mediating mechanism.

Neurochemical Markers in the Mammalian Brain: Structure, Roles in Synaptic Communication, and Pharmacological Relevance

BACKGROUND

Knowledge of molecular marker (typically protein or mRNA) expression in neural systems can provide insight to the chemical blueprint of signal processing and transmission, assist in tracking developmental or pathological progressions, and yield key information regarding potential medicinal targets. These markers are particularly relevant in the mammalian brain in the light of its unsurpassed cellular diversity. Accordingly, molecular expression profiling is rapidly becoming a major approach to classify neuron types. Despite a profusion of research, however, the biological functions of molecular markers commonly used to distinguish neuron types remain incompletely understood. Furthermore, most molecular markers of mammalian neuron types are also present in other organs, therefore complicating considerations of their potential pharmacological interactions.

OBJECTIVE

Here, we survey 15 prominent neurochemical markers from five categories, namely membrane transporters, calcium-binding proteins, neuropeptides, receptors, and extracellular matrix proteins, explaining their relation and relevance to synaptic communication.

METHOD

For each marker, we summarize fundamental structural features, cellular functionality, distributions within and outside the brain, as well as known drug effectors and mechanisms of action.

CONCLUSION

This essential primer thus links together the cellular complexity of the brain, the chemical properties of key molecular players in neurotransmission, and possible biomedical opportunities.

Integrated Analysis of Alzheimer's Disease and Schizophrenia Dataset Revealed Different Expression Pattern in Learning and Memory

Alzheimer's disease (AD) and schizophrenia (SZ) are both accompanied by impaired learning and memory functions. This study aims to explore the expression profiles of learning or memory genes between AD and SZ. We downloaded 10 AD and 10 SZ datasets from GEO-NCBI for integrated analysis. These datasets were processed using RMA algorithm and a global renormalization for all studies. Then Empirical Bayes algorithm was used to find the differentially expressed genes between patients and controls. The results showed that most of the differentially expressed genes were related to AD whereas the gene expression profile was little affected in the SZ. Furthermore, in the aspects of the number of differentially expressed genes, the fold change and the brain region, there was a great difference in the expression of learning or memory related genes between AD and SZ. In AD, the CALB1, GABRA5, and TAC1 were significantly downregulated in whole brain, frontal lobe, temporal lobe, and hippocampus. However, in SZ, only two genes CRHBP and CX3CR1 were downregulated in hippocampus, and other brain regions were not affected. The effect of these genes on learning or memory impairment has been widely studied. It was suggested that these genes may play a crucial role in AD or SZ pathogenesis. The different gene expression patterns between AD and SZ on learning and memory functions in different brain regions revealed in our study may help to understand the different mechanism between two diseases.

Type 2 diabetes-induced neuronal pathology in the piriform cortex of the rat is reversed by the GLP-1 receptor agonist exendin-4

Type 2 diabetes (T2D) patients often present olfactory dysfunction. However, the histopathological basis behind this has not been previously shown. Since the piriform cortex plays a crucial role in olfaction, we hypothesize that pathological changes in this brain area can occur in T2D patients along aging. Thus, we determined potential neuropathology in the piriform cortex of T2D rats, along aging. Furthermore, we determined the potential therapeutic role of the glucagon-like peptide-1 receptor (GLP1-R) agonist exendin-4 to counteract the identified T2D-induced neuropathology.

Young-adult and middle-aged T2D Goto-Kakizaki rats were compared to age-matched Wistars. Additional Goto-Kakizaki rats were treated for six weeks with exendin-4/vehicle before sacrifice. Potential T2D-induced neuropathology was assessed by quantifying NeuN-positive neurons and Calbindin-D28k-positive interneurons by immunohistochemistry and stereology methods. We also quantitatively measured Calbindin-D28k neuronal morphology and JNK phosphorylation-mediated cellular stress. PI3K/AKT signalling was assessed by immunohistochemistry, and potential apoptosis by TUNEL.

We show T2D-induced neuronal pathology in the piriform cortex along aging, characterized by atypical nuclear NeuN staining and increased JNK phosphorylation, without apoptosis. We also demonstrate the specific vulnerability of Calbindin-D28k interneurons. Finally, chronic treatment with exendin-4 substantially reversed the identified neuronal pathology in correlation with decreased JNK and increased AKT phosphorylation.

Our results reveal the histopathological basis to explain T2D olfactory dysfunction. We also show that the identified T2D-neuropathology can be counteracted by GLP-1R activation supporting recent research promoting the use of GLP-1R agonists against brain diseases. Whether the identified neuropathology could represent an early hallmark of cognitive decline in T2D remains to be determined.

Diabetes negatively affects cortical and striatal GABAergic neurons: an effect that is partially counteracted by exendin-4

Diabetes negatively affects specific subtypes of inhibitory neurons in brain areas that regulate sensory and motor functions. This impairment can be partially reversed by exendin-4 (Ex-4). The findings could contribute to the development of treatments against diabetic neurological complications.

Type 2 diabetic (T2D) patients often develop early cognitive and sensorimotor impairments. The pathophysiological mechanisms behind these problems are largely unknown. Recent studies demonstrate that dysfunctional γ-aminobutyric acid (GABAergic) neurons are involved in age-related cognitive decline. We hypothesized that similar, but earlier dysfunction is taking place under T2D in the neocortex and striatum (two brain areas important for cognition and sensorimotor functions). We also hypothesized that the T2D-induced effects are pharmacologically reversible by anti-diabetic drugs targeting the glucagon-like peptide-1 receptor (GLP-1R). We determined the effect of T2D on cortical and striatal GABAergic neurons positive for glutamic acid decarboxylase-67 (GAD67), calbindin (CB), parvalbumin (PV) and calretinin (CR) by using immunohistochemistry and quantitative microscopy. Young and middle-aged T2D Goto-Kakizaki (GK) (a model of spontaneous T2D) and Wistar rats were used. Furthermore, we determined the therapeutic potential of the GLP1-R agonist exendin-4 (Ex-4) by treating middle-aged GK rats for 6 weeks with 0.1 μg/kg Ex-4 twice daily. We show that T2D reduced the density of GAD67-positive neurons in the striatum and of CB-positive neurons in both striatum and neocortex. T2D also increased the average volume of PV-positive interneurons in the striatum. Ex-4 treatment increased the density of CB-positive neurons in the striatum of GK rats. Our data demonstrate that T2D negatively affects GAD67 and CB-positive GABAergic neurons in the brain during aging, potentially identifying some of the pathophysiological mechanisms to explain the increased prevalence of neurological complications in T2D. We also show a specific, positive effect of Ex-4 on striatal CB-positive neurons, which could be exploited in therapeutic perspective.

DNA repair and aging: the impact of the p53 family

Cells are constantly exposed to endogenous and exogenous factors that threaten the integrity of their DNA. The maintenance of genome stability is of paramount importance in the prevention of both cancer and aging processes. To deal with DNA damage, cells put into operation a sophisticated and coordinated mechanism, collectively known as DNA damage response (DDR). The DDR orchestrates different cellular processes, such as DNA repair, senescence and apoptosis. Among the key factors of the DDR, the related proteins p53, p63 and p73, all belonging to the same family of transcription factors, play multiple relevant roles. Indeed, the members of this family are directly involved in the induction of cell cycle arrest that is necessary to allow the cells to repair. Alternatively, they can promote cell death in case of prolonged or irreparable DNA damage. They also take part in a more direct task by modulating the expression of core factors involved in the process of DNA repair or by directly interacting with them. In this review we will analyze the fundamental roles of the p53 family in the aging process through their multifaceted function in DDR.

Emerging roles of the single EF-hand Ca2+ sensor tescalcin in the regulation of gene expression, cell growth and differentiation

Tescalcin (TESC, also known as calcineurin-homologous protein 3, CHP3) is a 24-kDa EF-hand Ca²⁺-binding protein that has recently emerged as a regulator of cell differentiation and growth. The TESC gene has also been linked to human brain abnormalities, and high expression of tescalcin has been found in several cancers. The expression level of tescalcin changes dramatically during development and upon signal-induced cell differentiation. Recent studies have shown that tescalcin is not only subjected to up- or down-regulation, but also has an active role in pathways that drive cell growth and differentiation programs. At the molecular level, there is compelling experimental evidence showing that tescalcin can directly interact with and regulate the activities of the Na⁺/H⁺ exchanger NHE1, subunit 4 of the COP9 signalosome (CSN4) and protein kinase glycogen-synthase kinase 3 (GSK3). In hematopoetic precursor cells, tescalcin has been shown to couple activation of the extracellular signal-regulated kinase (ERK) cascade to the expression of transcription factors that control cell differentiation. The purpose of this Commentary is to summarize recent efforts that have served to characterize the biochemical, genetic and physiological attributes of tescalcin, and its unique role in the regulation of various cellular functions.

Chronic stress affects the number of GABAergic neurons in the orbitofrontal cortex of rats

Cortical GABAergic dysfunctions have been documented by clinical studies in major depression. We used here an animal model for depression and investigated whether long-term stress exposure can affect the number of GABAergic neurons in the orbitofrontal cortex (OFC). Adult male rats were subjected to 7-weeks of daily stress exposure and behaviorally phenotyped as anhedonic or stress-resilient animals. GABAergic interneurons were identified by immunohistochemistry and systematically quantified. We analyzed calbindin-(CB), calretinin-(CR), cholecystokinin-(CCK), parvalbumin-(PV), neuropeptide Y-(NPY) and somatostatin-positive (SST+) neurons in the following specific subareas of the OFC: medial orbital (MO), ventral orbital (VO), lateral orbital (LO) and dorsolateral orbital (DLO) cortex. For comparison, we also analyzed the primary motor cortex (M1) as a non-limbic cortical area. Stress had a pronounced effect on CB+ neurons and reduced their densities by 40-50% in the MO, VO and DLO. Stress had no effect on CCK+, CR+, PV+, NPY+ and SST+ neurons in any cortical areas. None of the investigated GABAergic neurons were affected by stress in the primary motor cortex. Interestingly, in the stress-resilient animals, we observed a significantly increased density of CCK+ neurons in the VO. NPY+ neuron densities were also significantly different between the anhedonic and stress-resilient rats, but only in the LO. Our present data demonstrate that chronic stress can specifically reduce the density of calbindin-positive GABAergic neurons in the orbitofrontal cortex and suggest that NPY and CCK expression in the OFC may relate to the stress resilience of the animals.

Organ of Corti explants direct tonotopically graded morphology of spiral ganglion neurons in vitro

The spiral ganglion is a compelling model system to examine how morphological form contributes to sensory function. While the ganglion is composed mainly of a single class of type I neurons that make simple one-to-one connections with inner hair cell sensory receptors, it has an elaborate overall morphological design. Specific features, such as soma size and axon outgrowth, are graded along the spiral contour of the cochlea. To begin to understand the interplay between different regulators of neuronal morphology, we cocultured neuron explants with peripheral target tissues removed from distinct cochlear locations. Interestingly, these "hair cell microisolates" were capable of both increasing and decreasing neuronal somata size, without adversely affecting survival. Moreover, axon characteristics elaborated de novo by the primary afferents in culture were systematically regulated by the sensory endorgan. Apparent peripheral nervous system (PNS)-like and central nervous system (CNS)-like axonal profiles were established in our cocultures allowing an analysis of putative PNS/CNS axon length ratios. As predicted from the in vivo organization, PNS-like axon bundles elaborated by apical cocultures were longer than their basal counterparts and this phenotype was methodically altered when neuron explants were cocultured with microisolates from disparate cochlear regions. Thus, location-dependent signals within the organ of Corti may set the "address" of neurons within the spiral ganglion, allowing them to elaborate the appropriate tonotopically associated morphological features in order to carry out their signaling function. J. Comp. Neurol. 524:2182-2207, 2016. © 2015 Wiley Periodicals, Inc.

Calbindin Knockout Alters Sex-Specific Regulation of Behavior and Gene Expression in Amygdala and Prefrontal Cortex

Calbindin-D(28K) (Calb1), a high-affinity calcium buffer/sensor, shows abundant expression in neurons and has been associated with a number of neurobehavioral diseases, many of which are sexually dimorphic in incidence. Behavioral and physiological end points are affected by experimental manipulations of calbindin levels, including disruption of spatial learning, hippocampal long-term potentiation, and circadian rhythms. In this study, we investigated novel aspects of calbindin function on social behavior, anxiety-like behavior, and fear conditioning in adult mice of both sexes by comparing wild-type to littermate Calb1 KO mice. Because Calb1 mRNA and protein are sexually dimorphic in some areas of the brain, we hypothesized that sex differences in behavioral responses of these behaviors would be eliminated or revealed in Calb1 KO mice. We also examined gene expression in the amygdala and prefrontal cortex, two areas of the brain intimately connected with limbic system control of the behaviors tested, in response to sex and genotype. Our results demonstrate that fear memory and social behavior are altered in male knockout mice, and Calb1 KO mice of both sexes show less anxiety. Moreover, gene expression studies of the amygdala and prefrontal cortex revealed several significant genotype and sex effects in genes related to brain-derived neurotrophic factor signaling, hormone receptors, histone deacetylases, and γ-aminobutyric acid signaling. Our findings are the first to directly link calbindin with affective and social behaviors in rodents; moreover, the results suggest that sex differences in calbindin protein influence behavior.

Types and density of calbindin D28k-immunoreactive ganglion cells in mouse retina

Single-cell injection after immunocytochemistry is a reliable technique for classifying neurons by their morphological structure and their expression of a particular protein. The aim of the present study was to classify the morphological types of calbindin D28k-immunoreactive retinal ganglion cells in the mouse using single-cell injection after immunocytochemistry, to estimate the density of calbindin D28k-immunoreactive retinal ganglion cells in the mouse retina. Calbindin D28k is an important calcium-binding protein that is widely expressed in the central nervous system. Calbindin D28k-immunoreactive retinal ganglion cells were identified by immunocytochemistry and then iontophoretically injected with the lipophilic dye, DiI. Subsequently, the injected cells were imaged by confocal microscopy to classify calbindin D28k-immunoreactive retinal ganglion cells based on their dendritic ramification depth within the inner plexiform layer, field size, and morphology. The cells were heterogeneous in morphology: monostratified or bistratified, with small to large dendritic field size and sparse to dense dendritic arbors. At least 10 different morphological types (CB1-CB10) of calbindin D28k-immunoreactive retinal ganglion cells were found in the mouse retina. The density of each cell type was quite variable (1.98-23.76%). The density of calbindin D28k-immunoreactive cells in the ganglion cell layer of the mouse retina was 562 cells/mm(2), 8.18% of calbindin D28k-immunoreactive cells were axon-less displaced amacrine cells, 91.82% were retinal ganglion cells, and approximately 18.17% of mouse retinal ganglion cells expressed calbindin D28k. The selective expression of calbindin D28k in cells with different morphologies may provide important data for further physiological studies of the mouse retina.

Coronary artery calcifications predict long term cardiovascular events in non diabetic Caucasian hemodialysis patients

Vascular calcifications are frequent in chronic renal disease and are associated to significant cardiovascular morbidity and mortality. The long term predictive value of coronary artery calcifications detected by multi-layer spiral computed tomography for major cardiovascular events was evaluated in non-diabetic Caucasian patients on maintenance hemodialysis free of clinical cardiovascular disease. Two-hundred and five patients on maintenance hemodialysis were enrolled into this observational, prospective cohort study. Patients underwent a single cardiac multi-layer spiral computed tomography. Calcium load was quantified and patients grouped according to the Agatston score: group 1 (Agatston score: 0), group 2 (Agatston score 1-400), group 3 (Agatston score 401-1000) and group 4 (Agatston score >1000). Follow-up was longer than seven years. Primary endpoint was death from a major cardiovascular event. Actuarial survival was calculated separately in the four groups with Kaplan-Meier method. Patients who died from causes other than cardiovascular disease and transplanted patients were censored. The “log rank” test was employed to compare survival curves. One-hundred two patients (49.7%) died for a major cardiovascular event during the follow-up period. Seven-year actuarial survival was more than 90% for groups 1 and 2, but failed to about 50% for group 3 and to <10% for group 4. Hence, Agatston score >400 predicts a significantly higher cardiovascular mortality compared with Agatston score <400 (p<0.0001); furthermore, serum Parathyroid hormone levels > 300 pg/l were associated to a lower survival (p < 0.05). Extended coronary artery calcifications detected by cardiac multi-layer spiral computed tomography, strongly predicted long term cardiovascular mortality in non-diabetic Caucasian patients on maintenance hemodialysis. Moreover, it was not related to conventional indices of atherosclerosis, but to other non-traditional risk factors, as serum Parathyroid hormone levels. A full cost-benefit analysis is however necessary to justify a widespread use of cardiac multi-layer spiral computed tomography in clinical practice.

The Relative Contribution of NMDARs to Excitatory Postsynaptic Currents is Controlled by Ca(2+)-Induced Inactivation

NMDA receptors (NMDARs) are important mediators of excitatory synaptic transmission and plasticity. A hallmark of these channels is their high permeability to Ca(2+). At the same time, they are themselves inhibited by the elevation of intracellular Ca(2+) concentration. It is unclear however, whether the Ca(2+) entry associated with single NMDAR mediated synaptic events is sufficient to self-inhibit their activation. Such auto-regulation would have important effects on the dynamics of synaptic excitation in several central neuronal networks. Therefore, we studied NMDAR-mediated synaptic currents in mouse hippocampal CA1 pyramidal neurons. Postsynaptic responses to subthreshold Schaffer collateral stimulation depended strongly on the absence or presence of intracellular Ca(2+) buffers. Loading of pyramidal cells with exogenous Ca(2+) buffers increased the amplitude and decay time of NMDAR mediated EPSCs (EPSPs) and prolonged the time window for action potential (AP) generation. Our data indicate that the Ca(2+) influx mediated by unitary synaptic events is sufficient to produce detectable self-inhibition of NMDARs even at a physiological Mg(2+) concentration. Therefore, the contribution of NMDARs to synaptic excitation is strongly controlled by both previous synaptic activity as well as by the Ca(2+) buffer capacity of postsynaptic neurons.

Chronic maternal morphine alters calbindin D-28k expression pattern in postnatal mouse brain

The distribution pattern of calbindin (CB)-D28k-expressing neurons results to be altered in several brain regions of chronic morphine exposed adult mice. In this study, the influence of chronic maternal exposure to morphine on the distribution pattern of CB-D28k-expressing neurons in the brain of mouse offspring was investigated. Females of CD-1 mice were daily administered with saline or morphine for 7 days before mating, during the whole gestation period, and until 21 day post-partum. Their offspring were sacrificed on postnatal day 18, and the brains were examined by histology using cresyl violet and by immunohistochemistry using a rabbit polyclonal anti-CB-D28k antibody. Histology revealed no significant differences in the distribution pattern and the number of neurons between the offspring forebrain of the control group of mice and the two groups of mice treated with different doses of morphine. However, immunohistochemical analysis revealed that the number of CB-D28k-immunoreactive neurons remarkably decreased in the cingulate cortex, in the layers II-IV of the parietal cortex and in all regions of the hippocampus, while it increased in the layers V-VI of the parietal cortex and in the subicular region of the offspring brain of morphine treated mice. Overall, our findings demonstrate that maternal exposure to morphine alters the pattern of CB-D28k-expressing neuron pattern in specific regions of murine developing brain, in a layer- and dose-dependent way, thus suggesting that these alterations might represent a mechanism by which morphine modifies the functional aspects of developing brain.

Analyzing and Quantifying the Gain-of-Function Enhancement of IP3 Receptor Gating by Familial Alzheimer's Disease-Causing Mutants in Presenilins

Familial Alzheimer’s disease (FAD)-causing mutant presenilins (PS) interact with inositol 1,4,5-trisphosphate (IP₃) receptor (IP₃R) Ca²⁺ release channels resulting in enhanced IP₃R channel gating in an amyloid beta (Aβ) production-independent manner. This gain-of-function enhancement of IP₃R activity is considered to be the main reason behind the upregulation of intracellular Ca²⁺ signaling in the presence of optimal and suboptimal stimuli and spontaneous Ca²⁺ signals observed in cells expressing mutant PS. In this paper, we employed computational modeling of single IP₃R channel activity records obtained under optimal Ca²⁺ and multiple IP₃ concentrations to gain deeper insights into the enhancement of IP₃R function. We found that in addition to the high occupancy of the high-activity (H) mode and the low occupancy of the low-activity (L) mode, IP₃R in FAD-causing mutant PS-expressing cells exhibits significantly longer mean life-time for the H mode and shorter life-time for the L mode, leading to shorter mean close-time and hence high open probability of the channel in comparison to IP₃R in cells expressing wild-type PS. The model is then used to extrapolate the behavior of the channel to a wide range of IP₃ and Ca²⁺ concentrations and quantify the sensitivity of IP₃R to its two ligands. We show that the gain-of-function enhancement is sensitive to both IP₃ and Ca²⁺ and that very small amount of IP₃ is required to stimulate IP₃R channels in the presence of FAD-causing mutant PS to the same level of activity as channels in control cells stimulated by significantly higher IP₃ concentrations. We further demonstrate with simulations that the relatively longer time spent by IP₃R in the H mode leads to the observed higher frequency of local Ca²⁺ signals, which can account for the more frequent global Ca²⁺ signals observed, while the enhanced activity of the channel at extremely low ligand concentrations will lead to spontaneous Ca²⁺ signals in cells expressing FAD-causing mutant PS.

Aberrant Ca²⁺ signaling caused by IP₃R gating dysregulation is implicated in many neurodegenerative diseases such as Alzheimer’s, Huntington’s, Spinocerebellar ataxias, and endoplasmic reticulum stress-induced brain damage. Thus understanding IP₃R dysfunction is important for the etiology of these diseases. It was previously shown that FAD-causing mutant PS interacts with the IP₃R, leading to its gain-of-function enhancement in optimal Ca²⁺ and sub-saturating IP₃ concentrations. Here, we use data-driven modeling to provide deeper insights into the upregulation of IP₃R gating in a wide range of ligand concentrations and quantify the sensitivity of the channel to its ligands in the presence of mutant PS. Our simulations demonstrate that these changes can alter the statistics of local Ca²⁺ events and we speculate that they lead to Ca²⁺ signaling dysregulations at the whole cell level observed in FAD cells. These models will provide the foundation for future data-driven computational framework for local and global Ca²⁺ signals that will be used to judiciously isolate the primary pathways causing Ca²⁺ dysregulation in FAD from those that are downstream, and to study the effects of upregulation of IP₃R activity on cell function.

Multifunctional Effects of Mangosteen Pericarp on Cognition in C57BL/6J and Triple Transgenic Alzheimer's Mice

Mangosteen- (Garcinia mangostana-) based nutraceutical compounds have long been reported to possess multiple health-promoting properties. The current study investigated whether mangosteen pericarp (MP) could attenuate cognitive dysfunction. First, we found that treatment with MP significantly reduced the cell death and increased the brain-derived neurotrophic factor (BDNF) level in an organotypic hippocampal slice culture (OHSC). We then investigated the effects of age and MP diet on the cognitive function of male C57BL/6J (B6) mice. After 8-month dietary supplementation, the MP diet (5000 ppm) significantly attenuated the cognitive impairment associated with anti-inflammation, increasing BDNF level and decreasing p-tau (phospho-tau S202) in older B6 mice. We further applied MP dietary supplementation to triple transgenic Alzheimer's disease (3×Tg-AD) mice from 5 to 13 months old. The MP diet exerted neuroprotective, antioxidative, and anti-inflammatory effects and reduced the Aβ deposition and p-tau (S202/S262) levels in the hippocampus of 3×Tg-AD mice, which might further attenuate the deficit in spatial memory retrieval. Thus, these results revealed that the multifunctional properties of MP might offer a promising supplementary diet to attenuate cognitive dysfunction in AD.