Neuropeptide Y receptor agonists: Multiple effects on spontaneous activity in the paraventricular hypothalamus

In vitro rat hypothalamic slices were used to examine the ability of neuropeptide Y (NPY), and the putative Y₁ and Y₂ receptor agonists Pro³⁴]NPY, and C²]NPY, to modify spontaneous single-neuron discharge in the paraventricular nucleus (PVN). NPY and Pro³⁴]NPY, at high concentrations (1500 nM), decreased discharge rates. At intermediate concentrations (150 nM) these peptides produced multiple effects, including increases, decreases, and biphasic changes. At lower concentrations (0.15–15 nM), they typically increased discharge rates. In contrast, C²]NPY, at all concentrations (1.5–1500 nM), predominantly increased discharge rates. Thus, these NPY sybtype agonists have multiple effects on discharge rate, which may be due to action on multiple NPY receptor subtypes.