Fig. 6

Rapamycin treatment in infancy, but not adulthood, rescues BTBR mice social interaction deficits. A-C. BTBR mice were treated with rapamycin or vehicle from P4-P8 and tested in the three-chamber social interaction test at P30. A. Schematic of experimental design and heatmaps of time spent in each chamber during testing. B. Three chamber social interaction test. Time spent in the chamber with an empty enclosure (empty), middle chamber and chamber with an age-, strain- and sex-matched stranger mouse in the enclosure (social). Rapamycin-treated mice showed a preference for the chamber with the social target (Sidak’s post hoc test, Empty vs. Middle t₄₈ = 3.334 p = 0.005, Empty vs. Social t₄₈ = 3.799 p = 0.0012, Middle vs. Social t₄₈ = 7.132 p < 0.0001), which is absent in vehicle-treated BTBR mice (Sidak’s post hoc test, Empty vs. Middle t₄₈ = 3.937 p = 0.0008, Empty vs. Social t₄₈ = 1.982 p = 0.1513, Middle vs. Social t₄₈ = 1.954 p = 0.1601). C. Distance travelled in the social interaction test. There was no difference between vehicle- and rapamycin-treated mice. Vehicle-treated BTBR (VEH), n = 12 (7 females, 5 males); Rapamycin-treated BTBR (RAPA), n = 14 (8 females, 6 males). No sex differences were found for either group (p > 0.516). Male individual datapoints are depicted as squares, and female datapoints as circles for transparency. D-F. BTBR mice were treated with rapamycin or vehicle from P60-P64 and tested in the three-chamber social interaction test at P86. D. Schematic of experimental design and heatmaps of time spent in each chamber during testing. E. Three chamber social interaction test. Time spent in the chamber with an empty enclosure (empty), middle chamber and chamber with an age, strain and sex-matched stranger mouse in the enclosure (social). Neither vehicle or rapamycin treated mice showed a preference for the chamber with the social target over the empty chamber (VEH: Sidak’s post hoc test, Empty vs. Middle t₃₄ = 2.214 p = 0.097, Empty vs. Social t₃₄ = 2.012 p = 0.148, Middle vs. Social t₃₄ = 4.22 p = 0.0005; RAPA: Empty vs. Middle t₃₄ = 2.72 p = 0.030, Empty vs. Social t₃₄ = 0.557 p = 0.93, Middle vs. Social t₃₄ = 2.16 p = 0.11). F. Distance travelled in the social interaction test. There was no difference between vehicle- and rapamycin-treated mice. Vehicle-treated BTBR (VEH), n = 9 (5 females, 4 males); Rapamycin-treated BTBR (RAPA), n = 10 (5 females, 5 males). No sex differences were found for either group (p > 0.1185). Male individual datapoints are depicted as squares, and female datapoints as circles for transparency. G-H. Rapamycin treatment decreases phosphoS6 levels in the NAc of BTBR mice at P30. BTBR mice were treated with rapamycin or vehicle from P4-P8, kept in their homecage and then perfused at P30 for brain processing and immunohistochemistry against phosphoS6. G. Representative images of phosphoS6 staining in the NAc shell. H. Quantification of phosphoS6 intensity shows that rapamycin treatment reduced phosphoS6 levels at P30. Scale bar = 250 μm, n = 4 vehicle, 4 BTBR. *p < 0.05