Apomorphine anorexia: the role of dopamine cell body autoreceptors

Anorectic effects of apomorphine were studied in a microstructural analysis paradigm. Systemic apomorphine reduced food intake by reducing both the rate of eating and the time spent eating. Peripheral administration of sulpiride reversed the apomorphine effect on both eating rate and eating time but central administration of this neuroleptic into the ventral tegmental area (VTA) selectively reversed the apomorphine effect on eating time, sparing eating rate. Administration of apomorphine directly into the VTA reduced eating time but not eating rate; the effect on eating time was blocked by peripheral sulpiride. The results imply that the two components of apomorphine anorexia result from actions at different sites. Effects of apomorphine on eating time appear to result from an action on DA cell body autoreceptors. The apomorphine effect on eating rate appears to be mediated elsewhere.