development of biological psychiatric depression research authors transl the discovery of the antidepressive effects of imipramine and the mao inhibitors associated with the occasional depressions occurring during reserpine treatment was the starting point of modern research into depression the concern with the neurochemical actions of these substances led to putting forth the noradrenaline and serotonin hypothesis of depression in the mid60s according to this there is supposed to be a deficiency of noradrenaline andor serotonin at the nerve endings in depression this amine deficiency hypothesis has not been proved as yet in spite of intensive neurobiological research clinical as well as animal experiments in depressive patients with antidepressive drugs have led to the assumption that in endogenous depression particularly but also for the antidepressive mechanisms alpha and betaadrenergic receptor changes play an important part