Study on correlation between depressive behaviors and brain's interleukin-1β level in fluoxetine-insensitive mice / 中华行为医学与脑科学杂志

ABSTRACT

Objective To investigate the correlationship between depressed behaviors and interleukin-1β (IL-1β) in brain tissue in mice which are insensitive to fluoxetine,and to mimic the treatment resistant depression (TRD) in clinical condition.Methods 50 BALB/c mice were randomly divided into Control group (Control),Chronic unpredictable mild stress (CUMS) group and CUMS+fluoxetine group.Mice in Control group were raised ad libitum for 9 weeks,those in CUMS group received CUMS for 9 weeks and those in CUMS+fluoxetine group received 8 weeks' CUMS followed 1 week' s treatment with Fluoxetine(10 mg · kg-1 · d-1).At the end of the 9th week,mice in(CUMS + treatment)group were selected into antidepressant treatment-resistant mice(ATRM) as no remission and Depression Group (DM) as symptoms improved.Body mass test (BMT),open field test (OFT) and forces swim test (FST) were completed respectively in these 4 groups at the endpoint of the experiment,and the brain tissue were extracted after the tests for IL-1β Elisa test.Results (1) BMTthere was no effect of weightgain in ATRM after 1 week' s therapy with Fluoxetine.There was no difference in body-weight between ATRM ((18.56±7.56) g) and CUMS ((19.03± 8.58) g) mice,while compared with Control ((24.56±5.45) g) and DM mice ((20.12±9.17) g) ATRM and CUMS mile's body weight were significantly lower (P＜0.05).(2)OFT and FSTin OFT,there was no significant difference in of horizontal moving distance(F=0.355) either in the frequencies of entering the central zone (F=0.327) among the 4 groups;in OFT,the immobility time of ATRM ((241.50 ± ± 36.55) s) was significantly longer than that in DM ((156.00± 25.47) s) (F=13.573,P＜0.05).(3) Elisa test of IL-1βthe brain' s IL-1β serum level in ATRM ((164.90±46.70) pg/mg) was higher than those in Control ((69.68±6.56) pg/mg)),and DM ((93.09±4.65) pg/mg) (P＜0.01),while no difference with that in CUMS mice.Additionally,the depressive behaviors in ATRM showed its positive correlation with the IL-1β level in CNS (r=0.669,P=0.006).Conclusion CUMS can elicit the refractory depressive symptoms in BALB/c mice to simulate TRD' s characteristic,and the elevated level of IL-1 β within brain tissue may play an important role in the development of TRD.