The symbols can be translated as follows:



Electrical currents: In reality, the current is generated by depolarizations of cell membranes that are adjacent to each other. Small packages of neurotransmitters are secreted into the tiny spaces between brain cells (neurons) where it leads to the creation of microscopic currents in adjacent nerve cells. The current thus spreads from one cell to another; a microscopic chain reaction.



Electrical outlets: In reality these are post-synaptic receptors on the nerve cells. Synapses are the tiny gaps between brain cells where they interact with each other via the secretion of the neurotransmitters. In depressed patients, there is an increased number of post synaptic receptors generated. In treated depressed patients, over 1-2 weeks there is a reduction in the number of these receptors in a process called down regulation. Feeling better often tends to correspond with this down regulation process, or some other process we don't understand, which is why there is often a delay of 1-2 weeks between the time one starts taking an antidepressant and the time when one actually starts to feel better from it.



Neurotransmitters: The main neurotransmitter system affected by Wellbutrin is norepinephrine. Wellbutrin is part of a class called the Norepinephrine Dopamine Reuptake Inhibitors (NDRIs). By blocking the re-uptake of norepinephrine and dopamine, the medication increases the amount of norepinephrine and dopamine in the synapses between the cells thereby increasing the current. Thus starts the cascade that results ultimately in a renewed equilibrium.


Second Messenger Systems: Basically think of a pitcher brain cell throwing balls of norepinephrine to a catcher brain cell.  The catcher cell, after it catches the norepinephrine ball, has its own set of reactions. These are complicated and involve a cascade of chemical reactions involving the enzyme adenylate cyclase, Cyclic AMP (cAMP) and other microscopic intracellular substances. These chemical reactions may be important to the mechanism of action.


Hypothalamic Pituitary Axis (HPA): This is a different ball of wax involving the concept that a difficult childhood may lead to an overactive cortisol system, specifically an increase in Corticotrophin Releasing Factor(CRF). Maybe antidepressants work by decreasing CRF.


THE WEB: Maybe it is not the norepinephrine/dopamine current alone but a complex web involving multiple currents that is affected. Alternatively, maybe we are lumping together many distinct subtypes of depression when in reality different subtypes have entirely different mechanisms of action. Then there would not be "one" mechanism of action, but several. We don't know.