Lateralized neocortical control of T lymphocyte export from the thymus - I. Increased export after left cortical stimulation in behaviorally active rats, mediated by sympathetic pathways in the upper spinal cord

Electrical stimulation of left temporo-parieto-occipital (TPO) cortex in adult male Wistar rats during their behaviorally active phase (nighttime) transiently increased circulating levels of CD4+ and CD8+ T lymphocytes. Comparable stimulation of this cortex on the right decreased circulating levels of these cells. Responses to left or right cortical stimulation were diminished or absent in behaviorally inactive rats (daytime). Since blood glucocorticoid levels were similar before and after left or right stimulation, they did not appear to account for the lateralized changes observed. These lateralized effects were mediated by spinal cord autonomic pathways emerging at T1-T7 levels. In adult thymectomized rats, CD4+ and CD8+ T cells failed to increase after left sided stimulation. The results suggest that lateralized cerebral cortical functions can acutely and differentially influence blood T cell subset numbers. The results demonstrate a direct neocortical influence on thymic export of mature T cells, mediated by the sympathetic nervous system. (C) 2004 Elsevier B.V. All rights reserved.