This is different.However, most antidepressants work by blocking a certain transporter protein so that it can no longer do its “normal job”.
In this case, this would be the return of serotonin from the synaptic gap back to the pre-synaptic nerve cell, i.e. into the nerve cell that is located in front of the synaptic gap, not the one behind it.
As a result, more and more serotonin accumulates in the synaptic cleft, making it much more likely that the serotonin molecules may bind to the corresponding receptors that are located on the cell membrane of the post-synaptic nerve cell.This in turn causes the post-synaptic nerve cell to become more aroused by serotonin. It is thought that the antidepressant effect is based on this mechanism.
This mechanism of action mainly refers to the SSRIs (selective serotonin reuptake inhibitors).
Some antidepressants also have the same effect on norepinephrine (SNRI’s: Serotonin and Norepinephrine Reuptake Inhibitors) and sometimes to a lesser extent on dopamine.
Then there are e.g. NDRI’s (Noadrenaline and Dopamine Reuptake Inhibitors).These block the transporter protein, which transports norepinephrine and dopamine back into the pre-synaptic nerve cell.
If you are interested in the topic, you can search the Internet for the following keywords:
Tricyclic antidepressants and tetracyclic antidepressants (both types are in principle the oldest species available on AD, i.e. antidepressants); NaSSA (Noradrenergic and Specific Noradrenergic Antidepressants) – act by either antagonizing (“blocking”) certain serotonin and norepinephrine receptors or agonizing (activating); SSRI’s, SNRI’s, NDRI’s and SSRI’s; MAO inhibitors (selegilin, for example) act by inhibiting the enzyme (monoamine oxidase), which is responsible for splitting monoamines and thus inactivating: monoamines are serotonin, dopamine and norepinephrine.
I can’t think of more types of antidepressants spontaneously.
The reason why there are so many different is probably that there are as many different ways as possible to treat someone.If one type of AD does not (good) work, another can be tried.
I think that’s one reason.The other is probably money. The more (different) drugs there are on the market, the more the pharmaceutical industry deserves it.
I hope I could help.
P.S.: Only as a warning: MAO inhibitors should never be mixed with SSRIs, SNRI’s and/or SDRI’s.This is due to the fact that both types of substances have a strong synergistic effect. That is, they reinforce each other. This can lead to a certain potentially life-threatening complication (the serotonin syndrome) because too much serotonin is toxic.