Marta Maschietto

A potential role for the vanilloid receptor TRPV1 in the therapeutic effect of curcumin in dinitrobenzene sulphonic acid-induced colitis in mice

Abstract  A protective role of the transient potential vanilloid receptor 1 (TRPV1) in intestinal inflammation induced by dinitrobenzene sulphonic acid (DNBS) has been recently demonstrated. Curcumin, the major active component of turmeric, is also able to prevent and ameliorate the severity of the damage in DNBS‐induced colitis. We evaluated the possibility that curcumin (45 mg kg−1 day p.o. for 2 days before and 5 days after the induction of colitis) was able to reduce DNBS‐induced colitis in mice, by acting as a TRPV1 agonist. Macroscopic damage score, histological damage score and colonic myeloperoxidase (MPO) activity were significantly lower (by 71%, 65% and 73%, respectively; P < 0.01), in animals treated with curcumin compared with untreated animals. Capsazepine (30 mg kg−1, i.p.), a TRPV1 receptor antagonist, completely abolished the protective effects of curcumin. To extend these data in vitro, Xenopus oocytes expressing rat TRPV1 were examined. Capsaicin‐evoked currents (3.3 μmol L−1) disappeared subsequent either to removal of the agonist or subsequent to the addition of capsazepine. However, curcumin (30 μmol L−1) was ineffective both as regard direct modification of cell membrane currents and as regard interference with capsaicin‐mediated effects. As sensitization of the TRPV1 receptor by mediators of inflammation in damaged tissues has been shown previously, our results suggest that in inflamed, but not in normal tissue, curcumin can interact with the TRPV1 receptor to mediate its protective action in DNBS‐induced colitis.

Space and time-resolved gene expression experiments on cultured mammalian cells by a single-cell electroporation microarray

Single-cell experiments represent the next frontier for biochemical and gene expression research. Although bulk-scale methods averaging populations of cells have been traditionally used to investigate cellular behavior, they mask individual cell features and can lead to misleading or insufficient biological results. We report on a single-cell electroporation microarray enabling the transfection of pre-selected individual cells at different sites within the same culture (space-resolved), at arbitrarily chosen time points and even sequentially to the same cells (time-resolved). Delivery of impermeant molecules by single-cell electroporation was first proven to be finely tunable by acting on the electroporation protocol and then optimized for transfection of nucleic acids into Chinese Hamster Ovary (CHO-K1) cells. We focused on DNA oligonucleotides (ODNs), short interfering RNAs (siRNAs), and DNA plasmid vectors, thus providing a versatile and easy-to-use platform for time-resolved gene expression experiments in single mammalian cells.

SigMate: A MATLAB-based neuronal signal processing tool

Advances in neuronal probe technology to record brain activity have posed a significant challenge in performing necessary processing and analysis of the recorded data. To be able to infer meaningful conclusions from the recorded signals through these probes, sophisticated signal processing and analysis tools are required. This paper presents a MATLAB-based novel tool, ‘SigMate’, capable of performing various processing and analysis incorporating the available standard tools and our in-house custom tools. The present features include, data display (2D and 3D), baseline correction, stimulus artifact removal, noise characterization, file operations (file splitter, file concatenator, and file column rearranger), latency estimation, determination of cortical layer activation order, spike detection, spike sorting, and are gradually growing. This tool has been tested extensively for the recordings using the standard micropipettes as well as implantable neural probes based on EOSFETs (Electrolyte-Oxide-Semiconductor Field Effect Transistors) and will be made available to the community shortly.

On the Way to Large-Scale and High-Resolution Brain-Chip Interfacing

Brain-chip-interfaces (BCHIs) are hybrid entities where chips and nerve cells establish a close physical interaction allowing the transfer of information in one or both directions. Typical examples are represented by multi-site-recording chips interfaced to cultured neurons, cultured/acute brain slices, or implanted “in vivo”. This paper provides an overview on recent achievements in our laboratory in the field of BCHIs leading to enhancement of signals transmission from nerve cells to chip or from chip to nerve cells with an emphasis on in vivo interfacing, either in terms of signal-to-noise ratio or of spatiotemporal resolution. Oxide-insulated chips featuring large-scale and high-resolution arrays of stimulation and recording elements are presented as a promising technology for high spatiotemporal resolution interfacing, as recently demonstrated by recordings obtained from hippocampal slices and brain cortex in implanted animals. Finally, we report on an automated tool for processing and analysis of acquired signals by BCHIs.

Automatic detection of layer activation order in information processing pathways of rat barrel cortex under mechanical whisker stimulation

Whisking is the natural way by which rodents explore the environment. During whisking, microcircuits in the corresponding barrel columns get activated to segregate and integrate the tactile information through the information processing pathway. The local field potentials (LFPs) recorded from the barrel columns provide important information about this pathway. Different layers of the cortex get activated during this information processing, thus having precise information about the order of layer activation is desired. This work proposes an automated, computationally efficient and easy to implement method to determine the cortical layer activation for the signals recorded from barrel cortex of anesthetized rats upon mechanical whisker stimulation.

A High Resolution Bi-Directional Communication through a Brain-Chip Interface

Existing brain-machine interfacing techniques allow either high precision recordings from one or a few single neurons, or low spatial resolution recordings with a sparse sampling within the networks. Through our app-roach an efficient simultaneous bidirectional communication to the brain is realized using capacitively coupled recording and stimulation sites arranged in a large 2D multi-transistor array (MTA) with 1000 elements, integrated to a planar chip at high resolution (10μm pitch and below). The aim of the present work is to evaluate the reliability of a simple-generation silicon micro-device in recording neuronal signals from rat brain. Simultaneous recording of signals using this chip from the somatosensory cortex (S1) of living rat, are compared to standard in vivo recordings with a glass micropipette. We show that the two types of signals are identical, indicating the possibility to record signals at the same time from different sites and to perform a real-time electrical imaging of the brain cortex in vivo.

Slow Stimulus Artifact Removal through Peak-Valley Detection of Neuronal Signals Recorded from Somatosensory Cortex by High Resolution Brain-Chip Interface

The analysis of stimulus evoked potentials recorded using high resolution chips are very useful in understanding brain activity with greater details. However, the stimulus induced signals are often contaminated with stimulus artifacts. The artifact removal technique here discussed removes all such contaminations caused by the stimuli. The usage of peak-valley detection in estimating the artifact signature provides the benefit of removing these unwanted artifacts from the real neuronal recordings, diminishing the barrier of artifact shape and duration imposed by many existing techniques. Also, this technique provides the flexibility of automatic batch processing of neuronal signals. The artifact signature is estimated through the detection of peaks-and-valleys based on a threshold calculated using the signal’s standard deviation, thus overcoming the manual threshold selection. This technique provides the advantages of being simple, straightforward, and computationally efficient. The peak-valley detection approach has been demonstrated to be an efficient and accurate artifact and offset (baseline correction) removal method, as validated by analyzing high-resolution recordings from the rat somatosensory cortex (S1).

Intranasal Oxytocin and Vasopressin Modulate Divergent Brainwide Functional Substrates

The neuropeptides oxytocin (OXT) and vasopressin (AVP) have been identified as modulators of emotional social behaviors and associated with neuropsychiatric disorders characterized by social dysfunction. Experimental and therapeutic use of OXT and AVP via the intranasal route is the subject of extensive clinical research. However, the large-scale functional substrates directly engaged by these peptides and their functional dynamics remain elusive. By using cerebral blood volume (CBV) weighted fMRI in the mouse, we show that intranasal administration of OXT rapidly elicits the transient activation of cortical regions and a sustained activation of hippocampal and forebrain areas characterized by high oxytocin receptor density. By contrast, intranasal administration of AVP produced a robust and sustained deactivation in cortico-parietal, thalamic and mesolimbic regions. Importantly, intravenous administration of OXT and AVP did not recapitulate the patterns of modulation produced by intranasal dosing, supporting a central origin of the observed functional changes. In keeping with this notion, hippocampal local field potential recordings revealed multi-band power increases upon intranasal OXT administration. We also show that the selective OXT-derivative TGOT reproduced the pattern of activation elicited by OXT and that the deletion of OXT receptors does not affect AVP-mediated deactivation. Collectively, our data document divergent modulation of brainwide neural systems by intranasal administration of OXT and AVP, an effect that involves key substrates of social and emotional behavior. The observed divergence calls for a deeper investigation of the systems-level mechanisms by which exogenous OXT and AVP modulate brain function and exert their putative therapeutic effects.

A contour based automatic method to classify Local Field Potentials recorded from rat barrel cortex

Whisking is the natural way for the rodents to explore the environment. Using the Local Field Potentials (LFPs) recorded from the barrel columns of the rat somatosensory cortex (S1) is one of the ways to extract information about the signal processing pathway during tactile information processing. Studies have shown that intra-and trans-columnar microcircuits in the barrel cortex segregate and integrate information during this pathway activation. During each experiment many single sweeps (sometimes referred as raw traces) of signal are recorded as a result of underlying network activity and averaged to extract information from them. However, mostly these single sweeps are very different in their shapes and extracting the information provided by the shape is the most common way to decode the transmitted information about the network. In this work, we propose a method capable of classifying these single sweeps from an experiment based on their shapes. The shape specific information of the single sweeps provided by this method can be used in decoding the tactile information processing pathway with a higher precision.

High resolution cortical imaging using electrolyte-(metal)-oxide-semiconductor field effect transistors

Brain-machine interfaces are currently based on techniques allowing either to record at high resolution from one or a few single neurons, or low spatial resolution recordings with a sparse sampling within the networks. To better interface to circuitries and to understand their role in sensory systems or cognition, higher resolution probes are required. In this paper we report a novel technique capable of recording cortical signals at a high resolution providing an electrical imaging of the cortical region under examination. Imaging was performed using two different types of electrolyte-(metal)-oxide-semiconductor field effect transistor, E(M)OSFET based multi-transistor arrays (MTAs): 1) 64 recording elements, integrated into a planar chip at high resolution (pitch: 30 μm-40 μm); 2) a matrix of 128 × 128 recording elements, integrated at a higher resolution (pitch: 7.4 μm, type: EMOSFET). These silicon micro-devices were capable of simultaneous recording of neuronal signals from the somatosensory cortex (S1) of the rat brain and were suitable in performing a real-time electrical imaging of the brain cortex in-vivo.