Behavioural Specificity
If a drug reduces gross food intake following acute administration, a number of different studies can be performed to confirm that it is acting specifically on the mechanisms controlling food intake rather than producing non-specific behavioural disruption or drug-induced malaise.
Satiety Sequence Profiling
This technique can be performed in rats or mice and couples behavioural observations with measurement of food intake. It examines the effects of drugs on the four components of the natural satiety sequence (feeding followed by activity, grooming and resting) that occurs when an animal eats until it is full. Animals are also closely observed for any other overt behavioural effects which could affect food intake.
The test can therefore be used to assess whether drugs are decreasing food intake by physiological mechanisms (ie by enhancing the natural process of satiety) or by inducing non-specific disruption of normal feeding behaviour (eg by producing sedation, excitation or stereotypy). It can be performed after both acute and repeated drug administration (ie as part of chronic feeding studies).
Pica (Kaolin Intake)
Some drugs may decrease food intake by producing gastrointestinal malaise which can be difficult to detect as the animals may look behaviourally normal. Rats and mice lack the emetic response but the persistent eating of non-nutritive substances in rodents can be used to measure illness-response behaviour analogous to vomiting in other species. These animals are thought to consume the inert material to absorb the toxin and expel the noxious substance from the gastrointestinal tract.
This behaviour is called pica and is normally assessed by measuring the effects of drugs on kaolin intake. For example, a clinically acceptable antiobesity agent would be expected to reduce food intake in rodents at doses that did not induce kaolin consumption.
