Differential regulation of neuropeptide Y receptors in the brains of NPY knock-out mice

Abstract

To study the effect of NPY deletion on the regulation of its receptors in the NPY knockout (NPY KO) mice, the expression and binding of NPY receptors were investigated by in situ hybridization and receptor autoradiography using 125I-[Leu 31,Pro 34]PYY and 125I-PYY 3-36 as radioligands. A 6-fold increase in Y2 receptor mRNA was observed in the CA1 region of the hippocampus in NPY KO mice, but a significant change could not be detected for Y1, Y4, Y5 and y6 receptors. Receptor binding reveals a 60–400% increase of Y2 receptor binding in multiple brain areas. A similar increase in Y1 receptor binding was seen only in the hypothalamus. These results demonstrate the NPY receptor expression is altered in mice deficient for its natural ligand.