LOWER GABA(A) RECEPTOR-BINDING IN THE AMYGDALA AND HYPOTHALAMUS OF SPONTANEOUSLY HYPERTENSIVE RATS

The central GABAergic system is associated with normal blood pressure regulation, but the role of GABA receptors in genetic hypertension remains unclear. This study was conducted to investigate GABA(A) receptor binding in several brain regions of spontaneously hypertensive (SHR) rats during development of hypertension. GABA(A) receptor binding was labeled with [S-35]TBPS and was assessed by quantitative autoradiography with the aid of a computer-assisted image analysis system. Densities of GABA(A) receptor binding sites were significantly lower in all hypothalamic and amygdaloid nuclei evaluated in 4-week-old SHR rats, when compared with their age-matched normotensive Wistar-Kyoto rats. At 12 weeks of age, GABA(A) receptor binding remained significantly lower in the central amygdaloid nucleus and paraventricular hypothalamic nucleus of SHR rats. Collectively, the results suggest that GABA(A) initiation and maintenance of hypertension. In conclusion, this study supports a notion that downregulation of GABA(A) receptor binding occurs in the hypothalamus and amygdala of SHR rats and may play a role in genetic hypertension.