<em>In-Vivo</em> Calcium Imaging of Sensory Neurons in the Rat Trigeminal Ganglion

Jeremy Y. Gedeon; Jorge Baruch Pineda-Farias; Michael  S. Gold

doi:10.3791/65978

In Vivo Imaging del calcio dei neuroni sensoriali nel ganglio trigeminale del ratto

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Neuroscience

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JoVE Journal Neuroscience

In-Vivo Calcium Imaging of Sensory Neurons in the Rat Trigeminal Ganglion

In Vivo Imaging del calcio dei neuroni sensoriali nel ganglio trigeminale del ratto

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04:39 min

February 9, 2024

DOI: 10.3791/65978-v

Jeremy Y. Gedeon^1,2,3, Jorge Baruch Pineda-Farias^2,3, Michael S. Gold^2,3

¹Center for Neuroscience at the University of Pittsburgh, ²Department of Neurobiology,University of Pittsburgh School of Medicine, ³Pittsburgh Center for Pain Research,University of Pittsburgh

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Overview

This study uses a novel approach to in vivo visualization of genetically encoded calcium indicators (GECI) to analyze sensory neuron signaling in rat trigeminal ganglia. The research focuses on characterizing changes in sensory coding and afferent subpopulations in relation to neuropathic pain following trigeminal nerve injury.

Key Study Components

Area of Science

Neuroscience
Pain Biology
Neuropathic Pain

Background

Understanding peripheral mechanisms of pain is crucial for developing better therapeutic strategies.
Research on trigeminal nerve injury reveals differences in the response of trigeminal vs. somatic afferents.
Previous assumptions about neuropathic pain focus predominantly on central nervous system changes.
There is a potential role of the peripheral nervous system that requires further investigation.

Purpose of Study

To characterize sensory neuron responses in rat models of trigeminal nerve injury.
To identify specific afferent subpopulations contributing to neuropathic pain.
To explore potential therapeutic targets for pain management.

Methods Used

In vivo imaging using genetically encoded calcium indicators (GECI) in rat trigeminal ganglia.
Rats were anesthetized and specific surgical procedures were performed to expose the trigeminal ganglia.
Mechanical stimuli were applied to assess neuronal responses during imaging.
Fluorescent imaging of neuronal activity was conducted over set timelines.
The study emphasizes differences in response patterns based on injury and stimulus type.

Main Results

Notable differences in trigeminal and somatic afferent responses were observed following nerve injury.
Upregulation of Nav 1.1 in trigeminal nerves indicates its importance in neuropathic pain.
Specific stimuli elicited distinct neuronal responses, highlighting potential peripheral contributions to neuropathic pain.
Imaging revealed significant changes in neuronal excitability and response amplitudes based on stimulus application.

Conclusions

This study demonstrates the utility of GECI for analyzing neuronal activity and pain mechanisms in the peripheral nervous system.
It highlights the complexity of neuropathic pain, suggesting further examination of peripheral contributions is necessary.
The findings may inform improved strategies for understanding and treating neuropathic pain in humans.

Frequently Asked Questions

What are the advantages of using rats over mice for this study?

Rats provide a larger model that can simplify surgical procedures and may more closely represent human pain mechanisms compared to mice.

How is the trigeminal nerve injury model implemented?

The model involves specific surgical techniques to expose and evaluate the trigeminal ganglia in anesthetized rat pups.

What types of data are collected during the imaging procedures?

The study collects data on neuronal responses, including excitability changes and fluorescence imaging of activity in response to mechanical stimuli.

How can the findings be adapted for therapeutic development?

Insights from the study regarding specific ion channels like Nav 1.1 can guide the development of selective therapeutic interventions for neuropathic pain.

Are there any limitations to the GECI method used?

While GECI provides valuable insights into neuronal activity, the method may have challenges related to the resolution and specificity of signals in complex tissues.

What implications do the results have for understanding pain mechanisms?

The study underscores the importance of exploring peripheral nervous system changes, suggesting that pain mechanisms involve more than just central nervous system alterations.

Gli indicatori di calcio geneticamente codificati (GECI) consentono una solida analisi a livello di popolazione della segnalazione sensoriale dei neuroni. Qui, abbiamo sviluppato un nuovo approccio che consente la visualizzazione GECI in vivo dell'attività dei neuroni dei gangli trigeminali del ratto.

L'obiettivo generale del nostro laboratorio è quello di comprendere i meccanismi periferici del dolore, e il mio progetto indaga specificamente il dolore associato alla lesione del nervo trigemino. La preparazione che vi mostro oggi ci permette di caratterizzare i cambiamenti nel rivestimento sensoriale e di identificare le sottopopolazioni afferenti che contribuiscono al dolore neuropatico. Quindi abbiamo dimostrato che ci sono differenze tra le afferenze trigeminali e somatiche in risposta alla lesione nervosa.

NaV1.1 in particolare è preferenzialmente sovraregolato nel nervo trigemino, suggerendo che i bloccanti selettivi per NaV1.1 possono essere utilizzati per identificare diverse sottopopolazioni afferenti che contribuiscono al dolore neuropatico. Quindi i topi transgenici sono utilizzati più ampiamente al momento in combinazione con una varietà di strategie basate sull'imaging e sull'omica. Tradurre i dati generati nei topi in altre specie, se non negli esseri umani.

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