Anxiety can have a great effect upon the behavior of individuals exposed to stressful situations. In many instances this anxiety may prevent the emission of behaviors that are necessary to alleviate the stressful situation (e.g., making it impossible to study for an upcoming examination that one is anxious about). In many instances minor tranquilizers are prescribed by physicians to help decrease anxiety in their anxious patients. Such individuals can become dependent on these drugs and thus may persistently self-administer and abuse the compound. This research proposal is for investigations of the neurochemical changes that occur in the brains of animals exposed to a stressful situation resulting in anxiety. The objectives of the research are a) to study changes in neurotransmitter systems during the acquisition and extinction of an animal model for anxiety; and b) to concurrently study the acute and chronic effects of minor tranquilizers on the behavior and neurotransmitter systems. The animal model consists of inducing the conditioned emotional response (conditioned suppression of positively reinfoced responding) in rats and measuring changes in the turnover of biogenic amines (serotonin, dopamine, norepinephrine and acetylcholine) in brain areas which interact to process emotion. Since benzodiazepines, barbituates, meprobamate and alcohol are known to act on neurotransmitter systems in naive animals, it is important to establish their role in reversing conditioned suppression. Evidence exists to suggest that neurochemical mechanisms differ in naive versus behaving animals. These drugs have a tranquilizing effect due to a complex interaction between neurochemistry and individual components of the anxiety-producing environment. Following an in-depth analysis of these multiple interactions, one can characterize the neurochemical changes that occur as a result of anxiety and the alleviation of these changes by minor tranquilizers. A better understanding of the brain mechanisms associated with anxiety and how they are affected by minor tranquilizers may permit more effective treatment of this condition and the development of more specific anti-anxiety agents to minimize the abuse of these compounds by humans.