Salbutamol, d-amphetamine and d-fenfluramine reduce sucrose intake in freely fed rats by acting on different neurochemical mechanisms.

The effects of various doses of salbutamol, d-amphetamine and d-fenfluramine were studied on sucrose intake by freely-fed rats. All the drugs reduced sucrose consumption dose-dependently. Bilateral electrolytic lesions in the ventral noradrenergic bundle, which deplete hypothalamic noradrenaline, antagonized the effect of 1.25 mg/kg d-amphetamine on sucrose intake. A dose of 2.5 mg/kg d, 1-propranolol, a beta adrenergic blocker, prevented the effect of 10 mg/kg salbutamol but the dose of 5 mg/kg did not significantly change the effect of 0.6 or 1.25 mg/kg d-amphetamine. Captopril (35 mg/kg) reduced salbutamol's effect on water intake, but not on sucrose intake. Metergoline, 1 mg/kg, a central serotonin antagonist, but not xylamidine 2 mg/kg, a 5HT antagonist with limited access to the brain, counteracted the effect of 2.5 mg/kg d-fenfluramine on sucrose intake. These findings suggest a role for serotoninergic and adrenergic mechanisms in inhibiting ingestive behaviour maintained mainly by taste.