This award from the U.S.-Argentina Cooperative Science Program supports collaborative research in neuroendocrinology to be conducted by Professor Bruce S. McEwen of the Laboratory of Neuroendocrinology at the Rockefeller University and Dr. Alejandro F. De Nicola of the Faculty of Medicine at the University of Buenos Aires, Argentina. The focus of the project is to study the mechanism of action of aldosterone in the brain. The research will investigate the distribution within the brain and regulation by glucocorticoids and mineralocorticoids of mRNA's for the three subtypes of the alpha subunit of Na, K ATPase. In situ hybridization histochemistry will be used to localize and map mRNA's in various brain regions and to study their regional regulation by glutocorticoids and mineralocorticoids in male and female rat brains where there may also be sex differences and estrogen affects. The award will foster continuation of a fruitful U.S.-Argentina collaboration.