The mechanism of action of antidepressant treatments: basic aspects.

Antidepressant drugs and electroconvulsive shock (ECS) have, following repeated administration, been shown to produce diverse biochemical changes in rodent brain. Most drugs and ECS decrease the density of beta-adrenoceptors in the forebrain and several drugs and ECS decrease the function of alpha 2-adrenoceptors. Antidepressant treatments also attenuate the temperature response to the 5-HT1A agonist 8-OH-DPAT but 5-HT2-receptor number and function are both decreased by antidepressant drugs but increased by ECS. GABAB receptor number and function are increased by antidepressant treatments. It remains unclear which of these changes are involved in the therapeutic mechanism of action.