The influence of a targeted deletion of the IFNγ gene on emotional behaviors

Evidence suggests that interferon-gamma (IFN gamma) plays an important rule in CNS function and development. While the paucity of agents that selectively modify IFN gamma production or interaction with its receptor makes analyses of its potential behavioral relevance difficult, mice with null mutations of the IFN gamma gene have been used to investigate the potential role of IFN gamma in emotional behaviors. C57B1/6 (B6) mice with null mutations of the IFN gamma gene (IFN gamma (-/-) showed significantly increased emotionality compared to the wild-type (IFN gamma (+/+)) B6 mice. This was manifested in performance in the elevated plus maze as well as increased defecation scores and decreased locomotor activity both in novel environments and following a sonic stimulus. In contrast, the general level of emotionality of both IFN gamma (+/+) and (-/-) BALB/c (C) mice was substantially greater than that of either of the BS mouse groups. While C IFN gamma (-/-) showed increased immobility in response to novelty, other indices of emotionality of C IFN gamma (-/-) mice were not significantly different from those of the C IFN gamma(+/+) mice. In summary, the lack of IFN gamma appears to contribute to increased emotionality, but the basal behaviors of the parental strain (e.g., BALB/c) may overshadow the expression of this emotionality. While mice with null mutations of the IFN gamma gene may be useful tools for investigating the rule of IFN gamma in brain function and behavior. the influence of the parent strain genome(s) on the behaviors in question must be taken into account. (C) 1998 Academic Press.