Acute stress increases neuropeptide Y mRNA within the arcuate nucleus and hilus of the dentate gyrus

Abstract

The effects acute restraint stress on neuropeptide Y (NPY) mRNA expression were determined within the dentate gyrus and arcuate nucleus, where the effects of adrenal steroid action were previously reported. Adult male rats were exposed to 1 h of restraint stress and then sacrificed immediately, 6 h, or 24 h later. Controls were undisturbed. Stress increased NPY mRNA levels in both the arcuate nucleus and in the hilar region of the hippocampus with different time courses. NPY mRNA increased in the arcuate at 24 h, but not earlier, as determined by film autoradiography. Single cell grain analysis was performed in the dentate gyrus hilus because the NPY mRNA was heterogeneously distributed and revealed that the number of cells expressing NPY mRNA increased 6 h after stress, returning to control levels within 24 h. These results fit with previously reported effects of adrenal steroids modulating arcuate nucleus NPY expression through the adrenal steroid Type II receptors. In the hilus where adrenal steroid Type I receptors have been reported to suppress NPY mRNA levels, the effect of stress is in the opposite direction to that of adrenal steroid action and a more complex regulation of NPY expression is indicated.