Fenfluramine anorexia: a peripheral locus of action

Area of Science:

• Neuroscience
• Pharmacology
• Gastroenterology

Background:

• Amphetamine and fenfluramine are known to affect feeding behaviors.
• Understanding the mechanisms by which these drugs influence appetite and eating patterns is crucial.

Purpose of the Study:

• To investigate the distinct effects of amphetamine and fenfluramine on feeding patterns.
• To elucidate the role of gastric emptying and gastro-intestinal signaling in fenfluramine's anorectic effects.

Main Methods:

• Administration of amphetamine and fenfluramine to rats to observe feeding patterns.
• Measurement of meal size, frequency, and post-meal intervals.
• Assessment of gastric emptying rates following drug administration.
• Investigation using midbrain raphe lesions and intracerebroventricular administration.

Main Results:

• Fenfluramine induced a regular feeding pattern with reduced meal size and prolonged post-meal intervals, linked to decreased gastric emptying.
• Amphetamine caused anorexia and nibbling, with less pronounced effects on gastric emptying.
• Midbrain raphe lesions did not affect fenfluramine's impact on gastric emptying or overall food intake.
• Intracerebroventricular fenfluramine did not suppress feeding, suggesting peripheral mechanisms.

Conclusions:

• Fenfluramine's anorectic effect is primarily mediated by short-term signals originating from the upper gastro-intestinal tract.
• Gastric emptying plays a significant role in fenfluramine's control over feeding behavior.
• Amphetamine's effects on feeding are less dependent on gastric emptying compared to fenfluramine.