We thank Caroline Bouchard from the animal facility for the rat work. A.S. holds a J.A. De S&#232;ve master fellowship, and B.P. a COPSE fellowship from the Universit&#233; de Montr&#233;al This work was funded by grants attributed to J.B. from FRQS-Pfizer and start-up funds from H&#244;pital du Sacr&#233;-Coeur de Montr&#233;al Research Center.

Ethics statement: The animal protocol for this project obtained the approval from the Animal Care Committee of the H&#244;pital du Sacr&#233;-Coeur de Montr&#233;al in compliance with the guidelines of the Canadian Council on Animal Care.
1. Catheter Preparation before Stereotaxic Surgery
<ol>
	<li>Cut PE50 catheters (6 cm in length) that will be used to connect cannula with osmotic pumps (see Figure 1A). Fill PE50 catheters with artificial cerebrospinal fluid (aCSF) and seal both ends of the catheters. Keep the catheter at 4 &#176;C until used.</li>
</ol>
2. Cannula Implantation by Stereotaxy
<ol>
	<li>Perform the surgery in sterile conditions. Sterilize all the surgical instruments and materials by autoclaving. Clean the stereotaxic apparatus and the working area thoroughly, and disinfected with a 70% ethanol solution. Wear a surgical mask, hair bonnet and sterile gloves.</li>
	<li>Anesthetize rats by injecting intraperitoneally (i.p.) a solution of ketamine and xylazine (100 mg/kg and 10 mg/kg, respectively). Confirm anesthesia by checking movement after a gentle toe pinch.</li>
	<li>Inject a non-steroidal anti-inflammatory drug (Meloxicam; 1 mg/kg) subcutaneously (s.c.) to the anesthetized-animal at least 30 min prior to surgery.</li>
	<li>Shave the head of the animal using clippers and disinfect the skin with a solution of chlorhexidine gluconate 2% and isopropyl alcohol 2% three times. Apply veterinary ophthalmic ointment on eyes to prevent dryness while under anesthesia.</li>
	<li>Place the animal on a stereotaxic frame with the ear bars. Fix one cannula on the holder arm of the stereotaxic frame. Inject (s.c.) a local anesthetic agent (bupivacaine (1.5 mg/kg) and lidocaine (1.5 mg/kg) on the top of the head.&#160;Anesthesia is maintains during the whole procedure by placing a nose cone delivering 3% isoflurane. The entire surgical field should be draped off, but it was not done here to better demonstrate the technique.</li>
	<li>Make an incision of 3 cm on the top of the head with a scalpel. Install 4 clamps around the incision to leave the skull clear. Using a round-tip scissor, make a pocket (2 x 2 cm2) under the skin between shoulder blades of the animal.</li>
	<li>Scrape&#160;the periosteum of the skull with a blade. Apply a gauze pad on the skull if bleeding.</li>
	<li>Verify that the skull is flat and well aligned on the stereotaxic frame. To make sure that the skull is flat, check the height coordinates at the bregma and at the lambda. Take the coordinates of the bregma that will be used as the reference point.</li>
	<li>Starting from the bregma, calculate the coordinates of the two guide cannula that will be implanted bilaterally in the hippocampus (anteroposterior: - 0.42 cm; mediolateral: &#177; 0.30 cm; dorsoventral: - 0.28 cm according to the Paxinos and Watson rat brain atlas)29. Indicate the position of the cannula with a marker.</li>
	<li>Drill a hole (0.5 mm) in the skull at the implantation point of both cannula. Drill two other holes approximately 5 mm above and below those points to insert screws that will solidify cannula when applying dental cement.</li>
	<li>Cut one end of the catheter previously filled with aCSF with a scalpel, and insert it in the angle arm of the cannula. Fix the first cannula with dental cement. Avoid putting dental cement around the position on the second cannula.</li>
	<li>Let the dental cement dry for 2 - 3 min, then remove the holder arm from the first cannula, and fix the second cannula in it. Repeat steps 2.11 and 2.12. Put dummy cannula on both guide cannula. Ensure that the dummy and guide cannula are of the same length to prevent tissue infiltration and blocking the cannula.</li>
	<li>Insert the free end of both catheters in the pocket previously made between shoulder blades of the animal. Remove the clamps and stitch the skin with a suture thread 4-0. 
	NOTE: The top guide cannula needs to be accessible for upcoming A&#946;o infusions.</li>
	<li>Remove the animal from the stereotaxic frame and put it back in its cage. During post-surgical recovery, place the cage on a heating water blanket until the animal wakes up. The cage should be partially on the pad so the rat can move away from the heat if needed.&#160;&#160;Monitor the animal constantly until it regains sufficient consciousness to maintain sternal recumbency.</li>
	<li>Return rats to the animal facility to recover from the surgery for 10 days under close monitoring. 
	NOTE: Do not return an animal that has undergone surgery to the company of other animals until fully recovered. Meloxicam (1 mg/kg) is given once per day during two days following surgery to treat pain.</li>
</ol>
3. Osmotic Pump Installation
<ol>
	<li>One day before installation, fill osmotic pumps with 6E10 antibody (1 mg/ml; 100 &#181;l) and control IgG1 antibody (1 mg/ml; 100 &#181;l) according to the manufacturer&#39;s instructions under sterile condition. Keep the pumps in sterile distilled water at 37 &#176;C overnight to activate pumps.</li>
	<li>Anesthetize rats with isoflurane 3% to install osmotic pumps (0.5 &#181;l/hr for 7 days). Shave between shoulder blades and disinfect the skin with a solution of chlorhexidine gluconate 2% and isopropyl alcohol 2%. Make an incision of 2 cm with a scalpel between shoulder blades to locate the PE50 catheters connected to the guide cannula.</li>
	<li>Cut the end of the PE50 catheters containing dental cement with a scalpel. Connect the osmotic pumps to the PE50 catheters, and add some dental cement at the pump and catheter junction to secure the connection.</li>
	<li>Stitch the skin tightly with a suture thread 4-0. Put the animal back in its cage on a heating water&#160;pad. Observe the animal wake up rapidly from an isoflurane anesthesia (about 5 min). 
	NOTE: The surgery takes approximately 5 to 10 min.</li>
</ol>
4. A&#946;o Infusions in Awake and Freely Moving Rats
<ol>
	<li>Prepare the A&#946;o solution (0.2 &#181;g/&#181;l) as previously reported.28,30 Allow A&#946;o to aggregate dynamically and spontaneously for 1 hr at room temperature before infusion.</li>
	<li>Install two 10 &#181;l syringes on an infusion pump. Fill the syringes with 5 &#181;l of sterile distilled water. Cut two PE50 catheters to about 60 cm in length with a scalpel. Fill both catheters with sterile distilled water using 1 ml syringes and 21G needles.</li>
	<li>Keep the 1 ml syringes at one end of the catheter and connect the other end to the Hamilton syringes. Remove the 1 ml syringes and check that there is no air bubbles within the catheters.</li>
	<li>Insert internal cannula at the end of PE50 catheters. Using sterile distilled water, fill the internal cannula connected to PE50 catheters up to1 &#181;l on Hamilton syringes. Make an air bubble by pulling back the pistons up to 2 &#181;l.</li>
	<li>Mix the A&#946;o solution by pipetting up and down using a tip of minimum of adherence. Avoid forming bubbles during mixing. Fill both internal cannula with 1.5 &#181;l of A&#946;o solution by pulling back the pistons up to 3.5 &#181;l.</li>
	<li>Make lines with a marker before and after the air bubble done in both catheters. This serves as a check point of ongoing infusion. For infusion, bring the cage near the infusion pump and remove its cover.</li>
	<li>Place the rat in a snuggle and tightly scrape&#160;the arm of the snuggle around its neck to immobilize the head of the rat. Remove dummy cannula from the two guide cannula. Insert the internal cannula previously prepared in the guide cannula. Verify that they are fully inserted and well-fixed to the base of the guide cannula.</li>
	<li>Release rat from the snuggle and put it back in its cage to limit contention stress. Monitor closely to ensure that the catheters do not twist together and the infusion is done properly.</li>
	<li>Turn on the infusion pump. Inject 1 &#181;l of A&#946;o solution at a rate of 0.1 &#181;l/min (10 min). During infusion, check that the syringe piston moves from 3.5 &#181;l to 2.5 &#181;l, and that the air bubble in both PE50 catheters move continuously.</li>
	<li>Leave the internal cannula in place for another 5 min after infusion to allow efficient diffusion of A&#946;o solution. Bring the rat back in the snuggle to remove internal cannula and capped guide cannula to prevent reflux of the injected solution. Use dummy cannula that stop just before the angle arm of the cannula. Return the animal in its cage.</li>
	<li>Repeat A&#946;o infusion once per day over 6 consecutive days. Euthanize the animal by decapitation.</li>
</ol>

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Publication of this video-article is sponsored by ALZET Osmotic Pumps.

There are critical steps within this protocol that required special attention. When implanting the cannula, avoid putting dental cement when it is too liquid to prevent blocking the hole of the second cannula. It is important to place dental cement at the free end of the P50 catheter attached to the pump to prevent irritation and a possible inflammatory response. The day of the stereotaxic surgery, use dummy cannula that are the same length as guide cannula to avoid blocking cannula. However, after installing pumps use shorter dummy cannula that stop before the angle arm of the cannula to allow proper infusion of the solution from the pump to the hippocampus. Monitor closely A&#946;o infusions and verify that the air bubble done in catheters is moving continuously during infusions. Always make sure that the injecting cannula is completely inserted into the guide cannula during infusions.
If problem is encounter during A&#946; infusion, verify that the internal cannula is not blocked. If it is the case, flush sterile distilled water through the internal cannula. If the guide cannula is obstructed, turn the internal cannula into the guide cannula. Otherwise move the internal cannula up and down. Contention in the snuggle can be stressful for rats, especially on the first day. To decrease the stress of the animal, we recommend to manipulate and habituate rats to the snuggle before the stereotaxic surgery.
Many advantages can be attributed to this novel and flexible in vivo approach. Indeed, the nature of A&#946;o injected can be accurately control before infusion, and different type of A&#946; preparations (for example synthetic vs brain-derived A&#946; solutions) can be injected to evaluate their neurotoxicity in vivo. This model can also be used to investigate mechanisms by which various A&#946; species (e.g., monomers, low- and high-molecular-weight oligomers, protofibrils) can induce neurotoxic effects in vivo, and how treatments like immunotherapy might counteract their deleterious impact in the brain. Since the infusions are perform in awake, freely-moving animals, there are no confounding effects between anesthetic agents and the A&#946;o solution on signaling pathways, as shown in previous studies.32,33 Infusions in freely moving animal are also compatible with behavioral testing any time before and after the infusions.
Infusions of A&#946;o and pump installation can be done in animal of different ages to determine the effects of A&#946;o and treatments during aging. Since neurodegeneration occurs in vicinity of the infusion site, synapse and neuronal loss can be induced in different and localized brain regions. The collateral infusion of A&#946;o and control (vehicle or scramble A&#946;) allows controlling for any change within the same animal. Conversely, A&#946;o or control solutions can be injected bilaterally in the right and left hippocampus, for example when testing animals in behavioral tasks. Infusion of A&#946;o and treatment can be done simultaneously or alternatively pumps can be installed after A&#946;o infusion to evaluate if the treatment is effective after A&#946; deposition. The same protocol described here can also be used when doing intracerebroventricular infusions of A&#946;o. The effect of A&#946;o on intracellular signaling pathways can be evaluated before and after neuronal loss within a reasonably short time frame. The dose and number of A&#946; infusions can also be adjusted to obtain a more or less severe A&#946; pathogenicity.
Although very versatile, this technique has some limitations. Cannula implantation produces a mechanical disruption of the tissue and neuroinflammation in the first few days following surgery. Thus, it is essential to wait at least one week after surgery before starting A&#946;o infusion, and to add proper controls (injection of vehicle or inactive scramble A&#946;) to take into account these events. Also, only a small volume of A&#946;o can be infused to limit diffusion of the solution.
The osmotic pumps represent a convenient and unique delivery method for preclinical validation of agents designed to prevent A&#946;-induced neurodegeneration. Since immunotherapy with the 6E10 antibody has been shown previously to decrease A&#946; accumulation in the brain,31 we used the 6E10 antibody as a proof-of-concept to validate our new in vivo approach. The used of osmotic pumps in this model might now be used to develop novel disease modifying therapies that could prevent the deposition and neurotoxicity of A&#946;o in pre-clinical AD patients.

It was initially proposed that accumulation of insoluble A&#946; species in the brain was central to AD pathogenesis.1,2 However, amyloid plaques are also detected in some cognitively normal elderly.3-7 To overcome the poor correlation existing between plaque depositions and cognitive deficits in AD, latest reports have shown the presence of toxic soluble A&#946;o at the onset of the disease, which correlate much better with the clinical state of the patients.8-14 Since the process of A&#946; oligomerization is very dynamic, it was suggested that neurotoxicity is induced by various A&#946;o instead of only one specific type of oligomer.14-16 Since many studies have shown that A&#946;o can initiate synapse dysfunctions prior to synapse and neuronal loss,17-24 current theories indicate that A&#946;-related treatment might be effective in early AD rather than at later stages as tested so far in clinical trials.
One hallmark feature of AD pathogenesis is the massive and widespread cell death observed in the late stages of the disease, and the significant synapse and neuronal loss observed in localized brain regions when memory deficits become detectable at the clinical level. The perforant pathway that projects from the entorhinal cortex (EC) to the dentate gyrus (DG) is perturbed markedly at the early onset of AD.25,26 During the prodromal state of AD when mild cognitive impairment (MCI) becomes apparent significant cell death is detected in the EC as well as synaptic loss in the DG.25,26
Although a large body of evidence has pinpointed the toxic action of soluble A&#946;o in early AD,8-14 A&#946;o-induced neurodegeneration observed in neuronal culture or organotypic brain slice culture has been more challenging to reproduce in animal models.27 Most of the transgenic AD models overexpressing A&#946; have amyloid plaques, tau hyperphosphorylation, synaptic deficiency and memory deficits.27 However, these models have been much less successful in modelling cell death observed in the hippocampus of AD patients. To overcome these technical issues we developed a model based on intracerebral infusions of soluble A&#946;o. We reported earlier that repeated hippocampal infusions of soluble A&#946;o induce gradual neuronal loss and tau hyperphosphorylation, two pathological hallmarks associated with memory decline in AD.28 Here, we are showing a novel method to test AD therapies using cannula specially design for simultaneous infusions of A&#946;o and continuous infusion of A&#946;o antibody (6E10) with osmotic pumps.
Osmotic pumps provide a unique way to test in vivo the efficiency of any antibody (or other compounds) against A&#946;o-induced neurodegeneration directly at the infusion site of A&#946;o. Thus, these pumps represent a convenient tool to establish a solid proof-of-concept regarding the mechanisms of action of potential therapeutic agents in AD. Since recent reports point out the critical impact of soluble A&#946;o in the early stages of AD, many treatments directed toward A&#946;o are actually being tested by academic and pharmaceutical laboratories. This novel animal model allows mimicking the synaptic and neuronal loss observed in early AD, and osmotic pumps are used to infuse continuously treatment agents specifically at the A&#946;o infusion site. The repetitive failures of AD therapies tested over the last few years in mild to moderate patients as prompted researchers to initiate trials in pre-dementia patients before A&#946;o begin to accumulate abundantly and generate irreversible brain damage. In this context, testing new compounds that prevent the deposition and consequently the neurotoxicity of A&#946;o might be of interest in pre-clinical patients.

<table><tbody><tr><td>Artificial Cerebrospinal Fluid (aCSF)</td><td>Harvard Apparatus</td><td>59-7316</td><td></td></tr><tr><td>PE 50 Catheter thin wall</td><td>Plastics one</td><td>C232CT</td><td></td></tr><tr><td>Ketamine Hydrochloride (100 mg/ml)</td><td>Bioniche</td><td>1989529</td><td></td></tr><tr><td>Xylazine Hydrochloride (100 mg/ml)</td><td>Bimeda</td><td>8XYL004C</td><td></td></tr><tr><td>Meloxicam (5 mg/ml)</td><td>Norbrook</td><td>215670I01</td><td></td></tr><tr><td>Solution of chlorhexidine gluconate 2% and isopropyl alcohol 2%</td><td>Carefusion</td><td>260100C</td><td></td></tr><tr><td>Lidocaine Hydrochloride</td><td>Alveda Pharma</td><td>0122AG01</td><td></td></tr><tr><td>Bupivacaine Hydrochloride</td><td>Hospira</td><td>1559</td><td></td></tr><tr><td>ophthalmic ointment</td><td>Baussh and Lomb inc.</td><td>2125706</td><td></td></tr><tr><td>stereotaxic frame</td><td>Stoelting</td><td>51600</td><td></td></tr><tr><td>stereotaxic cannula holder arm</td><td>Harvard Apparatus</td><td>72-4837</td><td></td></tr><tr><td>Drill</td><td>Dremel</td><td>8050-N/18</td><td></td></tr><tr><td>Guide Cannula</td><td>Plastics one</td><td>326OPG/spc</td><td></td></tr><tr><td>Injection Cannula</td><td>Plastics one</td><td>C315I/spc</td><td></td></tr><tr><td>Dummy Cannula</td><td>Plastics one</td><td>C315DC/spc</td><td></td></tr><tr><td>Suture thread coated vicryl rapide 4-0</td><td>Ethicon</td><td>VR2297</td><td></td></tr><tr><td>Dental Acrylic Cement</td><td>Harvard Apparatus</td><td>72-6906</td><td></td></tr><tr><td>Screws</td><td>JI Morris Company</td><td>P0090CE125</td><td></td></tr><tr><td>6E10 antibody (mouse IgG1 isotype)&amp;nbsp;</td><td>BioLegend</td><td>803003</td><td></td></tr><tr><td>Mouse IgG1 isotype control antibody</td><td>Abcam</td><td>AB18447</td><td></td></tr><tr><td>Alzet osmotic pumps model 1007D</td><td>Durect corporation</td><td>290</td><td></td></tr><tr><td>Isoflurane</td><td>Baxter</td><td>CA2L9100</td><td></td></tr><tr><td>Amyloid-beta 1-42&amp;nbsp;</td><td>rPeptide</td><td>A-1163-1</td><td></td></tr><tr><td>Hamilton syringe (10 &amp;micro;l)</td><td>Fisher Scientique</td><td>14815279</td><td></td></tr><tr><td>Infusion Syringe Pump CMA 402</td><td>Harvard Apparatus</td><td>CMA8003110</td><td></td></tr><tr><td>Syringe 1 ml</td><td>BD</td><td>309659</td><td></td></tr><tr><td>Needle 21 G</td><td>Terumo</td><td>NN-2125R</td><td></td></tr><tr><td>Snuggle</td><td>Lomir Biomedical</td><td>RTS04</td><td></td></tr></tbody></table>

neurodegeneration in an animal model of chronic amyloid-beta oligomer infusion is counteracted by antibody treatment infused with osmotic pumps

Decline in hippocampal-dependent explicit memory (memory for facts and events) is one of the earliest clinical symptom of Alzheimer&#39;s disease (AD). It is well established that synapse loss and ensuing neurodegeneration are the best predictors for memory impairments in AD. Latest studies have emphasized the neurotoxic role of soluble amyloid-beta oligomers (A&#946;o) that begin to accumulate in the human brain approximately 10 to 15 yr before the clinical symptoms become apparent. Many reports indicate that soluble A&#946;o correlate with memory deficits in AD models and humans. The A&#946;o-induced neurodegeneration observed in neuronal and brain slice cultures has been more challenging to reproduce in many animal models. The model of repeated A&#946;o infusions shown here overcome this issue and allow addressing two key domains for developing new disease modifying therapies: identify biological markers to diagnose early AD, and determine the molecular mechanisms underpinning A&#946;o-induced memory deficits at the onset of AD. Since soluble A&#946;o aggregate relatively fast into insoluble A&#946; fibrils that correlate poorly with the clinical state of patients, soluble A&#946;o are prepared freshly and injected once per day during six days to produce marked cell death in the hippocampus. We used cannula specially design for simultaneous infusions of A&#946;o and continuous infusion of A&#946;o antibody (6E10) in the hippocampus using osmotic pumps. This innovative in vivo method can now be used in preclinical studies to validate the efficiency of new AD therapies that might prevent the deposition and neurotoxicity of A&#946;o in pre-dementia patients.

The neurotoxic effect of A&#946;o was investigated in Long-Evans rats by implanting cannula in the DG of the hippocampus. Soluble A&#946;o were injected every day over six consecutive days. We used cannula specially design for simultaneous infusions of A&#946;o and continuous infusion of 6E10 or control IgG1 antibody in the hippocampus using osmotic pumps (Figure 1A). For immunohistochemistry rats were anesthetized, perfused transcardially with 0.9% NaCl, and brains immersed in 4% paraformaldehyde solution for 48 hr and 15% sucrose solution for 24 hr. Free-floating coronal sections (40 &#181;m) were treated with 0.3% H2O2 for 30 min, blocked in 1% goat serum for 1 hr, and incubated overnight at 4 &#176;C with an anti-pan-A&#946; antibody. Sections were treated with 70% formic acid for 3 min before applying the antibody. Detection was performed using the ABC complex and a 0.05% 3,3-diaminobenzidine solution. Sections were mounted on gelatin-coated glass slides, air-dried 2 hr, dehydrated (30, 70, 95, and 100% alcohol), incubated in toluene 5 min, and coverslipped. For cresyl violet staining, sections were incubated 10 min in a 0.5% cresyl violet solution, incubated 1 min in a 0.5% acetic acid solution, decolored (70, 95, and 100% alcohol), immersed in toluene 5 min, and covered with glass coverslip.
The results presented here show the deposition of A&#946;o in the DG in vicinity of the infusion site, and cell death associated with this accumulation. We found that the level A&#946;o was substantially decreased by 6E10 antibody treatment (Figure 1B). Marked neurodegeneration was observed near the injecting site of A&#946;o, and was attenuated by 6E10 antibody treatment (Figure 1B). These results are consistent with A&#946;o accumulation that we observed in the DG following repeated A&#946;o infusions in mice.28 Clearance of amyloid deposition by immunotherapy with 6E10 antibody shown here is in line with another report done in a transgenic AD mouse model.31
<img alt="Figure 1" src="/files/ftp_upload/54215/54215fig1.jpg" /> 
Figure 1. Photo of the Animal with Bilateral Cannula During A&#946;o Infusion. A solution of A&#946;o (0.2 &#181;g/&#181;l; 1 &#181;l) was injected in awake and freely moving rats (once a day for 6 days) using PE50 catheters connected to internal cannula inserted into guide cannula. Treatment with control (Ctl) IgG1 or 6E10 antibody was infused directly at the site of A&#946;o infusion using osmotic pumps located subcutaneously between the shoulder blades of the animal. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54215/54215fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/54215/54215fig2.jpg" /> 
Figure 2. Neuronal Loss Induced by A&#946;o Deposition is Attenuated by 6E10 Antibody Treatment. A, A&#946;o (0.2 &#181;g/&#181;l; 1 &#181;l) was injected once a day during 6 consecutive days, and treated with Ctl (IgG1) or 6E10 antibody at the site of infusion using osmotic pumps. B, Representative accumulation of A&#946;o in the DG on a section immediately next to cannula insertion, and representative staining with cresyl violet showing cell loss. Scale bars: 50 &#181;m (n = 4) <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54215/54215fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Neurodegeneration in an Animal Model of Chronic Amyloid-beta Oligomer Infusion Is Counteracted by Antibody Treatment Infused with Osmotic Pumps at JoVE.com

Neurodegeneration in an Animal Model of Chronic Amyloid-beta Oligomer Infusion Is Counteracted by Antibody Treatment Infused with Osmotic Pumps

To study the effects of A&#946;o in vivo, we developed a model based on repeated hippocampal infusions of soluble A&#946;o coupled with continuous infusion of A&#946;o antibody (6E10) in the hippocampus using osmotic pumps to counteract the neurotoxic effect of A&#946;o.

Decline in hippocampal-dependent explicit memory (memory for facts and events) is one of the earliest clinical symptom of Alzheimer&#39;s disease (AD). It ...

neurodegeneration-an-animal-model-chronic-amyloid-beta-oligomer

Nanyang Technological University

Research

JoVE Journal

Medicine

9.2K Views.  Université de Montréal. To study the effects of Aβo in vivo, we developed a model based on repeated hippocampal infusions of soluble Aβo coupled with continuous infusion of Aβo antibody (6E10) in the hippocampus using osmotic pumps to counteract the neurotoxic effect of Aβo.

Video: Neurodegeneration in an Animal Model of Chronic Amyloid-beta Oligomer Infusion Is Counteracted by Antibody Treatment Infused with Osmotic Pumps

Preparation of Oligomeric &beta;-amyloid1-42 and Induction of Synaptic Plasticity Impairment on Hippocampal Slices

Impairment of synaptic connections is likely to underlie the subtle amnesic changes occurring at the early stages of Alzheimer s Disease (AD). &beta;-amyloid (A&beta;), a peptide produced in high amounts in AD, is known to reduce Long-Term Potentiation (LTP), a cellular correlate of learning and memory. Indeed, LTP impairment caused by A&beta; is a useful experimental paradigm for studying synaptic dysfunctions in AD models and for screening drugs capable of mitigating or reverting such synaptic impairments. Studies have shown that A&beta; produces the LTP disruption preferentially via its oligomeric form. Here we provide a detailed protocol for impairing LTP by perfusion of oligomerized synthetic A&beta;1-42 peptide onto acute hippocampal slices. In this video, we outline a step-by-step procedure for the preparation of oligomeric A&beta;1-42. Then, we follow an individual experiment in which LTP is reduced in hippocampal slices exposed to oligomerized A&beta;1-42 compared to slices in a control experiment where no A&beta;1-42 exposure had occurred.

Preparation of Oligomeric &#946;-amyloid1-42 and Induction of Synaptic Plasticity Impairment on Hippocampal Slices

One feature of Alzheimer's Disease is the elevation of A&beta;1-42 peptide. Here we provide a protocol for preparing synthetic A&beta;1-42 oligomers, which impairs hippocampal Long-Term Potentiation, a cellular correlate of memory. This procedure is useful for investigating mechanisms of A&beta;-induced pathology and drug screening.

Impairment of synaptic connections is likely to underlie the subtle amnesic changes occurring at the early stages of Alzheimer s Disease (AD). ...

Neuroscience

A11-positive &#946;-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis

&#946;-amyloid (A&#946;) is a hydrophobic peptide with an intrinsic tendency to self-assemble into aggregates. Among various aggregates, A&#946; oligomer is widely accepted as the leading neurotoxin in the progress of Alzheimer&#39;s disease (AD) and is considered to be the crucial event in the pathogenesis of AD. Therefore, A&#946; oligomer inhibitors might prevent neurodegeneration and have the potential to be developed as disease-modifying treatments of AD. However, different formation protocols of A&#946; oligomer might lead to oligomers with different characteristics. Moreover, there are not many methods to effectively screen A&#946;1-42 oligomer inhibitors. An A11 antibody can react with a subset of toxic A&#946;1-42 oligomer with anti-parallel &#946;-sheet structures. In this protocol, we describe how to prepare an A11-positive A&#946;1-42 oligomer-rich sample from a synthetic A&#946;1-42 peptide in vitro and to evaluate relative amounts of A11-positive A&#946;1-42 oligomer in samples by a dot blotting analysis using A11 and A&#946;1-42-specific 6E10 antibodies. Using this protocol, inhibitors of A11-positive A&#946;1-42 oligomer can also be screened from semi-quantitative experimental results.

This protocol describes how to prepare A&#946; oligomers from a synthetic peptide in vitro and to evaluate relative amounts of A&#946; oligomer by a dot blotting analysis.

&#946;-amyloid (A&#946;) is a hydrophobic peptide with an intrinsic tendency to self-assemble into aggregates. Among various aggregates, A&#946; oligomer ...

Biochemistry

Establishment of a Valuable Mimic of Alzheimer's Disease in Rat Animal Model by Intracerebroventricular Injection of Composited Amyloid Beta Protein

Alzheimer&#39;s disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and is accompanied by neuron loss and structure change. With the increase of AD patients worldwide, the pathology and treatment of the disease has become a focus in the International Pharmaceutical Industry. Thus, the establishment of the animal model to mimic AD in the laboratory is of great importance.
Here, we describe a detailed protocol for establishing a mimic of AD in a rat animal model though intracerebroventricular injection of amyloid beta protein 25-35 (A&#946;25-35) combined with aluminum trichloride (AlCl3) and anterodorsal thalamic nucleus injection of recombinant human transforming growth factor-&#946;1 (RHTGF-&#946;1) to rats. The related markers of AD were measured, including: spatial memory, neuronal structure and substructure, neuronal A&#946;, and neurofibrillary tangles (NFT) production. This rat model demonstrates spatial memory impairment, neuronal structure and substructure pathological changes, neuron intracellular A&#946; burden, and NFT aggregation, and provides a close mimic of the neuronal structure and function disorder to that of clinical AD patients. Thus, the presented AD rat modelprovides a valuable in vivo tool for exploring neuronal function, neuronal pathology, and drug screening of AD.

This is a protocol to mimic Alzheimer&#39;s Disease in rats by evaluation of spatial memory impairment, neuronal pathological changes, neuronal amyloid beta protein (A&#946;) burden, and neurofibrillary tangles aggregation, induced by the injection of A&#946;25-35 combined with aluminum trichloride and recombinant human transforming growth factor-&#946;1.

Alzheimer&#39;s disease (AD) is an irreversible, progressive brain disease that slowly destroys memory and is accompanied by neuron loss and structure ...

Behavior

Stereotaxic Infusion of Oligomeric Amyloid-beta into the Mouse Hippocampus

Alzheimer&#8217;s disease is a neurodegenerative disease affecting the aging population. A key neuropathological feature of the disease is the over-production of amyloid-beta and the deposition of amyloid-beta plaques in brain regions of the afflicted individuals. Throughout the years scientists have generated numerous Alzheimer&#8217;s disease mouse models that attempt to replicate the amyloid-beta pathology. Unfortunately, the mouse models only selectively mimic the disease features. Neuronal death, a prominent effect in the brains of Alzheimer&#8217;s disease patients, is noticeably lacking in these mice. Hence, we and others have employed a method of directly infusing soluble oligomeric species of amyloid-beta - forms of amyloid-beta that have been proven to be most toxic to neurons - stereotaxically into the brain. In this report we utilize male C57BL/6J mice to document this surgical technique of increasing amyloid-beta levels in a select brain region. The infusion target is the dentate gyrus of the hippocampus because this brain structure, along with the basal forebrain that is connected by the cholinergic circuit, represents one of the areas of degeneration in the disease. The results of elevating amyloid-beta in the dentate gyrus via stereotaxic infusion reveal increases in neuron loss in the dentate gyrus within 1 week, while there is a concomitant increase in cell death and cholinergic neuron loss in the vertical limb of the diagonal band of Broca of the basal forebrain. These effects are observed up to 2 weeks. Our data suggests that the current amyloid-beta infusion model provides an alternative mouse model to address region specific neuron death in a short-term basis. The advantage of this model is that amyloid-beta can be elevated in a spatial and temporal manner.

Here, we present a protocol for direct stereotaxic brain infusion of amyloid-beta. This methodology provides an alternative in vivo mouse model to address the short-term effects of amyloid-beta on brain neurons.

Alzheimer&#8217;s disease is a neurodegenerative disease affecting the aging population. A key neuropathological feature of the disease is the ...

Intracerebroventricular Injection of Amyloid-&#946; Peptides in Normal Mice to Acutely Induce Alzheimer-like Cognitive Deficits

Amyloid-&#946; (A&#946;) is a major pathological mediator of both familial and sporadic Alzheimer's disease (AD). In the brains of AD patients, progressive accumulation of A&#946; oligomers and plaques is observed. Such A&#946; abnormalities are believed to block long-term potentiation, impair synaptic function, and induce cognitive deficits. Clinical and experimental evidences have revealed that the acute increase of A&#946; levels in the brain allows development of Alzheimer-like phenotypes. Hence, a detailed protocol describing how to acutely generate an AD mouse model via the intracerebroventricular (ICV) injection of A&#946; is necessary in many cases. In this protocol, the steps of the experiment with an A&#946;-injected mouse are included, from the preparation of peptides to the testing of behavioral abnormalities. The process of preparing the tools and animal subjects before the injection, of injecting the A&#946; into the mouse brain via ICV injection, and of assessing the degree of cognitive impairment are easily explained throughout the protocol, with an emphasis on tips for effective ICV injection of A&#946;. By mimicking certain aspects of AD with a designated injection of A&#946;, researchers can bypass the aging process and focus on the downstream pathology of A&#946; abnormalities.

The amyloid-&#946; (A&#946;)-injected animal model enables the administration of a defined quantity and species of A&#946; fragments and reduces individual differences within each study group. This protocol describes the intracerebroventricular (ICV) injection of A&#946; without stereotactic instruments, enabling the production of Alzheimer-like behavioral abnormalities in normal mice.

Amyloid-&#946; (A&#946;) is a major pathological mediator of both familial and sporadic Alzheimer's disease (AD). In the brains of AD patients, ...

Quantitative 3D In Silico Modeling (q3DISM) of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease

Neuroinflammation is now recognized as a major etiological factor in neurodegenerative disease. Mononuclear phagocytes are innate immune cells responsible for phagocytosis and clearance of debris and detritus. These cells include CNS-resident macrophages known as microglia, and mononuclear phagocytes infiltrating from the periphery. Light microscopy has generally been used to visualize phagocytosis in rodent or human brain specimens. However, qualitative methods have not provided definitive evidence of in vivo phagocytosis. Here, we describe quantitative 3D in silico modeling (q3DISM), a robust method allowing for true 3D quantitation of amyloid-&#946; (A&#946;) phagocytosis by mononuclear phagocytes in rodent Alzheimer&#39;s Disease (AD) models. The method involves fluorescently visualizing A&#946; encapsulated within phagolysosomes in rodent brain sections. Large z-dimensional confocal datasets are then 3D reconstructed for quantitation of A&#946; spatially colocalized within the phagolysosome. We demonstrate the successful application of q3DISM to mouse and rat brains, but this methodology can be extended to virtually any phagocytic event in any tissue.

Quantitative 3D In Silico Modeling q3DISM of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease

We developed a methodology for quantitative 3D in silico modeling (q3DISM) of cerebral amyloid-&#946; (A&#946;) phagocytosis by mononuclear phagocytes in rodent models of Alzheimer&#39;s disease. This method can be generalized for the quantitation of virtually any phagocytic event in vivo.

Neuroinflammation is now recognized as a major etiological factor in neurodegenerative disease. Mononuclear phagocytes are innate immune cells responsible ...

Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing neuronal dysfunction which eventually leads to cognitive decline. Hyperphosphorylated tau aggregates in the neuron are believed to cause most of the pathology associated with AD. These aggregates are assumed to be released into the extracellular compartment and taken up by adjacent healthy neurons where they induce further tau aggregation. This &#34;prion-like&#34; spreading can be interrupted by antibodies capable of binding and &#34;neutralizing&#34; extracellular tau aggregates as shown in preclinical mouse models of AD. One of the proposed mechanisms by which therapeutic antibodies reduce pathology is antibody-mediated uptake and clearance of pathological aggregated forms of tau by microglia. Here, we describe a quantitative cell-based assay to assess tau uptake by microglia. This assay uses the mouse microglial cell line BV-2, allows for high specificity, low variability and medium throughput. Data generated with this assay can contribute to a better characterization of anti-tau antibody effector functions.

Here we describe a cell-based assay to quantitatively assess tau uptake by microglia with the aim of creating an investigational tool to better characterize the mechanisms of action of anti-tau antibodies.

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing ...

Controlled Infusion of A&beta; Peptide-Specific Antibodies and A&beta; Oligomers into the Rat Hippocampus

Source: Sajadi, A., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/54215">Neurodegeneration in an Animal Model of Chronic Amyloid-beta Oligomer Infusion Is Counteracted by Antibody Treatment Infused with Osmotic Pumps.</a> J. Vis. Exp. (2016).
This video demonstrates a technique for the continuous infusion of amyloid-beta (A&#946;) peptide-specific antibodies into the hippocampus of a rat. The study employs implanting a bilateral cannula system for a controlled infusion of A&#946; peptide-specific antibodies coupled with the infusion of soluble A&#946; oligomers (A&#946;o) into the rat hippocampus to study the interactions between the oligomers and the antibodies.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. ...

JoVE Encyclopedia of Experiments

Immunology

Antibody-Based Technologies

Antibody-Based Imaging and Detection Methods

Direct Stereotaxic Brain Infusion of Amyloid-Beta Proteins for an Alzheimer's Disease Model

Source: Jean, Y. Y. et al., <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/52805">Stereotaxic Infusion of Oligomeric Amyloid-beta into the Mouse Hippocampus.</a> J. Vis. Exp. (2015)
This video demonstrates the precise stereotaxic infusion of amyloid beta into the dentate gyrus to establish a mouse model of Alzheimer&#39;s disease. Accurate coordinate determination and controlled delivery of amyloid beta proteins result in neuronal degradation, disrupting memory processing and contributing to Alzheimer&#39;s disease development.

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review ...

Neuropathology

Neurodegenerative Diseases

Alzheimer's Disease: Treatment

Alzheimer&#39;s Disease (AD), a neurodegenerative disorder, is pathologically identified by amyloid plaques and neurofibrillary tangles composed of tau protein. AD pharmacotherapy aims to manage cognitive symptoms, delay disease progression, and treat behavioral symptoms. The treatment is primarily symptomatic and palliative, with no definitive disease-modifying therapy available. Cholinesterase inhibitors, including donepezil (Aricept), rivastigmine (Exelon), and galantamine (Razadyne), are first-line treatments for the first two stages of AD. These drugs work by inhibiting acetylcholinesterase (AChE), thus enhancing cholinergic transmission in the brain. The loss of cholinergic neurons is a characteristic of AD. Common adverse effects of these inhibitors include nausea, diarrhea, vomiting, anorexia, tremors, bradycardia, and muscle cramps.
Memantine (Namenda), an NMDA antagonist, is used in moderate to severe stages of AD as an adjunct or alternative to cholinesterase inhibitors. It acts as an NMDA receptor antagonist, limiting calcium ion influx into neurons and preventing neuronal damage caused by excessive glutamate. Memantine is generally well-tolerated, with few dose-dependent adverse events reported. Often, it is given in combination with an AChE inhibitor due to its different mechanism of action and potential neuroprotective effects. For behavioral and psychiatric symptoms in dementia (BPSD), SSRIs or atypical antipsychotics can be used alongside cholinesterase inhibitors and memantine. Several other drugs, including cholinomimetic drugs, MAO type B inhibitors, and NMDA receptor inhibitors, have been explored to treat AD. Furthermore, antibodies targeting amyloid-beta (A&#946;) have shown the potential to slow AD cognitive decline.
In summary, treating AD involves a multi-pronged approach focusing on symptom management, disease progression delay, and behavioral symptom treatment. However, these treatments do not alter the underlying neurodegenerative process of AD.

The goal of Alzheimer&#39;s disease or AD pharmacotherapy is to manage cognitive symptoms, delay disease progression, and treat behavioral symptoms, ...

Neurodegeneration in an Animal Model of Chronic Amyloid-beta Oligomer Infusion Is Counteracted by Antibody Treatment Infused with Osmotic Pumps

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