Name: an alternative approach to study primary events in neurodegeneration using ex vivo rat brain slices
Uploaded: 2018-04-11T15:00:00
Description: Watch this Scientific Journal Video about An Alternative Approach to Study Primary Events in Neurodegeneration Using Ex Vivo Rat Brain Slices at JoVE.com

This work was funded by Neuro-Bio Ltd. We would like to thank Dr. Giovanni Ferrati and Dr. Sergio Rotondo (Neuro-Bio) for their comments and advice on the manuscript.

All animal studies have been performed under approved protocols.
NOTE: In this section, the sequence of the main phases performed during the experimental procedure and the suggested time interval is provided (Figure 1). Moreover, a step-by-step description of the protocol is supplemented by an illustrative panel, showing critical actions ranging from brain removal to tissue homogenization after the incubation period (Figure 2). The de...

<ol>
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The principal aspect of this protocol, based on the&#160;well-established ex vivo brain technique, allows to synchronously test&#160;two specular hemislices, obtained from the same anatomical plane, monitoring their response after the application of a specific condition (control or treated); this therefore offers an experimental paradigm as tightly controlled as possible. The possibility of evaluating in a time-, dose-, and site-specific manner different neurochemicals related to neuronal impairment, as seen dur...

AD is a chronic pathology characterized by gradual neurodegenerative impairment affecting different brain areas, such as the entorhinal cortex (EC), BF, hippocampus (HC), and olfactory bulb (OB)1,2,3,4,5. The late stages of AD development lead to a progressive cognitive decline, making this disease the most common form of dementia, approximately accounting for 70% of all cases6. Despite extensive attempts to understand the initial stages causing AD, there is not currently a defined experimental indication elucidating them. In addition, the most popular theory - the &#34;amyloid hypothesis&#34; - is increasingly questioned since it does not provide a complete profile in explaining the AD pathobiology, nor a pharmaceutical target that has proved effective7,8,9.
An alternative theory which is receiving increasing attention suggests that the initial mechanisms occurring during neurodegeneration are related to a neuronal cluster primarily susceptible in AD3,10,11,12,13,14. This heterogeneous cellular hub encompassed within the BF, midbrain, and brainstem, projects to multiple regions, such as the EC, HC, and OB15,16. Despite its diversity in neuronal morphology and neurotransmitter synthesis, this core of cells shares a common feature in expressing AChE, which can also have a non-enzymatic function17,18. This non-classical role as a novel signaling molecule mediates&#160;calcium (Ca2+) flow into neurons which can undergo trophic or toxic events in relation to Ca2+ dose, availability, and neuronal age17,18,19.
During neurodegeneration, the observed cellular loss might be therefore associated to this non-enzymatic function17,18,20, which is attributable to a 30mer peptide (T30) cleaved from the AChE C-terminus20. In line with previous results, carried on cell culture and optical imaging18,21 preparations, we demonstrated, through a novel approach based on ex vivo rat brain slices containing BF structures, that&#160;T30 induced&#160;an AD-like profile22. Specifically, this new methodology offers a more physiological scenario than cell culture since it maintains many of the characteristics of an intact tissue, ranging from anatomical to circuitry preservation, albeit for a time window of hours. We applied this protocol to explore the events taking place during the early phases of neurodegeneration, monitoring the acute response upon T30 application.
Despite the large body of literature on using brain slices to investigate molecular pathways implied in neuronal damage or neurogenesis23,24, this protocol provides for the first time a more immediate and sensitive read out compared to the common use of organotypic slices. However, as is the case for organotypic brain sections, this acute slice procedure can also be adopted for several purposes, such as the evaluation of neuroprotective or neurotoxic molecules, discovery of primary molecular changes occurring in a specific process, immunohistochemical analysis, and pharmacological assays for central nervous system related pathologies.

<table>
	<tbody>
		<tr>
			<td>Sodium chloride (NaCl)</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>S7653</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>Potassium chloride (KCl)</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>P9333</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate (NaHCO3)</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>S5761</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>Magnesium sulphate heptahydrate (MgSO4 (7H2O))</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>63138</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>Potassium phosphate monobasic (KH2PO4)</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>P5655</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>Hepes salt</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>H7006</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>Hepes acid</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>H3375</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>G7528</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>Calcium chloride dehydrate</td>
			<td>Sigma-Aldrich, Germany</td>
			<td>223506</td>
			<td>Reagent for aCSF preparation</td>
		</tr>
		<tr>
			<td>T30 peptide</td>
			<td>Genosphere Biotechnologies, France</td>
			<td></td>
			<td>AChE-derived peptide tested</td>
		</tr>
		<tr>
			<td>Surgical dissecting kit</td>
			<td>World Precision Instruments, USA</td>
			<td>Item #: MOUSEKIT</td>
			<td>Brain removal step</td>
		</tr>
		<tr>
			<td>Surgical blades</td>
			<td>Swann-Morton, UK</td>
			<td>BS 2982</td>
			<td>Brain removal step</td>
		</tr>
		<tr>
			<td>Filter paper</td>
			<td>Fisher Scientific, USA</td>
			<td>11566873</td>
			<td>Brain preparation for slicing</td>
		</tr>
		<tr>
			<td>Glue</td>
			<td></td>
			<td></td>
			<td>Brain preparation for slicing</td>
		</tr>
		<tr>
			<td>Vibratome</td>
			<td>Leica, Germany</td>
			<td>VT1000 S</td>
			<td>Slicing</td>
		</tr>
		<tr>
			<td>Brushes</td>
			<td></td>
			<td></td>
			<td>Tissue handling</td>
		</tr>
		<tr>
			<td>Oxygen canister</td>
			<td></td>
			<td></td>
			<td>Sectioning and incubation phase</td>
		</tr>
		<tr>
			<td>1x Phosphate buffer saline (PBS)</td>
			<td>Fisher Scientific, USA</td>
			<td>BP2438-4</td>
			<td>Homogenization step</td>
		</tr>
		<tr>
			<td>Phosphatase inhibitors</td>
			<td>Fisher Scientific, USA</td>
			<td>1284-1650</td>
			<td>Homogenization step</td>
		</tr>
		<tr>
			<td>Protease inhibitors</td>
			<td>Roche complete PIC, USA</td>
			<td>4693116001</td>
			<td>Homogenization step</td>
		</tr>
		<tr>
			<td>Pestles</td>
			<td>Starlab, UK</td>
			<td>I1415-5390</td>
			<td>Homogenization step</td>
		</tr>
		<tr>
			<td>Microcentrifuge</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pierce 660 nm Protein Assay</td>
			<td>Thermo Scientific, USA</td>
			<td>22660</td>
			<td>Protein concentration</td>
		</tr>
	</tbody>
</table>

an alternative approach to study primary events in neurodegeneration using ex vivo rat brain slices

Despite&#160;numerous studies that attempt to develop reliable animal models&#160;which reflecting the primary processes underlying neurodegeneration, very few have been widely accepted. Here, we propose&#160;a new procedure&#160;adapted from the well-known ex vivo brain slice technique, which offers a closer in vivo-like scenario than in vitro preparations, for investigating the early events triggering cell degeneration, as observed in Alzheimer&#39;s disease (AD). This variation consists of simple and easily reproducible steps, which enable preservation of the anatomical cytoarchitecture of the selected brain region and its local functionality in a physiological milieu. Different anatomical areas can be obtained from the same brain, providing the opportunity to perform multiple experiments with the treatments in question in a site-, dose-, and time-dependent manner. Potential limitations&#160;which could affect the outcomes related to this methodology are related to the conservation of the tissue, i.e., the maintenance of its anatomical integrity during the slicing and incubation steps and the section thickness, which can influence the biochemical and immunohistochemical analysis. This approach can be employed for different purposes, such as exploring molecular mechanisms involved in physiological or pathological conditions, drug screening, or dose-response assays. Finally, this protocol could also reduce the number of animals employed in behavioral studies. The application reported here has been recently described and tested for the first time on ex vivo rat brain slices containing the basal forebrain (BF), which is one of the cerebral regions primarily affected in AD. Specifically, it has been demonstrated that the administration of a toxic peptide derived from the C-terminus of acetylcholinesterase (AChE) could prompt an AD-like profile, triggering, along the antero-posterior axis of the BF, a differential expression of proteins altered in AD, such as the alpha7 nicotinic receptor (&#945;7-nAChR), phosphorylated Tau (p-Tau), and amyloid beta (A&#946;).

The protocol presented here indicates that the administration of a toxic peptide, T30, modulates in a site-dependent manner the expression of &#945;7-nAChR, p-Tau, and A&#946; in BF-containing sections (Figure 3A). The nicotinic receptor shows a significant increase in the rostral-treated hemislice compared to its control counterpart (slice 1, p = 0.0310) (Figure 3B), while the intermediate slice does not reveal any chan...

Watch this Scientific Journal Video about An Alternative Approach to Study Primary Events in Neurodegeneration Using Ex Vivo Rat Brain Slices at JoVE.com

An Alternative Approach to Study Primary Events in Neurodegeneration Using Ex Vivo Rat Brain Slices

We present a method which can&#160;provide further insights into the early events underlying neurodegeneration and based on the established ex-vivo brain technique, combining the advantages of in vivo and in vitro experiments. Moreover, it represents a unique opportunity for direct comparison of treated and untreated group in the same anatomical plane.

An Alternative Approach to Study Primary Events in Neurodegeneration Using Ex Vivo Rat Brain Slices

Despite&#160;numerous studies that attempt to develop reliable animal models&#160;which reflecting the primary processes underlying neurodegeneration, ...

Research

JoVE Journal

Neuroscience

In vivo Laser Axotomy in C. elegans

In vivo Laser Axotomy in C. elegans

Neurons communicate with other cells via axons and dendrites, slender membrane extensions that contain pre- or post-synaptic specializations. If a neuron ...

A Rapid Approach to High-Resolution Fluorescence Imaging in Semi-Thick Brain Slices

A fundamental goal to both basic and clinical neuroscience is to better understand the identities, molecular makeup, and patterns of connectivity that are ...

GABA-activated Single-channel and Tonic Currents in Rat Brain Slices

The GABAA channels are present in all neurons and are located both at synapses and outside of synapses where they generate phasic and tonic currents, ...

Methods for Study of Neuronal Morphogenesis: Ex vivo RNAi Electroporation in Embryonic Murine Cerebral Cortex

Methods for Study of Neuronal Morphogenesis: Ex vivo RNAi Electroporation in Embryonic Murine Cerebral Cortex

The cerebral cortex directs higher cognitive functions. This six layered structure is generated in an inside-first, outside-last manner, in which the ...

Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains ...

Brain Slice Biotinylation: An Ex Vivo Approach to Measure Region-specific Plasma Membrane Protein Trafficking in Adult Neurons

Brain Slice Biotinylation: An Ex Vivo Approach to Measure Region-specific Plasma Membrane Protein Trafficking in Adult Neurons

Regulated endocytic trafficking is the central mechanism facilitating a variety of neuromodulatory events, by dynamically controlling receptor, ion ...

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal ...

Ex Vivo Optogenetic Dissection of Fear Circuits in Brain Slices

Ex Vivo Optogenetic Dissection of Fear Circuits in Brain Slices

Optogenetic approaches are now widely used to study the function of neural populations and circuits by combining targeted expression of light-activated ...

An Antibody Feeding Approach to Study Glutamate Receptor Trafficking in Dissociated Primary Hippocampal Cultures

Cellular responses to external stimuli heavily rely on the set of receptors expressed at the cell surface at a given moment. Accordingly, the population ...

Ballistic Labeling of Pyramidal Neurons in Brain Slices and in Primary Cell Culture

It has been reported that the size and shape of dendritic spines is related to their structural plasticity. To identify the morphological structure of ...