Brain nuclei and neural circuits in neuropathic pain and brain modulation mechanisms of acupuncture: a review on animal-based experimental research

Abstract

Neuropathic pain (NP) is known to be associated with abnormal changes in specific brain regions, but the complex neural network behind it is vast and complex and lacks a systematic summary. With the help of various animal models of NP, a literature search on NP brain regions and circuits revealed that the related brain nuclei included the periaqueductal gray (PAG), lateral habenula (LHb), medial prefrontal cortex (mPFC), and anterior cingulate cortex (ACC); the related brain circuits included the PAG-LHb and mPFC-ACC. Moreover, acupuncture and injurious information can affect different brain regions and influence brain functions via multiple aspects to play an analgesic role and improve synaptic plasticity by regulating the morphology and structure of brain synapses and the expression of synapse-related proteins; maintain the balance of excitatory and inhibitory neurons by regulating the secretion of glutamate, γ-aminobutyric acid, 5-hydroxytryptamine, and other neurotransmitters and receptors in the brain tissues; inhibit the overactivation of glial cells and reduce the release of pro-inflammatory mediators such as interleukins to reduce neuroinflammation in brain regions; maintain homeostasis of glucose metabolism and regulate the metabolic connections in the brain; and play a role in analgesia through the mediation of signaling pathways and signal transduction molecules. These factors help to deepen the understanding of NP brain circuits and the brain mechanisms of acupuncture analgesia.

New perspectives on migraine treatment: a review of the mechanisms and effects of complementary and alternative therapies

“…Migraine may be associated with electrolyte disturbances, and magnesium deficiency may induce migraine by affecting cortical inhibition or leading to abnormalities in glutamatergic neurotransmission, which is seen as a potential mechanism for the magnesium-migraine association ( 53 ). Magnesium is involved in the regulation of the nervous system through multiple pathways, not only regulating vasodilatation by affecting mitochondrial metabolism, neurotransmitter release, and substance P release, but also attenuating neuroinflammation by inhibiting the nuclear factor κB pathway in pro-inflammatory cells ( 54 , 55 ). Given the close link between inflammation and migraines, employing magnesium as a supplement emerges as a potent approach for the mitigation or prophylaxis of migraine episodes.…”

Neural circuit mechanisms of acupuncture effect: where are we now?

“…One of these components, the periaqueductal grey (PAG), serves as a central hub by engaging in the majority of higher-level central pain inhibitory pathways and triggering the descending inhibitory system. Acupuncture can alleviate pain by activating certain internal pain control structures or activating neuronal pathways in the inhibitory system that reduces pain sensation ( 29 ).…”