Name: using a bipolar electrode to create a temporal lobe epilepsy mouse model by electrical kindling of the amygdala
Uploaded: 2022-06-29T14:30:00
Description: Watch this Scientific Journal Video about Using a Bipolar Electrode to Create a Temporal Lobe Epilepsy Mouse Model by Electrical Kindling of the Amygdala at JoVE.com

The research was supported by the National Natural Science Foundation of China (No. 82030037, 81871009) and Beijing Municipal Health Commission (11000022T000000444685). We thank TopEdit (www.topeditsci.com) for its linguistic assistance during the preparation of this manuscript.

This experiment was approved by the Experimental Animal Ethics Committee of Xuanwu Hospital, Capital Medical University. All mice were kept in the animal laboratory of Xuanwu Hospital, Capital Medical University. This protocol is divided into four parts. The first two parts introduce the method of building the electrode and the electric circuit using a slip ring to connect the electrodes and the EEG recording/stimulation equipment. The third part describes the operation method of electrode implantation, and the fourth pa...

<ol>
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J., 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=The+spatiotemporal+dynamics+of+phase+synchronization+during+epileptogenesis+in+amygdala-kindling+mice.">The spatiotemporal dynamics of phase synchronization during epileptogenesis in amygdala-kindling mice.</a> PLoS One. 11 (4), 0153897 (2016).</li><li>Wang, Y., Wei, P., Yan, F., Luo, Y., Zhao, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+epilepsy:+A+phenotype-oriented+review.">Animal models of epilepsy: A phenotype-oriented review.</a> Aging and Disease. 13 (1), 215-231 (2022).</li><li>Fallah, M. S., Dlugosz, L., Scott, B. W., Thompson, M. D., Burnham, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antiseizure+effects+of+the+cannabinoids+in+the+amygdala-kindling+model.">Antiseizure effects of the cannabinoids in the amygdala-kindling model.</a> Epilepsia. 62 (9), 2274-2282 (2021).</li><li>Chipika, R. H., 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=Amygdala+pathology+in+amyotrophic+lateral+sclerosis+and+primary+lateral+sclerosis.">Amygdala pathology in amyotrophic lateral sclerosis and primary lateral sclerosis.</a> Journal of the Neurological Sciences. 417, 117039 (2020).</li><li>Kuchukhidze, 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=Emotional+recognition+in+patients+with+mesial+temporal+epilepsy+associated+with+enlarged+amygdala.">Emotional recognition in patients with mesial temporal epilepsy associated with enlarged amygdala.</a> Frontiers in Neurology. 12, 803787 (2021).</li><li>Soper, C., Wicker, E., Kulick, C. V., N'Gouemo, P., Forcelli, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optogenetic+activation+of+superior+colliculus+neurons+suppresses+seizures+originating+in+diverse+brain+networks.">Optogenetic activation of superior colliculus neurons suppresses seizures originating in diverse brain networks.</a> Neurobiology of Disease. 87, 102-115 (2016).</li><li>Devinsky, 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=Epilepsy.">Epilepsy.</a> Nature Reviews Disease Primers. 4, 18024 (2018).</li><li>Zhang, Z., 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=Interaction+between+thalamus+and+hippocampus+in+termination+of+amygdala-kindled+seizures+in+mice.">Interaction between thalamus and hippocampus in termination of amygdala-kindled seizures in mice.</a> Computational and Mathematical Methods in Medicine. 2016, 9580724 (2016).</li><li>Ghotbedin, Z., Janahmadi, M., Mirnajafi-Zadeh, J., Behzadi, G., Semnanian, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+low+frequency+stimulation+of+the+kindling+site+preserves+the+electrophysiological+properties+of+the+rat+hippocampal+CA1+pyramidal+neurons+from+the+destructive+effects+of+amygdala+kindling:+the+basis+for+a+possible+promising+epilepsy+therapy.">Electrical low frequency stimulation of the kindling site preserves the electrophysiological properties of the rat hippocampal CA1 pyramidal neurons from the destructive effects of amygdala kindling: the basis for a possible promising epilepsy therapy.</a> Brain Stimulation. 6 (4), 515-523 (2013).</li><li>Hristova, K., 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=Medial+septal+GABAergic+neurons+reduce+seizure+duration+upon+optogenetic+closed-loop+stimulation.">Medial septal GABAergic neurons reduce seizure duration upon optogenetic closed-loop stimulation.</a> Brain. 144 (5), 1576-1589 (2021).</li></ol>

Epilepsy is a group of diseases with multiple manifestations and diverse causes18; it should be noted that no single model can be used for all types of epilepsy, and researchers must select an appropriate model for their specific study. The present study introduces one of the most accessible methods of electrode fabrication. Various parts of this method can be adjusted to adapt to different experimental conditions.
This method utilizes electrodes with both stimulating a...

Temporal lobe epilepsy (TLE) is the most prevalent type of epilepsy and has a high risk of conversion into drug-resistant epilepsy. Surgery, such as selective amygdalohippocampectomy, is an effective treatment for TLE, and the epileptogenesis and ictogenesis of the disease are still under investigation1,2. Pathogenesis of TLE has been shown to occur not only in the hippocampus but also extensively in the amygdala3,4. For example, both amygdala sclerosis and amygdala enlargement have been frequently reported as the origins of TLE seizures5,6. The importance of the amygdala cannot be underestimated; an amygdala model is essential for the study of epileptogenesis, and a clear illustration of this model is urgently needed.
Several approaches have been proposed to induce seizures in animal models. In the past, convulsant drugs were injected intraperitoneally at an early stage7. Although this method was convenient, the location of epileptic foci was uncertain. With the development of stereotactic technology and a detailed animal brain atlas, intracranial drug injection was applied to solve the problem of localization8. However, a lack of intervention for severe seizures during the acute stage resulted in a high mortality rate, and chronic spontaneous seizures were accompanied by the problem of unstable interictal and seizure frequency9,10. Finally, the electrical kindling method was developed; this method periodically stimulates specific brain regions several times, allowing seizures to be induced with definite control of both the location and the onset time11.
An advantage of this method is that the intracranial implantation of electrodes is minimally invasive12. Furthermore, the severity of the seizure is controllable by the termination of the stimuli, reducing the mortality caused by the seizures. These changes solved the shortcomings of the previous approaches. Notably, this model can adequately mimic human seizures and is especially suitable for the study of status epilepticus (SE) because of its ability to induce SE quickly13. It can also be used for anti-epileptic drug screening14 and in studies on the mechanism of epilepsy. Finally, it is well known that the amygdala is closely associated with memory modulation, reward processing, and emotion15. Disorders of these mental functions are often encountered in epileptic patients and, thus, the amygdala epilepsy model may be a better choice for studying emotional problems in epilepsy16.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Alexa Fluor 488-conjugated Donkey anti-Rabbit IgG</td>
			<td>invitrogen</td>
			<td>A-21206</td>
			<td></td>
		</tr>
		<tr>
			<td>c-Fos antibody</td>
			<td></td>
			<td>ab222699</td>
			<td></td>
		</tr>
		<tr>
			<td>Cranial drill</td>
			<td>SANS</td>
			<td>SA302</td>
			<td></td>
		</tr>
		<tr>
			<td>dental cement</td>
			<td>NISSIN</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>EEG recording and stimulation equipment</td>
			<td>Neuracle Technology (Changzhou) Co., Ltd</td>
			<td>NSHHFS-210803</td>
			<td></td>
		</tr>
		<tr>
			<td>lead-free tin wire</td>
			<td>BAKON</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Pin header/Female header</td>
			<td>XIANMISI</td>
			<td></td>
			<td>spacing of 1.27 mm</td>
		</tr>
		<tr>
			<td>Silver wire</td>
			<td>A-M systems</td>
			<td>786000</td>
			<td></td>
		</tr>
		<tr>
			<td>Slip ring</td>
			<td>Senring Electronics Co.,Ltd</td>
			<td>SNM008-04</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten wire</td>
			<td>A-M systems</td>
			<td>796000</td>
			<td></td>
		</tr>
		<tr>
			<td>ultrafine multi-stand wire</td>
			<td>Shenzhen Chengxing wire and cable</td>
			<td>UL10064-FEP</td>
			<td></td>
		</tr>
		<tr>
			<td>welding equipment</td>
			<td>BAKON</td>
			<td>BK881</td>
			<td></td>
		</tr>
	</tbody>
</table>

using a bipolar electrode to create a temporal lobe epilepsy mouse model by electrical kindling of the amygdala

The amygdala is one of the most common origins of seizures, and the amygdala mouse model is essential for the illustration of epilepsy. However, few studies have described the experimental protocol in detail. This paper illustrates the whole process of amygdala electrical kindling epilepsy model making, with the introduction of a method of bipolar electrode fabrication. This electrode can both stimulate and record, reducing brain injury caused by implanting separate electrodes for stimulation and recording. For long-term electroencephalogram (EEG) recording purposes, slip rings were used to eliminate the record interruption caused by cable tangles and falling off.
After periodic stimulation (60 Hz, 1 s every 15 min) of the basolateral amygdala (AP: 1.67 mm, L: 2.7 mm, V: 4.9 mm) for 19.83 &plusmn; 5.742 times, full kindling was observed in six mice (defined as induction of three continuous grade V episodes classified by Racine's scale). An intracranial EEG was recorded throughout the entire kindling process, and an epileptic discharge in the amygdala lasting 20-70 s was observed after kindling. Therefore, this is a robust protocol for modeling epilepsy originating from the amygdala, and the method is suitable for revealing the role of the amygdala in temporal lobe epilepsy. This research contributes to future studies on the mechanisms of mesial temporal lobe epilepsy and novel antiepileptogenic drugs.

The electrode and circuit enable the EEG to be recorded and function as a stimulation (Figure 1); this setup avoids the complexity of implanting recording and stimulating electrodes separately and minimizes damage to the brain tissue. The application of slip rings allows electrode connection with all types of devices.
We performed electrode implantation surgery on six healthy adult male C57BL/6 mice, and electrical stimulation was performed 2 weeks after surgery. ...

Watch this Scientific Journal Video about Using a Bipolar Electrode to Create a Temporal Lobe Epilepsy Mouse Model by Electrical Kindling of the Amygdala at JoVE.com

Using a Bipolar Electrode to Create a Temporal Lobe Epilepsy Mouse Model by Electrical Kindling of the Amygdala

The amygdala plays a key role in temporal lobe epilepsy, which originates in and propagates from this structure. This article provides a detailed description of the fabrication of deep brain electrodes with both recording and stimulating functions. It introduces a model of medial temporal lobe epilepsy originating from the amygdala.

The amygdala is one of the most common origins of seizures, and the amygdala mouse model is essential for the illustration of epilepsy. However, few ...

This protocol proposed a model of epilepsy with amygdala as its origin. It paves the way to the investigation of mesial temporal lobe structures. This model could be interpreted as the basis of the experiment.As this protocol is a low-cost and efficient method so it can be carried out quickly in most of the laboratories. Demonstrating the procedure will be Yongchang Lu, a postgraduate in our laboratory. Begin by gathering the pre-prepared components starting with two-centimeter long pieces of Teflon-coated tungsten wire with a bear diameter of 76.2 micrometers.One piece of silver wire with a bear diameter of 127 micrometers of the same length and one set of two by two gauged rope pins. Use a lighter to burn one end of each tungsten wire to remove five millimeters of the insulation coating. Peel a section of ultra fine multi-strand wire.Unwrap from the bottom to the upper end where it starts to get dark continuing to the top. Combine this super fine wire and the tungsten wire by pinching one end and gently twisting the other, enabling the two materials to be easily entwined together. Gently pull to ensure that the wires are tightly wrapped and cut off the excess super fine wire.Try to keep the tungsten wire straight throughout the process. Fix the rope pin to the clamp on the welding table with the longer side of the pins facing outward. Use the syringe needle to pick up some solder paste and apply it to the pins.Heat the welding torch to 320 degrees Celsius. Melt and smear some lead-free tin wire with the torch tip. Overlap the upper end of the tungsten wire with one needle of the rope pins and use the solder on the torch to bond the tungsten wire to the pin.Weld another tungsten wire and another silver wire to the rope pin in the same way so that each wire corresponds to a needle. Cut two heat-shrinkable tubes slightly longer than the upper end of the tungsten wire. Put them on the solder joint of two tungsten wires ensuring that the conductive part is fully covered in the tube so that the circuit of the two tungsten wires is not placed in series.Remove the electrode from the welding table clamp and hold the electrode gently with large pliers as it is easy for electrodes to lose their shape when heating the shrinkable tube. Use a good thermal conductivity clamp with slightly more force. Turn on the air duct and heat until a temperature of 320 degrees Celsius is reached.Blow the heat-shrinkable tube for several seconds until it is tightened. Reinforce the electrode with hot melt adhesive. Hold the two tungsten wires and twist them together, keeping their ends apart.Trim the twisted tungsten wires to approximately 10 millimeters in length so that the separation at the ends does not exceed 0.5 millimeters. Check the electrodes with a multi-meter by placing one bar of the multi-meter on the unwelded side of the rope pins and gently touching the end of tungsten wire or silver wire to the other bar. Checking whether the circuit is smooth.Ensure that the lines are not placed in series. Peel off five millimeters of the insulation skin at each end to expose the metal wire inside. Add a section of heat-shrinkable tubing to each starter wire.Weld each wire with the EEG device connector plug. Shrink the heat-shrinkable tube with hot air. Add a section of heat-shrinkable tube to each rotor wire.Screw the conducting parts of the red and orange wires together and weld them to a joint and the header to fit the rope pin. Weld the other two wires on the header to each joint. Weigh the mouse.When the mouse is fully anesthetized, shave hair from the eye to the ear area with a razor. Fix the mouse on the stereotaxic frame. Put the front upper teeth into the incisor bar and insert both ear bars to equal depths into the ears.Apply erythromycin eye ointment to the eyes to prevent dryness and blindness caused by bright light during surgery. Disinfect the surgical area at least three times with alternating swabs of iodophor and 75%alcohol. Make a longitudinal incision to fully expose the surgical area or make a triangular incision as long as it exposes the anterior and posterior fontanelles and electrode implanting sites.Roll a small piece of cotton into a ball and wet it with 3%hydrogen peroxide. Remove the soft tissue attached to the skull by gently rubbing the exposed area with a small cotton ball until the anterior and posterior fontanelle are seen. Adjust the anterior and posterior heights so that the anterior and posterior fontanelle is horizontal.Consider the position of the anterior fontanelle to be the origin of the axes. Fix a stainless steel screw to the left cerebellar skull. Set the coordinates for the amygdala kindling from the bregma and adjust the stereotaxic device to locate this spot and mark it.Drill a hole on the march spot with a 0.5 millimeter diameter skull drill. Fix the electrodes to the locating rod of the stereotaxic device. Place the electrode vertically above the hole and drop the position to minus 4.9 millimeters slowly.Wrap the silver wire around the screw thrice. Taking care not to shake the electrode body during operation. Mix dental cement and to gently apply it to the electrode and skull surface.When the dental cement hardens, modify the outside until the cement that encloses the fixed electrode turns into a cone. Then release the electrode from the stereotaxic device. Remove the mouse and place it back in the cage.Keeping it separate from the other mice. Put the mouse in a customized box with slippering cables connecting the electrode on the mouse's head and the EEG device. Run the cable through a hole in the box lid and adjust the length left in the box to allow the mouse to move freely.Turn on the EEG device and ensure it works correctly. Set the stimulator parameters to deliver one millisecond monophasic square wave pulses at 60 hertz for a one second train duration for 10 stimulation cycles. Start with a current intensity of 50 microamperes for the first stimulation.Monitor the EEG for after discharge characterized by high frequency spikes. If no after discharge is observed add 25 microamperes to the next stimulus and continue this process every 10 minutes until an after discharge is observed and lasts five seconds. Stimulate the mouse with the determined current intensity every 15 minutes, no more than 20 times a day.Monitor the behavioral responses to the stimulus. The electrode implantation surgery was performed on six healthy adult males C57 black 6 mice and electrical stimulation was performed two weeks post-surgery. The behavioral seizure level gradually increased with the number of stimuli increasing and the number of stimuli required for complete kindling was recorded.The EEG after discharges lasted five to 15 seconds. Then the intracranial spontaneous discharges intensified and behavioral symptoms began. Seizure duration was usually less than one minute which reduces the risk of death from severe convulsions resulting in apnea.The expression of c-Fos in the brain tissue was detected by immunohistochemistry two hours after complete kindling. The results show that the expression of c-Fos in the ipsilateral amygdala significantly increased verifying the feasibility of this model. The separation of tungsten wire ends should not exceed half millimeters otherwise it'll not get through the brain hole.The length of the electrode should not be too long otherwise it'll affect activity of mice.

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Identification of Olfactory Volatiles using Gas Chromatography-Multi-unit Recordings (GCMR) in the Insect Antennal Lobe

All organisms inhabit a world full of sensory stimuli that determine their behavioral and physiological response to their environment. Olfaction is especially important in insects, which use their olfactory systems to respond to, and discriminate amongst, complex odor stimuli. These odors elicit behaviors that mediate processes such as reproduction and habitat selection1-3. Additionally, chemical sensing by insects mediates behaviors that are highly significant for agriculture and human health, including pollination4-6, herbivory of food crops7, and transmission of disease8,9. Identification of olfactory signals and their role in insect behavior is thus important for understanding both ecological processes and human food resources and well-being.
	To date, the identification of volatiles that drive insect behavior has been difficult and often tedious. Current techniques include gas chromatography-coupled electroantennogram recording (GC-EAG), and gas chromatography-coupled single sensillum recordings (GC-SSR)10-12. These techniques proved to be vital in the identification of bioactive compounds. We have developed a method that uses gas chromatography coupled to multi-channel electrophysiological recordings (termed 'GCMR') from neurons in the antennal lobe (AL; the insect's primary olfactory center)13,14. This state-of-the-art technique allows us to probe how odor information is represented in the insect brain. Moreover, because neural responses to odors at this level of olfactory processing are highly sensitive owing to the degree of convergence of the antenna's receptor neurons into AL neurons, AL recordings will allow the detection of active constituents of natural odors efficiently and with high sensitivity. Here we describe GCMR and give an example of its use.
	Several general steps are involved in the detection of bioactive volatiles and insect response. Volatiles first need to be collected from sources of interest (in this example we use flowers from the genus Mimulus (Phyrmaceae)) and characterized as needed using standard GC-MS techniques14-16. Insects are prepared for study using minimal dissection, after which a recording electrode is inserted into the antennal lobe and multi-channel neural recording begins. Post-processing of the neural data then reveals which particular odorants cause significant neural responses by the insect nervous system.
	Although the example we present here is specific to pollination studies, GCMR can be expanded to a wide range of study organisms and volatile sources. For instance, this method can be used in the identification of odorants attracting or repelling vector insects and crop pests. Moreover, GCMR can also be used to identify attractants for beneficial insects, such as pollinators. The technique may be expanded to non-insect subjects as well.

Identification of Olfactory Volatiles using Gas Chromatography-Multi-unit Recordings GCMR in the Insect Antennal Lobe

Olfactory cues mediate many different behaviors in insects, and are often complex mixtures comprised of tens to hundreds of volatile compounds. Using gas chromatography with multi-channel recording in the insect antennal lobe, we describe a method for the identification of bioactive compounds.

All  organisms inhabit a world full of sensory stimuli that determine their  behavioral and physiological response to their environment. Olfaction is ...

Trypsin Digest Protocol to Analyze the Retinal Vasculature of a Mouse Model

Trypsin digest is the gold standard method to analyze the retinal vasculature 1-5. It allows visualization of the entire network of complex three-dimensional retinal blood vessels and capillaries by creating a two-dimensional flat-mount of the interconnected vascular channels after digestion of the non-vascular components of the retina. This allows one to study various pathologic vascular changes, such as microaneurysms, capillary degeneration, and abnormal endothelial to pericyte ratios. However, the method is technically challenging, especially in mice, which have become the most widely available animal model to study the retina because of the ease of genetic manipulations 6,7. In the mouse eye, it is particularly difficult to completely remove the non-vascular components while maintaining the overall architecture of the retinal blood vessels. To date, there is a dearth of literature that describes the trypsin digest technique in detail in the mouse. This manuscript provides a detailed step-by-step methodology of the trypsin digest in mouse retina, while also providing tips on troubleshooting difficult steps.

Trypsin digest is one of the most commonly used methods to analyze retinal vasculature. This manuscript describes the method in detail, including key alterations to optimize the technique and remove the non-vascular tissue while preserving the overall architecture of the vessels.

Trypsin digest is the gold standard method to analyze the retinal vasculature 1-5. It allows visualization of the entire network of complex ...

A Comprehensive Protocol for Manual Segmentation of the Medial Temporal Lobe Structures

The present paper describes a comprehensive protocol for manual tracing of the set of brain regions comprising the medial temporal lobe (MTL): amygdala, hippocampus, and the associated parahippocampal regions (perirhinal, entorhinal,&#160;and parahippocampal proper). Unlike most other tracing protocols available, typically focusing on certain MTL areas (e.g., amygdala and/or hippocampus), the integrative perspective adopted by the present tracing guidelines allows for clear localization of all MTL subregions. By integrating information from a variety of sources, including extant tracing protocols separately targeting various MTL structures, histological reports, and brain atlases, and with the complement of illustrative visual materials, the present protocol provides an accurate, intuitive, and convenient guide for understanding the MTL anatomy. The need for such tracing guidelines is also emphasized by illustrating possible differences between automatic and manual segmentation protocols. This knowledge can be applied toward research involving not only structural MRI investigations but also structural-functional colocalization and fMRI signal extraction from anatomically defined ROIs, in healthy and clinical groups alike.

The present work provides a comprehensive set of guidelines for manually tracing the medial temporal lobe (MTL) structures. This protocol can be applied to research involving structural and/or combined structural-functional magnetic resonance imaging (MRI) investigations of the MTL, in both healthy and clinical groups.

The present paper describes a comprehensive protocol for manual tracing of the set of brain regions comprising the medial temporal lobe (MTL): amygdala, ...

Pentylenetetrazole-Induced Kindling Mouse Model

Pentylenetetrazole (PTZ) is a GABA-A receptor antagonist. An intraperitoneal injection of PTZ into an animal induces an acute, severe seizure at a high dose, whereas sequential injections of a subconvulsive dose have been used for the development of chemical kindling, an epilepsy model. A single low-dose injection of PTZ induces a mild seizure without convulsion. However, repetitive low-dose injections of PTZ decrease the threshold to evoke a convulsive seizure. Finally, continuous low-dose administration of PTZ induces a severe tonic-clonic seizure. This method is simple and widely applicable to investigate the pathophysiology of epilepsy, which is defined as a chronic disease that involves repetitive seizures. This chemical kindling protocol causes repetitive seizures in animals. With this method, vulnerability to PTZ-mediated seizures or the degree of aggravation of epileptic seizures was estimated. These advantages have led to the use of this method for screening anti-epileptic drugs and epilepsy-related genes. In addition, this method has been used to investigate neuronal damage after epileptic seizures because the histological changes observed in the brains of epileptic patients also appear in the brains of chemical-kindled animals. Thus, this protocol is useful for conveniently producing animal models of epilepsy.

This protocol describes a method of chemical kindling with pentylenetetrazole and provides a mouse model of epilepsy. This protocol can also be used to investigate vulnerability to seizure induction and pathogenesis after epileptic seizures in mice.

Pentylenetetrazole (PTZ) is a GABA-A receptor antagonist. An intraperitoneal injection of PTZ into an animal induces an acute, severe seizure at a high ...

The Power of Interstimulus Interval for the Assessment of Temporal Processing in Rodents

Temporal processing deficits have been implicated as a potential elemental dimension of higher-level cognitive processes, commonly observed in neurocognitive disorders. Despite the popularization of prepulse inhibition (PPI) in recent years, many current protocols promote using a percent of control measure, thereby precluding the assessment of temporal processing. The present study used cross-modal PPI and gap prepulse inhibition (gap-PPI) to demonstrate the benefits of employing a range of interstimulus intervals (ISIs) to delineate effects of sensory modality, psychostimulant exposure, and age. Assessment of sensory modality, psychostimulant exposure, and age reveals the utility of an approach varying the interstimulus interval (ISI) to establish the shape of the ISI function, including increases (sharper curve inflections) or decreases (flattening of the response amplitude curve) in startle amplitude. Additionally, shifts in peak response inhibition, suggestive of a differential sensitivity to the manipulation of ISI, are often revealed. Thus, the systematic manipulation of ISI affords a critical opportunity to evaluate temporal processing, which may reveal the underlying neural mechanisms involved in neurocognitive disorders.

Temporal processing, a preattentive process, may underlie deficits in higher-level cognitive processes, including attention, commonly observed in neurocognitive disorders. Using prepulse inhibition as an exemplar paradigm, we present a protocol for manipulating interstimulus interval (ISI) to establish the shape of the ISI function to provide an assessment of temporal processing.

Temporal processing deficits have been implicated as a potential elemental dimension of higher-level cognitive processes, commonly observed in ...

Behavioral And Physiological Analysis In A Zebrafish Model Of Epilepsy

Epilepsy represents one of the most common neurological disorders, affecting an estimated 50 million people worldwide. Recent advances in genetic research have uncovered a large spectrum of genes implicated in various forms of epilepsy, highlighting the heterogeneous nature of this disorder. Appropriate animal models are essential for investigating the pathological mechanisms triggered by genetic mutations implicated in epilepsy and for developing specialized, targeted therapies. In recent years, zebrafish has emerged as a valuable vertebrate organism for modeling epilepsies, with the use of both genetic manipulation and exposure to known epileptogenic drugs, such as pentylenetetrazole (PTZ), to identify novel anti-epileptic therapeutics. Deleterious mutations in the mTOR regulator DEPDC5 have been associated with various forms of focal epilepsies and knock-down of the zebrafish orthologue causes hyperactivity associated with spontaneous seizure-like episodes, as well as enhanced electrographic activity and characteristic turn wheel swimming. Here, we described the method involved in generating the DEPDC5 loss-of-function model and illustrate the protocol for assessing motor activity at 28 and 48 h post fertilization (hpf), as well as a method for recording field activity in the zebrafish optic tectum. An illustration of the effect of the epileptogenic drug PTZ on neuronal activity over time is also provided.

Here, we present a protocol for the development and the characterization of a zebrafish model of epilepsy resulting from the transient inhibition of the DEPDC5 gene.

Epilepsy represents one of the most common neurological disorders, affecting an estimated 50 million people worldwide. Recent advances in genetic research ...

Successful In vivo Calcium Imaging with a Head-Mount Miniaturized Microscope in the Amygdala of Freely Behaving Mouse

In vivo real-time monitoring of neuronal activities in freely moving animals is one of key approaches to link neuronal activity to behavior. For this purpose, an in vivo imaging technique that detects calcium transients in neurons using genetically encoded calcium indicators (GECIs), a miniaturized fluorescence microscope, and a gradient refractive index (GRIN) lens has been developed and successfully applied to many brain structures1,2,3,4,5,6. This imaging technique is particularly powerful because it enables chronic simultaneous imaging of genetically defined cell populations for a long-term period up to several weeks. Although useful, this imaging technique has not been easily applied to brain structures that locate deep within the brain such as amygdala, an essential brain structure for emotional processing and associative fear memory7. There are several factors that make it difficult to apply the imaging technique to the amygdala. For instance, motion artifacts usually occur more frequently during the imaging conducted in the deeper brain regions because a head-mount microscope implanted deep in the brain is relatively unstable. Another problem is that the lateral ventricle is positioned close to the implanted GRIN lens and its movement during respiration may cause highly irregular motion artifacts that cannot be easily corrected, which makes it difficult to form a stable imaging view. Furthermore, because cells in the amygdala are usually quiet at a resting or anesthetized state, it is hard to find and focus the target cells expressing GECI in the amygdala during baseplating procedure for later imaging. This protocol provides a helpful guideline for how to efficiently target cells expressing GECI in the amygdala with head-mount miniaturized microscope for successful in vivo calcium imaging in such a deeper brain region. It is noted that this protocol is based on a particular system (e.g., Inscopix) but not restricted to it.

In vivo microendoscopic calcium imaging is an invaluable tool that enables real-time monitoring of neuronal activities in freely behaving animals. However, applying this technique to the amygdala has been difficult. This protocol aims to provide a useful guideline for successfully targeting amygdala cells with a miniaturized microscope in mice.

In vivo real-time monitoring of neuronal activities in freely moving animals is one of key approaches to link neuronal activity to behavior. For this ...

A Behavioral Screen for Heat-Induced Seizures in Mouse Models of Epilepsy

Transgenic mouse models have proved to be powerful tools in studying various aspects of human neurological disorders, including epilepsy. The SCN1A-associated genetic epilepsies comprise a wide spectrum of seizure disorders with incomplete penetrance and clinical variability. SCN1A mutations can result in a large variety of seizure phenotype ranging from simple, self-limited fever-associated febrile seizures (FS), moderate-level genetic epilepsy with febrile seizures plus (GEFS+) to more severe Dravet Syndrome (DS). Although FS are commonly seen in children below 6-7 years of age who do not have genetic epilepsy, FS in GEFS+ patients continue to occur into adulthood. Traditionally, experimental FS have been induced in mice by exposing the animal to a stream of dry air or heating lamps, and the rate of change in body temperature is often not well controlled. Here, we describe a custom-built heating chamber, with a plexiglass front, that is fitted with a digital temperature controller and a heater-equipped electric fan, which can send heated forced air into the test arena in a temperature-controlled manner. The body temperature of a mouse placed in the chamber, monitored through a rectal probe, can be increased to 40-42 &#176;C in a reproducible manner by increasing the temperature inside the chamber. Continual visual monitoring of the animals during the heating period demonstrates induction of heat-induced seizures in mice carrying an FS mutation at a body temperature that does not elicit behavioral seizures in wild-type litter mates. Animals can be easily removed from the chamber and placed on a cooling pad to rapidly return body temperature to normal. This method provides for a simple, rapid, and reproducible screening protocol for the occurrence of heat-induced seizures in epilepsy mouse models.

The goal of the method is to screen for hyperthermia or heat-induced seizures in mouse models. The protocol describes the use of a custom-built chamber with continuous monitoring of the body temperature to determine whether elevated body temperature leads to seizures.

Transgenic mouse models have proved to be powerful tools in studying various aspects of human neurological disorders, including epilepsy. The ...

Preparation and Implantation of Electrodes for Electrically Kindling VGAT-Cre Mice to Generate a Model for Temporal Lobe Epilepsy

It was discovered that electrical kindling of VGAT-Cre mice led to the spontaneous motor and electrographic seizures. A recent paper focused on how unique VGAT-Cre mice were used in developing spontaneous recurring seizures (SRS) after kindling and a likely mechanism - insertion of Cre into the VGAT gene - disrupted its expression and reduced GABAergic tone. The present study extends these observations to a larger cohort of mice, focusing on key issues such as how long the SRS continues after kindling and the effect of the animal's sex and age. This report describes the protocols for the following key steps: making headsets with hippocampal depth electrodes for electrical stimulation and for reading the electroencephalogram; surgery to affix the headset securely on the mouse's skull so that it does not fall off; and key details of the electrical kindling protocol such as duration of the pulse, frequency of train, duration of train, and amount of current injected. The kindling protocol is robust in that it reliably leads to epilepsy in most VGAT-Cre mice, providing a new model to test for novel antiepileptogenic drugs.

This report describes the methods to generate a model of temporal lobe epilepsy based on the electrical kindling of transgenic VGAT-Cre mice. Kindled VGAT-Cre mice may be useful in determining what causes epilepsy and for screening novel therapies.

It was discovered that electrical kindling of VGAT-Cre mice led to the spontaneous motor and electrographic seizures. A recent paper focused on how unique ...

Registration of Calcium Transients in Mouse Neuromuscular Junction with High Temporal Resolution using Confocal Microscopy

Estimation of the presynaptic calcium level is a key task in studying synaptic transmission since calcium entry into the presynaptic cell triggers a cascade of events leading to neurotransmitter release. Moreover, changes in presynaptic calcium levels mediate the activity of many intracellular proteins and play an important role in synaptic plasticity. Studying calcium signaling is also important for finding ways to treat neurodegenerative diseases. The neuromuscular junction is a suitable model for studying synaptic plasticity, as it has only one type of neurotransmitter. This article describes the method for loading a calcium-sensitive dye through the cut nerve bundle into the mice's motor nerve endings. This method allows the estimation of all parameters related to intracellular calcium changes, such as basal calcium level and calcium transient. Since the influx of calcium from the cell exterior into the nerve terminals and its binding/unbinding to the calcium-sensitive dye occur within the range of a few milliseconds, a speedy imaging system is required to record these events. Indeed, high-speed cameras are commonly used for the registration of fast calcium changes, but they have low image resolution parameters. The protocol presented here for recording calcium transient allows extremely good spatial-temporal resolution provided by confocal microscopy.

The protocol describes the method of loading a fluorescent calcium dye through the cut nerve into mouse motor nerve terminals. In addition, a unique method for recording fast calcium transients in the peripheral nerve endings using confocal microscopy is presented.

Estimation of the presynaptic calcium level is a key task in studying synaptic transmission since calcium entry into the presynaptic cell triggers a ...