Therefore, if you're planning a long journey, you should always apply for the Russian visa before you leave. It's possible to get a tourist visa support at any moment before your journey, however, you can only apply for a tourist visa not earlier than 90 days before the date of your first entry to Russia.
Serotonin is a common neuromediator in the brain. It belongs to the group of so-called biogenic amines, relatively simple chemicals that facilitate the transfer of signals between the cells of the body.
SSRIs block the reabsorption (reuptake) of the neurotransmitter serotonin in the brain. Changing the balance of serotonin seems to help brain cells send and receive chemical messages, which in turn boosts mood. Most antidepressants work by changing the levels of one or more of these neurotransmitters.