Sensitivity of housekeeping genes in the hypothalamus to mismatch in diets between pre- and postnatal periods in mice

Housekeeping genes are used as internal controls in gene expression studies, but their expression levels vary according to tissue types and experimental treatments. A nutritional mismatch between pre- and postnatal periods, wherein the in utero nutritional environment is suboptimal and post-weaning diet is rich in fat, results in altered hypothalamic expression levels of genes that regulate the offspring's physiology, metabolism and behavior. The present study investigated hypothalamic expression of the housekeeping genes glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-actin and 18s ribosomal RNA (18s rRNA) in offspring subjected to this pre- and postnatal dietary mismatch. Pregnant MF1 mice were fed standard chow (C, 18% casein) or protein restricted (PR, 9% casein) diet throughout pregnancy. Weaned offspring were fed to adulthood a high fat (HF, 45% kcal fat) or chow (21% kcal fat) diet to generate the C/HF, C/C, PR/HF and PR/C groups. Hypothalamic and cerebral cortex tissues were collected from these offspring at 16 weeks of age and analyzed for gene transcript levels by quantitative real time PCR. Hypothalamic GAPDH mRNA levels were higher in PR/HF male and female offspring vs. all other groups (p < 0.001 in males). Conversely, hypothalamic β-actin and 18s rRNA levels were similar in all treatment groups and sex. In the cerebral cortex, GAPDH and β-actin levels were similar in all groups and sex. The result suggests that β-actin and 18s rRNA are suitable internal controls for gene expression studies in the hypothalamus, while the stability of GAPDH is compromised, under the condition of a nutritional mismatch between pre- and postnatal periods.