Central and peripheral cardiovascular effects of beta-endorphin in normotensive and spontaneously hypertensive rats and in rats rendered hypertensive by deoxycorticosterone acetate administration.

: The cardiovascular effects of beta-endorphin [beta-LPH-(61-91)] were investigated after systemic (i.v.) and central (third ventricle and right lateral ventricle) administration in urethane-anesthetized rats. beta-Endorphin (10 and 100 micrograms/kg i.v. or 40 micrograms into the third ventricle or into the lateral ventricle) in normotensive animals induced a decrease in blood pressure and bradycardia. The same dose of beta-endorphin by systemic and central administration induced much more pronounced cardiovascular effects in spontaneously hypertensive rats and in rats rendered hypertensive by DOCA administration than in normotensive rats. Naloxone i.v. pretreatment reduced the cardiovascular effects induced by beta-endorphin.