Serotonin-1A receptor responsiveness in stress and following adaptation to stress.
Stress is one of the environmental factors that may predispose psychiatric illness such as, depression. Stress may come from external environment in the form of stimuli such as heat, cold, loud noise and lack of oxygen. A deficiency of serotonin (5-hydroxytryptamine; 5-HT) is described in human depression. Parallel studies on experimental animals show that exposure to an uncontrollable stress inducing situation elicits behavioral deficits and increases serotonin metabolism in the brain. Stress-induced behavioral deficits and the increases of brain serotonin did not occur when the stress was administered repeatedly for 5 days, suggesting adaptation has occurred. The present study shows that responses to 8-hydroxy-2-(di-n-propylamino)tetraline (8-OH-DPAT), a selective 5-HT 1A agonist decreased following exposure to single stress and the decreases were normalized following adaptation to stress. The drug 8-OH-DPAT was also found to attenuate stress-induced behavioral deficits. The results are discussed in the context of stress-induced psychiatric disorder such as, depression and its treatment by 5-HT 1A agonist.