Ventral Anterior-Lateral Complex of the Thalamus Mediates Chronic Stress-Induced Pain Hypersensitivity and Underlies Electroacupuncture Analgesia.

Researchers have discovered how chronic psychological stress can lead to increased pain sensitivity throughout the body, and how electroacupuncture may help relieve this type of pain. Scientists studied male mice exposed to chronic restraint stress, which mimics the effects of ongoing psychological stress in humans. They found that stressed mice developed heightened sensitivity to both touch and heat, experienced abdominal pain, and showed spontaneous pain behaviors—similar to what people with chronic stress often report.

The study identified a specific brain region called the ventral anterior-lateral thalamic complex (VAL) as a key player in stress-related pain. When researchers turned off certain neurons in this area, the pain hypersensitivity disappeared. When they activated these same neurons in unstressed mice, the animals suddenly developed pain sensitivity, proving this brain region's critical role.

Importantly, the researchers tested electroacupuncture—a form of acupuncture that adds mild electrical stimulation—at two commonly used points: Zusanli (ST36) on the leg and Sanyinjiao (SP6) near the ankle. Electroacupuncture successfully reduced all types of stress-induced pain in the mice. The treatment worked partly by calming the overactive neurons in the VAL brain region, though it appeared to use additional pathways for relieving abdominal and spontaneous pain.

For patients suffering from chronic stress and concurrent pain conditions, this research provides scientific evidence that electroacupuncture may offer real relief by targeting specific brain mechanisms involved in stress-pain interactions. This is particularly relevant for people whose pain doesn't stem from physical injury but from ongoing emotional or psychological stress. Always seek treatment from a licensed acupuncturist trained in electroacupuncture techniques.

This preclinical study establishes the ventral anterior-lateral thalamic complex (VAL) as a critical mediator of chronic stress-induced pain hypersensitivity. Using a chronic restraint stress (CRS) model in male mice, researchers demonstrated that CRS induced mechanical allodynia (hindpaw and abdominal), thermal hyperalgesia, and spontaneous pain behaviors. Chemogenetic manipulation revealed that VAL CaMKIIα-positive neurons are both necessary and sufficient for these pain phenotypes—inhibition reversed CRS-induced hypersensitivity, while activation in naive mice replicated the full pain spectrum. Electroacupuncture at ST36 and SP6 significantly ameliorated all CRS-induced pain modalities. Mechanistic analysis showed EA's effects on hindpaw mechanical and thermal hyperalgesia operate through VAL CaMKIIα neuronal suppression, while abdominal allodynia and spontaneous pain relief involve alternative pathways, as evidenced by persistent EA efficacy during chemogenetic activation. Clinical implications suggest electroacupuncture may effectively address stress-related pain comorbidities through multiple neural mechanisms, warranting investigation in human populations with chronic stress and pain overlap.