Electroacupuncture reverses task-dependent long-term memory deficits in rats with chronic neuropathic pain

Abstract Background Chronic pain is frequently accompanied by cognitive dysfunction, while according to the limited cognitive resource hypothesis, persistent pain may consume finite neural processing capacity, thereby impairing cognitive performance, particularly under high cognitive demand. Electroacupuncture (EA) alleviates neuropathic pain and may improve cognitive function, but its effect on task-dependent memory deficits associated with chronic neuropathic pain remains insufficiently defined. This study investigated whether spared nerve injury (SNI)-induced neuropathic pain selectively impairs memory under high cognitive demand and whether repeated EA reverses these deficits. Results SNI induced robust mechanical hypersensitivity in rats but did not produce detectable impairments in novel object recognition (NOR) or novel object location (NOL) performance under low-difficulty conditions. Under high-difficulty conditions, SNI rats showed impaired long-term object recognition memory (NOR), whereas NOL performance remained unaffected. When object novelty and spatial relocation were combined in a higher-demand task (NOR + NOL), SNI rats showed impaired performance across the object-recognition and subsequent location components. Repeated EA intervention at Zusanli (ST36) and Sanyinjiao (SP6) attenuated mechanical hypersensitivity and restored impaired performance in high-demand memory tasks. Immunofluorescence analysis showed that SNI reduced the percentage of CaMKII-positive cells that showed c-Fos immunoreactivity in rostral anterior cingulate cortex (rACC). In contrast, EA increased this proportion to a level comparable to that in sham-operated rats. Conclusions Chronic neuropathic pain selectively disrupts long-term memory performance under high cognitive demand, supporting a resource-competition model of pain–cognition interaction. Repeated EA alleviates mechanical hypersensitivity and improves task-dependent memory performance, and these behavioral effects may be associated with a higher proportion of rACC CaMKII-positive cells showing c-Fos immunoreactivity.