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Apomorphine anorexia: a behavioural and neuropharmacological analysis
Abstract:
Anorectic effects of apomorphine were studied in a microstructural analysis paradigm. Low doses of apomorphine (less than 0.1 mg/kg SC) reduced food intake, by reducing both the rate of eating and eating time. The neuroleptics haloperidol and thioridazine blocked the effect of apomorphine on eating time, but not on eating rate. Anorectic effects elicited by apomorphine administration to the ventral tegmental area and, to a lesser extent, the substantia nigra were mediated by a selective reduction of eating time. Effects of apomorphine on eating time appear to result from an action at presynaptic dopamine receptors; the mechanism of the effect of apomorphine on eating rate is unclear.
Insights
Apomorphine reduces food intake by decreasing eating rate and time. Neuroleptics block the effect on eating time, suggesting dopamine receptor involvement in appetite regulation.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- Apomorphine is known to affect feeding behavior.
- Understanding the precise mechanisms of appetite regulation is crucial for treating eating disorders.
Purpose of the Study:
- To investigate the microstructural components of apomorphine-induced anorexia.
- To explore the role of dopamine receptors in mediating these effects.
Main Methods:
- Microstructural analysis of feeding behavior in response to apomorphine.
- Administration of apomorphine to specific brain regions (ventral tegmental area, substantia nigra).
- Assessment of the effects of neuroleptics (haloperidol, thioridazine) on apomorphine's actions.
Main Results:
- Low-dose apomorphine reduced food intake by decreasing both eating rate and time.
- Neuroleptics blocked the effect of apomorphine on eating time but not eating rate.
- Apomorphine's anorectic effects in the ventral tegmental area and substantia nigra were primarily mediated by reduced eating time.
Conclusions:
- Apomorphine's effect on eating time is likely mediated by presynaptic dopamine receptors.
- The mechanism underlying apomorphine's effect on eating rate remains undetermined.
- Selective reduction in eating time is a key component of apomorphine-induced anorexia.