EFFECTS OF PHENYLPROPANOLAMINE ON REGULATORY AND NONREGULATORY INGESTION IN ADULT-RATS

This experiment examined the effects of phenylpropanolamine (0.0, 5.0, 10.0, 20.0 mg/kg PPA) on regulatory (RG) and nonregulatory (NRG) eati ng and drinking in rats using a within-subjects design. Administration of PPA produced dose-dependent reductions in eating in animals depriv ed to 80-85% of baseline weight, and reduced drinking after 23.5-h of water deprivation. Nonregulatory eating, elicited by tail pinch in non deprived animals, was similarly inhibited. Nonregulatory drinking was elicited in the schedule-induced polydipsia (SIP) paradigm. Water cons umption, locomotion, licking, lick efficiency (licks/ml water), and en tries into the food magazine were simultaneously measured. At the lowe st dose, only locomotion was significantly reduced. At 10.0 mg/kg, lic k efficiency and entries into the food magazine were also significantl y reduced, while all measured behaviors, including licking and water c onsumption, were decreased by the highest dose of PPA. The reduction i n lick efficiency suggested a PPA-induced motor impairment in the capa city for licking. Considered together, these results indicated that th e observed decreases in regulatory and nonregulatory eating and drinki ng could be at least partially accounted for by the drug's effects on behaviors contributing to ingestion, as well as apparent motor impairm ents in ingestive behavior at higher doses.