Changes of hippocampal levels of pro-inflammatory cytokines in rats with depression induced by neuropathic pain / 临床麻醉学杂志

ABSTRACT

Objective To observe changes of hippocampal levels of pro-inflammatory cytokines in rats with neuropathic pain-induced depression, and to explore the relationship between hippocampal levels of pro-inflammatory cytokines and severity of depression.Methods Twenty-eight adult male rats were randomly divided into two groups group sham (n=14) and spared nerve injury (group SNI) (n=14).Mechanical withdrawal thresholds (MWT) were measured 1 day before and 7, 14 and 21 days after operation.Sucrose preference test and forced swim test were tested 1-3 days before and 21-23 days after operation.After test, hippocampus was collected.The hippocampal levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) were measured by ELISA.Correlational relationships between hippocampal levels of pro-inflammatory cytokines and sucrose preference were evaluated.Results Compared with group sham, MWT was decreased 7, 14, 21 days after operation (P<0.001).Group SNI displayed decreased sucrose preference 21 days after operation (P<0.01) and increased immobility time in FST 23 days after operation (P<0.05).The levels of IL-6 and TNF-α were increased in hippocampus (P<0.05 or P<0.01).No significant difference was observed in IL-1β.The hippocampal levels of IL-1β (r2=0.60,P<0.01), IL-6 (r2=0.55,P<0.01) and TNF-α(r2=0.60,P<0.01) were negatively correlated with sucrose preference.Conclusion The hippocampal levels of pro-inflammatory cytokines IL-6 and TNF-α are increased in rats with depression induced by neuropathic pain, and the levels of hippocampal pro-inflammatory cytokines are negatively correlated with the severity of depression.