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

The effects acute restraint stress on neuropeptide Y (NPY) mRNA expression were determined within the dentate gyrus and arcuate nucleus, where the eff ects of adrenal steroid action were previously reported. Adult male rats we re 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 wit h different time courses. NPY mRNA increased in the arcuate at 24 h, but no t earlier, as determined by film autoradiography. Single cell grain analysi s was performed in the dentate gyrus hilus because the NPY mRNA was heterog eneously distributed and revealed that the number of cells expressing NPY m RNA increased 6 h after stress, returning to control levels within 24 h. Th ese results fit with previously reported effects of adrenal steroids modula ting arcuate nucleus NPY expression through the adrenal steroid Type II rec eptors. In the hilus when adrenal steroid Type I receptors have been report ed to suppress NPY mRNA levels, the effect of stress is in the opposite dir ection to that of adrenal steroid action and a more complex regulation of N PY expression is indicated. (C) 2000 Elsevier Science B.V. All rights reser ved.