Sucrose sham-feeding in the rat after administration of the selective dopamine D 2 receptor agonist N-0437, d-amphetamine or cocaine

Abstract

Drugs which act as agonists at dopamine receptors, or which increase dopamine release (e.g., d-amphetamine, cocaine) are known to reduce food intake. The present experiments investigated, for the first time, the effects of a highly selective dopamine D 2 receptor agonist, N-0437 (0.3–3.0 mg/kg, IP), on 5% sucrose sham-feeding in gastric fistulated rats, and compared these results with those of d-amphetamine (0.1–3.0 mg/kg, IP) and cocaine (3.0–10.0 mg/kg, IP). The results showed that sucrose sham-feeding was resistant to the effects of N-0437, even though the D 2 agonist dose-relatedly reduced sucrose real-feeding in intact animals. The two psychomotor stimulants, d-amphetamine and cocaine, produced some reductions in sham-feeding, although in the case of the highest dose of d-amphetamine, the pronounced reduction in the consumption of sucrose was probably secondary to induced behavioral stereotype. The results suggest that D 2 receptor stimulation may interact with satiety cues to reduce ingestion of sucrose, but that in the absence of potent satiety stimuli D 2 receptor stimulation is stimulation is ineffective. Furthermore, N-0437 appeared not to be equivalent to either d-amphetamine or cocaine in their effects to reduce sucrose sham-feeding.