Area postrema lesions elevate NPY levels and decrease anxiety-related behavior in rats.

Intracerebroventricular administration of neuropeptide Y (NPY) has been shown to reduce anxiety-like effects in rodents and also profoundly alter feeding. The area postrema-lesioned (APX) rat model of food motivated behavior overconsumes palatable foods and expresses significantly higher levels of NPY in the hypothalamus than sham-lesioned control rats. For this reason, we examined APX rats in the open field test, which is a standard measure of anxiety- or fear-related behavior and also investigated NPY mRNA levels in the hippocampus, amygdala and hypothalamus. We found that APX rats display reduced anxiety-like behavior in the open field test as indicated by spending increased time in the center of the field as opposed to the perimeter of the field. NPY mRNA levels were also found to be significantly elevated in the amygdala, hippocampus and arcuate nucleus of the hypothalamus of APX rats when compared to sham-lesioned rats. These results support the action of limbic NPY to reduce anxiety-like behavior in a rodent model that appears to express higher than normal NPY levels.