This work was partly supported by JSPS KAKENHI grant numbers 24700349, 24659093, 25293239, JP18H02536, and 17K07086, MEXT KAKENHI grant numbers 25110737 and 23110525, AMED Grant Number JP18ek0109311, and the SENSHIN Medical Research Foundation and the Japan Epilepsy Research Foundation.

All experimental procedures were approved by the Animal Care and Use Committee of the Tokyo Metropolitan Institute of Medical Science. Postnatal 8 - 16-week-old mice are recommended. Any inbred strain is acceptable for the experiment. C57BL/6 mice are more resistant to PTZ, whereas BALB/c and Swiss albino mice are more sensitive to PTZ. C57BL/6 were used in this study. Vulnerability to PTZ also depends on the age of the mouse. Compared to younger mice, older mice are more refractory to PTZ35. The ...

The authors declare no conflicts of interest.

Here, we present a widely accessible protocol for the establishment of a pharmacological animal model of epilepsy. PTZ-mediated chemical kindling has a long history and is a commonly accepted model for the study of the histopathology and cellular pathology of epilepsy41. The chemical kindling model of epilepsy has been reviewed previously by Suzdak and Jansen, 199542. Pharmacological seizure induction, especially with PTZ, is an easy and simple method for evoking severe sei...

Epilepsy is a chronic neurological disorder that is characterized by recurrent seizures and affects approximately 1% of people. The underlying mechanisms of epileptogenesis and seizure generation in epilepsy patients cannot be fully clarified in clinical studies. Therefore, an appropriate animal model is required for the study of epilepsy1.
A variety of animal models of epilepsy have been used to investigate the physiology of epilepsy and to identify anti-epileptic drugs2,3. Among these models, pharmacological seizure induction is a common method used to generate an animal model for the investigation of the pathology of epilepsy4. This method is inexpensive and simple. Electrode-mediated kindling is also a commonly used method, but the costs of this procedure are higher, and the method requires surgical and electrical skills to induce repetitive seizures5.
Pharmacological induction is also advantageous because the timing and number of seizures are easily controlled. Genetic mouse models that exhibit spontaneous seizures are also used in the study of epilepsy. However, predicting when and how often the seizures arise in these genetic models may be impossible6. A monitoring system is required to observe the epileptic behavior of genetically modified mice6.
Kainic acid, pilocarpine and pentylenetetrazole (PTZ) are widely used as seizure-inducing drugs7. Kainic acid is an agonist for glutamate receptors, and pilocarpine activates cholinergic receptors. PTZ is a gamma aminobutyric acid (GABA)-A receptor antagonist8. PTZ suppresses the function of inhibitory synapses, leading to increased neuronal activity. This regulation causes generalized seizures in animals9. A single injection of kainic acid and pilocarpine can induce acute seizures, especially status epilepticus (SE)10,11 and kainic acid- or pilocarpine-mediated SE promotes chronic spontaneous and recurrent seizures12,13. Electroencephalographic (EEG) recordings and behavior analysis have indicated that spontaneous recurrent seizures are observed a month after a single injection12,13. A single injection of a convulsive dose of PTZ also induces acute seizure. However, chronic spontaneous seizures after a single injection of PTZ are difficult to promote. Chronic administration of PTZ is required to induce repetitive seizures14. In either method, the generation of repetitive seizures is able to induce a pathology more similar to that of human epilepsy than the generation of acute seizures. In the case of PTZ, each injection evokes a seizure, and seizure severity becomes more severe in a stepwise manner with each injection. Finally, a single low-dose PTZ injection induces a severe tonic-clonic seizure. In this phase, each injection evokes severe seizures. In addition, the seizure latency and duration also change over the course of the injections. The latency to tonic seizure often becomes shorter in the latter phase of kindling15. Furthermore, seizure aggravation is accompanied by a prolonged seizure duration16. Investigating the molecular mechanism regulating the seizure severity, latency, and duration is useful for screening anti-epileptic drugs17,18,19.
Seizures are commonly induced by a single systemic administration of PTZ, and the recovery is very fast, within 30 min4,5. Thus, the number of seizures is more controllable in the PTZ-kindling model. However, EEG monitoring has indicated that generalized spikes may be seen up to 12 h after PTZ-mediated seizure20. Therefore, animals should preferably remain under observation for 24 h after the myoclonic or tonic seizure21 for more precise analysis of the kindling mechanisms.
The administration of anti-epileptic drugs, such as ethosuximide, valproate, phenobarbital, vigabatrin, and retigabine3, before or after PTZ injection mitigates the aggravation of the seizure severity3,22,23. Similarly, knockout mice that lack genes involved in seizure exacerbation, such as matrix metalloproteinase-924, FGF-2225 and neuritin26, have been shown to exhibit reduced seizure severity after multiple PTZ injections. In addition, observing histopathological alterations after epileptic seizures is possible with this method. In patients with temporal lobe epilepsy, there are typical histological changes in the brain, such as mossy fiber sprouting27,28, abnormal granule neuron migration29, astrogliosis30, neuronal cell death in the hippocampus31,32, and hippocampal sclerosis33. Similar changes are observed in epileptic model animals. Among the available methods, PTZ-mediated chemical kindling is a good, reproducible and inexpensive method to produce an animal model of epilepsy. In a pilocarpine-mediated SE model, seizure control is difficult and many mice die or fail to develop SE34. In contrast, mortality and seizure severity are more controllable in the PTZ model. Additionally, PTZ is less expensive than kainic acid, and skills in mouse brain surgery are not required for drug administration.

<table>
	<tbody>
		<tr>
			<td>Pentylenetetrazole</td>
			<td>Sigma-Aldrich</td>
			<td>P6500</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>MANAC</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse</td>
			<td>CLEA Japan</td>
			<td></td>
			<td>C57Bl/6NJcl, postnatal 8 week, male</td>
		</tr>
		<tr>
			<td>Syringe (1mL)</td>
			<td>Terumo</td>
			<td>SS-01T</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle(27G x 3/4&#34;) (0.40 x 19 mm)</td>
			<td>Terumo</td>
			<td>NN-2719S</td>
			<td></td>
		</tr>
		<tr>
			<td>Weighing scale</td>
			<td>Mettler</td>
			<td>PE2000</td>
			<td>This item is a discontinued product. Almost equivalent to FX-2000i with FXi-12-JA from A&#38;D company.</td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>nacalai tesque</td>
			<td>31511-05</td>
			<td></td>
		</tr>
		<tr>
			<td>Peristatic pump</td>
			<td>ATTO</td>
			<td>SJ1211</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>nacalai tesque</td>
			<td>30404-45</td>
			<td></td>
		</tr>
		<tr>
			<td>Microtome</td>
			<td>Yamato</td>
			<td>REM-700</td>
			<td>This item is a discontinued product. Almost equivalent to REM-710</td>
		</tr>
		<tr>
			<td>Microtome blade</td>
			<td>Feather</td>
			<td>S35</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>X-100</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-synaptoporin antibody</td>
			<td>Synaptic systems</td>
			<td>102 002</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-ZnT3 antibody</td>
			<td>Synaptic systems</td>
			<td>197 002</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-doublecortin</td>
			<td>Santa Cruz</td>
			<td>sc-8066</td>
			<td>This item is a discontinued product. We did not test equivalent product (sc-271390).</td>
		</tr>
		<tr>
			<td>Contextual fear discrimination test apparatus</td>
			<td>O&#39;hara</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Three chamber test apparatus</td>
			<td>Muromachi</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Repetitive injection of PTZ induces an increase in seizure severity. Six C57BL/6 mice were treated with PTZ, and another 6 mice were treated with saline as a control group. The PTZ dose was 35 mg/kg, and 10 injections were administered. The seizure score gradually increased with PTZ injections, whereas no seizures or abnormal behaviors were evoked by saline injections (Figure 2). ANOVA followed by Bonferroni test showed a significant difference between the PT...

Watch this Scientific Journal Video about Pentylenetetrazole-Induced Kindling Mouse Model at JoVE.com

Pentylenetetrazole-Induced Kindling Mouse Model

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 ...

pentylenetetrazole-induced-kindling-mouse-model

Research

Education

JoVE Core

JoVE Journal

Pharmacology

Neuroscience

Unit 1

Pharmacotherapy of the Epilepsies

SCIENTISTS IN ACTION

31.8K vistas.  Tokyo Metropolitan Institute of Medical Science. Este protocolo describe un método de química inflamación con pentylenetetrazole y proporciona un modelo de ratón de la epilepsia. Este protocolo también puede utilizarse para investigar la vulnerabilidad a la inducción de convulsiones y de la patogenesia después de las crisis epilépticas en los ratones.