Coexistence of oxytocin and tyrosine hydroxylase in the rat hypothalamus, an immunocytochemical study.

Immunocytochemical double labelling was used to determine the structural relationship of oxytocin (OT) and tyrosine hydroxylase (TH) containing perikarya and processes in the rat hypothalamus. Extrahypothalamic TH fibers, as well as parvocellular TH neurons were found to form contacts with OT cells. A fraction of the OT neurons contained TH immunoreactivity. It is likely that in addition to the classical mesencephalic afferences also hypothalamic interneurons and magnocellular dopaminergic neurons control the hypothalamo neurohypophysial system.