What can result from noise stress in laboratory animals?

Noise stress in laboratory animals can lead to various physiological and behavioral changes, one of the most significant being the enlargement of the adrenal glands. When animals are exposed to stressors such as loud or unpredictable noises, their bodies respond by activating the hypothalamic-pituitary-adrenal (HPA) axis. This activation results in the production of stress hormones, primarily cortisol in most species.

The adrenal glands, responsible for producing these hormones, can enlarge as a result of chronic stress exposure. This glandular enlargement is an indicator of the animal's physiological response to the continuous stress that can affect their overall health and well-being.

While other options might imply positive or unrelated outcomes to noise stress, such as improved breeding efficiency or better auditory health, these do not align with established scientific understanding. Instead, the enlargement of the adrenal glands reflects a biological response that can lead to various adverse effects on health and behavior. Increased stress can compromise immune function, lead to alterations in breeding outcomes, and affect overall animal welfare, highlighting the importance of managing environmental factors in laboratory settings.