ABSTRACT
Tyrosine Hydroxylase Immunostaining Because DA agents are used successfully in the treatment of many RLS cases (see Chapter 25), tyrosine hydroxylase immunostaining was used to evaluate the presence and morphological integrity of the DA neurons in the substantia nigra. None of the RLS cases had any histologic abnormality in this major DA region. No differences between the control and RLS brains were observed in the staining intensity or the appearance of these neurons and associated processes in any of the midbrain structures after staining with antiserum to tyrosine hydroxylase. In addition to the substantia nigra, we attempted to identify the DA cluster of neurons identified as A11 in the human diencephalon because this nucleus gives rise to the descending DA pathway and has been suggested as being involved in RLS (6) in animal studies. Although a cluster of DA neurons representing A11 could not be specifically identified in the human diencephalon, there were clearly tyrosine hydroxylase neurons present in this region in both controls and RLS, but they were too widely dispersed to generate data.
