Sucrose intake unaffected by fenfluramine but suppressed by amphetamine administration

The present study examined the acute effects of the anorectic agents, fenfluramine and amphetamine, on nutrient selection in male Sprague-Dawley rats. One group of animals received continuous access to both granulated sucrose and Purina chow (presented in separate cups), while the other group received only Purina chow. Four doses of fenfluramine (0, 1.5, 3.0, 6.0 mg/kg) and four doses of amphetamine (0, 0.5, 1.0, 2.0 mg/kg) were tested. Injections were given at the beginning of the feeding period, and nutrient intakes were measured at 2, 4, and 8 h postinjection. While both fenfluramine and amphetamine resulted in similar overall decreases in caloric intakes, the two drugs produced different effects on nutrient selection. Following fenfluramine administration, sucrose intakes remained relatively unaffected, while Purina chow intakes showed pronounced suppression. In contrast, amphetamine administration resulted in a more equal suppression of both sucrose and Purina chow intakes. While the overall decreases in food intake seen with fenfluramine and amphetamine may be linked to changes in central neurotransmitter levels, the sparing of sucrose consumption observed with fenfluramine may also involve drug-induced changes in peripheral metabolism.