upregulation-downregulation hypothesis

up·reg·u·la·tion-down·reg·u·la·tion hy·poth·e·sis

(ŭp'reg-yū-lā'shŭn-down'reg-yū-lā'shŭn hī-poth'ĕ-sis) A theory of the neurochemical basis of depression (an elaboration of the monoamine hypothesis) linking it to an increase in number (upregulation) of postsynaptic monoamine receptors, which are then effectively decreased in number (downregulation) as a result of antidepressant activity.
See also: monoamine hypothesis