We observed that mice fed with the FMCD showed highly impaired acquisition of fear memory, which led to a very low level of freezing during the memory test the subsequent day. Restriction of food intake induced delayed acquisition of fear memory, but that delay did not affect the freezing level during the memory test, i.e., the consolidation ability of the acquired fear was intact. These results suggest that although complete deficiency of methyl donors impaired the acquisition of fear memory, low intake of methyl donors can prevent the impairment of acquisition, consolidation and retrieval of memory. Interestingly, up-regulation of hippocampal Dnmt3a and 3b mRNAs was observed after fear conditioning in a previous rat study, and Dnmt inhibition blocked synaptic plasticity in a hippocampal slice. Thus, our results support those previous results and suggest that Dnmt also plays an important role in acquisition of hippocampal memory in mice. It should be emphasized that a normal diet after 3-week restriction of methyl donors in the developmental period seemed to recover the fear-memory acquisition but that impaired memory was still observed in adults. Lack of methyl donors in the developmental period might have caused persistent impairment of the capacity for consolidation or retrieval of acquired fear. As to the results of elevated-plus maze test, both types of food restriction appeared to alter the anxiety-like behavior measured by the time spent in the open arm in both the juvenile and adult mice groups in opposite ways. Both experimental groups showed decreased anxiety-like behavior in their juvenile period, but elevated anxiety-like behavior in CUDC-907 HDAC inhibitor adulthood, after ad libitum intake of a normal diet. There have been inconsistent results in previous studies with animals fed with diets lacking long-lasting methyl donors such as Vitamin Bs and choline after weaning. Although with a different time schedule, one such study with male rats reported a decrease in anxiety-like behavior, supporting our results. In contrast, another report with male and female mice did not observe such decrease in anxiety-like behavior. Alternatively, because behavioral changes in our study were observed in very similar ways in both experimental groups, it should be considered that the food restriction itself might have had the anxiolytic effect on juvenile mice, consistent with previous dietary restriction studies. In the present study, locomotor activities among groups did not affect behavioral results because the total distance during the EPM and %freezing during acclimation period were not significantly different among groups. In the current study, we investigated the hippocampal mRNA expressions of NMDA receptor subunits of NR1, NR2A and NR2B, and GABA receptor subunits of a2 and a3 to determine whether expressions of those receptors were involved in the mechanism behind the behavioral changes in the experimental mice groups. The NMDA receptor is considered to play a crucial role in the formation of hippocampal memory. In our study, FMCD and FR mice revealed low expression of the NR2B gene, suggesting that the reduced intake of methyl donors may induce the decrease of NR2B gene expression by global rearrangement of DNA methylation patterns.