- Maike Hamke: Department of Psychiatry and Psychotherapy, University of Freiburg Medical School, Germany.
The neuropeptide substance P (SP) has been found to be possibly involved in the etiology of affective and anxiety disorders. However, the molecular mechanisms underlying this involvement are still poorly understood. In this study, we used macroarrays to investigate the differential gene expression profile induced by SP, particularly of genes which have been shown to be involved in the pathophysiology of affective disorders. As a model system, we used the human astrocytoma cell line U373 MG as well as primary rat astroglial cells, which both are known to express functional neurokinin-1 receptors (NK-1-R) and to secret various cytokines upon stimulation with SP. Among several regulated genes, we found that SP (100 and 1000 nM) induced the expression of the corticotropin-releasing factor receptor 1 (CRF1 receptor). Further analyses revealed that this induction was mediated (a) via NK-1-R, as the selective NK-1-R-antagonist L-733,060 (1 microM) strongly inhibited SP-induced CRF1 receptor expression, and (b) intracellularly, by protein kinase C, p42/44 and p38 mitogen-activated protein kinases (MAPK), as shown by using specific inhibitors of signal transduction pathways. In conclusion, this study demonstrates that SP induces CRF1 receptor expression in cells of the CNS, which may be of potential interest for a better understanding of the interplay between SP and the stress hormone axis and, thus, diseases like affective or anxiety disorders. Further studies are needed to substantiate this link in vivo.