[Mechanistic role of spinal Lamb1 in negative emotion

objectivesNeuropathic pain is frequently accompanied by anxiety and depressive symptoms, resulting in a comorbid state of pain and negative emotions, the underlying mechanisms of which remain incompletely understood. This study aims to investigate the regulatory mechanism of the descending anterior cingulate cortex (ACC)-spinal dorsal horn (SDH) pathway in negative emotion-facilitated neuropathic pain and to identify and validate key molecules acting at the spinal level.

methodsMale Sprague-Dawley rats were used to establish a chronic unpredictable mild stress (CUMS) combined with chronic constriction injury (CCI) model to mimic negative emotion-facilitated neuropathic pain. CUMS was administered for 21 days, with 2 different stressors randomly applied each day. The CCI model was established by ligation of the left sciatic nerve. Depression-like behaviors were assessed using the sucrose preference test (SPT) and forced swimming test, and the mechanical pain threshold was measured using the von Frey test. To selectively inhibit ACC-SDH projection neurons, a retrograde adeno-associated virus (AAV) expressing cyclization recombination enzyme (Cre) was injected into the SDH, while a Cre-dependent hM4Di virus was injected into the ACC. Clozapine-N-oxide (CNO) was then administered intraperitoneally for 14 consecutive days, followed by behavioral assessments. On postoperative day 7 after CCI, lumbar enlargement spinal cord tissues were collected for transcriptomic sequencing to identify differentially expressed genes. Gene ontology (GO) and pathway enrichment analyses were performed to characterize the functional features of candidate molecules. Western blotting (WB) and immunofluorescence staining were used to validate the expression changes, distribution, and cellular localization of the candidate molecule laminin subunit beta-1 (

resultsCUMS induced marked depression-like behaviors in rats and further aggravated CCI-induced mechanical hypersensitivity. After inhibition of the ACC-SDH pathway, the mechanical pain threshold was significantly increased from postoperative day 3 to day 10 after CCI, with the most pronounced effect observed on postoperative day 7 (all

conclusionsLamb1 at the spinal level participates in the regulation of negative emotion-facilitated neuropathic pain by the ACC-SDH pathway. From the perspective of descending brain-spinal cord regulation, this study reveals a spinal molecular basis underlying the comorbidity of pain and negative emotions and provides a potential basis for developing new strategies to intervene in negative emotion-associated neuropathic pain.