Painful and non-painful effects of low doses of morphine in migraine sufferers partly depend on excitatory amino acids and gamma-aminobutyric acid.

Having a differential sensitivity to morphine can distinguish migraine suffers from healthy people who are headache-exempt. The aim of the present study was to investigate whether such an abnormal response to morphine challenge is entirely dependent on opioid receptor activation. A role for excitatory amino acids and gamma-aminobutyric acid has been proposed on the basis of the effect of diazepam.