This study has been supported by the Edmond and Lily Safra Center for Brain Sciences (SB fellowship), The Legacy Heritage Biomedical Science Partnership Program of the Israel Science Foundation (Grant No. 378/11, to HS) and the German Israeli Foundation for Scientific Research and Development (G.I.F) (Grant No. 1093-32.2/2010, to HS).

1. Lentivirus Preparation
<ol>
	<li>Grow HEK-293FT cells to 90% confluence.</li>
	<li>On the day of transfection change cell medium to serum-free DMEM supplemented with 1 mM glutamine and 50 mg/ml penicillin-streptomycin.</li>
	<li>Co-transfect the cells with a pLKO.1-Puro vector and with plasmids coding for the delta R8.2 and VSV-G moieties and the miRNA of interest, using 10 &mu;l of 1 mg/ml polyethylenimine as a carrier 9.</li>
	<li>Collect packaged lentiviruses at 24 hr and 48 hr post-transfection, filter through 0.45 &mu;m filter.</li>
	<li>Concentrate the lentiviruses using ultracentrifugation in 70,000 x g, for 2 hr and 15 &deg;C, aliquot and store at -70 &deg;C.</li>
	<li>Measure virus titer by infecting HEK-293T cells with serially diluted virus preparations (1 to 10-6 ml of vector per well). The resulting titer (a minimum of ~1&times;109 infectious particles per ml is recommended) is evaluated for expression of the gene of interest, using puromycin selection and by quantifying GFP expressing viruses through counting fluorescent cells.</li>
</ol>
For more detailed protocol of lentivirus preparation see 10.
2. Preparing Animals for Surgery
<ol>
	<li>Surgeons garb should include surgical gown, sterile gloves, cap and mask.</li>
	<li>Weigh the animal, then anesthetize it with an IP-injection of a Ketamine mixture, with the volume proportional to the animal weight as specified for each drug. For a Ketamine/Xylazine mixture, a dose range of 80-200 mg/kg Ketamine and 7-20 mg/kg Xylazine is usually used for mice.</li>
	<li>Wait until the animal is fully anesthetized, then check for lack of withdrawal reflex in the hind limb of the animal by extending the limb and then pressing it with your finger.</li>
	<li>Inject the animal subcutaneously with Rimadyl, as specified on the box, for pain relief. Typical dose range for Rymadil is 5-10 mg.</li>
	<li>Place the animal on a heating pad to keep a steady body temperature and moisten the eyes with ointment.</li>
	<li>Shave the area between the two ears with a trimming machine.</li>
	<li>Sanitize the skin with betadine.</li>
</ol>
3. Exposure of the Skull and Drilling
<ol>
	<li>Place the animal inside the stereotact by adjusting the rods into the crevices just anterior to the animal's ears.</li>
	<li>Use a scalpel to make an anterior-posterior incision of about 1.5 cm between the ears and keep it open with surgery clamps (serfines).</li>
	<li>Clean the surface of the skull with a cotton swab until the intersection between the coronal suture and sagittal sutures; i.e. the bregma and the intersection between the coronal and lambdoid sutures; i.e. lambda, are visible.</li>
	<li>Point the tip of the syringe, held by the stereotact, to the bregma point, at all three axes. Write down the coordinates. This point would be considered as the zero point in all three axes.</li>
	<li>Lift the syringe in the vertical axis so that a planar movement would not scratch the skull and move the syringe head to the correct location. Hippocampal CA1 injections require the following coordinates relative to the bregma in mm: -2 at the anterior/posterior axis, &plusmn;1.8 at the lateral/medial axis and -1.5 at the dorsal/ventral axis.</li>
	<li>Lower the tip of the syringe until it touches the skull and mark the spot with a marker. Remove the syringe back to avoid stabbing.</li>
	<li>Drill a shallow hole, only in the skull bone using a fine driller. Hold the driller steady so it would not continue to drill into the soft tissue underneath. You can prevent this by steadying one hand with the other and by drilling in short pulses.</li>
</ol>
4. Injection of the Lentivirus
<ol>
	<li>Withdraw 0.5 ml of the concentrated lentivirus solution.</li>
	<li>Place the syringe above the hole and slowly lower it vertically until it reaches the surface of the skull. Continue to lower the syringe into the brain very slowly. At this step some bleeding might occur which does not necessarily indicate a failed penetration. If bleeding occurs mop it up with a cotton swab.</li>
	<li>Set the digital pump to 0.02 ml/min (0.5 &mu;l would be injected in 25 min) and start infusion. Slow infusion allows for effective spreading of the virus into the tissue and prevents back flow. In some syringe types consider inserting the syringe for an extra depth of 0.5 mm before retreating to original coordinates and infusing.</li>
	<li>After infusion is completed wait for additional 5 min to allow the material to spread into the brain instead of retreating back into the canal formed by the syringe.</li>
	<li>Remove the syringe very slowly and watch for back flows. If a back flow is observed at this step, a fraction of the injected material was probably lost.</li>
</ol>
5. Wound Sealing and Recovery
<ol>
	<li>Seal the wound with histoacryl. Be sure to avoid leaking of the histoacryl into the eyes.</li>
	<li>Inject the animal intraperitoneally (IP) with 1 ml pre-heated saline, to avoid dehydration.</li>
	<li>Place the animal in a recovery cage that is positioned on a heated pad. Watch the animal while it recovers for an additional hour.</li>
</ol>
In case of weight loss, inappetance, weakness/inability to obtain feed or water, moribund state or infection, euthanasia of the animal should be performed. Acceptable methods for euthanasia of rodents are barbiturates, inhalant anesthetics, CO2, CO, or potassium chloride in conjunction with general anesthesia.
After 4 to 6 weeks, assess the animal's navigation memory is assessed in the Morris Water Maze. The lentivirus will usually infect most cells within the injection sphere.
6. Behavioral Assessment in the Morris Water Maze
<ol>
	<li>Train the animals in the Morris Water Maze. For exact training and testing protocol see 11. After each trial, dry the animal with a dry towel, replace it in its cage and refresh the water in the tank.</li>
	<li>Test the animals in the Morris Water Maze for 3 consecutive days, 4 trials each day. Each day insert the animal into the maze in each of the 4 directions of the maze (north, south, east and west) in a changing order, for example day one: east-west-north-south, day two: west-south-north-east. Wipe the animals after each trial.</li>
	<li>During the test trials track the animal with a tracking system such as the Noldus tracking system.</li>
	<li>After the 12th test trial, insert the animal into the water tank without the platform for one minute. This would be used to analyze the searching strategy the animal is taking.</li>
	<li>Analyze the data as suggested in 12.</li>
</ol>

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	<li>Siegel, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+functional+screen+implicates+microRNA-138-dependent+regulation+of+the+depalmitoylation+enzyme+APT1+in+dendritic+spine+morphogenesis.">A functional screen implicates microRNA-138-dependent regulation of the depalmitoylation enzyme APT1 in dendritic spine morphogenesis.</a> Nature Cell Biology. 11, 705-716 (2009).</li><li>Jin, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biochemical+and+genetic+interaction+between+the+fragile+X+mental+retardation+protein+and+the+microRNA+pathway.">Biochemical and genetic interaction between the fragile X mental retardation protein and the microRNA pathway.</a> Nature Neuroscience. 7, 113-117 (2004).</li><li>Simon, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+microRNA+miR-1+regulates+a+MEF-2-dependent+retrograde+signal+at+neuromuscular+junctions.">The microRNA miR-1 regulates a MEF-2-dependent retrograde signal at neuromuscular junctions.</a> Cell. 133, 903-915 (2008).</li><li>Consiglio, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+gene+therapy+of+metachromatic+leukodystrophy+by+lentiviral+vectors:+correction+of+neuropathology+and+protection+against+learning+impairments+in+affected+mice.">In vivo gene therapy of metachromatic leukodystrophy by lentiviral vectors: correction of neuropathology and protection against learning impairments in affected mice.</a> Nature Medicine. 7, 310-316 (2001).</li><li>Jakobsson, J., Lundberg, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lentiviral+vectors+for+use+in+the+central+nervous+system.">Lentiviral vectors for use in the central nervous system.</a> Molecular Therapy: The Journal of the American Society of Gene Therapy. 13, 484-493 (2006).</li><li>Berson, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cholinergic-associated+loss+of+hnRNP-A/B+in+Alzheimer's+disease+impairs+cortical+splicing+and+cognitive+function+in+mice.">Cholinergic-associated loss of hnRNP-A/B in Alzheimer's disease impairs cortical splicing and cognitive function in mice.</a> EMBO Molecular Medicine. , (2012).</li><li>Haramati, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MicroRNA+as+repressors+of+stress-induced+anxiety:+the+case+of+amygdalar+miR-34.">MicroRNA as repressors of stress-induced anxiety: the case of amygdalar miR-34.</a> The Journal of Neuroscience: The Official Journal of the Society for Neuroscience. 31, 14191-14203 (2011).</li><li>Shaltiel, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hippocampal+microRNA-132+mediates+stress-inducible+cognitive+deficits+through+its+acetylcholinesterase+target.">Hippocampal microRNA-132 mediates stress-inducible cognitive deficits through its acetylcholinesterase target.</a> Brain Structure &amp; Function. , 10-1007 (2012).</li><li>Boussif, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+versatile+vector+for+gene+and+oligonucleotide+transfer+into+cells+in+culture+and+in+vivo:+polyethylenimine.">A versatile vector for gene and oligonucleotide transfer into cells in culture and in vivo: polyethylenimine.</a> Proceedings of the National Academy of Sciences of the United States of America. 92, 7297-7301 (1995).</li><li>Mendenhall, A., Lesnik, J., Mukherjee, C., Antes, T., Sengupta, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Packaging+HIV-+or+FIV-based+lentivector+expression+constructs+&amp;+transduction+of+VSV-G+pseudotyped+viral+particles.">Packaging HIV- or FIV-based lentivector expression constructs &amp; transduction of VSV-G pseudotyped viral particles.</a> J. 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The authors declare that they have no competing financial interests.

Stereotactic injection of a lentivirus is a relatively rapid method for in vivo assessment for both up- or down- regulation of different genes and miRNAs. The main alternative is a genetically engineered mouse which is a much more laborious and time consuming technique then direct lentivirus injection. In addition, the up regulation, in lentivirus injection, occurs at a specific time in the adult mouse and does not include any possibility of leakiness during development, as is most often the case in the genetica...

The role of particular miRNAs in nervous system functioning has recently been challenged by lentiviral injection in several studies. MiRNAs have been found to be crucial for maintaining and re-shaping synapse structure 1, synaptogenesis 2 and synapse remodeling and maintenance 3. These studies strongly suggest that miRNAs are engaged, via multileveled regulatory effects in both the shaping up and in maintaining the main output of the nervous system, cognitive function. Stereotactic injection of lentivirus particles into specific regions in the rodent brain enables searching for alterations in synapse morphology and neuronal activity, and was used for establishing the functional significance of over-expressed transcripts 4,5. Direct infection of neurons at well-defined brain areas with miRNA-expressing lentiviruses may be implicated in studies of aging, brain disorders and neurodegeneration; Studies of miRNAs in the realm of behavioral regulation 6-8 are at a far less advanced state, and stereotactic injection of miRNA-expressing lentivirus particles followed by behavioral tests may be useful for such purposes. A considerably more laborious method for inducing over- or under-expression involves genetically engineered knock-in or knockout mice. Genetic systems can further allow for conditional and temporal control on expression (e.g. Cre-Lox, Tet systems), but these hardly offer the spatial specificity of the injection procedure and there is almost always a certain amount of leakiness. Also, the engineering procedures do not require surgery and can be used across laboratories with relatively good reproducibility; however, they are slower and require much more manpower and financial resources. In addition, the temporal control of the over- or under-expression in injected mice is far more accurate compared to genetically engineered mice.

<table><tbody><tr><td colspan="4">&lt;strong&gt;Equipment&lt;/strong&gt;</td></tr><tr><td>Rodent weigh scale</td><td>Burtons (UK)</td><td>115-455</td><td></td></tr><tr><td>heating pad</td><td>FIRst&lt;sup&gt;&lt;/sup&gt;Technology</td><td>DCT-25</td><td></td></tr><tr><td>trimming machine</td><td>Stoelting</td><td>51465</td><td></td></tr><tr><td>stereotact</td><td>Stoelting</td><td>51730</td><td></td></tr><tr><td>Scalpel and blades</td><td>Kent scientific</td><td>INS500348</td><td></td></tr><tr><td>Harland syringe</td><td>Hamilton</td><td>7632-01</td><td></td></tr><tr><td>driller</td><td>Stoelting</td><td>51449</td><td></td></tr><tr><td>digital pump</td><td>Harvard apparatus</td><td>704507</td><td></td></tr><tr><td>Water tank and platform</td><td>Stoelting</td><td>60135</td><td></td></tr><tr><td colspan="4">&lt;strong&gt;Reagents&lt;/strong&gt;</td></tr><tr><td>ketamine </td><td>Vetoquinol(Lure France)</td><td>3055503</td><td></td></tr><tr><td>domitor</td><td>Orion pharma</td><td>107140-10</td><td></td></tr><tr><td>Rimadyl</td><td>Pfizer animal health</td><td>24751</td><td></td></tr><tr><td>moisture ointment - Synthomycine 5%</td><td>Rekah Pharmaceutical</td><td>195</td><td> </td></tr><tr><td>histoacryl</td><td>Braun</td><td>112101</td><td></td></tr><tr><td>saline</td><td>Sigma Aldrich</td><td>D8662</td><td></td></tr></tbody></table>

stereotactic injection of microrna-expressing lentiviruses to the mouse hippocampus ca1 region and assessment of the behavioral outcome

MicroRNAs (miRNAs) are small regulatory single-stranded RNA molecules around 22 nucleotides long that may each target numerous mRNA transcripts and dim an entire gene expression pathway by inducing destruction and/or inhibiting translation of these targets. Several miRNAs play key roles in maintaining neuronal structure and function and in higher-level brain functions, and methods are sought for manipulating their levels for exploring these functions. Here, we present a direct in vivo method for examining the cognitive consequences of enforced miRNAs excess in mice by stereotactic injection of miRNA-encoding virus particles. Specifically, the current protocol involves injection into the hippocampal CA1 region, which contributes to mammalian memory consolidation, learning, and stress responses, and offers a convenient injection site. The coordinates are measured according to the mouse bregma and virus perfusion is digitally controlled and kept very slow. After injection, the surgery wound is sealed and the animals recover. Lentiviruses encoding silencers of the corresponding mRNA targets serve to implicate the specific miRNA/target interaction responsible for the observed effect, with na&iuml;ve mice, mice injected with saline and mice injected with "empty" lentivirus vectors as controls. One month post-injection, the animals are examined in the Morris Water Maze (MWM) for assessing their navigation learning and memory abilities. The MWM is a round tank filled with colored water with a small platform submerged 1 cm below the water surface. Steady visual cues around the tank allow for spatial navigation (sound and the earth's magnetic field may also assist the animals in navigating). Video camera monitoring enables measuring the route of swim and the time to find and amount the platform. The mouse is first taught that mounting the hidden platform offers an escape from the enforced swimming; it is then tested for using this escape and finally, the platform is removed and probe tests examine if the mouse remembers its previous location. Repeated tests over several consecutive days highlight improved performance of tested mice at shorter latencies to find and mount the platform, and as more direct routes to reach the platform or its location. Failure to show such improvement represents impaired learning and memory and/or anxiety, which may then be tested specifically (e.g. in the elevated plus maze). This approach enables validation of specific miRNAs and target transcripts in the studied cognitive and/or stress-related processes.

Injection of 0.5 &mu;l lentivirus into the CA1 region in the mouse hippocampus, with the flow rate indicated in the protocol section yields an infected sphere of about 1 mm in the rostral-caudal axis, and about 0.5 mm in the medial-lateral and the anterior-posterior axes (Figure 3).
<img alt="Figure 1" src="/files/ftp_upload/50170/50170fig1.jpg" /> 
 Figure 1. Bregma point and injection apparatus. (a)...

Watch this Scientific Journal Video about Stereotactic Injection of MicroRNA-expressing Lentiviruses to the Mouse Hippocampus CA1 Region and Assessment of the Behavioral Outcome at JoVE.com

Stereotactic Injection of MicroRNA-expressing Lentiviruses to the Mouse Hippocampus CA1 Region and Assessment of the Behavioral Outcome

MicroRNAs have significant roles in brain structure and function. Here we describe a method to enforce hippocampal miRNA over-expression using stereotactic injection of an engineered miRNA-expressing lentivirus. This approach can serve as a relatively rapid way to assess the in vivo effects of over-expressed miRNAs in specific brain regions.

MicroRNAs (miRNAs) are small regulatory single-stranded RNA molecules around 22 nucleotides long that may each target numerous mRNA transcripts and dim an ...

stereotactic-injection-microrna-expressing-lentiviruses-to-mouse

Universidad de Cartagena UDEC

Research

JoVE Journal

Behavior

22.8K Views.  The Hebrew University of Jerusalem. MicroRNAs have significant roles in brain structure and function. Here we describe a method to enforce hippocampal miRNA over-expression using stereotactic injection of an engineered miRNA-expressing lentivirus. This approach can serve as a relatively rapid way to assess the in vivo effects of over-expressed miRNAs in specific brain regions.

Video: Stereotactic Injection of MicroRNA-expressing Lentiviruses to the Mouse Hippocampus CA1 Region and Assessment of the Behavioral Outcome

Stereotaxic Microinjection of Viral Vectors Expressing Cre Recombinase to Study the Role of Target Genes in Cocaine Conditioned Place Preference

Microinjecting recombinant adenoassociated viral (rAAV) vectors expressing Cre recombinase into distinct mouse brain regions to selectively knockout genes of interest allows for enhanced temporally- and regionally-specific control of gene deletion, compared to existing methods. While conditional deletion can also be achieved by mating mice that express Cre recombinase under the control of specific gene promoters with mice carrying a floxed gene, stereotaxic microinjection allows for targeting of discrete brain areas at experimenter-determined time points of interest. In the context of cocaine conditioned place preference, and other cocaine behavioral paradigms such as self-administration or psychomotor sensitization that can involve withdrawal, extinction and/or reinstatement phases, this technique is particularly useful in exploring the unique contribution of target genes to these distinct phases of behavioral models of cocaine-induced plasticity. Specifically, this technique allows for selective ablation of target genes during discrete phases of a behavior to test their contribution to the behavior across time. Ultimately, this understanding allows for more targeted therapeutics that are best able to address the most potent risk factors that present themselves during each phase of addictive behavior.

This article describes how to microinject viral vectors into mouse brain and then test in a conditioned place preference paradigm that includes an acquisition, extinction and reinstatement phase.

Microinjecting recombinant adenoassociated viral (rAAV) vectors expressing Cre recombinase into distinct mouse brain regions to selectively knockout genes ...

Applying Stereotactic Injection Technique to Study Genetic Effects on Animal Behaviors

Stereotactic injection is a useful technique to deliver high titer lentiviruses to targeted brain areas in mice. Lentiviruses can either overexpress or knockdown gene expression in a relatively focused region without significant damage to the brain tissue. After recovery, the injected mouse can be tested on various behavioral tasks such as the Open Field Test (OFT) and the Forced Swim Test (FST). The OFT is designed to assess locomotion and the anxious phenotype in mice by measuring the amount of time that a mouse spends in the center of a novel open field. A more anxious mouse will spend significantly less time in the center of the novel field compared to controls. The FST assesses the anti-depressive phenotype by quantifying the amount of time that mice spend immobile when placed into a bucket of water. A mouse with an anti-depressive phenotype will spend significantly less time immobile compared to control animals. The goal of this protocol is to use the stereotactic injection of a lentivirus in conjunction with behavioral tests to assess how genetic factors modulate animal behaviors.

Stereotactic injection of lentiviruses expressing cDNAs or shRNAs can modulate gene expression in specific brain areas of mice. Here, we present a protocol to combine stereotactic injections with behavioral tasks, such as the Open Field Test (OFT) and the Forced Swim Test (FST).

Stereotactic injection is a useful technique to deliver high titer lentiviruses to targeted brain areas in mice. Lentiviruses can either overexpress or ...

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 ...

Neuroscience

A Simple Alternative to Stereotactic Injection for Brain Specific Knockdown of miRNA

MicroRNAs (miRNAs) are key regulators of gene expression. In the brain, vital processes like neurodevelopment and neuronal functions depend on the correct expression of microRNAs. Perturbation of microRNAs in the brain can be used to model neurodegenerative diseases by modulating neuronal cell death. Currently, stereotactic injection is used to deliver miRNA knockdown agents to specific location in the brain. Here, we discuss strategies to design antagomirs against miRNA with locked nucleotide modifications (LNA). Subsequently describe a method for brain specific delivery of antagomirs, uniformly across different regions of the brain. This method is simple and widely applicable since it overcomes the surgery, associated injury and limitation of local delivery in stereotactic injections. We prepared a complex of neurotropic, cell-penetrating peptide Rabies Virus Glycoprotein (RVG) with antagomir against miRNA-29 and injected through tail vein, to specifically deliver in the brain. The antagomir design incorporated features that allow specific targeting of the miRNA and formation of non-covalent complexes with the peptide. The knock-down of the miRNA in neuronal cells, resulted in apoptotic cell death and associated behavioural defects. Thus, the method can be used for acute models of neuro-degeneration through the perturbation of miRNAs.

MicroRNAs play crucial roles in the brain and are potential targets for modeling neuro-degeneration. However, perturbing miRNA levels is challenging due to the short length of miRNA and inaccessibility of the brain tissue. This video presents a method for antagomir design and brain specific delivery using a neuropeptide in mice.

MicroRNAs (miRNAs) are key regulators of gene expression.  In the brain, vital processes like neurodevelopment and neuronal functions depend on the ...

Designing, Packaging, and Delivery of High Titer CRISPR Retro and Lentiviruses via Stereotaxic Injection

Replication defective lentiviruses or retroviruses are capable of stably integrating transgenes into the genome of an infected host cell. This technique has been widely used to encode fluorescent proteins, opto- or chemo-genetic controllers of cell activity, or heterologous expression of human genes in model organisms. These viruses have also successfully been used to deliver recombinases to relevant target sites in transgenic animals, or even deliver small hairpin or micro RNAs in order to manipulate gene expression. While these techniques have been fruitful, they rely on transgenic animals (recombinases) or frequently lack high efficacy and specificity (shRNA/miRNA). In contrast, the CRISPR/Cas system uses an exogenous Cas nuclease which targets specific sites in an organism's genome via an exogenous guide RNA in order to induce double stranded breaks in DNA. These breaks are then repaired by non-homologous end joining (NHEJ), producing insertion and deletion (indel) mutations that can result in deleterious missense or nonsense mutations. This manuscript provides detailed methods for the design, production, injection, and validation of single lenti/retro virus particles that can stably transduce neurons to express a fluorescent reporter, Cas9, and sgRNAs to knockout genes in a model organism.

The CRISPR/Cas9 system offers the potential to make targeted genome editing accessible and affordable to the scientific community. This protocol is intended to demonstrate how to create viruses that will knockout a gene of interest using the CRISPR/Cas9 system, and then inject them stereotaxically into the adult mouse brain.

Replication defective lentiviruses or retroviruses are capable of stably integrating transgenes into the genome of an infected host cell. This technique ...

Assaying Circuit Specific Regulation of Adult Hippocampal Neural Precursor Cells

Adult neurogenesis is a dynamic process by which newly activated neural stem cells (NSCs) in the subgranular zone (SGZ) of the dentate gyrus (DG) generate new neurons, which integrate into an existing neural circuit and contribute to specific hippocampal functions. Importantly, adult neurogenesis is highly susceptible to environmental stimuli, which allows for activity-dependent regulation of various cognitive functions. A vast range of neural circuits from various brain regions orchestrates these complex cognitive functions. It is therefore important to understand how specific neural circuits regulate adult neurogenesis. Here, we describe a protocol to manipulate neural circuit activity using designer receptor exclusively activated by designer drugs (DREADDs) technology that regulates NSCs and newborn progeny in rodents. This comprehensive protocol includes stereotaxic injection of viral particles, chemogenetic stimulation of specific neural circuits, thymidine analog administration, tissue processing, immunofluorescence labeling, confocal imaging, and imaging analysis of various stages of neural precursor cells. This protocol provides detailed instructions on antigen retrieval techniques used to visualize NSCs and their progeny and describes a simple, yet effective way to modulate brain circuits using clozapine N-oxide (CNO) or CNO-containing drinking water and DREADDs-expressing viruses. The strength of this protocol lies in its adaptability to study a diverse range of neural circuits that influence adult neurogenesis derived from NSCs.

The goal of this protocol is to describe an approach for analyzing behavior of adult neural stem/progenitor cells in response to chemogenetic manipulation of a specific local neural circuit.

Adult neurogenesis is a dynamic process by which newly activated neural stem cells (NSCs) in the subgranular zone (SGZ) of the dentate gyrus (DG) generate ...

Non-invasive Strategies for Chronic Manipulation of DREADD-controlled Neuronal Activity

Chemogenetic strategies have emerged as reliable tools for remote control of neuronal activity. Among these, designer receptors exclusively activated by designer drugs (DREADDs) have become the most popular chemogenetic approach used in modern neuroscience. Most studies deliver the ligand clozapine-N-oxide (CNO) using a single intraperitoneal injection, which is suitable for the acute activation/inhibition of the targeted neuronal population. There are, however, only a few examples of strategies for chronic modulation of DREADD-controlled neurons, the majority of which rely on the use of delivery systems that require surgical intervention. Here, we expand on two non-invasive strategies for delivering the ligand CNO to chronically manipulate neural population in mice. CNO was administered either by using repetitive (daily) eye-drops, or chronically through the animal&#39;s drinking water. These non-invasive paradigms result in robust activation of the designer receptors that persisted throughout the CNO treatments. The methods described here offer alternatives for the chronic DREADD-mediated control of neuronal activity and may be useful for experiments designed to evaluate behavior in freely moving animals, focusing on less-invasive CNO delivery methods.

Here we describe two non-invasive methods to chronically control neuronal activity using chemogenetics in mice. Eye-drops were used to deliver clozapine-N-oxide (CNO) daily. We also describe two methods for prolonged administration of CNO in drinking water. These strategies for chronic neuronal control require minimal intervention reducing animals&#8217; stress.

Chemogenetic strategies have emerged as reliable tools for remote control of neuronal activity. Among these, designer receptors exclusively activated by ...

Craniotomy Procedure for Visualizing Neuronal Activities in Hippocampus of Behaving Mice

Imaging neuronal activities at single-cell resolution in awake behaving animals is a very powerful approach for the investigation of neural circuit functions in systems neuroscience. However, high absorbance and scattering of light in mammalian tissue limit intravital imaging mostly to superficial brain regions, leaving deep-brain areas, such as the hippocampus, out of reach for optical microscopy. In this video, we show the preparation and implantation of the custom-made imaging window to enable chronic in vivo imaging of the dorsal hippocampal CA1 region in head-fixed behaving mice. The custom-made window is supplemented with an infusion cannula that allows targeted delivery of viral vectors and drugs to the imaging area. By combining this preparation with wide-field imaging, we performed a long-term recording of neuronal activity using a fluorescent calcium indicator from large subsets of neurons in behaving mice over several weeks. We also demonstrated the applicability of this preparation for voltage imaging with single-spike resolution. High-performance genetically encoded indicators of neuronal activity and scientific CMOS cameras allowed the recurrent visualization of subcellular morphological details of single neurons at high temporal resolution. We also discuss the advantages and potential limitations of the described method and its compatibility with other imaging techniques.

This article demonstrates the preparation of a custom-made imaging window supplemented with infusion cannula and its implantation onto the CA1 region of the hippocampus in mice.

Imaging neuronal activities at single-cell resolution in awake behaving animals is a very powerful approach for the investigation of neural circuit ...

Rodent Stereotaxic Surgery

Stereotaxic (or stereotactic) surgery is a method used to manipulate the brain of living animals. This technique allows researchers to accurately target deep structures within the brain through the use of a stereotaxic atlas, which provides the 3D coordinates of each area with respect to anatomical landmarks on the skull. After the skull is exposed, anesthetized animals are mounted on a specialized instrument known as a stereotaxic frame, which enables the precise placement of experimental tools at the defined coordinates. Stereotaxic surgery is a versatile approach that can be used to generate lesions, manipulate gene expression, or deliver experimental agents to the brain.This video-article provides a general overview of the principles behind stereotaxic surgery, including instructions for using a stereotaxic atlas and the stereotaxic frame, and an introduction to reading the Vernier scale for measurement of probe movements. The subsequent discussion outlines the steps required to perform the surgical procedure. Lastly, a broad range of technical applications are presented, such as the insertion of electrical probes to measure brain activity and genetic manipulation of brain tissue.

Stereotaxic (or stereotactic) surgery is a method used to manipulate the brain of living animals. This technique allows researchers to accurately target ...

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Advanced Biology

MicroRNA-Mediated Inhibition of Excitatory Postsynaptic Currents in Mouse Hippocampal Slices

Source: Thalhammer, A., et al. <a href="https://appjove.unicartagenaproxy.elogim.com/v/57223">Combining Optogenetics with Artificial microRNAs to Characterize the Effects of Gene Knockdown on Presynaptic Function within Intact Neuronal Circuits.</a> J. Vis. Exp. (2018)
This video demonstrates microRNA-mediated inhibition of excitatory synaptic currents in mouse hippocampal brain slices. The CA3 neurons were infected with a recombinant viral vector harboring a construct for expressing a fluorescent reporter, a light-activated membrane channel, and a microRNA that downregulates the expression of voltage-gated calcium channels. Upon placing a slice in a recording chamber and patching a CA1 neuron with a recording pipette, light pulses were used to stimulate the light-activated channel, resulting in an ion influx and generating an action potential. The absence of voltage-gated calcium channels in CA3 neurons inhibits neurotransmitter release, causing inhibition of excitatory postsynaptic currents in the synaptically-connected CA1 neurons.

1. Assessing the Role of Presynaptic Proteins in Intact Neuronal Circuits by Targeted Stimulation of Knocked-down Neurons with Optogenetics
NOTE: The ...