The L-kynurenine signalling pathway in trigeminal pain processing: a potential therapeutic target in migraine?

INTRODUCTION: In recent years the kynurenine family of compounds, metabolites of tryptophan, has become an area of intensive research because of its neuroactive properties. Two metabolites of this family have become of interest in relation to migraine and pain processing. DISCUSSION: Experimental studies have shown that kynurenic acid (KYNA) plays an important role in the transmission of sensory impulses in the trigeminovascular system and that increased levels of KYNA decrease the sensitivity of the cerebral cortex to cortical spreading depression. Furthermore, another metabolite of the kynurenine family, L-kynurenine, exerts vasodilating effects similar to nitric oxide by increasing cyclic guanosine monophosphate.
CONCLUSION: This review summarizes current knowledge of the role of kynurenine signalling in trigeminal and central pain processing, including its therapeutic prospects in migraine treatment.