Down-regulation of the GABA-ergic system in selected brain areas of spontaneously hypertensive rats (SHR).

The relevance of GABA-ergic system in hypertensive state has been studied. GABA content, GAD activity and GABA-A receptor binding in various brain areas in age-matched spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto rats (WKY) was compared. Out of 9 brain areas studied the GABA content was significantly lower in the substantia nigra, hypothalamus, hypothalamus posterior and hippocampus of SHR rats. GAD activity was lowered in the hypothalamus and hippocampus of young SHR and adult SHR rats (4, 8, 14 weeks old). Scatchard analysis of the binding isotherms indicated a lower Bmax of the binding sites in the hypothalamus and hippocampus of 8 and 14 weeks old SHR rats. These results suggest that activity of GABA-ergic system differs substantially in SHR and WKY rats brain. Furthermore, these differences appear already in young prehypertensive SHR rats as well as in the early stages of hypertension.