Detection of tissue kallikrein and kinn B1 and B2 receptor mRNAs in human brain by in situ RT-PCR

Tissue kallikrein (TK) and kinin receptors have been immune-localized in va rious areas of the human nervous system, suggesting that the kallikrein-kin in system (KKS) may be functionally active in the brain. The aim of this st udy was to determine the cellular expression of TK and kinin B1 and B2 rece ptor mRNAs in specific regions of the human brain by in situ reverse transc riptase polymerase chain reaction. Autopsy samples of the brain, spinal cor d, kidney and salivary gland were embedded in paraffin. Sections (5 mum), a dhered onto silane coated glass slides, were treated with Proteinase K and DNase, followed by reverse transcription polymerase chain reaction with spe cific KKS primers and digoxigenin-dUTP, Detection of the digoxigenin-label demonstrated localization of TK, B1 and B2 mRNAs in the cytoplasm of some n euronal cell bodies in the hypothalamus. thalamus, frontal cortex and spina l cord. TK mRNA was also observed in the ependymal cells lining the cerebra l ventricles and epithelial cells of the choroid plexus. In the choroid ple xus, only B1 gene expression was observed in some choroidal epithelial cell s while no B2 labeling was detected. The identification of mRNAs to TK, B1 and B2 kinin receptors in human nervous tissue supports previous evidence f or the presence of the KKS in the brain and confirms localized protein synt hesis.