Physiological and behavioral responses to stress: What does a rat find stressful?

While numerous environmental manipulations are commonly used as "stressors" in laboratory animals, there are few data to indicate which of these are perceived as stressful by the rat, or whether some manipulations are more stressful than others. In the present study, the authors used bioradiotelemetry to examine changes in heart rate, body temperature, and locomotor activity as indices of stressor responsivity in the rat.