Figure 2.

Environmental enrichment reverses the sustained behavioral deficits that are induced by perinatal fentanyl exposure. A, Timeline depicting behavioral assays and a schematic of the open field test. n = 15–20 mice per group. B, C, Perinatal fentanyl exposure increases distance traveled across time. D, E, Perinatal fentanyl-exposed mice raised with environmental enrichment have comparable distance traveled with vehicle controls but spend less time in the center area of the open field. Fentanyl-exposed mice raised with environmental enrichment spend more time in the center area of the open field, comparable to vehicle controls. F, Graphic depicting von Frey tactile stimulation on the plantar surface of the hind paw. G, There were no differences across groups in the paw withdrawal threshold to tactile stimulation. n = 11–19 mice per group. H, Standard-housed fentanyl-exposed mice have a higher number of paw withdrawal responses to repeated stimuli than standard-housed vehicle mice. Fentanyl-exposed mice raised with environmental enrichment have a lower number of paw withdrawal responses, comparable to vehicle mice raised in standard and enriched environment. Data depict means, p values, and 95% confidence intervals.