DEVELOPMENTAL EXPRESSION OF VASOPRESSIN IN THE HUMAN HYPOTHALAMUS - DOUBLE-LABELING WITH INSITU HYBRIDIZATION AND IMMUNOCYTOCHEMISTRY

The developmental expression of arginine vasopressin (VP) and VP mRNA in human hypothalamus was studied using combined immunocytochemistry (ICC) for VP-neurophysin II and in situ hybridization (ISH) for VP mRNA. Routine formalin-fixed autopsy material was used from 22 cases ranging in age from 18 wk of gestation to 21 yr. VP-neurophysin II immunoreactive cells were detected in the supraoptic, accessory supraoptic, and paraventricular nuclei of all brains examined. The average size of the immunocytochemically labeled cells increased until birth and remained constant thereafter. VP mRNA was first detected in cells at 21 wk gestation; 3 wk after the first detectable VP by ICC. After 27 wk of gestation, consistent and strong signals were obtained from the specimens that were double-labeled for both immunoreactive VP-neurophysin II and VP mRNA. Three populations of double-labeled cells were identified: type 1, intensely positive for both ISH and ICC (most magnocellular neurons); type 2, positive for ISH and weak or negative for ICC (rare and generally found in younger fetuses), and type 3, positive for ICC and weak or negative for ISH (mostly scattered in accessory nuclei). Thus, double-labeling techniques can be routinely used on frozen or paraffin sections of human autopsy material for the simultaneous assessment of both message and peptide. In the human fetus, the relatively late appearance of adult-like levels of VP mRNA in the magnocellular neuroendocrine cells suggests an association with the development of functional synaptic interactions in this system.