A neurochemical differentiation between exposure to stress and the development of learned helplessness

Abstract Both learned helplessness and stress produce deficits in escape/avoidance behavior. The yoked control paradigm was used to compare these two phenomena, with pairs of animals exposed to the same amount of shock—in one case controllable (stress) and in the other uncontrollable (learned helplessness). Stressed animals demonstrated a transient (one day) elevation in serotonin levels in the septal synaptosomal pellet. On the other hand, animals subjected to uncontrollable footshock sustained a significant decrease in septal synaptosomal serotonin for five days. Similar differences were found in the anterior cortex, but not in the posterior cortex or hippocampus. This work demonstrates the importance of using appropriate controls in neurochemical and pharmacologic research with learned helplessness.