Cholinergic Stimulation Modulates Apoptosis and Differentiation of Murine Thymocytes via a Nicotinic Effect on Thymic Epithelium

Abstract Effects of cholinergic agonists/antagonists on apoptosis and differentiation of murine thymus cells were investigated in two in vitro models. Treatment with 10 −7 M carbachol was found to counteract the effects of a cortical thymus epithelial cell line (TEC 1.4), on apoptosis and the ratio of CD4 CD8 DP/DN cells in cocultured fetal tjymus lobes. A medullary line (TEC 2.3) did not influence apoptosis in fetal thymus lobes. Both TEC lines had the same strong apoptotic effect on thymus cells in suspension, but only the effect of TEC 1.4 was counteracted by carbachol. This cholinergic influence on TEC 1.4 cells is mediated via nicotinic cholinergic receptors, since d-tubocurarine, but not atropine, effectively blocked the effect of carbachol. The results suggest that cholinergic signals to thymic epithelial cells may have regulatory influence on thymic differentiation and selection processes.