Differential glial and vascular expression of endothelins and their receptors in rat brain after neurotrauma

We characterized the time-course, intensity of expression and cellular orig in of components of the endothelin (ET) system in the rat brain after a sta ndardized neurotrauma (cryogenic lesion of the parietal cortex). ET mRNAs w ere expressed at sham level after neurotrauma, whereas immunoreactivity for ET-1 was enhanced in glia and endothelium of the lesioned hemisphere and b oth hippocampi. The number of ET-3 positive mononuclear cells in the lesion perimeter increased starting at 24h after injury. At 48h after neurotrauma , ET-receptor immunoreactivity was increased in astrocytes. In basilar arte ry endothelium, ETB-immunoreactivity was reduced at 48h to 72h recovering a t 7 days whereas ETA-receptor and ET-peptide immunoreactivities were not al tered. In summary, neurotrauma leads to a multicellular stimulation of endo thelins in the brain along with a delayed selective loss of vascular ETB-re ceptors. These changes seem to be posttranscriptional and cell type specifi c. They favor vasoconstriction increasing the risk of late vasospasm and is chemia.