How antidepressants work. PART 3

Here is the last part of the material about Antidepressants and it is actually about them. After 2 long and sweet parts of a preface here is the last one which describes depression build-up process.
People with depression usually have problems with poor sleep, low mood and appetite, loss of energy and interest or pleasure etc. It is a common illness, affecting 3% of the population per year. The main theory about why this happens is the so-called "monoamine hypothesis".

We know that serotonin and noradrenaline in the brain are involved with control of sleep/wake, emotions, mood, arousal, emotion, drive, temperature regulation, feeding etc. Thus, if a person has too little serotonin and noradrenaline in the part of the brain that controls mood, this will produce too little activity, and that part of the brain become slower and less effective. This will lower mood.

In depression, it is known that there are reduced levels of serotonin and noradrenaline. These reduced levels lead to a lowering of mood. The full reasons are not fully known but stress may well play a part in causing this.

"Normal" communication between cells:

"Reduced" nerve activity e.g. as in depression:

There are lots of other theories about how depression occurs e.g. genetics, how the brain develops, stress etc. There may in fact be many causes and in each person there may be a combination of these. Stress may in fact cause changes in the brain which then result in reduced levels of serotonin and noradrenaline. Transmitters other than much serotonin and noradrenaline are probably also involved.

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How MAOI Antidepressants work

Now let us look carefully at different types of antidepressants. But before doing this, I'd strongly recommens you to read the preface (Parts 1, 2, 3) before you continue to specific types of medicines.

As we understood from the preface,"There are many chemical messengers (or "neurotransmitters") called "monoamines" which occur naturally in the body. One of the effects that monoamines have is on mood. If the levels of monoamines in the body are high we may feel 'high', and if they are low we may feel 'low'. MAOIs stop the breakdown of these monoamines. They block the monoamine oxidase enzyme which breaks down the transmitter, so the next time an impulse comes along, there is more transmitter, a stronger message is passed, and activity in that part of the brain is increased. By stopping the breakdown of these, the MAOIs may bring back the amounts of monoamines to normal. This helps to improve mood in people who are feeling low or depressed.""Reduced" nerve activity but with (mono-amine oxidase) enzyme blocked (or inhibited), and increased messages passed:

Side-effects:
Some antidepressants e.g. the tricyclics, block the reuptake of serotonin and noradrenaline. Others mainly block the reuptake of just serotonin e.g. the SSRIs. The MAOIs block the monoamine enzyme which breaks down noradrenaline, serotonin and some other transmitters. They are Monoamine Oxidase Inhibitors.
Unfortunately, the MAOIs also block an enzyme in the body which breaks down other compounds. One of these is an amino acid called tyramine. Tyramine is an essential compound which the body needs, and is found in many foods. However, if you have too much tyramine in the body, it can make your blood pressure rise. Foods such as cheese, yeast and meat extracts etc contain lots of tyramine. If you eat any of these foods while taking an MAOI, your body can not break down (or metabolise) the tyramine. You then get an excess of tyramine in the body, which increases your blood pressure very quickly. This can at cause headaches initially but can be very dangerous and has caused many deaths.
The MAOIs also affect other transmitters which are broken down by the MAO enzyme.
- Affecting your noradrenaline may also sometimes upset your blood pressure e.g. you may feel dizzy when you stand up etc.

Source.

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