Biology subjects

Falappa, M.

Publications and source records attributed to Falappa, M..

4 recordsLinked to original sources

bioRxiv2023

Human-derived cortical neurospheroids coupled to passive, high-density and 3D MEAs: a valid platform for functional tests

With the advent of human-induced pluripotent stem cells (hiPSCs) differentiation protocols, different methods to create in-vitro human-derived neuronal networks have been proposed. Although monolayer cultures represent a valid model, adding three-dimensionality would make them more representative of an in-vivo environment. Thus, human-derived neurospheroids and brain-organoids are becoming increasingly used for in-vitro disease modeling. Achieving control over the final cell composition and investigating the exhibited electrophysiological activity is still a challenge. Thence, platforms capable of measuring and characterizing the functional aspects of these samples are needed. Here, we propose a method to rapid generate neurospheroids of human origin with control over cell composition that can be used for functional investigations. We show a characterization of the electrophysiological activity exhibited by the neurospheroids by presenting for the first-time results from the main micro-electrodes arrays (MEAs) types available on the market (passive electrode, C-MOS electrodes, 3D electrodes). Neurospheroids grown in free culture and transferred on MEA exhibited functional activity that can be chemically and electrically modulated. Our results indicates that this model holds great potential for in-depth study of signal transmission to drug screening, disease modeling and offers a reproducible and stable platform for in-vitro functional testing.

bioengineering↗

bioRxiv2019

Paternally expressed imprinted Snord116 and Peg3 regulate hypothalamic orexin neurons

Imprinted genes are highly expressed in the hypothalamus; however, whether specific imprinted genes affect hypothalamic neuromodulators and their functions is unknown. It has been suggested that Prader-Willi syndrome (PWS), a neurodevelopmental disorder caused by lack of paternal expression at chromosome 15q11-q13, is characterised by hypothalamic insufficiency. Here, we investigate the role of the paternally expressed Snord116 gene within the context of sleep and metabolic abnormalities of PWS, and we report a novel role of this imprinted gene in the function and organisation of the two main neuromodulatory systems of the lateral hypothalamus (LH), namely, the orexin (OX) and melanin concentrating hormone (MCH) systems. We observe that the dynamics between neuronal discharge in the LH and the sleep-wake states of mice with paternal deletion of Snord116 (PWScrm+/p-) are compromised. This abnormal state-dependent neuronal activity is paralleled by a significant reduction in OX neurons in the LH of mutants. Therefore, we propose that an imbalance between OX- and MCH-expressing neurons in the LH of mutants reflects a series of deficits manifested in the PWS, such as dysregulation of rapid eye movement (REM) sleep, food intake and temperature control.\n\nHighlightsO_LISnord116 regulates neuronal activity in the lateral hypothalamus (LH), which is time-locked with cortical states of sleep.\nC_LIO_LILoss of Snord116 reduces orexin neurons in the LH and affects sleep homeostasis and thermoregulation in mice.\nC_LIO_LISnord116 and Peg3 independently control orexin expression in the LH.\nC_LIO_LIPaternally expressed alleles maximize the patrilineal effects in the control of REM sleep by the LH in mammals.\nC_LI

neuroscience↗

bioRxiv2019

The paternally imprinted gene Snord116 regulates cortical neuronal activity

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder that is characterized by rapid eye movement (REM) sleep abnormalities. The disease is caused by genomic imprinting defects that are inherited through the paternal line. Among the genes located in the PWS region on chromosome 15 (15q11-q13), small nucleolar RNA 116 (Snord116) has been previously associated with intrusions of REM sleep into wakefulness in both humans and mice.\n\nHere, we further explore the processes of sleep regulation by studying the PWScrm+/p- mouse line, which carries a paternal deletion of Snord116. We focused on microstructural electrophysiological components of sleep, such as REM sleep features and sleep spindles within NREM sleep. While the former are thought to contribute to neuronal network formation early in brain development, the latter are markers of thalamocortical processes. Both signals are often compromised in neurodevelopmental disorders and influence functional properties of cortical neurons. Thus, we isolated and characterized the intrinsic activity of cortical neurons using in vitro microelectrode array (MEA) studies.\n\nOur results indicate that the Snord116 gene in mice selectively influences REM sleep properties, such as theta rhythms and the organization of REM episodes throughout sleep-wake cycles. Moreover, sleep spindles present specific abnormalities in PWS model systems, indicating that these features of sleep may translate as potential biomarkers in human PWS. We observed abnormalities in the synchronization of cortical neuronal activity that are accounted for by high levels of norepinephrine.\n\nIn conclusion, our results provide support for an important role of Snord116 in regulating brain activity during sleep and, in particular, cortical neuronal properties, thereby opening new avenues for developing interventions in PWS.\n\nSignificance StatementWe found that the Snord116 gene, a major player in Prader-Willi syndrome (PWS), significantly impacts REM sleep and its regulation. Additionally, we found that sleep spindles, a subtle electroencephalography (EEG) marker that occurs during NREM sleep, are dysregulated in PWS mice that carry a paternal deletion of the Snord116 gene. Using a combination of in vivo and in vitro experiments, we identified sleep features at the network and molecular level that suggest that Snord116 is fundamental in the synchronization of neuronal networks. Our study also provides a new pre-clinical tool to investigate the pathophysiology of sleep in PWS.

neuroscience↗

bioRxiv2019

Post-acute administration of the GABAA α5 antagonist S44819 promotes recovery of peripheral limb fine motor skills after permanent distal middle cerebral artery occlusion in rats

BackgroundIschemic stroke induces hypoexcitability of the peri-infarct cortex by increased tonic GABA activity, which impairs stroke recovery. The GABAA 5 antagonist S44819 has recently been shown to promote post-ischemic motor-coordination recovery after transient proximal middle cerebral artery occlusion (MCAO) in mice. The effects of S44819 on post-ischemic skilled limb movement recovery have so far not yet been assessed in rats.\n\nMethodsMale Sprague-Dawley rats were subjected to permanent distal MCAO. Starting 3 days post-stroke, vehicle or S44819 (3 or 10 mg/kg) were delivered orally twice a day for 28 days. A single pellet reaching test was performed at baseline, before treatment onset and at weekly intervals thereafter. Animals were sacrificed at 45 days post-stroke (that is, at 42 days post-treatment onset) after 14 days of drug washout. Body weight was monitored, and infarct size was determined by histology.\n\nResultsS44819, administered at 10 mg/kg but not 3 mg/kg significantly improved single pellet reaching performance over 45 days (F(2,96)=22.43, p<0.001). Body weight was not altered. S44819 had no effect on infarct size.\n\nConclusionOur data indicate that post-acute administration of S44819 at 10 mg/kg promotes skilled forelimb movements. The effect was maintained after S44819 wash out.

neuroscience↗