BRAIN MONOAMINERGIC, NEUROENDOCRINE, AND IMMUNE-RESPONSES TO AN IMMUNE CHALLENGE IN RELATION TO BRAIN AND BEHAVIORAL LATERALIZATION

Host responses to immune challenges involve central neurotransmission, the hypothalamo-pituitary adrenal axis, and the immune system. In the present work, we investigated the possibility of an asymmetry in the modification of brain monoamine metabolism induced by a systemic injec tion of lipopolysaccharide (LPS) in adult female mice. We also studied the possible influence of behavioral lateralization, as assessed by a paw preference test, on the reactivity of the nervous, neuroendocrine , and immune systems to a LPS challenge. The results showed that LPS a dministration induced an enhanced brain activity as demonstrated by an increase in noradrenergic, serotoninergic, and dopaminergic metabolis m. Increased serotonin metabolism, observed in the hypothalamus and hi ppocampus, only occurred on the left side. Furthermore, the increase i n serotonin turnover in the medial hypothalamus, the elevation of plas ma adrenocorticotropin levels, and the decrease in T lymphocyte prolif eration were observed in right-handed and ambidextrous mice but not in left-handed animals. Taken together, the results demonstrate that an immune challenge could induce neurochemical, neuroendocrine, and immun e responses similar to those of stress, suggesting that LPS may be a s tress inducer. Interestingly, these responses that may be asymmetrical ly expressed appear to depend on behavioral lateralization. (C) 1994 A cademic Press, Inc.