Distal infraorbital nerve injury: a model for persistent facial pain in mice

This study characterizes the impact of a distal infraorbital nerve injury, called DIONI, which consists of ligature and transection of distal fibers of the infraorbital nerve. We assessed nociception using a conflict paradigm and optogenetics, and a set of reward, aversion, spatial, temporal, and competition tasks in the IntelliCage to study multiple aspects of cognition, circadian rhythms, and social interactions in groups of mice in home cage environments. Mice with DIONI developed cold and mechanical allodynia, and hypersensitivity towards blue light stimulation. They maintained a long-lasting memory of aversive stimuli (airpuff from above), but had no difficulty in learning appetitive tasks, which consisted in developing a preference for a rewarding corner in the IntelliCage. Indeed, they were more strongly “addicted” to sugar than sham mice but temporarily failed to relearn the location of rewarding sites after corner switching (reversal learning). They were mildly overactive in some tasks but without disruptions of circadian rhythms or impact on social structure. They adopted a strategy to maintain licking with fewer nosepokes, presumably trying to avoid mechanical stimulation of the snout. The results suggest that mice with DIONI develop strong aversive memories and some cognitive inflexibility, but create adaptive strategies to cope with the persistent trigeminal hypersensitivity.
Source: Pain - Category: Anesthesiology Tags: Research Paper Source Type: research