Methyl donor supplementation blocks the adverse effects of maternal high fat diet on offspring physiology

Abstract

Maternal consumption of a high fat diet during pregnancy increases the offspring risk for obesity. Using a mouse model, we have previously shown that maternal consumption of a high fat (60%) diet leads to global and gene specific decreases in DNA methylation in the brain of the offspring. The present experiments were designed to attempt to reverse this DNA hypomethylation through supplementation of the maternal diet with methyl donors, and to determine whether methyl donor supplementation could block or attenuate phenotypes associated with maternal consumption of a HF diet. Metabolic and behavioral (fat preference) outcomes were assessed in male and female adult offspring. Expression of the mu-opioid receptor and dopamine transporter mRNA, as well as global DNA methylation were measured in the brain. Supplementation of the maternal diet with methyl donors attenuated the development of some of the adverse effects seen in offspring from dams fed a high fat diet; including weight gain, increased fat preference (males), changes in CNS gene expression and global hypomethylation in the prefrontal cortex. Notable sex differences were observed. These findings identify the importance of balanced methylation status during pregnancy, particularly in the context of a maternal high fat diet, for optimal offspring outcome.

Figure 1. Body weight change over time.

Body weights of male (A) and female (B) offspring were measured from 12–50 weeks of age. Male offspring from HF-fed dams (white bars) weighed significantly more than offspring from control fed dams (black bars) at 12 weeks of age, and this difference was normalized in offspring from methyl donor supplemented dams. Female offspring (B) from HF-fed dams (white bars) weighed significantly more than offspring from control fed dams (black bars) throughout the experiment. *p<0.05 (Bonferroni posthoc), *a and *b designate a main effect for maternal diet.

Figure 2. Metabolic rate at 12 weeks of age.

Metabolic rate (oxygen consumption) at 12 weeks was measured in males (A, B) and females (C, D). Male offspring from HF-fed dams (white bars) have a significantly reduced metabolic rate (A) as compared to controls (black bars), and there is no difference in metabolic rate in the methyl donor supplemented groups (gray bars). Percent change analysis showed that in the unsupplemented groups, maternal HF diet leads to a significant decrease in VO2, while in the supplemented groups, these values do not differ (B). In females, offspring from HF-fed dams (white bars) have a significantly reduced metabolic rate (C) as compared to controls (black bars), and in the methyl donor supplemented groups, the offspring from HF-fed dams have a significantly increased metabolic rate (gray bars). This pattern is evident in the percent change analysis (D). *p<0.05 (Bonferroni posthoc), (actual p-values displayed in the bars in 1B, 1D). (n = 6/group).

Figure 3. Locomotor activity at 12 weeks of age.

Locomotor activity was measured at 12 weeks of age in males (A, B) and females (C, D). At 12 weeks of age, the percent change in locomotor activity as a result of maternal HF diet consumption is significantly decreased in the unsupplemented groups, and not different in the methyl donor supplemented groups (1B). In female offspring, the methyl donor supplementation led to a significant decrease in locomotor activity in females, regardless of the fat content of the maternal diet (1C). (n = 6/group).

Figure 4. Locomotor activity at 20 weeks of age.

Locomotor activity was measured at 20 weeks of age in males (A, B) and females (C, D). At 20 weeks of age, the percent change in locomotor activity as a result of maternal HF diet consumption is not changed in the unsupplemented groups, and in the methyl donor supplemented groups the animals from dams fed a high fat diet have a significant increase in locomotor activity (1B). In female offspring, the methyl donor supplementation led to a significant decrease in locomotor activity in females, regardless of the fat content of the maternal diet (1C). **p<0.01 (Bonferroni posthoc) (n = 6/group).

Figure 5. Fat preference.

Males (top) from HF-fed dams (white bar) have a significantly increased preference for fat, as compared to control offspring (black bars), when tested at 40 weeks of age (main effect for maternal diet indicated by “a”). This difference in normalized in offspring from the methyl donor supplemented groups (gray bars). *p<0.05 (n = 6/group). There is no difference in fat preference in the females (bottom).

Figure 6. DAT and MOR mRNA expression is altered in the central reward circuitry in male and female offspring at 50 weeks of age.

DAT mRNA (A) in the VTA is significantly increased in males from HF-fed dams. Maternal HF diet consumption leads to increased MOR mRNA (B) in the NAc (males and females) and PFC (females only). These mRNA changes are normalized in the methyl donor supplemented groups. *p<0.05, **p<0.01 (n = 5/group).

Figure 7. Changes in global DNA methylation in the PFC, NAc and VTA.

In the male PFC, offspring from dams fed a HF diet showed global hypomethylation that was corrected in the supplemented groups. In the male VTA and female PFC, there was a significant main effect for maternal diet (regardless of supplementation status, designated with the letter “a”, p<0.05) and in the male NAc, there was a main effect for supplementation. *p<0.01, **p<0.001. (n = 5/group).