Name: Autor em destaque: Avançando a estimulação da medula espinhal - explorando as respostas celulares dos neurônios motores por meio da eletrofisiologia do patch-clamp
Uploaded: 2023-09-08T14:15:00
Description: Watch this Scientific Journal Video about Advancing Spinal Cord Stimulation - Exploring the Cellular Responses of Motor Neurons Through Patch-Clamp Electrophysiology at JoVE.com

Este estudo foi financiado pela Fundação Nacional de Ciências Naturais da China para Jovens Acadêmicos (52207254 e 82301657) e pelo Fundo de Ciência de Pós-doutorado da China (2022M711833).

O Comitê Institucional de Cuidados e Uso de Animais aprovou todos os experimentos com animais e os estudos foram conduzidos de acordo com as normas pertinentes de bem-estar animal.
1. Preparação dos animais
<ol><li>Animais<ol><li>Informações sobre alojamento: Ratos Sprague-Dawley machos domésticos (10-14 dias pós-natal, P10-P14) em um ambiente específico livre de patógenos. NOTA: As condições da sala foram mantidas em 20 °C ± 2 °C, umidade: 50%-60%, com um c...

Compreendendo as respostas do neurônio motor à estimulação da medula espinhal

<ol>
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(116), e54525 (2016).</li><li>Sharples, S. A., Miles, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maturation+of+persistent+and+hyperpolarization-activated+inward+currents+shapes+the+differential+activation+of+motoneuron+subtypes+during+postnatal+development.">Maturation of persistent and hyperpolarization-activated inward currents shapes the differential activation of motoneuron subtypes during postnatal development.</a> Elife. 10, e71385 (2021).</li><li>Bhumbra, G. S., Beato, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recurrent+excitation+between+motoneurones+propagates+across+segments+and+is+purely+glutamatergic.">Recurrent excitation between motoneurones propagates across segments and is purely glutamatergic.</a> PLoS Biology. 16 (3), e2003586 (2018).</li><li>Leroy, F., Lamotte d'Incamps, B., Imhoff-Manuel, R. D., Zytnicki, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+intrinsic+hyperexcitability+does+not+contribute+to+motoneuron+degeneration+in+amyotrophic+lateral+sclerosis.">Early intrinsic hyperexcitability does not contribute to motoneuron degeneration in amyotrophic lateral sclerosis.</a> Elife. 3, 04046 (2014).</li><li>Tahir, R. A., Pabaney, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Therapeutic+hypothermia+and+ischemic+stroke:+A+literature+review.">Therapeutic hypothermia and ischemic stroke: A literature review.</a> Surgical Neurology International. 7, S381-S386 (2016).</li><li>Lu, Y., 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=Management+of+intractable+pain+in+patients+with+implanted+spinal+cord+stimulation+devices+during+the+COVID-19+pandemic+using+a+remote+and+wireless+programming+system.">Management of intractable pain in patients with implanted spinal cord stimulation devices during the COVID-19 pandemic using a remote and wireless programming system.</a> Frontiers in Neuroscience. 14, 594696 (2020).</li><li>Yao, Q., 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=Wireless+epidural+electrical+stimulation+in+combination+with+serotonin+agonists+improves+intraspinal+metabolism+in+spinal+cord+injury+rats.">Wireless epidural electrical stimulation in combination with serotonin agonists improves intraspinal metabolism in spinal cord injury rats.</a> Neuromodulation. 24 (3), 416-426 (2021).</li><li>Arlotti, M., Rahman, A., Minhas, P., Bikson, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Axon+terminal+polarization+induced+by+weak+uniform+dc+electric+fields:+a+modeling+study.">Axon terminal polarization induced by weak uniform dc electric fields: a modeling study.</a> 2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society. , 4575-4578 (2012).</li><li>Espino, C. M., 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=Na(V)1.1+is+essential+for+proprioceptive+signaling+and+motor+behaviors.">Na(V)1.1 is essential for proprioceptive signaling and motor behaviors.</a> Elife. 11, e79917 (2022).</li><li>Romer, S. H., Deardorff, A. S., Fyffe, R. E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+molecular+rheostat:+Kv2.1+currents+maintain+or+suppress+repetitive+firing+in+motoneurons.">A molecular rheostat: Kv2.1 currents maintain or suppress repetitive firing in motoneurons.</a> The Journal of Physiology. 597 (14), 3769-3786 (2019).</li><li>Yao, X., 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=Structures+of+the+R-type+human+Ca(v)2.3+channel+reveal+conformational+crosstalk+of+the+intracellular+segments.">Structures of the R-type human Ca(v)2.3 channel reveal conformational crosstalk of the intracellular segments.</a> Nature Communications. 13 (1), 7358 (2022).</li><li>Bandres, M. F., Gomes, J., McPherson, J. 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(70), e4312 (2012).</li><li>Luo, X., Wang, S., Rutkove, S. B., Sanchez, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonhomogeneous+volume+conduction+effects+affecting+needle+electromyography:+an+analytical+and+simulation+study.">Nonhomogeneous volume conduction effects affecting needle electromyography: an analytical and simulation study.</a> Physiological Measurement. 42 (11), (2021).</li><li>Barra, B., 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=Epidural+electrical+stimulation+of+the+cervical+dorsal+roots+restores+voluntary+upper+limb+control+in+paralyzed+monkeys.">Epidural electrical stimulation of the cervical dorsal roots restores voluntary upper limb control in paralyzed monkeys.</a> Nature Neuroscience. 25 (7), 924-934 (2022).</li><li>Powell, M. 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A informação do movimento modulada pela SCS é finalmente convergente para os neurônios motores. Portanto, tomar os neurônios motores como alvo da pesquisa pode simplificar o desenho do estudo e revelar o mecanismo de neuromodulação da SCS mais diretamente. Para registrar simultaneamente diversas características de estímulos e respostas celulares, um patch-clamp é um bom método para estudar as características eletrofisiológicas em escala unicelular. No entanto, ainda existem algumas dificuldades, incluindo co...

A estimulação da medula espinhal (ECS) pode efetivamente restaurar a função locomotora após a lesão medular (LME). Andreas Rowald e col. relataram que a ECS possibilita a função locomotora e do tronco dos membros inferiores em um único dia1. Explorar o mecanismo biológico da SCS para recuperação locomotora é um campo de pesquisa crítico e de tendência para o desenvolvimento de uma estratégia SCS mais precisa. Por exemplo, a equipe de Grégoire Courtine demonstrou que o interneurônio excitatório Vsx2 e os neurônios Hoxa10 na medula espinhal são os neurônios-chave para responder à SCS, e a neuromodulação célula-específica é viável para restaurar a capacidade de andar do rato após a LME2. No entanto, poucos estudos enfocam o mecanismo elétrico da SCS em escala unicelular. Embora seja bem conhecido que o estímulo de corrente contínua supralimiar pode eliciar os potenciais de ação (PAs) no experimento clássico com lulas 3,4,5, ainda não está claro como a estimulação elétrica alternada pulsada, como a ECS, afeta a geração do sinal motor.
Dada a complexidade dos circuitos neurais intraespinhais, a seleção apropriada para a população celular é importante para investigar o mecanismo elétrico da SCS. Embora o ECS restaure a função motora ativando a via proprioceptiva6, os neurônios motores são a unidade final para executar o comando motor, derivado da integração da entrada aferente de informações proprioceptivas7. Portanto, estudar diretamente as características elétricas dos neurônios motores com SCS pode nos ajudar a entender a lógica subjacente da modulação motora espinhal.
Como sabemos, patch-clamp é o método padrão-ouro para registro eletrofisiológico celular com resolução espaço-temporal extremamentealta8. Portanto, este estudo descreve um método que utiliza um patch clamp para estudar as respostas elétricas dos neurônios motores à SCS. Comparado com o patch-clamp9 do cérebro, o patch-clamp da medula espinhal é mais difícil devido aos seguintes motivos: (1) A medula espinhal é protegida pelo canal vertebral com volume minúsculo, o que requer micromanipulação muito fina e manutenção rigorosa do gelo para obter melhor viabilidade celular. (2) Como a medula espinhal é muito fina para ser fixada na bandeja de corte, ela deve ser imersa em agarose de baixo ponto de fusão e aparada após a solidificação.
Assim, este método fornece detalhes técnicos na dissecção da medula espinhal e na manutenção da viabilidade celular ao mesmo tempo, de modo a estudar suavemente o mecanismo elétrico da SCS em neurônios motores e evitar tentativas e erros desnecessários.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Adenosine 5&#8217;-triphosphate magnesium salt</td>
			<td>Sigma</td>
			<td>A9187</td>
			<td></td>
		</tr>
		<tr>
			<td>Ascorbic Acid</td>
			<td>Sigma</td>
			<td>A4034</td>
			<td></td>
		</tr>
		<tr>
			<td>CaCl2&#183;2H2O</td>
			<td>Sigma</td>
			<td>C5080</td>
			<td></td>
		</tr>
		<tr>
			<td>Choline Chloride</td>
			<td>Sigma</td>
			<td>C7527</td>
			<td></td>
		</tr>
		<tr>
			<td>Cover slide tweezers</td>
			<td>VETUS</td>
			<td>36A-SA</td>
			<td>Clip a slice</td>
		</tr>
		<tr>
			<td>D-Glucose</td>
			<td>Sigma</td>
			<td>G8270</td>
			<td></td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Sigma</td>
			<td>E4378</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine scissors</td>
			<td>RWD Life Science</td>
			<td>S12006-10</td>
			<td>Cut the diaphragm</td>
		</tr>
		<tr>
			<td>Fluorescence Light Source</td>
			<td>Olympus&#160;</td>
			<td>U-HGLGPS</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluoro-Gold</td>
			<td>Fluorochrome</td>
			<td>Fluorochrome</td>
			<td>Label the motor neuron</td>
		</tr>
		<tr>
			<td>Guanosine 5&#8242;-triphosphate sodium salt hydrate</td>
			<td>Sigma</td>
			<td>G8877</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma</td>
			<td>H3375</td>
			<td></td>
		</tr>
		<tr>
			<td>infrared CCD camera</td>
			<td>Dage-MTI</td>
			<td>IR-1000E</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sigma</td>
			<td>P5405</td>
			<td></td>
		</tr>
		<tr>
			<td>K-gluconate</td>
			<td>Sigma</td>
			<td>P1847</td>
			<td></td>
		</tr>
		<tr>
			<td>Low melting point agarose</td>
			<td>Sigma</td>
			<td>A9414</td>
			<td></td>
		</tr>
		<tr>
			<td>MgSO4&#183;7H2O</td>
			<td>Sigma</td>
			<td>M2773</td>
			<td></td>
		</tr>
		<tr>
			<td>Micromanipulator&#160;</td>
			<td>Sutter Instrument&#160;</td>
			<td>MP-200</td>
			<td></td>
		</tr>
		<tr>
			<td>Micropipette puller</td>
			<td>Sutter instrument</td>
			<td>P1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro-scissors&#160;</td>
			<td>Jinzhong</td>
			<td>wa1020</td>
			<td>Laminectomy</td>
		</tr>
		<tr>
			<td>Microscope for anatomy</td>
			<td>Olympus&#160;</td>
			<td>SZX10</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope for ecletrophysiology</td>
			<td>Olympus&#160;</td>
			<td>BX51WI</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro-toothed tweezers</td>
			<td>RWD Life Science</td>
			<td>F11008-09</td>
			<td>Lift the cut vertebral body</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma</td>
			<td>S5886</td>
			<td></td>
		</tr>
		<tr>
			<td>NaH2PO4</td>
			<td>Sigma</td>
			<td>S8282</td>
			<td></td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>Sigma</td>
			<td>V900182</td>
			<td></td>
		</tr>
		<tr>
			<td>Na-Phosphocreatine</td>
			<td>Sigma</td>
			<td>P7936</td>
			<td></td>
		</tr>
		<tr>
			<td>Objective lens for ecletrophysiology</td>
			<td>Olympus&#160;</td>
			<td>LUMPLFLN60XW</td>
			<td>working distance 2 mm&#160;</td>
		</tr>
		<tr>
			<td>Osmometer&#160;</td>
			<td>Advanced&#160;</td>
			<td>FISKE 210</td>
			<td></td>
		</tr>
		<tr>
			<td>Patch-clamp amplifier&#160;</td>
			<td>Axon&#160;</td>
			<td>Multiclamp 700B</td>
			<td></td>
		</tr>
		<tr>
			<td>Patch-clamp digitizer</td>
			<td>Axon&#160;</td>
			<td>Digidata 1550B</td>
			<td></td>
		</tr>
		<tr>
			<td>pH meter&#160;</td>
			<td>Mettler Toledo&#160;</td>
			<td>FE28</td>
			<td></td>
		</tr>
		<tr>
			<td>Slice Anchor</td>
			<td>Multichannel system</td>
			<td>SHD-27H</td>
			<td></td>
		</tr>
		<tr>
			<td>Spinal cord stimulatior</td>
			<td>PINS</td>
			<td>T901</td>
			<td></td>
		</tr>
		<tr>
			<td>Toothed tweezer</td>
			<td>RWD Life Science</td>
			<td>F13030-10</td>
			<td>Lift the xiphoid</td>
		</tr>
		<tr>
			<td>Vibratome</td>
			<td>Leica</td>
			<td>VT1200S</td>
			<td></td>
		</tr>
		<tr>
			<td>Wide band ultraviolet excitation filter</td>
			<td>Olympus&#160;</td>
			<td>U-MF2</td>
			<td></td>
		</tr>
	</tbody>
</table>

the ex vivo preparation of spinal cord slice for the whole-cell patch-clamp recording in motor neurons during spinal cord stimulation

A estimulação da medula espinhal (ECS) pode efetivamente restaurar a função locomotora após a lesão medular (LME). Como os neurônios motores são a unidade final para executar comportamentos sensório-motores, estudar diretamente as respostas elétricas dos neurônios motores com SCS pode nos ajudar a entender a lógica subjacente da modulação motora espinhal. Para registrar simultaneamente diversas características de estímulos e respostas celulares, um patch-clamp é um bom método para estudar as características eletrofisiológicas em escala unicelular. No entanto, ainda existem algumas dificuldades complexas para atingir esse objetivo, incluindo a manutenção da viabilidade celular, a separação rápida da medula espinhal da estrutura óssea e o uso do SCS para induzir com sucesso potenciais de ação. Aqui, apresentamos um protocolo detalhado usando patch-clamp para estudar as respostas elétricas dos neurônios motores à SCS com alta resolução espaço-temporal, o que pode ajudar o pesquisador a melhorar suas habilidades em separar a medula espinhal e manter a viabilidade celular, ao mesmo tempo em que estuda suavemente o mecanismo elétrico da SCS no neurônio motor e evitar tentativas e erros desnecessários.

Spinal cord stimulation (SCS) can effectively restore locomotor function after spinal cord injury (SCI). Andreas Rowald et al. reported that SCS enables lower limb locomotor and trunk function within a single day1. Exploring the biological mechanism of SCS for locomotor recovery is a critical and trending research field for developing a more precise SCS strategy. For example, Gr&#233;goire Courtine&#39;s team demonstrated that excitatory Vsx2 interneuron and Hoxa10 neurons in the spinal cord are the key neurons to response to SCS, and cell-specific neuromodulation is feasible to restore the rat walking ability after SCI2. However, few studies focus on the electrical mechanism of SCS at a single-cell scale. Although it is well-known that the suprathreshold direct current stimulus can elicit the action potentials (APs) in the classic squid experiment3,4,5, how the pulsed alternating electrical stimulation, such as SCS, affects the motor signal generation is still unclear.
Given the complexity of intraspinal neural circuits, appropriate selection for cell population is important for investigating the electrical mechanism of SCS. Although SCS restores motor function by activating the proprioceptive pathway6, the motor neurons are the final unit to execute the motor command, derived from integrating proprioception information afferent input7. Therefore, directly studying the electrical characteristics of motor neurons with SCS can help us understand the underlying logic of spinal motor modulation.
As we know, patch-clamp is the golden-standard method for cellularly electrophysiological recording with extremely high spatiotemporal resolution8. Therefore, this study describes a method using a patch clamp to study the electrical responses of motor neurons to SCS. Compared with the brain patch-clamp9, the spinal cord patch-clamp is more difficult due to the following reasons: (1) The spinal cord is protected by the vertebral canal with tiny volume, which requires very fine micromanipulation and rigorous ice-cold maintenance to obtain better cell viability. (2) Because the spinal cord is too slender to be secured on the cutting tray, it should be immersed in low-melting point agarose and trimmed after solidification.
Hence, this method provides technical details in dissecting the spinal cord and maintaining the cell viability at the same time so as to smoothly study the electrical mechanism of SCS on motor neurons and avoid unnecessary trials and mistakes.

Autor em destaque: Avançando a estimulação da medula espinhal - explorando as respostas celulares dos neurônios motores por meio da eletrofisiologia do patch-clamp 

A Preparação Ex Vivo do Corte da Medula Espinhal para o Registro de Patch-Clamp de Células Inteiras em Neurônios Motores Durante a Estimulação da Medula Espinhal

Spinal cord stimulation can help patients resolve most motion functions after injury. Most neurons are to execute sensory mode behaviors. Studying the electric response of most neurons can aid in understanding the underlying logic of spinal load neuromodulation.A patch clamp is the golden standard method for cellular electrophysiological recordings with the extremely high spatial temporal resolution. Therefore, this study describes a method using a patch clamp to simultaneously record the aortas stimulus characteristics and cellular responses of motor neurons at a single-cell scale. Compared with the brain patch clamp, the spinal cord patch clamp is more difficult, because the spinal cord is well protected by the vertebral canal with tiny volume.Therefore, this protocol provides technical details in quickly micro dissecting the spinal cord and reverse maintenance to obtain better cell viability. Patch clamp allows a unique understanding of the synaptic transmissions and the understanding of action potentials, coding pattern activities by the spinal cord stimulation.

Graças à rigorosa manutenção a baixa temperatura durante a operação fina (Figura 1 Suplementar, Figura 2 Suplementar e Figura 1), a viabilidade celular foi boa o suficiente para realizar registros eletrofisiológicos subsequentes. Para simular ao máximo o cenário clínico, utilizamos a micromanipulação para posicionar o cátodo e o ânodo do SCS próximos à linha média dorsal e ao EDRED, respectivamente (Figura 2), o que poderia inic...

Watch this Scientific Journal Video about Advancing Spinal Cord Stimulation - Exploring the Cellular Responses of Motor Neurons Through Patch-Clamp Electrophysiology at JoVE.com

Este protocolo descreve um método que utiliza um patch-clamp para estudar as respostas elétricas dos neurônios motores à estimulação da medula espinhal (SCS) com alta resolução espaço-temporal, o que pode ajudar os pesquisadores a melhorar suas habilidades em separar a medula espinhal e manter a viabilidade celular simultaneamente.

Spinal cord stimulation (SCS) can effectively restore locomotor function after spinal cord injury (SCI). Because the motor neurons are the final unit to ...

A estimulação da medula espinhal pode ajudar os pacientes a resolver a maioria das funções de movimento após a lesão. A maioria dos neurônios deve executar comportamentos de modo sensorial. Estudar a resposta elétrica da maioria dos neurônios pode ajudar na compreensão da lógica subjacente da neuromodulação da carga espinhal.A pinça de remendo é o método padrão-ouro para registros eletrofisiológicos celulares com altíssima resolução espaço-temporal. Portanto, este estudo descreve um método que utiliza um patch clamp para registrar simultaneamente as características do estímulo da aorta e as respostas celulares dos neurônios motores em escala unicelular. Em comparação com a pinça do remendo cerebral, a pinça do remendo da medula espinhal é mais difícil, porque a medula espinhal é bem protegida pelo canal vertebral com volume minúsculo.Portanto, este protocolo fornece detalhes técnicos na microdissecação rápida da medula espinhal e manutenção reversa para obter melhor viabilidade celular. Patch clamp permite uma compreensão única das transmissões sinápticas e a compreensão dos potenciais de ação, codificando atividades padrão pela estimulação da medula espinhal.

the-ex-vivo-preparation-spinal-cord-slice-for-whole-cell-patch-clamp

Research

JoVE Journal

Neuroscience

The Ex vivo Preparation of Spinal Cord Slice for the Whole-Cell Patch-Clamp Recording in Motor Neurons During Spinal Cord Stimulation

Spinal cord stimulation (SCS) can effectively restore locomotor function after spinal cord injury (SCI). Because the motor neurons are the final unit to execute sensorimotor behaviors, directly studying the electrical responses of motor neurons with SCS can help us understand the underlying logic of spinal motor modulation. To simultaneously record diverse stimulus characteristics and cellular responses, a patch-clamp is a good method to study the electrophysiological characteristics at a single-cell scale. However, there are still some complex difficulties in achieving this goal, including maintaining cell viability, quickly separating the spinal cord from the bony structure, and using the SCS to successfully induce action potentials. Here, we present a detailed protocol using patch-clamp to study the electrical responses of motor neurons to SCS with high spatiotemporal resolution, which can help researcher improve their skills in separating the spinal cord and maintaining the cell viability at the same time to smoothly study the electrical mechanism of SCS on motor neuron and avoid unnecessary trial and mistake.

This protocol describes a method using a patch-clamp to study the electrical responses of motor neurons to spinal cord stimulation (SCS) with high spatiotemporal resolution, which can help researchers improve their skills in separating the spinal cord and maintaining cell viability simultaneously.

Neurociência

Spinal Cord Dissection for the Whole-Cell Patch-Clamp Recording in Motor Neurons

After exposing the heart of an anesthetized rat, cut the right atrium using fine scissors and inject 100 milliliters of chilled perfusing fluid at approximately two milliliters per second within one minute. Position the rat in the prone position. Cut the spine at the anterior superior iliac spine and the curvature shifting point of the thoracic column.Immediately place the isolated spine into the oxygenated ice cold perfusing solution to wash off residual blood and fat tissue. Then transfer the isolated spine to the anatomical tray with its dorsal side up and the rostral end near the operator. Fill the tray with 50 milliliters of continuously oxygenated ice cold cutting solution.Under a dissection microscope, cut the vertebral pedicles on both sides from the rostral end using micro scissors. Next, delicately sever the dura mater along its dorsal midline with micro scissors. Lift the rostral part of the spinal cord carefully and cut the nerve root, leaving about one millimeter reserved.After the spinal cord has been separated from the vertebral canal, secure it with the ventral side facing up using two insect pins. Trim any excessive nerve roots, leaving about one millimeter intact. Then separate the lumbar enlargement to a length of six to seven millimeters using a micro scissor.

Dissecção da Medula Espinhal para o Registro de Patch-Clamp de Células Inteiras em Neurônios Motores

Preparation of Spinal Cord Slice for the Whole-Cell Patch-Clamp Recording in Motor Neurons

After dissecting the spinal cord and separating the lumbar enlargement, place the lumbar enlargement on a 35 degree slope with the dorsal side up and the caudal side down. Absorb any excess water on the tissue surface using an absorbent filter paper. Carefully pour the molten agarose gel into the Petri dish containing the lumbar enlargement.Position the Petri dish in the ice water mixture to ensure rapid gel cooling. Shape the gel into a cube of 15 by 10 by 10 millimeters, and mount it onto the specimen disc using super glue. Adjust the vibratome settings to a thickness of 350 micrometers, a speed of 0.14 to 0.16 millimeters per second, an amplitude of one millimeter, and a vibration frequency of 85 hertz.Now, use the cover slide tweezers to clip a slice and place it into the incubation chamber, filled with continuously oxygenated artificial cerebrospinal fluid.

Preparação de Corte de Medula Espinhal para o Registro de Patch-Clamp de Células Inteiras em Neurônios Motores

Patch-Clamp Recording to Study the Electrical Responses of Motor Neurons to Spinal Cord Stimulation

To begin, place the prepared spinal cord slice in the recording chamber. Then place the anode of the micro-manipulation system near the dorsal midline in the cathode close to the dorsal root entry zone for proper spinal cord stimulator positioning. Now switch to a 60X objective lens to identify a healthy neuron having a smooth and bright surface without visible nuclei.Slightly decrease the infrared intensity, turn on the fluorescent light source, and adjust the light filter to the wideband ultraviolet excitation option. Now, select an appropriate Fluoro-Gold-positive motor neuron and gradually lower the electrode until it is near the neuron. As the pipette contacts its surface, look for a small membrane indentation at the tip level and release the previously-applied positive pressure.Then apply negative pressure to the pipette using a syringe and wait until the resistance value rises to gigaohms on the software interface. Clamp the membrane potential at minus 70 millivolts. Press the fast capacitance compensation button on the amplifier's software interface, then apply a brief negative pressure to rupture the cell membrane and press the slow capacitance compensation button on the amplifier's software interface.Apply the spinal cord stimulation for one to two seconds keeping the amplitude between one and 10 milliamperes. Determine the motor threshold by gradually increasing the stimulation amplitude until the first action potential is observed. Distinguish delayed and immediate firing motor neurons using a five-second depolarizing current injection around rheobase in the current clamp mode.After turning off the spinal cord stimulation, continue recording the membrane potentials to capture the spontaneous action potentials firing. When the amplitude of spinal cord stimulation was raised, the membrane potential was increased, and the action potentials were triggered every 10 to 20 pulses. After the spinal cord stimulation was turned off, the neuron fired a series of spontaneous action potentials for a short period of time.Then, the resting membrane potential returned to minus 65 millivolts.