1. Intra-amygdala MPEP is analgesic during bladder distention.
Intra-amygdala MPEP is analgesic during bladder distention. A, Infusion of a mGluR5 antagonist, MPEP (0.01 nmol), into the right CeA (n = 6) induced an analgesic response to graded bladder distention in the noxious range compared with baseline (pretreatment) values. The inset shows representative EMG traces to 70 and 80 mmHg distention at baseline and following MPEP treatment (step represents 20 s distention stimulus). Brain atlas insets show cannula targeting with black stars indicative of cannula tip. B, Treatment with intra-amygdala injection of vehicle (aCSF) (n = 6) induced a significant increase in evoked response during bladder distention. However, this change was in the opposite direction of treatment with MPEP and likely represents a small nonspecific effect possibly due to repeated bladder distention. Brain atlas insets show cannula targeting with white stars indicative of cannula tip. C, In a separate cohort, pretreatment with MPEP (n = 7) before a single round of higher noxious pressure bladder distention (i.e., no baseline distention) induced a significant decrease in the evoked response compared with vehicle-treated mice (n = 6). Brain atlas insets show cannula targeting with solid black stars indicative of cannula tip of MPEP-treated mice and white stars indicative of cannula tip of vehicle-treated mice (***p < 0.001, two-way ANOVA main effect of treatment; +++p < 0.001, Bonferroni's post test compared with indicated baseline value; *p < 0.05, Student's t test compared with vehicle-treated group). Error bars indicate SEM.
Lara W. Crock et al. J. Neurosci. 2012;32:
©2012 by Society for Neuroscience