Possible involvement of central C-type natriuretic polypeptide receptor on water intake in spontaneously hypertensive rats, but not in normotensive Wistar-Kyoto rats.

The present study was designed to examine the possible role of brain C-type natriuretic polypeptide receptor (GC-B) in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto rats (WKY). The level of GC-B mRNA in various regions of the brain in both SHR and WKY was examined in the present study. The GC-B mRNA was unevenly distributed in rat brain, the transcript being expressed predominantly in the hypothalamus and cerebellum but comparatively at low level in the striatum and septum. However, the level in the septum was 3-fold higher in SHR than than in age-matched WKY, while no differences were observed in other regions of the brain. Intracerebroventricular administration of antisense oligonucleotide to GC-B mRNA inhibits the night-time water intake in SHR, but not in WKY. However, the daily food intake was not significantly altered by the injection of antisense oligonucleotide in both strains. These results demonstrate that the brain GC-B mRNA, particularly in septum, is increased in SHR and this increase may be closely related to the regulation of water-drinking behaviour in SHR.