Behavioral Measures
OFT: At 7 days, results revealed a significant interaction between exposure and treatment in females, F (2,24) = 4.356,p = 0.024. Post hoc comparisons revealed that MK+Sal (Mean[M] = 762.696, Standard Deviation[SD] = 123.944) was trending towards traveling significantly more than Ctrl+Sal (M = 600.930, SD = 160.251), MD = 161.765, q = 1.683, p = 0.105, and MK+LowHU (M = 498.434, SD = 211.761) was significantly less active than MK+Sal (M = 762.696, SD = 123.944), MD = 264.262, q = 2.749, p = 0.021. At 17 days, differences were significant, F (5,54) = 7.065,p < 0.001. Post hoc comparisons revealed that compared to Ctrl+Sal (M = 507.541, SD = 171.562), MK+Sal (M = 889.621, SD = 312.669), MD = 382.080, q = 3.755, p = 0.002, and MK+HighHU (M = 992.224, SD = 277.479), MD = 484.683, q = 4.763,p < 0.001, traveled significantly more. In males, results were significant, F (5,24) = 7.843, p < 0.001. Post hoc comparisons revealed that compared to Ctrl+Sal (M = 479.282, SD = 198.022), MK+HighHU (M = 1157.157, SD = 300.419) traveled significantly more, MD = 677.874, q = 5127, p < 0.001. In females, results were significant, F (5,24) = 8.487,p < 0.001. Post hoc comparisons revealed that MK+Sal (M = 1132.174, SD = 194.739) traveled significantly more than Ctrl+Sal (M = 535.799, SD = 158.165), MD = 596.375, q = 5.761, p< 0.001, Ctrl+LowHU (M = 668.763, SD = 83.481), MD = 463.411,q = 4.477, p < 0.001, Ctrl+HighHU (M = 712.275, SD = 96.458), MD 419.899, q = 4.057, p = 0.002, MK+LowHU (M = 603.433, SD = 257.934), MD = 528.741, q = 5.108, p< 0.001, and MK+HighHU (M = 827.292, SD = 122.390), MD = 304.882, q = 2.945, p = 0.029 (See Figure 1).
SIT: At 7 days, results revealed a main effect of exposure on SI, F (1,53) = 6.051, p = 0.017. Post hoc comparisons revealed that MK+Sal mice (M = 1.845, SD = 0.22) had a significantly lower SI than Ctrl+Sal mice (M = 2.605, SD = 0.216), MD = 0.759,q = 2.439, p = 0.018. Moreover, MK+Sal (M = 1.677, SD = 0.395) had an SI that was marginally lower than Ctrl+Sal (M = 2.764, SD = 0.375), MD = 1.087, q = 1.997, p = 0.051. In males, results showed a significant main effect of exposure on SI,F (1,24) = 9.002, p = 0.006. Post hoc comparisons revealed that MK+Sal mice (M = 1.777, SD = 0.777) had a significantly lower SI than Ctrl+Sal mice (M = 3.115, SD = 1.481), MD = 1.339, q = 3,p = 0.006. In females, results showed a significant interaction between exposure and treatment, F (2,24) = 3.777, p = 0.037. Post hoc comparisons revealed that MK+Sal (M = 1.596, SD = 0.244) had a significantly lower SI than Ctrl+Sal (M = 3.046, SD = 1.834), MD = 1.45, q = 2.451, p = 0.022 (See Figure 2).
FST: At 7 days, results revealed a significant interaction between exposure and treatment, F (2,54) = 5.952, p = 0.005. Post hoc comparisons revealed that MK+LowHU (M = 119.114, SD = 67.534) was significantly less immobile than MK+Sal (M = 164.754, SD = 36.058), MD = 45.640, q = 2.563, p = 0.025, and Ctrl+LowHU (M = 181, 238, SD = 18.418), MD = 62.125, q = 3.488, p < 0.001. In females, results showed a significant interaction between exposure and treatment, F (2,24) = 7.180, p = 0.004. Post hoc comparisons revealed MK+LowHU (M = 79.794, SD = 75.388) spent significantly less time being immobile than MK+Sal (M = 161.268, SD = 25.60), MD = 81.474, q = 3.074, p = 0.010. At 17 days, results were significant, F (5,54) = 3.058 , p = 0.017. Post hoc comparisons revealed that compared to Ctrl+Sal (M = 179.729, SD = 34.305), both MK+Sal (M = 218.972, SD = 27.616), MD = 39.243, q = 2.984, p = 0.018, and MK+HighHU (M = 223.827, SD = 14.747), MD = 44.098, q = 3.353, p = 0.007, were significantly more immobile. In males, results trended towards a significant main effect of exposure, F (1,24) = 3.403, p = 0.077. Post hoc comparisons trended towards MK+Sal mice (M = 208.368, SD = 27.631) being more immobile than control mice (M = 186.820, SD = 35.807), MD = 21.548,q = 1.845, p = 0.077. In females, results trended towards a significant main effect of exposure, F (1,24) = 2.976, p= 0.097. Post hoc comparisons revealed that MK+Sal (M = 236.797, SD = 4.435) were significantly more immobile than Ctrl+Sal (M = 196.991, SD = 35.908), MD = 39.806, q = 2.223, p = 0.036, and MK+LowHU (M = 193.755, SD = 40.899), MD = 43.042, q = 2.404, p = 0.045 (See Figure 3).
NORT: At 7 days, results were significant, F (5,52) = 4.148, p = 0.003. Post hoc comparisons revealed that MK+Sal (M = -15.35, SD = 22.633) had a significantly lower difference time with the novel object than Ctrl+Sal (M = 15.436, SD = 22.623), MD = 30.786,q = 2.77, p = 0.033, Ctrl+HighHU (M = 16.712, SD = 21.955), MD = 32.062, q = 2.885, p = 0.024, MK+LowHU (M = 29.871, SD = 34.836), MD = 45.221, q = 3.39, p = 0.001, and MK+HighHU (M = 17.847, SD = 24.296), MD = 33.197, q = 2.907,p = 0.023. In males, results were significant, F (5,24) = 3.107, p = 0.027. Post hoc comparisons revealed that MK+Sal (M = -24.120, SD = 24.009) had a significantly lower difference time with the novel object than MK+LowHU (M = 40.368, SD = 43.596), MD = 64.488,q = 3.518, p = 0.008. In females, results were significant, F (5,21) = 2.942, p = 0.036. Post hoc comparisons revealed that MK+Sal (M = -6.75, SD = 19.592) had significantly lower difference time with the novel object than Ctrl+Sal (M = 32.28, SD = 10.949), MD = 38.86, q = 2.845, p = 0.04, and Ctrl+HighHU (M = 31.567, SD = 20.43), MD = 38.147, q = 2.962,p = 0.031. At 17 days, the full analysis was not significant. In females, results were significant, F (5,23) = 2.781, p = 0.042. Post hoc comparisons revealed that MK+Sal (M = -15.357, SD = 32.087) had significantly lower difference time with the novel object than MK+LowHU (M = 66.435, SD = 42.025), MD = 81.792, q = 3.202, p = 0.016 (See Figure 4).