Intergenerational and parent of origin effects of maternal calorie restriction on Igf2 expression in the adult rat hippocampus.

Insulin-like growth factor 2 (Igf2) regulates development, memory and adult neurogenesis in the hippocampus. Calorie restriction (CR) is known to modulate non-neuronal Igf2 expression intergenerationally, but its effect has not been evaluated on brain Igf2. Here, Sprague-Dawley (S) dams underwent moderate CR between gestational days 8-21. To identify parent of origin expression pattern of the imprinted Igf2 gene, their offspring (SS F1) were mated with naïve male or female Brown Norway (B) rats to obtain the second generation (BS and SB F2) progeny. CR did not affect adult hippocampal Igf2 transcript levels in SS F1 males or their BS F2 progeny, but increased it in SS F1 females and their SB F2 offspring. The preferentially maternal Igf2 expression in the SB F2 control male hippocampus relaxed to biallelic with CR, with no effect of grandmaternal diet in any other groups. Thus, allele-specific and total expression of hippocampal Igf2 is affected by maternal, grandmaternal CR in a strain and sex-specific manner.