Tottering and leaner mutations perturb transient developmental expression of tyrosine hydroxylase in embryologically distinct Purkinje cells.

The mouse mutants tottering and leaner exhibit neurologic disorders associated, in part, with global noradrenergic hyperinnervation. Therefore, the expression of tyrosine hydroxylase (TH) mRNA and protein was examined in mutant and control mice. TH expression was normal in the major catecholaminergic nuclei. However, TH was expressed in vermal Purkinje cells of adult mutant but not control mice. TH expression in the Purkinje cells of both mutants was first observed on P21 and persisted throughout adulthood; in contrast, Purkinje cells of normal mice expressed TH transiently during development from P21 to P35. Thus, tottering and leaner mice are deficient in suppressing the normal transient expression of TH in developing Purkinje cells, suggesting that the protein encoded by the tg locus may play a crucial role in neuronal development.