SUPPRESSED NEUROPEPTIDE-Y (NPY) MESSENGER-RNA IN RAT AMYGDALA FOLLOWING RESTRAINT STRESS

We have previously demonstrated that NPY produces anxiolytic-like effe cts through actions in the amygdala, and that anxiogenic-like effects of restraint stress are mediated through this structure. Here, we exam ined the effects of restraint stress on NPY mRNA levels in amygdala an d several other brain regions. A sensitive solution hybridization-RNas e protection assay (RPA) was developed, employing a combination of int ernal and external standards, which allowed absolute quantitation of N PY mRNA in tissue-samples of less than 10 mg. NPY mRNA levels were det ermined, following a l-h restraint stress, in homogenates of tissue fr om the amygdala, neocortex, striatum and hypothalamus, and the time co urse of these effects was examined. A highly significant decrease in N PY-mRNA levels was seen in the amygdala at 1 h and 2 h following restr aint, with levels returning to normal within 10 h. A similar effect wa s seen in the neocortex, but was less pronounced and slower in onset. Striatal and hypothalamic NPY expression was not significantly affecte d. Tissue levels of NPY-peptide were modestly decreased in the amygdal a at 1 h following restraint and had returned to normal within 4 h. Th e present findings support the hypothesis that anxiety related behavio ral effects of stress may in part be mediated through modulation of NP Y function in the amygdala. (C) 1998 Elsevier Science B.V. All rights reserved.