Food deprivation and age modulate neuropeptide gene expression in the murine hypothalamus and adrenal gland.

We have developed a rapid and simple method for quantitative Northern blot analysis of rare messenger RNA species from single mouse hypothalami and adrenals. This technique has allowed us to study the effects of food deprivation on neuropeptide gene expression in the mouse hypothalamus and adrenal gland. The potential modulatory effects of sex and age were also investigated. Food deprivation induced a two-fold increase in the amount of hypothalamic neuropeptide Y (NPY) mRNA, but did not increase NPY mRNA in the brainstem. Age had a significant effect on levels of NPY messenger RNA levels in the hypothalamus. However, there were no gender-associated effects. Sexually immature females (6 weeks old) had higher levels of NPY expression than mature females (9 weeks old). In contrast, in the adrenal gland, increasing maturity was associated with higher levels of NPY mRNA. As in the hypothalamus, fasting caused approximately two-fold increases in NPY mRNA over levels in the ad libitum fed state for both mature and immature mice. Thus, hypothalamic NPY neurons are responsive to nutritional deprivation and developmental status, suggesting that NPY neurons may be important in energy homeostasis.