title: Co-localization of tyrosine hydroxylase and phenylethanolamine-N-methyltransferase immunoreactivity in the rat retina: a re-examination using double labeling on semi-thin sections.
abstract: The precise morphology and distribution of phenylethanolamine-N-methyltransferase (PNMT)-immunoreactive cells has been observed and compared with the previously described tyrosine hydroxylase (TH)-immunoreactive cells, in the rat retina. The PNMT-positive cells are small amacrine neurons, located either in the inner nuclear layer or in the ganglion-cell layer. They send processes mainly to the middle sublayer and to a lesser extent to the outermost sublayer of the inner plexiform layer. They resemble the small TH-positive bouquet cells described previously. In order to ascertain the relationship between PNMT-positive cells and TH-positive bouquet cells, a double immunohistochemical labeling technique, using anti-TH and anti-PNMT antisera, has been developed on semi-thin sections. The result of these experiments clearly indicate that the populations of TH-positive cells and PNMT-positive (presumably epinephrinergic) cells are separated. The absence of TH enzyme in the PNMT-positive cells raises the question of the enzymatic activity of PNMT, which appears to be different from the classical pathway of catecholamine biosynthesis in the retina.
mesh_terms: D000818:Animals; D005260:Female; D007124:Immunoenzyme Techniques; D008297:Male; D010625:Phenylethanolamine N-Methyltransferase / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000166:cytology / Q000201:enzymology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D014446:Tyrosine 3-Monooxygenase; D010625:Phenylethanolamine N-Methyltransferase