Anne-Sophie Wattiez1,2, Olivia J Gaul3, Adisa Kuburas3, Erik Zorilla4, Jayme S Waite3, Bianca N Mason3,5, William C Castonguay3, Mengya Wang6, Bennett R Robertson3, Andrew F Russo3,7,8. 1. Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd, Iowa City, IA, 52242, USA. anne-sophie-wattiez@uiowa.edu. 2. Center for the Prevention and Treatment of Visual Loss, Veterans Administration Health Center, Iowa City, IA, 52246, USA. anne-sophie-wattiez@uiowa.edu. 3. Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd, Iowa City, IA, 52242, USA. 4. Neuroscience Program, University of Iowa, Iowa City, IA, 52242, USA. 5. Present address: Brain and Behavior Sciences, Center for Advanced Pain Studies, University of Texas at Dallas, 800 West Campbell Rd, Richardson, TX, 75080, USA. 6. Department of Pharmacology, University of Iowa, Iowa City, IA, 52242, USA. 7. Center for the Prevention and Treatment of Visual Loss, Veterans Administration Health Center, Iowa City, IA, 52246, USA. 8. Department of Neurology, University of Iowa, Iowa City, IA, 52242, USA.
Abstract
BACKGROUND: Circadian patterns of migraine attacks have been reported by patients but remain understudied. In animal models, circadian phases are generally not taken into consideration. In particular, rodents are nocturnal animals, yet they are most often tested during their inactive phase during the day. This study aims to test the validity of CGRP-induced behavioral changes in mice by comparing responses during the active and inactive phases. METHODS: Male and female mice of the outbred CD1 strain were administered vehicle (PBS) or CGRP (0.1 mg/kg, i.p.) to induce migraine-like symptoms. Animals were tested for activity (homecage movement and voluntary wheel running), light aversive behavior, and spontaneous pain at different times of the day and night. RESULTS: Peripheral administration of CGRP decreased the activity of mice during the first hour after administration, induced light aversive behavior, and spontaneous pain during that same period of time. Both phenotypes were observed no matter what time of the day or night they were assessed. CONCLUSIONS: A decrease in wheel activity is an additional clinically relevant phenotype observed in this model, which is reminiscent of the reduction in normal physical activity observed in migraine patients. The ability of peripheral CGRP to induce migraine-like symptoms in mice is independent of the phase of the circadian cycle. Therefore, preclinical assessment of migraine-like phenotypes can likely be done during the more convenient inactive phase of mice.
BACKGROUND: Circadian patterns of migraine attacks have been reported by patients but remain understudied. In animal models, circadian phases are generally not taken into consideration. In particular, rodents are nocturnal animals, yet they are most often tested during their inactive phase during the day. This study aims to test the validity of CGRP-induced behavioral changes in mice by comparing responses during the active and inactive phases. METHODS: Male and female mice of the outbred CD1 strain were administered vehicle (PBS) or CGRP (0.1 mg/kg, i.p.) to induce migraine-like symptoms. Animals were tested for activity (homecage movement and voluntary wheel running), light aversive behavior, and spontaneous pain at different times of the day and night. RESULTS: Peripheral administration of CGRP decreased the activity of mice during the first hour after administration, induced light aversive behavior, and spontaneous pain during that same period of time. Both phenotypes were observed no matter what time of the day or night they were assessed. CONCLUSIONS: A decrease in wheel activity is an additional clinically relevant phenotype observed in this model, which is reminiscent of the reduction in normal physical activity observed in migrainepatients. The ability of peripheral CGRP to induce migraine-like symptoms in mice is independent of the phase of the circadian cycle. Therefore, preclinical assessment of migraine-like phenotypes can likely be done during the more convenient inactive phase of mice.