Presence of mother prompts dissociation of sickness behavior, fever, and hypothalamic gene expression in lipopolysaccharide-injected guinea pig pups.

During infection, sickness behaviors, such as a hunched stance with piloerection, can facilitate host resistance by supporting the generation and maintenance of fever. Fever, in turn, is mediated by hypothalamic neuroimmune signaling. Sickness behaviors, however, can also be influenced by social stimuli. In this study, guinea pig pups were injected with lipopolysaccharide to simulate a bacterial infection and then exposed to a novel, threatening environment while either with their mother or alone. We found that the presence of the mother suppressed sickness behavior, but enhanced fever, and had no measureable effect on gene expression of hypothalamic mediators of fever. This 3-way dissociation induced by the mother's presence is interpreted in terms of the differential adaptive consequences of behavioral and febrile responses for pups in this situation. The results contribute to a growing literature linking immunological and social processes.