Brain, behavior, and immunity
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Brain Behav. Immun. · Jul 2005
Comparative StudySocial stress and the regulation of tumor necrosis factor-alpha secretion.
Social disruption (SDR), a murine model of social stress, altered the phenotype and function of spleen immune cells. Previous reports indicated that following SDR spleens contained higher numbers of CD11b+ monocytes, and these cells were less sensitive to the inhibitory effects of glucocorticoids on cell viability. Additionally, lipopolysaccharide (LPS)-stimulated splenocytes from SDR mice secreted higher levels of the proinflammatory cytokines tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 compared to splenocytes from controls. ⋯ We report that SDR increased TNFalpha secretion from an enriched fraction of CD11b+ monocytes stimulated with LPS. Additionally, SDR altered the kinetics of TNFalpha release from LPS-stimulated splenocytes and induced minor changes in the suppressive effects of corticosterone and norepinephrine on LPS-induced TNFalpha secretion. These results are in agreement with the notion that complex interactions mediate the response to social stress.
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Brain Behav. Immun. · Jul 2005
Clinical Trial Controlled Clinical TrialCortical correlates of false expectations during pain intensity judgments--a possible manifestation of placebo/nocebo cognitions.
We investigated the effects of expectation on intensity ratings and somatosensory evoked magnetic fields and electrical potentials following painful infrared laser stimuli in six healthy subjects. The stimulus series contained trials preceded by different auditory cues which either contained valid, invalid or no information about the upcoming laser intensity. High and low intensities occurred equally probable across cue types. ⋯ Its amplitude also varied with stimulus intensity, but failed to show any cue validity effects. This result suggests a priming of early cortical nociceptive sensitivity by cues signaling pain severity. A possible contribution of the SII cortex to the manifestation of nocebo/placebo cognitions is discussed.