SHORT REPORTSMedication overuse headache following repeated morphine, but not [INCREMENT]9-tetrahydrocannabinol administration in the female ratKandasamy, Rama; Dawson, Cole T.c; Hilgendorf, Tammy N.c; Morgan, Michael M.a,b,cAuthor Information aDepartment of Integrative Physiology and Neuroscience, Graduate Program in Neuroscience bTranslational Addiction Research Center, Washington State University, Pullman cDepartment of Psychology, Washington State University Vancouver, Vancouver, Washington, USA Correspondence to Ram Kandasamy, PhD, Department of Integrative Physiology and Neuroscience, Graduate Program in Neuroscience, Washington State University Vancouver, 14204 NE Salmon Creek Avenue, Vancouver, WA 98686, USA E-mail: email@example.com Received November 6, 2017 Accepted January 9, 2018 Behavioural Pharmacology: August 2018 - Volume 29 - Issue 5 - p 469-472 doi: 10.1097/FBP.0000000000000382 Buy Metrics Abstract The potential of [INCREMENT]9-tetrahydrocannabinol (THC) as a treatment for migraine depends on antinociceptive efficacy with repeated administration. Although morphine has good antinociceptive efficacy, repeated administration causes medication overuse headache (MOH) – a condition in which the intensity/frequency of migraine increases. The present study compared the effect of repeated morphine or THC administration on the magnitude and duration of migraine-like pain induced by a microinjection of allyl isothiocyanate (AITC) onto the dura mater of female rats. Acute administration of THC or morphine prevented AITC-induced depression of wheel running. This antinociception was maintained in rats treated repeatedly with THC, but not following repeated administration of morphine. Moreover, repeated morphine, but not THC administration, extended the duration of AITC-induced depression of wheel running. These data indicate that tolerance and MOH develop rapidly to morphine administration. The lack of tolerance and MOH to THC indicates that THC may be an especially effective long-term treatment against migraine. Copyright © 2018 YEAR Wolters Kluwer Health, Inc. All rights reserved.