Fig. 2: Deletion of PPARα in the dentate gyrus (DG) impairs contextual fear extinction. | Translational Psychiatry

Fig. 2: Deletion of PPARα in the dentate gyrus (DG) impairs contextual fear extinction.

From: Peroxisome proliferator-activated receptor-α activation facilitates contextual fear extinction and modulates intrinsic excitability of dentate gyrus neurons

Fig. 2

a Experimental procedure for DG-specific knockdown of PPARα using CRISPR-Cas9 system. Cre-dependent Cas9 mice were microinjected with AAV2/9-Cre and/or AAV2/9-sgPPARα into the DG. b Schematic of AAV vector and sgRNA design targeting the mouse PPARα locus. The Illumina sequencing reads showed the successful genomic editing of mouse PPARα gene with designed sgRNA. c Representative immunofluorescence images of Cre-dependent Cas9 mice with injection of AAV2/9-sgPPARα and AAV2/9-Cre into the DG. Green: sgPPARα; Red: Cre recombinase. Bar: 25 μm. d Representative immunoblot of the DG from Cre-dependent Cas9 mice microinjected with AAV2/9-sgPPARα (Cas9-DGgRNA) alone or together with AAV2/9-Cre (Cas9-DGgRNA+Cre) showed clear Cre-dependent induction of Cas9 expression and partial deletion of PPARα in the DG (t(6) = 3.059, p = 0.0222). **p < 0.01 compared with Cas9-DGgRNA group. e DG-specific deletion of PPARα impairs contextual fear extinction. Upper, experimental time line. Lower, contextual fear acquisition (left, genotype: F (1,31) = 0.2453, p = 0.6239; shock: F (4,124) = 122.2, p < 0.0001; genotype × shock: F (4,124) = 0.2811, p = 0.8897), fear retrieval (middle left, t(31) = 0.6753, p = 0.5045), fear extinction (middle right, genotype: F (1,31) = 4.326, p = 0.0459; day: F (3,93) = 21.46, p < 0.0001; genotype × day: F (3,93) = 2.968, p = 0.0359) and the rate of extinction (right, genotype: F (1,31) = 2.202, p = 0.1479; day: F (3,93) = 22.32, p < 0.0001; genotype × day: F (3,93) = 3.489, p = 0.0188) in Cas9-DGgRNA+Cre. Cas9-DGgRNA+Cre, n = 21; Cas9-DGgRNA, n = 12. f Open field test. Left, time spent in the center, t(34) = 0.3557, p = 0.7243; Right, total distance traveled, t(34) = 1.430, p = 0.1618. g Elevated plus-maze test. Left, percentage of open arm entry (t(34) = 0.4754, p = 0.6376); Right, time spent in the open arms (t(34) = 0.9897, p =0.3293); Cas9-DGgRNA+Cre, n = 21; Cas9-DGgRNA, n = 15. h Hot-plate test. Cas9-DGgRNA+Cre mice displayed similar paw withdrawal latency in reaction to heat stimulus in comparison with Cas9-DGgRNA mice (t(27) = 1.070, p = 0.2942). i Visual cliff test. Cas9-DGgRNA+Cre mice displayed normal visual depth perception compared with Cas9-DGgRNA mice (t(27) = 0.07253, p = 0.9427). Cas9-DGgRNA+Cre, n = 17; Cas9-DGgRNA, n = 12. *p < 0.05 compared with Cas9-DGgRNA control mice. Data are presented as mean ± s.e.m.

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