[Excessive prolactinemic response to sulpiride in patients with mild essential hypertension. Index of diminished hypothalamic dopaminergic activity].

Plasma prolactin concentrations and prolactinaemic response to sulpiride, a prolactin releaser with pituitary dopamine receptor blocking activity, were examined in 16 subjects with mild essential hypertension and in 20 patients with long-sustained essential hypertension. When compared with 16 normotensive controls only the former showed raised plasma renin activity (P < 0.001) and higher plasma prolactin levels either after two-hour ambulation (P < 0.05) or at supine rest (P < 0.05). The average of maximal sulpiride-induced prolactin values was 157 +/- 53 ng/ml (mean +/- SD) in the mild hypertensive, significantly different from 60.2 +/- 21.4 ng/ml (mean +/- SD) as resulted in the controls (P < 0.001). In contrast, patients with sustained hypertension had a mean level of 60.2 +/- 21.4 ng/ml (mean +/- SD), indifferent from the one of the normal volunteers. It is suggested that the excessive prolactinaemic response to sulpiride detected in patients with mild hypertension reflects a reduced hypothalamic dopaminergic activity and that such an alteration may assume some pathogenetic relevance in the natural history of essential hypertension. Further, in the mild hypertensive a positive prolactin-renin correlation was found (r = + 0.76; P < 0.01), so suggesting that in these patients a peripheral sympathetic overactivity is associated to an impaired central dopamine control. The individuation of such cases may be important since they could benefit by dopamine agonists as L-dopa and bromocriptine.