[Implication of enkephalins in central cardiovascular regulation in the rat]

[D-ala2]-met-enkephalinamide injected intracisternally in anaesthetized rats induced a centrally-mediated increase in blood pressure. The pressor response appeared to be due to activation of opiate receptors and mediated through the sympathetic nervous system. The hypotension observed with high doses may be induced by the respiratory depression. The intracisternal injection of an antagonist of opioid compounds (diprenorphine) caused a similar blood pressure decrease in spontaneously hypertensive rats (SHR) and normotensive control Wistar Kyoto rats (WKY). Our data suggest a central pressor effect of enkephalins in anaesthetized rats. This represents an important argument concerning a role of endogenous opioids in blood pressure control but suggests that brain stem endogenous opioids may not be involved in the mechanism of hypertension.