Effects of opioid peptides administered in conscious rats on the changes in blood adrenaline leves caused by immobilization stress.

Abstract

Abstract-Effectsof several opioid peptides administered in the lateral cerebro ventricle on the changes in blood adrenaline (AD) levels were examined at 10 , 20 and 30 min after the start of immobilization in conscious rats. 8-Endorphin, (D Ala2) -Met-enkephalinamide, morphiceptin and (D-Ala2, D-Leu5)-enkephalinamide produced significantly lower elevations of AD than the control, and the effect was enhanced by naloxone. The effect of dynorphin, however, was almost the same as that of the control.