Assessment of anxiety was described earlier in this chapter (“Behavioral Screening of Genetically Modified Animals, Assessment of Anxiety”).
Several testing paradigms assess responsiveness of rodents to drugs that have abuse potential, including paradigms involving self-administration of alcohol, cocaine, morphine, or nicotine (Crawley, 1999; Grahame and Cunningham, 1995). Self-administration is typically achieved by requiring the rodent to press a lever or display a place preference. Tolerance, dependence, and withdrawal symptoms can be studied. With this approach, transgenic mice may have locomotor or coordination difficulties that interfere with self-administration (McClearn and Vandenbergh, 2000). Additional information is provided in Chapter 8 (“Addictive Agents”).
The primary goal of the preceding behavioral assays is the induction of stress or aversive states. It is important for the investigator to determine the earliest possible or least severe endpoint when the manipulation has adverse effects on an animal. Any behavioral test that subjects animals to water has the potential for evoking a stress response. Therefore, it is important that the time that the animal is in the water be minimized and that animals be monitored closely to avoid unnecessary stress. Animals should be dried thoroughly after the swim test, and it is advisable to place their cages on a heating pad for several minutes. The use of unregulated heating pads or heat lamps should be avoided as they can develop hot spots and cause thermal burns.
Continuous monitoring is also important for automated tasks, such as tasks that use roto-rods, platforms, or other devices in which animals may be injured. Because of the likelihood of multiple testing, excellent record keeping is imperative.
Some neuroscience research involves exposing animals to behavioral stressors. These manipulations can be social (such as involving social separation or mixing of unfamiliar animals) or nonsocial (such as exposing animals to novel environments or restricting behavioral activity).
This research focuses on three avenues of investigation. The first is aimed at understanding the effects of exposure to behavioral stressors on aspects of neural function or conversely understanding how neural manipulation affects responses to behavioral stressors (von Borrell, 1995). For example, a pregnant monkey