In patients, spontaneous (non-evoked) pain responses provide a more accurate representation of the pain experience than do responses that are evoked by an artificial stimulus. Therefore, the development of animal models that measure spontaneous nociceptive behaviors may provide a significant translational tool for a better understanding
of pain neurobiology. Methods.— C57BL/6 mice received either an injection of 0.9% saline solution or complete Freund’s adjuvant into the right masseter muscle. Animals were video-recorded and then analyzed by an observer Fludarabine blind to the experiment group. The duration of different facial grooming patterns performed in the area of injection were measured. After 2 hours, mice were euthanized and perfused, and the brainstem was removed. Fos protein expression in the trigeminal nucleus caudalis was quantified using immunohistochemistry to investigate nociceptive-specific neuronal activation. A separate group of animals was treated with morphine sulfate to determine the nociceptive-specific nature of their behaviors. Results.— We characterized and quantified 3 distinct patterns of acute grooming behaviors: forepaw
LBH589 order rubbing, lower lip skin/cheek rubbing against enclosure floor, and hindpaw scratching. These behaviors occurred with a reproducible frequency and time course, and were inhibited by the analgesic morphine. Complete Freund’s adjuvant-injected animals also showed Fos labeling consistent with neuronal activation in nociceptive-specific pathways of the trigeminal nucleus after 2 hours. Conclusions.— These behaviors and their correlated cellular responses represent a model of trigeminal pain that can be used to better understand basic mechanisms of orofacial pain and identify new therapeutic approaches to this
common and challenging condition. “
“(Headache 2010;50:1587-1596) Objective.— The aim of the present study was to evaluate a possible MCE involvement of 2 polymorphisms of the serotonin 5HT2A receptor gene (A-1438G and C516T) as risk factors for medication overuse headache (MOH) and whether the presence of these polymorphic variants might determine differences within MOH patients in monthly drug consumption. Background.— Despite a growing scientific interest in the mechanisms underlying the pathophysiology of MOH, few studies have focused on the role of genetics in the development of the disease, as well as on the genetic determinants of the inter-individual variability in the number of drug doses taken per month. Methods.— Our study was performed by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism on genomic DNA extracted from peripheral blood of 227 MOH patients and 312 control subjects.