Endorphins can further decompose to small fragments, oligomers, which are still active.
Oligomers pass the blood-brain barrier more readily. Enzymatic degradation of small-chain endorphins is accomplished by dipeptidyl carboxypeptidase, enkephalinases, angiotensinases, and other enzymes. This limits their lifetime in the unbound state. Opiate receptors presynaptically inhibit transmission of excitatory pathways. Endorphins are also involved in glucose regulation.