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. Author manuscript; available in PMC: 2018 Dec 1.
Published in final edited form as: Exp Neurol. 2017 Aug 19;298(Pt A):1–12. doi: 10.1016/j.expneurol.2017.08.010

Figure 4. Activation of CRF neurons in the CeAmy increased SIA in control mice, whereas the inhibition of amygdala CRF neurons for the full duration of the pain period relieved the mechanical allodynia and restored SIA in mice with neuropathic pain.

Figure 4

Panel A: Activation of CRF neurons expressing AAV-DREADD/Gq by a single injection of CNO did not change the tail-flick response latency of unstressed mice, but increased the response latency after a forced swim, Two-Way ANOVA, * - significant for interaction (stress × treatment), F1, 30 = 5.3, P < 0.05. Panel B: The mice expressing the inhibitory AAV-DREADD/Gi in CeAmy CRF neurons and treated with CNO in their drinking water developed mechanical allodynia after cuff placement, but their mechanical paw withdrawal threshold increased by day 15 of the CNO treatment, Two-Way Repeated Measures ANOVA, * - significant for interaction (treatment × subjects), F3,21 = 3.2, P < 0.05. Panel C: While the inhibition of CRF neurons for the entire pain period did not change tail-flick response latency of unstressed mice, it increased the tail-flick response latency after a forced swim, Two-Way ANOVA, *** - significant for interaction (stress × treatment), F1, 40 = 85.6, P < 0.001.

Panels D to F: Expression of AAV-DREADD/Gi viral constructs in the CeAmy and their colocalization with CRF-ir after fifteen days of CNO treatment. Panel D: A dense network of CRF-ir fibers that primarily occupy CeL, but are also visible in neighboring CeC and CeM subdivisions of CeAmy. Panel E: The expression of AAV-DREADD/Gi is confined to CeAmy, where the colocalization of DREADD/Gi with CRF-ir is indicated by a yellow tone in panel F.

Panels G to I: The arrows in these high magnification images show the colocalization of CRF-ir positive fibers with mCherry-ir, the fluorescent reporter of AAV-DREADD/Gi.

Abbreviations: BLA - basolateral amygdala, CeC - centrocentral nucleus, CeM -cenrtromedial nucleus, CeL- centrolateral nucleus, FS – forced swim. Scale bar = 200 μm in D to F and scale bar = 10 μm in G to I.