Neuropeptide Y - The Role of NPY in Food Intake

The Role of NPY in Food Intake

Behaviorial assays in orexigenic studies, in which rats are the model organism, have been done collectively with immunoassays and in situ hybridization studies to confirm that elevating NPYergic activity does indeed increase food intake. In these studies, exogenous NPY, an NPY agonist such as dexamethasone or N-acetyl NPY (24-36) are injected into the third ventricle or at the level of the hypothalamus with a cannula.

Furthermore, these studies unanimously demonstrate that the stimulation of NPYergic activity via the administration of certain NPY agonists increases food intake compared to baseline data in rats. The effects of NPYergic activity on food intake is also demonstrated by the blockade of certain NPY receptors (Y1 and Y5 receptors), which, as was expected, inhibited NPYergic activity; thus, decreases food intake. However, a 1999 study by King et al. demonstrated the effects of the activation of the NPY autoreceptor Y2, which has been shown to inhibit the release of NPY and thus acts to regulate food intake upon its activation. In this study a highly selective Y2 antagonist, BIIE0246 was administered locally into the ARC. Radioimmunoassay data, following the injection of BIIE0246, shows a significant increase in NPY release compared to the control group. Though the pharmacological half-life of exogenous NPY, other agonists, and antagonist is still obscure, the effects are not long lasting and the rat body employs an excellent ability to regulate and normalize abnormal NPY levels and therefore food consumption.