[Abstract Title]. - Society for Neuroscience

corticosterone, brain monoamine utilization, and brain cytokine mRNA expression are
exaggerated. As behavioral variations following an immune challenge are often dependent on
environmental context, it was of interest to investigate whether synergistic or additive effects
would also be present when the immune challenge preceded the social stressor. In fact, there was
reason to believe that sickness behavior represents a luxury that animals cannot afford in the face
of ongoing threat, and hence would be less pronounced under these conditions. Mice received
acute LPS (10 κg) treatment immediately before or following a 1-hour social disruption stressor
(e.g., regrouping mice after a prolonged period of isolation) and the effects on sickness behavior,
and on neuroendocrine, cytokine and monoamine variations were assessed. As predicted, when
LPS was administered following the social stressor, sickness behavior, corticosterone as well as
monoamine utilization within the hippocampus and prefrontal cortex were markedly increased.
However, when the stressor was applied after LPS administration, the sickness behavior
ordinarily elicited by LPS was abolished. In addition, plasma corticosterone levels were
dramatically increased by the social stressor, to the degree that a ceiling effect largely precluded
detection of further elevations by LPS treatment. Identical findings were also obtained with
norepinephrine utilization within the prefrontal cortex. Together, these findings suggest that
synergistic effects between psychosocial stressors and LPS treatment are only apparent when the
immune challenge is administered following the social stressor. Although the interaction
between LPS and psychosocial stressors produce dramatic behavioral and neurochemical effects,
these appear to be mediated by the context in which the challenge is administered, and is
influenced by the timing and order of the treatments.
Disclosures: J.E. Gibb , None; M. Audet, None; B.P. Wann, None; H. Anisman, None.
Poster
280. Stress and the Brain: Stress and Neuroimmunology I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 280.3/NN3
Topic: E.06.c. Stress and neuroimmunology
Support: NSF IOS-05-54514 (to RS)
NICHD 05751-33 (to DP)
NIMH 67782 (to RS)
Title: Mast cells in the brain influence anxiety-like behaviors