Early changes in noradrenaline content of some brain nuclei in spontaneously hypertensive rats.

1. The noradrenaline content of individual brain nuclei was measured by using high-pressure liquid chromatography coupled with electrochemical detection. 2. This study was performed on spontaneously hypertensive rats during the development of hypertension (4 and 12 weeks) and also on deoxycorticosterone-salt hypertensive rats after 1 and 4 weeks of treatment. 3. In young spontaneously hypertensive rats a significant decrease in noradrenaline content was observed in some medullary and hypothalamic nuclei which are involved in cardiovascular regulation. No change was observed after deoxycorticosterone-salt treatment. 4. It is proposed that a change in adrenergic activity, restricted to brain cardiovascular centres, could represent a mechanism triggering spontaneous hypertension.