Neuropeptide Y (NPY) is a potent endogenous stimulator of food intake. In a
ddition to stimulating increased food intake, when paired with a novel-flav
ored solution, NPY produces an aversion to that flavor Hence, exogenous NPY
elicits 2 seemingly opposing behaviors, increased feeding and the formatio
n of a conditioned taste aversion. One interpretation of these data is that
NPY produces some form of malaise or visceral illness. NPY's orexigenic an
d malaise-inducing properties were tested in rats with 2 measures sensitive
to malaise, increased kaolin consumption (pica behavior) and failure to ex
press need-induced sodium intake. Administration of NPY resulted in increas
ed food intake, increased kaolin consumption, and decreased need-induced so
dium intake. These data support the hypothesis that exogenous NPY has both
orexigenic and malaise-inducing properties.