Dynamics, localization and activation of NF-kappa B during long-term memory consolidation in mice

NF-kappa B es un factor de transcripción cuya activación es necesaria para laconsolidación de la memoria a largo plazo en varias especies. Este factor de transcripciónse activa y se transloca al núcleo de las células en una ventana temporal específica durantela consolidación. NF-kappa B tiene una amplia distribución en el sistema nervioso, con unafuerte presencia en dendritas y terminales sinápticas. Esta tesis se centra en la activación,localización y dinámica de NF-kappa B en tareas de aprendizaje que se adquieren con unsolo ensayo, la evitación inhibitoria (IA) y una tarea adquirida en el mismo contexto pero designo opuesto. Los ratones son entrenados de dos modos diferentes; ya sea recibiendo o no unestímulo eléctrico al entrar en un compartimiento oscuro (aversivo con choque eléctrico vs.apetitivo sin choque). Cuarenta y ocho horas después el desempeño de los animales esevaluado. Durante la sesión de evaluación, las latencias de entrada al compartimientooscuro (independientemente del tipo de entrenamiento) fueron significativamente diferentesal día de entrenamiento y a las latencias de un grupo control que en el día delentrenamiento recibe un choque no relacionado con el contexto. Además, la actividadnuclear de NF-kappa B se vió aumentada durante la consolidación de ambas tareascomparando con animales control y naïve. La inhibición de NF-kappa B con sulfasalazinainyectada en el hipocampo, amígdala o el núcleo accumbens inmediatamente luego delentrenamiento produjo un deterioro en la retención de la memoria en ambas versiones de latarea. Los resultados sugieren que en ratón, NF-kappa B es un paso molecular crítico endiferentes áreas del cerebro para la consolidación de la memoria de largo término en unatarea de evitación inhibitoria y en una versión “apetitiva” de la misma. La activación de este factor de transcripción en el núcleo de las células delhipocampo ha sido descrita a exhaustivamente. La presencia del factor de transcripción enla sinapsis nos llevó a investigar un posible rol local en la sinapsis, activación y dinámica eneste sitio. En este trabajo se describen los cambios en la localización sináptica de NF-kappa B y de su actividad, durante la consolidación de la memoria a largo plazo, tanto de la tareaaversiva como apetitiva asociada al IA. La comparación de la actividad sinaptosomal ynuclear de NF-kappa B indican diferentes dinámicas para ambas localizaciones. Además,se identifican dos fracciones de NF-kappa B sinaptosomal, una que se obtiene soluble en elcontenido sinaptosomal (fracción libre) y la otra se encuentra fuertemente unida a lasmembranas sinaptosomales. Durante las primeras etapas de la consolidación la fracciónlibre se activa, la fracción asociada a membrana aumenta mientras que la cantidad de lafracción libre disminuye. Estos resultados sugieren que la activación sináptica de NF-kappa B y su translocación a membranas son parte de la consolidación de la memoria a largoplazo en ratones. Existen evidencias que demuestran que NF-kappa B se activa a través de laactividad del receptor de NMDA. Tomando en cuenta este dato se apuntó a disociar la señaleléctrica que llega al núcleo de la señal de transducción molecular local en la sinapsis paraestudiar la función sináptica local del NF-kappa B. Para abordar este objetivo se trabajó conpéptidos que impiden la interacción de PSD-95 (proteína de andamiaje postsináptico) con elreceptor de NMDA. En este trabajo se muestra que la inyección intra-hipocampo de estepéptido interfiere de forma reversible con la consolidación de la memoria de Evitación Inhibitoria (IA). Los resultados presentados en esta tesis aportan datos cruciales para entender lafunción sináptica local del NF-kappa B durante la consolidación de la memoria, tanto paralas tareas de aprendizaje aversivas como apetitivas.NF-kappa B is a transcription factor whose activation has been shown to benecessary for long-term memory consolidation in several species. This transcription factor isactivated and translocates to the nucleus of cells in a specific temporal window duringconsolidation. NF-kappa B has a wide distribution in the nervous system, with awell-reported presence in dendrites and synaptic terminals. This thesis focuses on theactivation, localization and dynamics of NF-kappa B in a one trial learning task associated tothe inhibitory avoidance (IA) setting. Mice were trained either receiving or not a footshock when entering a darkcompartment (aversive vs “appetitive” learning). Forty eight hours after training, latencies tostep-through regardless of its training condition were significantly different from training dayand from testing latencies of a control group that only receives a shock unrelated to context. Moreover, nuclear NF-kappa B DNA-binding activity was augmented in the aversive and theappetitive tasks when compared with control and naïve animals. NF-kappa B inhibition by Sulfasalazine injected either in the Hippocampus, Amygdala or Nucleus Accumbensimmediately after training was able to impair retention in both training versions. The resultssuggest that NF-kappa B is a critical molecular step, in different brain areas on memoryconsolidation. The activation of NF-kappa B in the nucleus has been thoroughly described ofhippocampal cells but the presence of the transcription factor at the synapse led us toinvestigate a possible local role, activation and dynamics at this site. Here I report changesin synaptosomal NF-kappa B synaptic localization and activity, during long-term memoryconsolidation of both the aversive and appetitive learning tasks associated to the IA. Activitycomparison of synaptosomal and nuclear NF-kappa B, indicate different dynamics for bothlocalizations. In this work two pools of synaptosomal NF-kappa B are identified, oneobtained with the synaptoplasm (free fraction) and the second bound to the synaptosomalmembranes. During the early steps of consolidation the first pool is activated, as themembrane associated transcription factor fraction increases and concomitantly the freefraction decreases. These results suggest that the activation of synaptic NF-kappa B and itstranslocation to membranes are part of the consolidation of long-term memory in mice. It has been reported that NF-kappa B is activated through NMDA receptor activity. Taking this data into account, I aimed to dissociate the electrical signal that reaches thenucleus of the local molecular transduction signal at the synapse, to study the local synapticfunction of NF-kappa B. To address this I worked with peptides that impede the interaction of PSD-95 (postsynaptic scaffold protein) with the NMDA receptor. This work shows that theintra-hippocampus injection of this peptide reversibly interferes with the consolidation ofmemory in the aversive version of task IA. The results presented in this thesis lay valuable groundwork for future investigation ofthe local synaptic role of NF-kappa B during memory consolidation, both for aversive andappetitive learning tasks.Fil: Salles, Angeles. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

A 2.6-gram sound and movement tag for studying the acoustic scene and kinematics of echolocating bats

This study was supported by the Carlsberg Foundation via a Semper Ardens grant, ONR, N00014-17-1- 2736; AFOSR FA9550-14-1-0398, and NSF NCS-FO:1734744 and a Human Frontiers Science Program Long-Term Fellowship to AS. These experiments were approved by The Danish Council for Experiments on Animals under permit number: 2016-15-0201-00989 and by the Johns Hopkins University Animal Care and Use Committee under protocol number BA17A107. We thank Uwe Firzlaff and Lutz Wiegrebe for their help.1. To study sensorimotor behaviour in wild animals, it is necessary to synchronously record the sensory inputs available to the animal, and its movements. To do this, we have developed a biologging device that can record the primary sensory information and the associated movements during foraging and navigating in echolocating bats. 2. This 2.6 -gram tag records the sonar calls and echoes from an ultrasonic microphone, while simultaneously sampling fine-scale movement in three dimensions from wideband accelerometers and magnetometers. In this study, we tested the tag on an European noctula (Nyctalus noctula) during target approaches and on four big brown bats (Eptesicus fuscus) during prey interception in a flight room. 3. We show that the tag records both the outgoing calls and echoes returning from objects at biologically relevant distances. Inertial sensor data enables the detection of behavioural events such as flying, turning, and resting. In addition, individual wing-beats can be tracked and synchronized to the bat's sound emissions to study the coordination of different motor events. 4. By recording the primary acoustic flow of bats concomitant with associated behaviours on a very fine time-scale, this type of biologging method will foster a deeper understanding of how sensory inputs guide feeding behaviours in the wild.PostprintPeer reviewe

Crucial role for sensory nerves and Na/H exchanger inhibition in dapagliflozin and empagliflozin-induced arterial relaxation.

AIMS: Sodium/glucose transporter 2 (SGLT2 or SLC5A2) inhibitors lower blood glucose and are also approved treatments for heart failure independent of raised glucose. Various studies have showed that SGLT2 inhibitors relax arteries but the underlying mechanisms are poorly understood and responses variable across arterial beds. We speculated that SGLT2 inhibitor-mediated arterial relaxation is dependent upon calcitonin gene-related peptide (CGRP) from sensory nerves independent of glucose transport. METHODS AND RESULTS: The functional effects of SGLT1 and 2 inhibitors (mizagliflozin, dapagliflozin, empagliflozin) and the sodium/hydrogen exchanger 1 (NHE1) blocker cariporide were determined on pre-contracted resistance arteries (mesenteric and cardiac septal arteries) as well as main renal conduit arteries from male Wistar rats using Wire-Myography. SGLT2, CGRP, TRPV1 and NHE1, expression was determined by Western blot and immunohistochemistry. Kv7.4/5/KCNE4 and TRPV1 currents were measured in the presence and absence of dapagliflozin and empagliflozin.All SGLT inhibitors (1µM-100µM) and cariporide (30µM) relaxed mesenteric arteries but had negligible effect on renal or septal arteries. Immunohistochemistry with TRPV1 and CGRP antibodies revealed a dense innervation of sensory nerves in mesenteric arteries that were absent in renal and septal arteries. Consistent with a greater sensory nerve component, the TRPV1 agonist capsaicin relaxed mesenteric arteries more effectively than renal or septal arteries. In mesenteric arteries, relaxations to dapagliflozin, empagliflozin and cariporide were attenuated by the CGRP receptor antagonist BIBN-4096, depletion of sensory nerves with capsaicin, and blockade of TRPV1 or Kv7 channels. Neither dapagliflozin nor empagliflozin activated heterologously expressed TRPV1 channels or Kv7 channels directly. Sensory nerves also expressed NHE1 but not SGLT2 and cariporide pre-application as well as knockdown of NHE1 by translation stop morpholinos prevented the relaxant response to SGLT2 inhibitors. CONCLUSIONS: SGLT2 inhibitors relax mesenteric arteries by promoting the release of CGRP from sensory nerves in a NHE1-dependent manner

Adaptive Echolocation and Flight Behaviors in Bats Can Inspire Technology Innovations for Sonar Tracking and Interception

Target tracking and interception in a dynamic world proves to be a fundamental challenge faced by both animals and artificial systems. To track moving objects under natural conditions, agents must employ strategies to mitigate interference and conditions of uncertainty. Animal studies of prey tracking and capture reveal biological solutions, which can inspire new technologies, particularly for operations in complex and noisy environments. By reviewing research on target tracking and interception by echolocating bats, we aim to highlight biological solutions that could inform new approaches to artificial sonar tracking and navigation systems. Most bat species use wideband echolocation signals to navigate dense forests and hunt for evasive insects in the dark. Importantly, bats exhibit rapid adaptations in flight trajectory, sonar beam aim, and echolocation signal design, which appear to be key to the success of these animals in a variety of tasks. The rich suite of adaptive behaviors of echolocating bats could be leveraged in new sonar tracking technologies by implementing dynamic sensorimotor feedback control of wideband sonar signal design, head, and ear movements

Synaptic NF-kappa B pathway in neuronal plasticity and memory

Several transcription factors are present at the synapse, and among these are the Rel-NF-kappa B pathway components. NF-kappa B is a constitutive transcription factor, with a strong presence in the brain of which a considerable part is located in the neuropiles. This localization of the transcription factor, plus evidence pointing to different functions, is what gave place to two general hypotheses for synaptic NF-kappa B: (a) The transcription factor plays a role in the synapse to nucleus communication, and it is retrogradely transported from polarized localizations to regulate gene expression; (b) The transcription factor modulates the synaptic function locally. Evidence indicates that both mechanisms can operate simultaneously; here we will present different possibilities of these hypotheses that are supported by an increasing amount of data. We pay special attention to the local role of the transcription factor at the synapse, and based in the described evidence from different animal models, we propose several processes in which the transcription factor may change the synaptic strength.Fil: Salles, Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Romano, Arturo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Freudenthal, Ramiro A. M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Surface expression of NMDA receptor changes during memory consolidation in the crab Neohelice granulata

The aim of the present study was to analyze the surface expression of the NMDA-like receptors during the consolidation of contextual learning in the crab Neohelice granulata. Memory storage is based on alterations in the strength of synaptic connections between neurons. The glutamatergic synapses undergo various forms of N-methyl-D aspartate receptor (NMDAR)-dependent changes in strength, a process that affects the abundance of other receptors at the synapse and underlies some forms of learning and memory. Here we propose a direct regulation of the NMDAR. Changes in NMDAR's functionality might be induced by the modification of the subunit's expression or cellular trafficking. This trafficking does not only include NMDAR's movement between synaptic and extra-synaptic localizations but also the cycling between intracellular compartments and the plasma membrane, a process called surface expression. Consolidation of contextual learning affects the surface expression of the receptor without affecting its general expression. The surface expression of the GluN1 subunit of the NMDAR is down-regulated immediately after training, up-regulated 3 h after training and returns to nave and control levels 24 h after training. The changes in NMDAR surface expression observed in the central brain are not seen in the thoracic ganglion. A similar increment in surface expression of GluN1 in the central brain is observed 3 h after administration of the competitive GABAA receptor antagonist, bicuculline. These consolidation changes are part of a plasticity event that first, during the down-regulation, stabilizes the trace and later, at 3-h post-training, changes the threshold for synapse activation.Fil: Hepp, Yanil. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Salles, Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Carbo, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Pedreira, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Freudenthal, Ramiro A. M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Auditory processing of communication calls in interacting bats

Summary: There is strong evidence that social context plays a role in the processing of acoustic signals. Yet, the circuits and mechanisms that govern this process are still not fully understood. The insectivorous big brown bat, Eptesicus fuscus, emits a wide array of communication calls, including food-claiming calls, aggressive calls, and appeasement calls. We implemented a competitive foraging task to explore the influence of behavioral context on auditory midbrain responses to conspecific social calls. We recorded neural population responses from the inferior colliculus (IC) of freely interacting bats and analyzed data with respect to social context. Analysis of our neural recordings from the IC shows stronger population responses to individual calls during social events. For the first time, neural recordings from the IC of a copulating bat were obtained. Our results indicate that social context enhances neuronal population responses to social vocalizations in the bat IC