Objective To explore possible mechanism of auricular electroacupuncture on depression. Methods A total of 24 Sprague Dawley（SD） rats were randomized into a blank group

a model group

an auricular concha electroacupuncture（CEA） group and an auricular-rim electroacupuncture（ARE） group with 6 rats in each group. The rats in the blank group were fed normally

and the depression model was induced by chronic unpredictable mild stress method combined with solitary condition for continuous 35 days. CEA group received electro-acupuncture intervention in the cavities of bilateral ear concha 1 hour before stress every day; ARE group received electro-acupuncture intervention in rat bilateral ear rim

each for 30 min in both groups

lasting 21 d. There was no intervention for the blank group and the model group. Body weight

sucrose consumption and open-field test behavior of each group were recorded before modeling

on the 14 th day of modeling and on the 21 st day of intervention. The expression levels of rat prefrontal cortex nucleotide-binding oligomerization domain-like receptor protein 3（NLRP3）

nuclear transcription factor κB（NF-κB）

and interleukin 1β（IL-1β） in each group was detected by Western blot method after 21 days intervention. Results Compared with the blank group

the body weight

sucrose consumption and horizontal crossing grid and vertical stand times of open-field test behavior were significantly decreased in the model group after modeling 14 days and intervention 21 days（P<0.01）. Compared with the model group

after the intervention for 21 days

the body weight of the rats in the CEA group was significantly increased（P<0.05）; sugar water preference index

horizontal crossing grid number and standing times in open field experiment were significantly increased in both intervention groups（P<0.01）. Among them

the improvement of water preference index of CEA group was better than that of ARE group（P<0.05）. Compared with the blank group

the expressions of NF-κB

NLRP3 and IL-1β in the prefrontal cortex of the model group were significantly increased（P<0.01）. Compared with the model group

the prefrontal cortex NF-κB p65 level in the CEA group was significantly lower（P<0.01）; the expressions of NLRP3 and IL-1β in the prefrontal cortex of both groups were significantly decreased（P<0.05 or P<0.01）. Conclusion Electroacupuncture at auricular concha is able to improve depressive behavior in rats. The mechanism may be related to reducing the level of NF-κB in the prefrontal cortex and activation of NLRP3 inflammasomes

reducing IL-1β secretion

alleviating brain damage caused by inflammatory reactions.