Characterization of the in vitro propagation of epileptiform electrophysiological activity in organotypic hippocampal slice cultures coupled to 3D microelectrode arrays

AbstractIntracellular tau inclusions are a pathological hallmark of Alzheimer's disease, progressive supranuclear palsy, corticobasal degeneration and other sporadic neurodegenerative tauopathies. Recent in vitro and in vivo studies have shown that tau aggregates may spread to neighbouring cells and functionally connected brain regions, where they can seed further tau aggregation. This process is referred to as tau propagation. Here we describe an ex vivo system using organotypic hippocampal slice cultures (OHCs) which recapitulates aspects of this phenomenon. OHCs are explants of hippocampal tissue which may be maintained in culture for months. They maintain their synaptic connections and multicellular 3D architecture whilst also permitting direct control of the environment and direct access for various analysis types. We inoculated OHCs prepared from P301S mouse pups with brain homogenate from terminally ill P301S mice and then examined the slices for viability and the production and localization of insoluble phosphorylated tau. We show that following seeding, phosphorylated insoluble tau accumulate in a time and concentration dependent manner within OHCs. Furthermore, we show the ability of the conformation dependent anti-tau antibody, MC1, to compromise tau accrual in OHCs, thus showcasing the potential of this therapeutic approach and the utility of OHCs as an ex vivo model system for assessing such therapeutics.

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Dexmedetomidine Attenuates Isoflurane-induced Neurocognitive Impairment in Neonatal Rats

Anesthesiology ◽

10.1097/aln.0b013e31819daedd ◽

2009 ◽

Vol 110 (5) ◽

pp. 1077-1085 ◽

Cited By ~ 275

Author(s):

Robert D. Sanders ◽

Jing Xu ◽

Yi Shu ◽

Adam Januszewski ◽

Sunil Halder ◽

...

Keyword(s):

Caspase 3 ◽

Hippocampal Slice ◽

Gamma Amino Butyric Acid ◽

Amino Butyric Acid ◽

Hippocampal Slice Cultures ◽

Acid Type ◽

Alpha2 Adrenoceptor ◽

Organotypic Hippocampal Slice Cultures

Background Neuroapoptosis is induced by the administration of anesthetic agents to the young. As alpha2 adrenoceptor signaling plays a trophic role during development and is neuroprotective in several settings of neuronal injury, the authors investigated whether dexmedetomidine could provide functional protection against isoflurane-induced injury. Methods Isoflurane-induced injury was provoked in organotypic hippocampal slice cultures in vitro or in vivo in postnatal day 7 rats by a 6-h exposure to 0.75% isoflurane with or without dexmedetomidine. In vivo, the alpha2 adrenoceptor antagonist atipamezole was used to identify if dexmedetomidine neuroprotection involved alpha2 adrenoceptor activation. The gamma-amino-butyric-acid type A antagonist, gabazine, was also added to the organotypic hippocampal slice cultures in the presence of isoflurane. Apoptosis was assessed using cleaved caspase-3 immunohistochemistry. Cognitive function was assessed in vivo on postnatal day 40 using fear conditioning. Results In vivo dexmedetomidine dose-dependently prevented isoflurane-induced injury in the hippocampus, thalamus, and cortex; this neuroprotection was attenuated by treatment with atipamezole. Although anesthetic treatment did not affect the acquisition of short-term memory, isoflurane did induce long-term memory impairment. This neurocognitive deficit was prevented by administration of dexmedetomidine, which also inhibited isoflurane-induced caspase-3 expression in organotypic hippocampal slice cultures in vitro; however, gabazine did not modify this neuroapoptosis. Conclusion Dexmedetomidine attenuates isoflurane-induced injury in the developing brain, providing neurocognitive protection. Isoflurane-induced injury in vitro appears to be independent of activation of the gamma-amino-butyric-acid type A receptor. If isoflurane-induced neuroapoptosis proves to be a clinical problem, administration of dexmedetomidine may be an important adjunct to prevent isoflurane-induced neurotoxicity.

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