Neophobicity Experiment
2 January 2006
Background information:
Observation # 1. Food deprived rats which feed to satiety on a first meal should consume a second meal of a more palatable food. This phenomenon in known as sensory specific satiety. However, in an attempt to demonstrate SSS, rats exposed to a novel food item for the first time (Froot Loops) failed to approach and consume the food as expected during an SSS experiment.
Observation # 2.
Rats are known to express neophobicity (fear of the unfamiliar or novel stimulus.) Food intake is commonly measured to assess a rat’s appetite. However, food intake may be reduced if the animal has to overcome a fear of a novel item, such as either the food or the container in which the food is placed. Once accustomed to a novel stimulus, it is likely that food intake would be unaffected by the environment.
Question # 1: Are rats hesitant to approach and eat a novel food?
Hypothesis # 1: The latency to consume rat chow (a familiar food) is not different from the latency to consume Froot Loops or FunYuns (both novel foods.)
Question # 2: Does the palatability of a novel food affect the latency to consume that food?
Hypothesis # 2: The latency to consume rat chow (a familiar food) is not different from the latency to consume Froot Loops or FunYuns (both novel foods.)
Question # 3. Does the palatability of a novel food affect the cumulative intake of that food?
Hypothesis # 3: The cumulative food intake of rat chow (a familiar food) is not different from the cumulative intake of Froot Loops or FunYuns (both novel foods.)
Confounding factors.
Possible neophobicity of the food must be separated from possible neophobicity of the container in which the food is delivered. To control for this, food containers were introduced to the subjects at 10:30 am, approximately 22 hours prior to the experiment in which novel foods were offered. Thus, rats were allowed 22 hours to overcome any neophobicity associated with the container in which the food is to be delivered.
Animals might be stressed by removal from the animal room to the laboratory in which the experiments are conducted. To minimize the impact of this upon feeding behavior, animals are allowed to acclimate to the new laboratory environment for at least 1 hour prior to the beginning of the experiment in which familiar and novel foods are offered.
Experimental Procedure:
Individually housed SD rats (n=21, body weight 413 29 grams) maintained on a 12 hour light:12 hour dark cycle (lights on at 7 am) were fed ad libitum on rat chow. Approximately 22 hours prior to the experiment (at 10:30 am), empty food containers were placed in the cages with the rats to allow the animals to become familiar with these objects. Food was removed 18 hours prior to the experiment. One hour prior to the experiment, animals were transferred to the room in which the experiment was to be conducted to allow acclimation to the novel environment and bedding was removed at this time. At time 0, a pre-weight container of rat chow containing rat chow was place in each cage and the latency to consume and cumulative food intake was recorded at 60 and 90 minutes. At the end of 90 minutes, rat chow was removed and an identical container with a second meal of either rat chow, Froot Loops, or Funyuns was placed in each cage. The latency to consume meal 2 was recorded, as was the cumulative food intake at 30 and 60 minutes after the introduction of the second meal.