Effect of cyclo(Leu-Gly) on the supersensitivity of dopamine receptors in spontaneously hypertensive rats.

Spontaneously hypertensive rats exhibited dopamine receptor supersensitivity as evidenced by a greater hypothermic response to apomorphine in comparison with normotensive Wistar-Kyoto rats. A single injection of cyclo(Leu-Gly) given prior to apomorphine administration did no alter apomorphine induced hypothermia in either the normotensive or the hypertensive rats. Chronic administration of cyclo(Leu-Gly) for 7 days did not affect apomorphine response in normotensive rats, but blocked the exaggerated response to apomorphine in the hypertensive rats. These studies suggest that cyclo(Leu-Gly) interacts with the dopamine receptors and that the central dopamine receptors may play a role in the pathophysiology of hypertension.