A few weeks can go by before antidepressants unfold their action. (Pixabay.com)

Diverse medications are now available that can be used for treating depression. Previously, tricyclic and tetracyclic antidepressants were commonly at the center of a therapy, however the selective serotonin re-uptake inhibitors (SSRI) have now established themselves over the course of the last decade.

All antidepressants share the characteristic that they influence the various neurotransmitter systems. The effects and side-effects of the various medications depend on which neurotransmitters they influence and on how many.

The older, classical medication (for ex. tricyclic antidepressants) intervene in several systems, whereas the more recent antidepressants (eg. SSRI) have a more targeted impact and are more compatible.

How do antidepressants work?

Find out more about the effect mechanisms of antidepressants.

Various medicinal mechanisms can help re-establish the balance as regards neurotransmitters:

  • Inhibiting the re-uptake of serotonine

After the neurotransmitters have “docked” onto the receptors of the postsynaptic neurons and have performed their signal transmission task, the transmitters are transported back into the pre-synaptic neuron. This mechanism is called “re-uptake”.

Specific active elements, the so-called re-uptake inhibitors, can block the particular transport molecule that is responsible for returning the neurotransmitters, meaning that the path of the neurotransmitters is basically blocked. They remain longer in the synaptic gap and can transmit the desired signals multiple times. The effect of older as well as more recent antidepressants is based on inhibiting the re-uptake.

  • Increasing the release of neurotransmitters

Generally speaking, the presynaptic neurons register if particular receptors have already released neurotransmitters in sufficient quantities. In case the medication is blocking these receptors, the release is not stopped, and the neurotransmitters “flood”, as it were, the synaptic gap.

  • Inhibiting the degradation of neurotransmitters

In a normally functioning cerebral metabolism, the formation and degradation of neurotransmitters are well balanced. Specific enzymes are involved in the degradation process. When these are inhibited by the use of medication, a higher amount of neurotransmitters are formed rather than deteriorated, which leads to a higher concentration. The so-called MAO-inhibitors are based on the same principle.

Text: Helga Grafe – 11/2015
Translation from German: MyH – 06/2016

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