Cellular localization of atrial natriuretic peptide and tissue kallikrein in the human hypothalamus.

In the kidney, renal atrial natriuretic peptide (ANP) is considered to play an important role in water and salt homeostasis. Immunoreactive ANP in the brain of lower invertebrates, such as the rat, has been shown to be localized in the hypothalamus and septum. Several studies have investigated the possibility of a regulatory system in the brain similar to that of the kidney. Since neuronal function is acutely sensitive to disturbances of the intracranial water and salt balance we have attempted to immunolocalize ANP-containing cells in the normal human hypothalamus, using a polyclonal antiserum specific to ANP. Also, we have observed tissue kallikrein (TK), using a polyclonal antiserum specific to TK, in the same areas as ANP. A regulatory role for TK on prolactin has been suggested as the rationale for the co-localization of these two hormones in human prolactinomas. Therefore, it could be suggested that TK plays a similar role in the processing of precursor ANP in the brain. It is contemplated to examine the status of these peptides in patients with cerebral oedema.