[Immunohistochemistry on tyrosine hydroxylase in the substantia nigra of human autopsied cases].

Despite the numerous data on the distribution of catecholamine (CA) neurons in a wide variety of species, data on that of human are rare because of technical difficulty in applying fluorescent histochemical methods. On the other hand, immunohistochemistry on tyrosine hydroxylase (TH) which was essential for synthesis of CA, was assumed to be applicable to human autopsied brain. We performed indirect immunoperoxidase study on TH using 10% formalin or buffered formalin fixed, paraffin embedded sections of the substantia nigra from 40 autopsied cases, ranging in age 7 to 70 years. TH was purified from the bovine adrenal medulla using the procedure described by Oka et al. with some modification. Purified TH was injected with Freund's complete adjuvant into rabbits. The specificity of the antiserum was demonstrated by the inhibition study of CA relating enzymes, double immunodiffusion and immunoelectrophoresis against tissue homogenate of bovine adrenal medulla. TH immunoreactive (TH-IR) products were restricted to the neuronal soma, axons and dendrities in almost all of the case except for the "dead brain" cases. TH-IR neurons were of large polygonal or multipolar cells, and closely correspond to melanin-pigmented neurons, located in the compact zone and scattered in the reticular zone in the substantia nigra. On the other hand, melanin free neurons in the reticular and compact zone, were of medium or small bipolar cells and were not stained. It was of interest that the non TH-IR melanin-pigmented neurons firstly appeared in the substantia nigra at third decade and increased their number with age.(ABSTRACT TRUNCATED AT 250 WORDS)