ANGIOTENSIN-RELATED INDUCTION OF IMMEDIATE-EARLY GENES IN RAT-BRAIN

Several studies are reviewed in which behavioral aspects of angiotensi n (Ang) II on fluid intake have been compared with induction of the im mediate early gene product, Fos, as a marker of neuronal activation in rat bain. Either peripheral or central administration of Ang II induc ed Fos along the lamina terminalis (SFO, MnPO, AV3V) and in the magnoc ellular neurosecretory groups (SO, PVH). A similar pattern is seen wit h central injection of renin. Both pharmacological and antisense oligo nucleotide probe studies indicate that an AT(1) receptor is involved, probably with the initial transduction in the SFO. Treatments that ind uce sodium appetite all induce Fos along the lamina terminalis, but us ually not in the SO or PVN. Kininase II inhibitors, such as captopril, acutely potentiate drinking to Ang I, but after chronic exposure they may inhibit water intake. In contrast, the dipsogenic effect of brady kinin which is manifest in the presence of acute captopril remains una ffected by chronic administration. This suggests that the sodium appet ite that appears with chronic captopril treatment may depend in part o n peptides other than Ang.