Article Figures & Data
Figures
- Figure 1.
Long-lasting effects of juvenile enrichment. WT (a) or ras-grf knock-out (b) mice (1 month old) were exposed to an enriched environment for 2 weeks and then placed back into conventional environment for various times. LTP was then assayed. Experiments represent mean ± SEM from at least six brain slices from at least two independent experiments. c, A timeline that explains these experiments (F0) and experiments described in Figure 2 (F1), and Figures 2⇓⇓–5 (F1 and F2). The bars represent the life cycle of each generation relative to each other and when animals were tested (arrows).
- Figure 2.
Adolescent offspring of enriched juvenile ras-grf knock-out mice display normal LTP even if they are raised in conventional environment. a, LTP assays on hippocampal slices from 1-month-old ras-grf1/grf2 double knock-out mice exposed to either a conventional environment (black squares) or 2 weeks of enriched environment (red circles). n is number of slices and N is number of animals used. b, LTP assays of 1-month-old F1 offspring of either enriched (red circles) or unenriched (black squares) ras-grf knock-out mice. c, LTP assays on hippocampal slices from 1-month-old WT mice exposed to either a conventional environment (black squares) or 2 weeks of enriched environment (red circles). d, LTP assays of 1-month-old F1 offspring of either enriched (red circles) or unenriched (black squares) WT mice. Inset traces show a typical fEPSP from each group, gray traces are taken from 5 min before TBS, the colored traces are taken 50 min after TBS. Calibration: 1 mV, 10 ms. e, Immunoblot of brain slices demonstrating GRF1 and GRF 2 expression in WT but not F1 generation ras-grf1/2 double knock-out mice (mutant offspring) from enriched parents. The data represent the average and SEM from at least three independent experiments.
- Figure 3.
Adolescent offspring of enriched mice display the same novel LTP inducing signaling pathway as their enriched parents. a, LTP assays on hippocampal slices from 1-month-old offspring of enriched ras-grf1/grf2 double knock-out mice pretreated with buffer (black squares), NMDA receptor inhibitor (AP-5, 100 μm) (red circles), or cAMP inhibitor (Rp-cAMPS, 100 μm) (green triangles). b, Same as in a except that samples were pretreated with vehicle (black squares), p38 inhibitor (SB203580, 5 μm), or inhibitor of Erk signaling (U0126, 20 μm) (green triangles). c, Same as in a except that offspring of enriched WT mice were studied and samples were pretreated with vehicle (black squares), p38 inhibitor (red circles), or cAMP inhibitor (green triangles). d, Same as in c except that offspring of enriched WT mice were studied and data were pooled from multiple experiments. The data represent the average and SEM from the indicated number of samples.
- Figure 4.
Mechanism of transmission of EE effects across generations. a, LTP assays on hippocampal slices from 1-month-old offspring of enriched female and unenriched male (black squares) or enriched male and unenriched female (red circles) ras-grf1/grf2 double knock-out mice. b, LTP assays on hippocampal slices from the offspring of enriched ras-grf knock-out mice but raised by unenriched foster mothers (EE-Biologic-black squares) or offspring of unenriched ras-grf knock-out mice raised by enriched foster mothers (EE-Foster-red circles). c, LTP assays on 1-month-old F1-generation offspring (black squares), or F2 second-generation offspring (red circles) of enriched ras-grf knock-out mice. Samples from 1-month-old unenriched ras-grf knock-out mice (green triangles) are also shown for comparison. d, LTP assays were performed on hippocampal slices from enriched ras-grf knock-out mice (red bars) and F1 offspring of enriched ras-grf knock-out mice (green bars) at 1 month of age. Mice were then returned to a conventional environment and assayed at 2 months of age and 3 months of age. Data are the average fold increase in fEPSP slopes from three experiments (Fig. 1C).
- Figure 5.
Effect of enrichment on contextual conditioning memory. a, ras-grf1/2 double knock-out mice have defective contextual conditioning memory. One-month-old wild-type mice (□) (n = 17) and ras-grf1/2 double knock-out mice (■) (n = 15) (F0) were subjected to one-trial paradigm training. There was no significant difference in baseline freezing before footshock (pre) or immediately after (post). A retention test was performed 24 h after training. The data represent the average and SEM from the indicated number of samples. The freezing response in ras-grf1/2 double knock-out mice was significantly lower than that in wild-type mice (p < 0.05, Mann–Whitney U test). b, Enrichment rescues deficient contextual conditioning memory in ras-grf1/2 double knock-out mice. One-month-old naive ras-grf1/2 double knock-out mice control (□) (n = 12) and enriched ras-grf1/2 double knock-out mice (■) (n = 12) were subjected to one-trial paradigm training as described in a. The freezing response in enriched ras-grf1/2 double knock-out mice was significantly higher than that in naive ras-grf1/2 double knock-out mice (p < 0.05, Mann–Whitney U test). c, Defective contextual conditioning memory is partially rescued in 1-month-old offspring of enriched juvenile ras-grf1/2 double knock-out mice. One-month-old offspring from two litters of either naive ras-grf1/2 double knock-out mice (□) (n = 15) or enriched ras-grf1/2 double knock-out mice (■) (n = 16) were subjected to one-trial paradigm training as in a. The freezing response in the offspring of enriched ras-grf1/2 double knock-out mice was significantly higher than that in naive ras-grf1/2 double knock-out mice (p < 0.05, Mann–Whitney U test). d, Defective contextual fear memory is not rescued in 3-month-old F1 offspring of enriched juvenile ras-grf1/2 knock-out mice. Experiments were performed as in a except that offspring of enriched knock-out mice were reared in a standard environment for 3 months before being tested for fear conditioning response (control, n = 12) (EE, n = 15). e, Defective contextual conditioning memory is not rescued in the F2 offspring of enriched juvenile ras-grf1/2 knock-out mice. Experiments were performed as in a except that 1-month-old F2 offspring of enriched knock-out mice were used (control, n = 11) (EE, n = 13).
Additional Files
Supplemental Data
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- supplemental material - Supplemental Legend
- supplemental material - Supplemental Figure
