SUMMARY Atrial natriuretic peptldes (atrial natriuretic factor, ANF) are present in a great number of brain areas inside and outside of the blood-brain barrier. The pattern of distribution implies the involvement of ANF in different physiological functions, such as blood pressure regulation, electrolyte and fluid bomeostasis, and modulation of the neuroendocrine system. To further investigate a possible involvement of central ANF in spontaneous hypertension, we measured levels of ANF in 18 selected, microdissected brain areas of prehypertensive (4-week-old) and hypertensive (12-week-oM) spontaneously hypertensive rats (SHR) and their normotensive control, Wistar-Kyoto rats (WKY), by radioimmunoassay. ANF was significantly decreased hi seven brain areas in SHR at both ages investigated; the most pronounced decreases were found in the subfornical organ, hi the perifornkal and periventricular hypothalamic nuclei, and hi the medial preoptic nucleus. In addition, in young SHR ANF was significantly decreased in the organum vascutosum laminae terminalls and increased hi the median eminence. After the development of hypertension, a significant decrease of ANF could be detected hi four more brain areas (bed nucleus of the stria terminalis, paraventrkular and arcuate nuclei, dorsal raphe nucleus) of SHR, as compared with normotensive controls, and the increase hi the median eminence was no longer detectable. These results suggest a role for ANF hi genetk hypertension and the specific importance of certain brain regions. (Hypertension 12: 519-524, 1988)
KEY WORDS • atrial natriuretic factor • brain • hypertension • spontaneously hypertensive ratsA TRIAL natriuretic peptides (atrial natriuretic / A factor, ANF) were first described in the JL A. mammalian cardiac atrium, where they are released into the general circulation to take part in the regulation of fluid homeostasis and blood pressure by acting on the kidneys, the adrenals, and the blood vessels.1 In addition to the peripheral actions of ANF, certain effects of circulating ANF may be centrally mediated, since binding sites for ANF have been localized in specific brain areas that lack a blood-brain barrier.2 -4 Furthermore, several lines of evidence indicate the existence of brain-born ANF. Immunohistochemical studies have demonstrated ANF-like material in neuronal perikarya, fibers, and terminals throughout the central nervous system,