Pufferfish and zebrafish have five distinct NPY receptor subtypes, but have lost appetite receptors Y1 and Y5

The two neuropeptide Y (NPY) receptors Y1 and Y5 stimulate feeding in mammals, but are missing in the euteleosts, zebrafish and pufferfish (Takifugu rubripes). Both species have five other subtypes called Y2, Y7, Ya, Yb, and Yc. RT-PCR studies in pufferfish show that all five are expressed in the brain and may mediate NPY effects on feeding. Y2, Ya, and Yb are also broadly expressed in peripheral organs. These results reveal interesting differences in the NPY system of teleosts and mammals that may have arisen in the genetic turmoil involving the basal ray-fin fish tetraploidization.