Tyrosine-hydroxylase immunoreactive fibres in the rat anterior pituitary.

Tyrosine-hydroxylase (TH)-like immunoreactivity was investigated in normal and oestrogenized rat anterior pituitaries in the light of recent studies showing a TH enzymatic activity in the gland and the presence of TH mRNA in endocrine cells. Sparse TH positive fibres, probably dopaminergic as assessed by the absence of dopamine-beta-hydroxylase (DBH) immunoreactivity, were detected in the anterior pituitary, but the detection of TH immunoreactivity in cells was unsuccessful.