Abnormal expression of tyrosine hydroxylase immunoreactivity in cerebellarcortex of ataxic mutant mice

Expression of tyrosine hydroxylase (TH) was examined immunohistochemically in the cerebellum of two ataxic mutants, Rolling mouse Nagoya (RMN) and dil ute-lethal mice (DL). In littermate controls of both mutants, a few TH-posi tive Purkinje cells were distributed sparsely and their number was smaller than in the mutants at any ages examined. In RMN, TH-positive Purkinje cell s were distributed in lobule IX and X, and were arranged into parasagittal bands at 2 weeks of age. TH-positive Purkinje cells increased in number and were widely distributed throughout the vermis at 3 weeks of age. In adult RMN, TH-positive Purkinje cells were found in all lobules of the cerebellum . Their parasagittal bands also became evident in the hemisphere. In DL, TH -positive Purkinje cells were mainly distributed in vermal lobules IX and X , and the flocculus at 3 weeks of age. They were also found as bands in lob ules IX and X. The results suggest that abnormal expression of TH in Purkin je cells may not be specific to the allelic group. Since TH promoter is act ivated by Ca2+, TH expression in the mutant Purkinje cells may predict neur onal dysfunction caused by alterations in cellular Ca2+ currents. (C) 1999 Elsevier Science B.V. All rights reserved.