INVIVO DISPOSITION AND METABOLISM OF ENKEPHALINS - RELATIONSHIP TO ANALGESIC PROPERTIES

  • 1 January 1978
    • journal article
    • research article
    • Vol. 20  (2) , 265-274
Abstract
After i.v. injection, both Met5-enkephalin and D-Ala2-Met5-enkephalinamide rapidly entered the brains of mice. Both peptides obtained similar concentrations. The t1/2 for D-Ala2-Met5-enkephalinamide in the brain (0.7 min) corresponds roughly to its analgestic t1/2 (1.7 min); thus, rapid metabolism appears to account for the short duration of analgesia seen with this compound. Met5-enkephalin, although attaining similar brain concentrations, failed to elicit analgesia. Rapid metabolism alone does not account for this lack of analgesic effect.