Fig. 2 | Neuropsychopharmacology

Fig. 2

From: Chronic opioid pretreatment potentiates the sensitization of fear learning by trauma

Fig. 2

Chronic opioid pretreatment does not alter shock sensitivity or anxiety. a Experiment Schematic. A week after chronic morphine/saline exposure, animals were tested in the EPM. The next day, shock reactivity was assessed. b Morphine-treated animals did not display altered exploration of the open arms of the EPM. c Morphine-treated animals did not display altered shock reactivity. See Supplemental Methods for details. Dashed line in c reflects pre-shock motion prior to the first shock, which did not differ between groups (t22 = 0.1, p = 0.92). d Experiment Schematic. A subset of animals which received morphine/saline and were fear conditioned with a single 2 s, 0.5 mA shock, were subsequently exposed to a series of auditory startle stimuli (2 s, 115 db, white noise, each separated by 1 min) in a novel environment, and were placed back in the startle-paired environment the next day. e Morphine-treated animals did not differ with respect to baseline motion or startle-induced increases in motion. f Morphine-treated animals did not differ with respect to baseline freezing when initially placed in the startle-paired environment but showed increased post-startle freezing, a learned behavior. Nevertheless, when placed back into the startle-paired environment the next day, morphine-treated animals did not significantly differ from saline-treated animals. Error bars reflect standard error of the mean. BL baseline. For ac, n = 12/group. For df, n = 13–14/group

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