Impact of IVC housing on emotionality and fear learning in male C3HeB/FeJ and C57BL/6J mice.

Housing conditions are known to influence laboratory animal behavior. However, it is not known whether housing mice in individually ventilated cages (IVCs) to maintain optimal hygienic conditions alters behavioral baselines established in conventional housing. This issue is important with regard to comparability and reproducibility of data. Therefore, we investigated the impact of IVC housing on emotionality and fear learning in male C3HeB/FeJ (C3H) and C57BL/6J (B6J) mice housed singly either in conventional type II cages with wire bar lids (Conventional), or in IVCs of the same size, but with smooth, untextured lids (IVC classic), thus acoustically attenuated from external stimuli and with limited climbing facilities compared to Conventional. To evaluate the role of climbing, additional mice were kept in IVCs with lids having wire bars ("grid") added to the inner surface (IVC grid). Spontaneous behavior, sensorimotor behavior, and fear learning were measured. IVC housing reduced activity and enhanced anxiety-related behavior in both strains, whereas grooming latency was reduced in B6J only. IVC housing increased Acoustic Startle Response in C3H but not in B6J mice. The "grid" did not compensate for these IVC housing effects. In contrast, B6J mice in IVC grid performed best in fear potentiated startle while B6J mice in IVC classic performed the worst, suggesting that climbing facilities combined with IVC housing facilitate FPS performance in singly-housed B6J males. Our data show that IVC housing can affect behavioral performance and can modulate behavioral parameters in a general and a strain-specific manner, thus having an impact on mouse functional genomics.