title: Atypical "seizure-like" activity in cortical reverberating networks in vitro can be caused by LPS-induced inflammation: a multi-electrode array study from a hundred neurons.
abstract: We show here that a mild sterile inflammation induced by the endotoxin lipopolysaccharide (LPS), in a neuron/astrocyte/microglial cortical network, modulates neuronal excitability and can initiate long-duration burst events resembling epileptiform seizures, a recognized feature of various central nervous neurodegenerative, neurological and acute systemic diseases associated with neuroinflammation. To study this action, we simultaneously analyzed the reverberating bursting activity of a hundred neurons by using in vitro multi-electrode array methods. ∼5 h after LPS application, we observed a net increase in the average number of spikes elicited in engaged cells and within each burst, but no changes neither in spike waveforms nor in burst rate. This effect was characterized by a slow, twofold exponential increase of the burst duration and the appearance of rarely occurring long burst events that were never seen during control recordings. These changes and the time-course of microglia-released proinflammatory cytokine, tumor necrosis factor-alpha (TNF-α), were blocked by pre-treatment with 50 nM minocycline, an established anti-inflammatory agent which was inactive when applied alone. Assay experiments also revealed that application of 60 pM exogenous TNF-α after 12-15 h, produced non-washable changes of neuronal excitability, completely different from those induced by LPS, suggesting that TNF-α release alone was not responsible for our observed findings. Our results indicate that the link between neuroinflammation and hyperexcitability can be unveiled by studying the long-term activity of in vitro neuronal/astrocyte/microglial networks.
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Gullo
authors.affiliation: Department of Biomolecular Sciences and Biotechnology, University of Milan, Milan Italy.
authors.forename: Alida
authors.initials: A
authors.lastname: Amadeo
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Donvito
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan Italy.
authors.forename: Marzia
authors.initials: M
authors.lastname: Lecchi
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Costa
authors.affiliation: UCL School of Pharmacy, University of London, London UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Constanti
authors.affiliation: Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan Italy.
authors.forename: Enzo
authors.initials: E
authors.lastname: Wanke
keywords: LPS; TNF-α; burst activity; minocycline; multi-electrode array; neocortical cultures; sterile inflammation