Increase of plasma methionine-enkephalin levels in patients at the acute stage of cerebral infarction.

We investigated the participation of endogenous opioid peptide in cerebral ischaemia. In 13 patients with supratentorial infarction, the plasma immunoreactive methionine-enkephalin concentration at the acute stage (30.77 +/- 3.54 pg/ml) was significantly higher than that at the chronic stage (20.37 +/- 2.07 pg/ml) or that of the control subjects (19.64 +/- 1.71 pg/ml). However, it was unrelated to infarct size or patient severity. The increased methionine-enkephalin, which appears to originate from the sympatho-adrenal system or infarcted brain, may play a role in the evolution of cerebral ischaemia.