Postpubertal feeding experience affects sex-specific spatial ability in rats

We previously reported that feeding with powdered diet after weaning (3 weeks of age) enhanced spatial ability, and increased the amount of acetylcholine (ACh) released in the dorsal hippocampus in female rats. In the present study, to specify the time when feeding conditions caused these effects, a radial 8-arm maze task and an in vivo microdialysis study were performed in both sexes of rats. In rats fed standard laboratory diet (i.e., pelleted diet), males learned the radial 8-arm maze faster than females. Moreover, the ACh release showed a distinct diurnal rhythm which was high during the dark phase and low during the light phase, but males showed a greater amount of ACh released in the dorsal hippocampus than females. However, in rats fed powdered diet after 6 weeks of age, no significant sex differences were observed in the radial 8-arm maze task or in the amount of ACh released, since feeding with powdered diet enhanced spatial ability, and increased the amount of ACh released only in females. These results suggest that feeding conditions after 6 weeks of age may contribute to the sex difference in the spatial ability associated with the changes in the amount of ACh released in the dorsal hippocampus in rats.