Chunk #3 — Problems of Successful Translation to Humans of Data from Animal Experimentation — The Influence of Laboratory Procedures and Environments on Experimental Results
Laboratory procedures and conditions exert influences on animals’ physiology and behaviors that are difficult to control and that can ultimately impact research outcomes. Animals in laboratories are involuntarily placed in artificial environments, usually in windowless rooms, for the duration of their lives. Captivity and the common features of biomedical laboratories—such as artificial lighting, human-produced noises, and restricted housing environments—can prevent species-typical behaviors, causing distress and abnormal behaviors among animals.8 Among the types of laboratory-generated distress is the phenomenon of contagious anxiety.9 Cortisone levels rise in monkeys watching other monkeys being restrained for blood collection.10 Blood pressure and heart rates elevate in rats watching other rats being decapitated.11 Routine laboratory procedures, such as catching an animal and removing him or her from the cage, in addition to the experimental procedures, cause significant and prolonged elevations in animals’ stress markers.12 These stress-related changes in physiological parameters caused by the laboratory procedures and environments can have significant effects on test results.13 Stressed rats, for example, develop chronic inflammatory conditions and intestinal leakage, which add variables that can confound data.14
