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A Neural Circuit from Thalamic Paraventricular Nucleus to Central Amygdala for the Facilitation of Neuropathic Pain
- Source :
- J Neurosci
- Publication Year :
- 2020
- Publisher :
- Society for Neuroscience, 2020.
-
Abstract
- As one of the thalamic midline nuclei, the thalamic paraventricular nucleus (PVT) is considered to be an important signal integration site for many descending and ascending pathways that modulate a variety of behaviors, including feeding, emotions, and drug-seeking. A recent study has demonstrated that the PVT is implicated in the acute visceral pain response, but it is unclear whether the PVT plays a critical role in the central processing of chronic pain. Here, we report that the neurons in the posterior portion of the PVT (pPVT) and their downstream pathway are involved in descending nociceptive facilitation regarding the development of neuropathic pain conditions in male rats. Lesions or inhibition of pPVT neurons alleviated mechanical allodynia induced by spared nerve injury (SNI). The excitability of pPVT-central amygdala (CeA) projection neurons was significantly increased in SNI rats. Importantly, selective optogenetic activation of the pPVT-CeA pathway induced obvious mechanical hypersensitivity in naive rats. In addition, we used rabies virus (RV)-based and cell-type-specific retrograde transsynaptic tracing techniques to define a novel neuronal circuit in which glutamatergic neurons in the vlPAG were the target of the pPVT-CeA descending facilitation pathway. Our data suggest that this pPVTGlu+-CeA-vlPAGGlu+circuit mediates central mechanisms of descending pain facilitation underlying persistent pain conditions.SIGNIFICANCE STATEMENTStudies have shown that the interactions between the posterior portion of the thalamic paraventricular nucleus (pPVT) and central amygdala (CeA) play a critical role in pain-related emotional regulation. However, most reports have associated this circuit with fear and anxiety behaviors. Here, an integrative approach of behavioral tests, electrophysiology, and immunohistochemistry was used to advance the novel concept that the pPVT-CeA pathway activation facilitates neuropathic pain processing. Using rabies virus (RV)-based and cell-type-specific retrograde transsynaptic tracing techniques, we found that glutamatergic neurons in the vlPAG were the target of the pPVT-CeA pathway. Thus, this study indicates the involvement of a pPVTGlu+-CeA-vlPAGGlu+pathway in a descending facilitatory mechanism underlying neuropathic pain.
- Subjects :
- Male
Nociception
SNi
Midline Thalamic Nuclei
Optogenetics
Amygdala
Rats, Sprague-Dawley
03 medical and health sciences
Glutamatergic
0302 clinical medicine
Neural Pathways
Image Processing, Computer-Assisted
Medicine
Animals
Periaqueductal Gray
Research Articles
030304 developmental biology
Neurons
0303 health sciences
Behavior, Animal
business.industry
General Neuroscience
Central Amygdaloid Nucleus
Chronic pain
Visceral pain
medicine.disease
Electrophysiological Phenomena
Rats
medicine.anatomical_structure
Hyperalgesia
Neuropathic pain
Neuralgia
medicine.symptom
business
Neuroscience
030217 neurology & neurosurgery
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- J Neurosci
- Accession number :
- edsair.doi.dedup.....6bdf5d6db2f66ccc3e6bdfb0a8d27277