TimE JOTJRNAL OF HISTOCREMISTRY AND CYTOCREMISTRY

The activities of nucleoside diphosphatases and thiamine pyrophosphatase (TPPase) that are associated with the Golgi apparatus and acid phosphatase were measured by quantita.. tive histochemical methods both in histologically pure nucleus supraopticus and in an adjacent area of the anterior hypothalamus of the rat. In the nucleus supraopticus UDP.. phosphohydrolase (UDPase), GDP-phosphohydrolase (GDPase) and TPPase activities increased 40% after a thirsting period of 3 days, while IDP-phosphohydrolase activity increased 18% and acid phosphatase activity decreased 25% after the same osmostic stress. The adjacent, nonsupraoptic anterior hypothalamic area did not show significant changes in activity of any of the enzymes studied. The activities of the Golgi-associated TPPase, UDPase and GDPase are likely to be reliable parameters for neurosecretory activity.