Animal Models in Neuroscience: A Focus on Stress

Abstract

Stress has been studied since the pioneering work of Selye in the mid-twentieth century (Selye, The stress of life. McGraw Hill, 1976). Thus, numerous animal models have been developed by basic research scientists, and they can be applied in acute or chronic stress studies. In addition, some are readily translatable to humans. Here, rodent models are reviewed, and their characteristics described. The effects of stress on higher-order brain functions such as mood and cognitive function are also described. In addition, since recent studies show that responses to stress by females can be different than males, sex as a biological variable is discussed, especially in relation to treatment of stress-related disorders. Chronic stressors generally impair performance of male rodents on commonly used memory tasks including radial arm maze, water maze, and object placement. In contrast, female rodents are either unaffected or show enhanced performance on the same tasks following the same stress. Anxiety increases in both sexes following chronic stress. Depression increases in males following stress, but effects in females are unclear since little rodent research on this topic has included females, despite the fact that human females have higher rates of depression than males. Morphology of neurons and activity of neurotransmitters are altered following stress and, like the behaviors, the changes are sexually dimorphic. Information from most animal models is translatable to humans and can be utilized to develop novel/more effective therapies for disorders which are precipitated by or related to stress such as anxiety, depression, post-traumatic stress disorder, and cognitive loss. With the World Health Organization naming stress the health epidemic of the twenty-first century, it is even more imperative to understand the neural underpinnings of stress.