A Tac1-Expressing Brainstem Pathway Underlies the Pathogenesis of Trigeminal Neuralgia

Area of Science:

• Neuroscience
• Pain Research
• Molecular Biology

Background:

• Trigeminal neuralgia (TN) is a severe facial pain disorder with poorly understood mechanisms.
• Existing treatments for TN often have limited efficacy or significant side effects.

Purpose of the Study:

• To elucidate the neuronal circuitry underlying trigeminal neuralgia pathogenesis.
• To identify potential therapeutic targets for TN treatment.

Main Methods:

• Utilized mouse models of TN.
• Employed chemogenetics to manipulate neuronal activity.
• Used retrograde viral tracing and electrophysiological recordings.
• Performed gene knockdown (Tac1) in specific neuronal populations.

Main Results:

• Identified a periphery-to-brain neural circuit involving the trigeminal ganglion (TG), spinal trigeminal nucleus (Sp5C), and parabrachial nucleus (PBN).
• Tachykinin 1 (Tac1)-expressing parabrachial nucleus (PBN^Tac1) neurons showed heightened responses and their inhibition prevented TN.
• PBN-projecting Sp5C neurons, predominantly expressing Tac1, were essential for TN-induced pain.
• Knockdown of Tac1 in Sp5C neurons significantly reduced TN pain hypersensitivity.

Conclusions:

• Unveiled a critical TG-Sp5C^Tac1-PBN^Tac1 pathway driving TN pathogenesis.
• This pathway represents a potential therapeutic target for managing trigeminal neuralgia.
• Findings advance the understanding of pain mechanisms in severe neurological disorders.