Cortical hyperexcitability and mechanism of medication-overuse headache.
The present study was conducted to determine the effect of acute (1 h) and chronic (daily dose for 30 days) paracetamol administration on the development of cortical spreading depression (CSD), CSD-evoked cortical hyperaemia and CSD-induced Fos expression in cerebral cortex and trigeminal nucleus caudalis (TNC). Paracetamol (200 mg/kg body weight, intraperitonealy) was administered to Wistar rats. CSD was elicited by topical application of solid KCl. Electrocorticogram and cortical blood flow were recorded. Results revealed that acute paracetamol administration substantially decreased the number of Fos-immunoreactive cells in the parietal cortex and TNC without causing change in CSD frequency. On the other hand, chronic paracetamol administration led to an increase in CSD frequency as well as CSD-evoked Fos expression in parietal cortex and TNC, indicating an increase in cortical excitability and facilitation of trigeminal nociception. Alteration of cortical excitability which leads to an increased susceptibility of CSD development can be a possible mechanism underlying medication-overuse headache.
Supornsilpchai
Weera
W
Department of Physiology, Faculty of Medicine, Chulalongkorn University, Patumwan, Bangkok, Thailand.
le Grand
Supang Maneesri
SM
Srikiatkhachorn
Anan
A
D000082:Acetaminophen / Q000633:toxicity; D000208:Acute Disease; D018712:Analgesics, Non-Narcotic / Q000633:toxicity; D000818:Animals; D002908:Chronic Disease; D013181:Cortical Spreading Depression / Q000187:drug effects* / Q000502:physiology*; D051271:Headache Disorders, Secondary / Q000209:etiology* / Q000503:physiopathology*; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D010296:Parietal Lobe / Q000098:blood supply / Q000187:drug effects* / Q000503:physiopathology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014278:Trigeminal Nuclei / Q000098:blood supply / Q000187:drug effects / Q000503:physiopathology
D018712:Analgesics, Non-Narcotic; D016760:Proto-Oncogene Proteins c-fos; D000082:Acetaminophen