EFFECTS OF DEXFENFLURAMINE ON GLUCOSE DRINKING AND GLUCOSE-CONDITIONED FLAVOR PREFERENCES IN RATS - TASTE VERSUS POSTINGESTIVE CONDITIONING

A comparison was made of the effects of dexfenfluramine (DF, 3-10 mg k g(-1)) on intake of and conditioning with glucose solutions varying in orostimulant properties (taste) and postingestive actions (calories), in rats. First, sham-feeding, using gastric-fistulated rats, was perf ormed to assess the orostimulant properties of the solutions, Then, tw o experiments were done. In the first experiment, we examined the effe cts of DF, given at doses of 13 and 10 mg kg(-1), on the intake of two glucose solutions having different orostimulant properties and differ ent caloric values. The solutions were a mix of 1% glucose plus 0.125% saccharin (low caloric, more orostimulant), and 4% glucose (high calo ric, less orostimulant). At doses of 10 mg kg(-1), DF administration m arkedly reduced intake of both solutions (P<0.05 vs Control Group, res pectively). In second experiment, we examined the effects of DF (10 mg kg(-1)) on flavour preference conditioning in two parts. In the first part of the experiment, rats consumed two distinctively flavoured sol utions having equal orostimulant properties but different caloric valu e for a conditioning period of 16 days. The solutions were a mix of 1% glucose plus 0.125% saccharin (low caloric), and 6.1% glucose (high c aloric). At the end of the conditioning period, the flavour paired wit h ingestion of more calories was subsequently preferred (P<0.05 vs low caloric glucose-saccharin mix). DF, when given during and after the c onditioning period, attenuated this flavour-calorie conditioning (P<0. 05 vs Control Group). In the second part of the experiment, rats were conditioned with flavours associated with a mix of 20% glucose plus 0. 4% citric acid and 20% glucose solutions. These solutions were equally caloric but differed in orostimulant properties. The flavour paired w ith better orostimulant properties was subsequently preferred (P<0.05 vs less orostimulant glucose-citric acid mix). DF, when given during a nd after the conditioning period, also attenuated this flavour-flavour conditioning (P<0.05 vs Control Group). These results suggest that DF may impair flavour preference learning. (C) 1996 The Italian Pharmaco logical Society