Conditioned taste reactivity in rats after phenylpropanolamine, d-amphetamine or lithium chloride

That an aversive property of phenylpropanolamine (PPA) in part contributes to its anorexic capacity is suggested by the demonstration of conditioned taste avoidance to PPA doses ranging from 10-40 mg/kg. In order to further evaluate the putative aversive property of PPA, the present experiment compared the effects of PPA on multiple measures of aversion (chin rubs, gaping) in the taste reactivity (TRT) paradigm with those produced by the classic agent lithium chloride and by amphetamine. Male rats were infused via an intraoral cannula with 0.5 M sucrose followed by injection with either vehicle, 127 mg/kg lithium chloride (LiCl), 1.5 or 3.0 mg/kg amphetamine or by 10, 20 or 40 mg/kg PPA. LiCl and 40 mg/kg PPA induced significant chin rub responses during conditioning but only the aversive response induced by 40 mg/kg PPA persisted during extinction trials. In contrast, lower doses of PPA (10 mg/kg, 20 mg/kg) were not aversive in the TRT paradigm. These results suggest that an aversive component is not contributing to anorexia induced by PPA within the dose range of 10-20 mg/kg, but that higher doses may further suppress appetite via an aversive action.