Painful and non-painful effects of low doses of morphine in migraine sufferers partly depend on excitatory amino acids and gamma-aminobutyric acid
Nicolodi, M.
International Journal of Clinical Pharmacology Research 18(2): 79-85
1998
ISSN/ISBN: 0251-1649 PMID: 9675625 Document Number: 496237
Having a differential sensitivity to morphine can distinguish migraine sufferers 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. As opposed to naloxone, this gamma-aminobutyric acid agonist was found to inhibit the adverse effects of low doses of morphine in migraine sufferers, while at the same time being able to almost abolish morphine-induced miosis in subjects who underwent a short-lasting chronic pretreatment. The capacity of diazepam either to control the adverse effects of morphine or to induce well-being in subjects known to suffer from a central neurogenic pain such as migraine, is noteworthy even regarding the clinical treatment of other painful conditions, such as deafferentation pain, which is known to be not satisfactorily treated by using morphine.