Claudio Cuello

eIF2α phosphorylation bidirectionally regulates the switch from short to long-term synaptic plasticity and memory

The late phase of long-term potentiation (LTP) and memory (LTM) requires new gene expression, but the molecular mechanisms that underlie these processes are not fully understood. Phosphorylation of eIF2alpha inhibits general translation but selectively stimulates translation of ATF4, a repressor of CREB-mediated late-LTP (L-LTP) and LTM. We used a pharmacogenetic bidirectional approach to examine the role of eIF2alpha phosphorylation in synaptic plasticity and behavioral learning. We show that in eIF2alpha(+/S51A) mice, in which eIF2alpha phosphorylation is reduced, the threshold for eliciting L-LTP in hippocampal slices is lowered, and memory is enhanced. In contrast, only early-LTP is evoked by repeated tetanic stimulation and LTM is impaired, when eIF2alpha phosphorylation is increased by injecting into the hippocampus a small molecule, Sal003, which prevents the dephosphorylation of eIF2alpha. These findings highlight the importance of a single phosphorylation site in eIF2alpha as a key regulator of L-LTP and LTM formation.

The hypothalamic arcuate nucleus-median eminence complex: Immunohistochemistry of transmitters, peptides and DARPP-32 with special reference to coexistence in dopamine neurons

In this paper, we describe the results of a series of experiments which have examined the distribution within the arcuate nucleus of the hypothalamus of neurons containing the following immunoreactivities: TH-LI, GAD-LI, NT-LI, GAL-LI, GRF-LI, Met-ENK-LI, Leu-ENK-LI, Met-ENK-7-LI, Met-ENK-8-LI, metorphamide-LI, DYN-LI, NPY-LI, SOM-LI, FMRFamide-LI, and CLIP-LI and ependymal tanycytes containing DARPP-32-LI. Using elution-restaining and double antibody staining techniques we have established numerous patterns of coexistence of these various neurotransmitters and neuropeptides. Thus, neurons containing TH-LI were, in some instances, also found to contain GAD-LI, NT-LI, GAL-LI, GRF-LI, Met-ENK-8-LI, Leu-ENK-LI, or DYN-LI or combinations of these compounds. For example, some TH-IR neurons also contained GAL-LI and GRF-LI, while other TH-IR. neurons were also seen to contain GRF- and NT-LI. These neurons may, in fact, contain even more compounds. NPY-IR neurons and those containing SOM-LI and CLIP-LI were distinct and separate from those containing TH-LI. The distribution of these different neurochemical types of neurons and their patterns of coexistence are summarized in Fig. 34, while the relative distribution patterns of immunoreactive fibres in the median eminence are summarized in Fig. 35.

Neurons with multiple messengers with special reference in neuroendocrine systems.

Publisher Summary This chapter presents the neurons with multiple messengers with special reference to neuroendocrine systems. Neurons of different types in the periphery and in the central nervous system, including neurosecretory cells, produce, store, and perhaps release more than one messenger molecule. The coexisting messengers in primitive neurons are stored in the same vesicles, as they are in mammalian endocrine cells at present. With the demand for faster communication, new types of vesicles, small synaptic vesicles, developed storing and releasing exclusively classical transmitters, being present in addition to the larger vesicles storing both classical transmitter and peptide(s). Interestingly, the neurosecretory cells, representing an intermediate between endocrine cells and neurons, contain a higher proportion of large dense core vesicles than neurons releasing their messengers at more or less well defined synapses. Studies in the peripheral nervous system suggest that the classical transmitters and peptides are, indeed, co-released and may interact in a cooperative way on effector cells. Therefore, interaction between different messengers released from the same nerve endings may be of several types and may, in a general sense, provide mechanisms for differential responses and for increasing the amount of information transferred at synapses. Multi-messenger transmission may represent a principle for increasing capacity for information transfer in the nervous system, a capacity which already appears enormous when considering just the number of neurons and their nerve endings in the mammalian nervous system. At present, the importance of peptides is in many cases difficult to evaluate, and it cannot be excluded that their role is considerably less significant than that of the classical transmitters.

Cholinergic and GABAergic neurotoxicity of some alkylating agents

A series of nitrogen mustard derivatives was tested for neurotoxic effects on cholinergic and GABAergic markers at three rat brain regions: hippocampus, striatum and cortex. All compounds were administered intracerebroventricularly, and the enzymatic activities were measured 7 days after treatment. The effects of synthesised nitrogen mustard derivatives with indole, quinoline and hemicholinium backbone structures were compared. Of these compounds, only the hemicholinium analogue showed some preferential neurotoxicity to cholinergic neurones, thus offering a basis for designing novel, more specific cholinergic neurotoxins.

COMBINED GLOBAL AND REGIONAL AMYLOID EFFECT ON THE DEFAULT MODE NETWORK LEADS TO COGNITIVE DECLINE

Figure 2. Tharick A. Pascoal, Sulantha S. Mathotaarachchi, Min Su Kang, Monica Shin, Andrea Lessa Benedet, Jean-Paul Soucy, Claudio Cuello, Serge Gauthier, Pedro Rosa-Neto, Hanne Struyfs, Kok Pin Ng, Joseph Therriault, McGill University, Montreal, QC, Canada; McGill University Research Centre for Studies in Aging, Verdun, QC, Canada; Centre for Studies on Prevention of Alzheimer’s Disease (StoP-AD Centre), Douglas Mental Health Institute, Verdun, QC, Canada; Douglas Mental Health Institute, Montreal, QC, Canada; Translational Neuroimaging Laboratory McGill University, Verdun, QC, Canada; PERFORM Centre Concordia University, Montr eal, QC, Canada; University of Montreal Hospital Centre, Montreal, QC, Canada; Douglas Hospital Research Centre, Verdun, QC, Canada; Douglas Mental Health University Institute, Montreal, QC, Canada; Reference Center for Biological Markers of Dementia (BIODEM), Laboratory of Neurochemistry and Behavior, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium; Institute Born-Bunge, University of Antwerp, Antwerp, Belgium; NationalNeuroscience Institute, Singapore, Singapore. Contact e-mail: tharick. alipascoal@mail.mcgill.ca

PRECLINICAL ASSESSMENT OF KAL-ABP TARGET ENGAGEMENT AND EFFICACY USING PET, MRI AND CSF BIOMARKERS

Background: Several lines of evidence suggest a central role of amyloid-b-peptide (Ab) in the pathogenesis of Alzheimer’s disease (AD). More than Ab fibrils, small soluble and prion-like propagating Ab oligomers are suspected to be the major toxic species responsible for disease development and progression. Therefore, eradication of these Ab oligomers is our principal objective for therapy of AD. Previously, we have identified the fully D-enantiomeric peptide D3 by mirror image phage display selection and showed that it was able to specifically eliminate Ab oligomers and convert them into nontoxic species. D3 was able to reduce plaque load in transgenic AD mouse models, and improved cognition even after oral application [1]. More recently, we developed derivatives of D3 with improved properties during a lead optimization strategy that focused primarily on the Ab oligomer elimination efficiency. Methods:We used our newly developed Ab-QIAD (quantitative determination of interference with Ab aggregate size distribution) to quantitatively measure Ab oligomer elimination efficiency and thus target engagement [2]. Morris water maze and novel object recognition experiments in several transgenic mouse models were used to measure cognition enhancement of the compounds. SHIRPA and Rotarod assays were used to follow neurodegeneration in the TBA2.1 mouse model and its inhibition by our compounds. Results:As expected from D-peptides, D3 and its derivatives showed superior pharmacokinetic properties, such as long half-lives and high oral bioavailability [3, 4]. The presented compounds were able to eliminate Ab oligomers as well as to enhance cognition and slow down neurodegeneration even after oral application. In addition, I will summarize our newest data, including stability, pharmacokinetic and pre-clinical safety data on our most efficient drug candidate for its first in man, first in class, clinical phase I study. Conclusions:D-enentiomeric peptides that specifically and efficiently eliminate Ab oligomers are able to enhance cognition and impede neurodegeneration even when orally applied. [1] Funke et al., ACS Chem. Neurosci. 1, 639-648 (2010). [2] Brener et al., Sci. Rep. 5, 13222 (2015). [3] Jiang et al., PLoS One 10, e0128553 (2015). [4] Leithold et al., Pharm Res. 33, 33(2):328336 (2016).

EARLY REMODELING OF BRAIN METABOLIC ARCHITECTURE IN A TRANSGENIC RAT MODEL OF ALZHEIMER'S DISEASE

Conclusions: [18 F]NAV4694 (K D 1⁄42.4nM) has a wider dynamic range than [11 C]PIB (K D 1⁄44.5nM) possibly due to high affinity. Additionally, ratio between CER and WM was significantly higher for [18 F]NAV4694, which suggests lower non-specific binding than [11 C]PiB. The competition study showed that [18 F]NAV4694 cannot be fully displaced by [11 C]PIB in the HIP, which suggests binding in early forms of amyloid. Finally, these robust in vitro properties support the unique binding properties of [18 F] NAV4694 and highlight the potential of [18 F]NAV4694 for early diagnosis in AD.

AMYLOIDOSIS CHANGES ASSOCIATIONS BETWEEN HIPPOCAMPUS VOLUME AND BRAIN METABOLIC DECLINES

BETWEEN HIPPOCAMPUS VOLUME AND BRAIN METABOLIC DECLINES Min Su Kang, Maxime Parent, Monica Shin, Eduardo Rigon Zimmer, Antonia Aliaga, Axel Mathieu, Sulantha Sanjeewa Mathotaarachchi, Sara Mohades, Sarinporn Manitsirikul, Jean-Paul Soucy, Serge Gauthier, Claudio Cuello, Pedro Rosa-Neto, McGill University, Verdun, Quebec, Canada; McGill University, Montreal, Quebec, Canada; McGill University, Montreal, Quebec, Canada; Douglas Hospital, Verdun, Quebec, Canada; 5 McGill Center-McGill Centre for Studies in Aging, Montreal, Quebec, Canada; 6 McGill Center for Studies in Aging, Montreal, Quebec, Canada; McGill University, Montreal, Quebec, Canada. Contact e-mail: peter.ms.kang@gmail.com

Assessment of hippocampal volumetry in a transgenic Alzheimer's disease rat

pial towhite matter surfaces were computed across the entire cerebral cortex using an automated image processing method. An intensity profile was generated along each streamline for b-amyloid, GFAP, and NeuN qIHC volumes, and these profiles were averaged over neuroanatomical regions-ofinterest. Comparisons were performed between Tg and WT groups. Results:Distinct cortical laminar profiles were observed for b-amyloid and astrocytes in the Tg mice. While heavy bands of astrogliosis were typically found in superficial and deep cortex, b-amyloid deposits were most abundant in the mid-cortical layers. We also identified previously unreported differences in the regional, multi-parametric, cortical laminar profiles between Tg andWTmice.Conclusions:Our robust, fully-automated method for extraction of cortical laminar profiles of multiple, co-registered IHC markers across the entire mouse cerebral cortex revealed unique observations regarding the patterns of AD-associated alterations in APP Tg mice. We are currently generating similar laminar profiles of vascular and synaptic density in order to obtain a comprehensive picture of neuronal, glial, and vascular pathological changes. Future studies will interrogate the relationships between these cellular measures and in vivo structural and functional imaging data, which will improve our understanding of the complex pathophysiological process underlying AD.

Characterization of APPsi transgenic rats for cognitive deficits and brain pathology

Background:Alzheimer’s disease is one of themost devastating neurodegenerative diseases of the 21st century. Pathological aggregation of the amyloid precursor protein (APP) in the brain of AD patients is thought to be one of themain causes for the observed progressive cognitive decline in affected people. So far, mostly transgenic mouse models are used to mimic the pathology of AD. Some o these models reflect the pathology of AD strikingly well but harbor the disadvantages of mice models in general.Methods:We therefore characterized the transgenic rat model by Claudio Cuello and his team (Leon et al. 2010) that expresses the human APP751 cDNAwith Swedish (K679N/ N671L) and Indiana (V717F) mutations under the regulatory control of the rat Thy-1 promoter. High-APP expressing animals of both sexes were tested over age for behavioral deficits like general health, activity andmemory in the open field test, forced swim test, elevated plusmaze,Morris watermaze, new object recognition and passive avoidance test. Brain, CSF and plasma amyloid b38, 40 and 42 levels were analyzed using the immunosorbent assay MSD-ISA. Brain pathology was assessed immunohistologically for amyloid and amyloid depositions and for brain inflammation i.e. astrogliosis and activated microglia. Results: Our results show that these rats have altered activity levels and memory deficits as measured by different cognitive tests already in early age. Furthermore, amyloid b38, 40 and 42 levels in the cerebrospinal fluid and in the brain of rats increase over age and this can be supported by brain amyloid immunohistochemical results. Accordingly, brain inflammation, which is altered already in the youngest age group, is elevated in all age groups. Conclusions: This transgenic rat model thus not only provides AD specific behavioral deficits but also corresponding brain pathology that starts earl y and increases over age. Since rats are more suitable to performmost behavioral tests compared to mice the APPsi transgenic rat model presents an appropriate alternative to well established transgenic APP mouse models for AD research as well as novel compound tests against AD.