Existence of L-dopa immunoreactive neurons in the rat preoptic area and anterior hypothalamus.

We demonstrate the presence of L-DOPA (L-3,4-dihydroxyphenylalanine)-labelled cell bodies and fibers in the rat preoptic and anterior hypothalamic areas, using a rabbit polyclonal antiserum against conjugated L-DOPA and a glutaraldehyde coupled immunohistochemical technique. In contrast, using a monoclonal anti conjugated dopamine (DA) antibody, no DA labelled neurons were detectable in the preoptic region, whereas a few weakly immunostained DA neurons began to appear in the ventral part of the medial preoptic area. These observations point to the hypothesis that these cells contain mainly L-DOPA neurons in the preoptic and anterior hypothalamic areas. Thus, we suggest that L-DOPA plays a more important role in the hypothalamic functions than has been hitherto assumed.