Correlation between two animal models of state anxiety in Kunming mice: evidence from open field test and light-dark box

Abstract

Objective To explore the correlation between open field test(OFT) and light-dark box(LDB), as two animal models of state anxiety in Kunming mice. Methods The behavior of adult, male, Kunming mice in OFT and LDB was recorded by sequence, for five minutes, with a one-week inter-trial interval. The following parameters were evaluated: percentage of time exploring in the OFT central area(OFT-Ctime%); percentage of squares crossing in the OFT central area(OFT-Ccross%); total number of squares crossing in OFT(OFT-Cross); total number of rears in the OFT(OFT-Rear); number of fecal boli in OFT(OFT-FB); percentage of time exploring in the LDB light area(LDB-Ltime%); percentage of squares crossing in the LDB light area(LDB-Lcross%); and percentage of rears in the LDB light area(LDB-Lrear%); transitions between two areas in LDB(LDB-Transition); total number of squares crossing in LDB(LDB-Cross); total number of rears in LDB(LDB-Rear); number of fecal boli in LDB(LDB-FB). Subsequently, factor analysis, cluster analysis and correlation analysis were calculated for these parameters. Results Factor analysis and cluster analysis of variances from either OFT or LDB revealed a three behavioral dimensions: anxiety factor(loaded by OFT-Ctime%, OFT-Ccross% or LDB-Ltime%, LDB-Lcross%, LDB-Lrear%), activity factor(loaded by OFT-Cross, OFT-Rear or LDB-Transition, LDB-Cross, LDB-Rear) and emotionality factor(loaded by OFT-FB or LDB-FB). While all the variances from both OFT and LDB in combination were analyzed, it could be seen as five components: ′LDB-anxiety factor(loaded by LDB-Ltime%, LDB-Lcross% and LDB-Lrear%), ′OFT-anxiety factor (loaded by OFT-Ctime% and OFT-Ccross%), ′LDB-activity factor (loaded by LDB-Transition, LDB-Cross and LDB-Rear), ′OFT-LDB-emotionality factor(loaded by OFT-FB and LDB-FB) and ′OFT-activity factor (loaded by OFT-Cross and OFT-Rear). Good correlation were found between OFT/LDB factors alone and in combination, such as OFT-emotionality factor and LDB-emotionality factor(Pearson=0.383, P<0.05), LDB-anxiety factor and ′LDB-anxiety factor(Pearson=0.989, P<0.01), OFT-anxiety factor and ′OFT-anxiety factor(Pearson=0.934, P<0.01), LDB-activity factor and ′LDB-activity factor(Pearson=0.956, P<0.01), OFT/LDB-emotionality factor and ′OFT-LDB-emotionality factor(Pearson=0.835, P<0.01; Pearson=0.696, P<0.01), OFT-activity factor and ′OFT-activity factor(Pearson=0.926, P<0.01). Conclusion Either OFT or LDB comprised three behavioral dimensions: anxiety factor, activity factor and emotionality factor; however, it was difficult to establish face validity as a point-to-point concordance between OFT and LDB. Attention should be paid to heterogeneity of animal models when OFT and LDB were in combination as a behavionomics to evaluate anxiolytics in Kunming mice. Key words: Open field test; Light-dark box; Animal model; State anxiety; Correlation; Kunming mice