LOCALIZATION OF TYPE-I INTERLEUKIN-1 RECEPTOR MESSENGER-RNA IN THE RAT-BRAIN

The distribution of type I interleukin-1 receptor (IL-1R1) mRNA in the rat brain was examined by in situ hybridization technique. IL-1R1 mRN A was expressed in several brain regions including the anterior olfact ory nucleus, medial thalamic nucleus. posterior thalamic nucleus, baso lateral amygdaloid nucleus, ventromedial hypothalamic nucleus, arcuate nucleus, median eminence, mesencephalic trigeminal nucleus, motor tri geminal nucleus, facial nucleus and Purkinje cells of the cerebellum. Furthermore, we identified neuronal expression of IL-1R1 mRNA using si multaneous detection (double in situ hybridization) of IL-1R1 mRNA wit h neuron specific enolase mRNA. In addition to the expression in neuro nal cells, IL-1R1 mRNA was also expressed on the vascular walls and th e epithelial cells of the choroid plexus and the ventricles. These fin dings suggest the possibility that IL-1 produces its multiple effects on the central nervous system through the actions not only on neuronal cells but also on endothelial and epithelial cells.