We have used reverse transcription/polymerase chain reaction (RT-PCR) and Western blotting with an anti-peptide antibody to study the expression of the alpha-component of the receptor for ciliary neurotrophic factor (CNTFR alpha) in rat nervous tissue. At the early postnatal stage CNTFR alpha protein could be detected in all parts of the nervous system studied (and also in muscle and liver). It was particularly abundant in pons, cerebellum, spinal cord, retina and sciatic nerve. In adult tissues the content was dramatically reduced except for olfactory bulb and cortex, where CNTFR alpha protein was upregulated during development. Only in part of the tissues, expression of CNTFR alpha mRNA and its developmental regulation paralleled that of the protein. These differences are partly explainable by the different cellular localization of mRNA and the membrane associated receptor protein, but, in addition, they suggest the existence of different regulatory mechanisms for CNTFR alpha. Our results support the idea that CNTF plays an important role during the development of the nervous system and that CNTF actions may be found in many brain regions and target cells.