Thinking and worry
Semax and Selank began with different hopes
Russian scientists made Semax to study memory and Selank to study anxiety. Most tests used animals; your safety and likely benefit remain uncertain.
The early hopes still need stronger tests
Russian scientists hoped Semax would help memory and Selank would ease anxiety. They made the compounds in a lab, then tested mostly rats and mice.
Cognitive means thinking; nootropic means intended to help thinking or memory. Those words name the research hopes, rather than benefits proved for you.
A peptide contains a few linked parts also used to make proteins. Semax and Selank are peptides, but their parts and aims differ.
Injured rats supplied some hopeful Semax findings about memory and nerve survival. Selank tests asked whether anxiety could ease without leaving the rats sleepy.
The human studies are limited and mostly come from Russian research centers. Neither compound has FDA or EMA approval from the US or EU medicine agencies.
You may be wondering whether either compound could help your memory or worry. An animal's response cannot settle whether the compound will help your daily life, since a test of injured tissue or learned behavior in a rat leaves many human questions unanswered.
Study links let you check which animals or people received the compound and how they responded. These pages offer reading, with no products, medical care or human amounts to take.
The word research does not mean safe for you
Proteins help your body repair damage and carry out its daily work. A peptide uses fewer of the small parts that make a protein.
Scientists can copy part of a natural substance when making a peptide. They can also change parts to affect how quickly the body breaks the peptide down.
Tests of Semax and Selank used animals and cells in dishes. A few small studies also involved people with particular health problems.
Research sellers use the word research because the compounds are meant for lab work. That label doesn't prove useful treatment or lasting safety for your health.
For healthy people, repeated use still leaves basic questions about benefit and harm. A result from an injured rat cannot show whether your thinking would improve.
One rat test used a single 50 micrograms, or millionths of a gram, for each kilogram of rat weight through the nose. Each rat's amount depended on how much the rat weighed.
The figure describes the rats' test, with each kilogram meaning a measure of body weight. The rats were a breed kept for lab work, rather than people receiving treatment.
A natural starting substance can explain why scientists decided to test a compound, but copying that substance does not prove that the new compound will help you or be safe with your medicines. The animal amount gives no starting amount for a person.
The rat tests measured different kinds of changes
Most results concern rats or mice, so you cannot expect the same changes. The tests often measured brain tissue, rather than useful changes in daily life.
Semax borrows part of a hormone, a substance that carries messages around your body. Scientists added end parts to slow Semax's breakdown.
Rat brain cells took early steps toward making more proteins that support nerves [3][4]. One test also found more finished protein, though the changes differed between brain areas.
In injured rats, Semax changed how cells used genes linked to defenses and blood vessels [2]. Genes carry directions that cells read when making proteins; those changes alone don't prove stronger defenses or better blood flow.
Semax also stuck briefly to the surfaces of rat brain cells [4]. Finding that contact helps explain how Semax reaches cells, but doesn't show better memory.
Selank began with a natural substance involved in the immune system. Its makers added end parts like Semax's, while keeping a different main part.
In rat tissue, Selank helped more of a calming brain chemical stick to cells [8]. In another lab test, natural calming substances broke down more slowly [7].
Within one hour, rat brain cells made more or fewer copies from 45 genes [10]. Cells read those copies to make proteins involved in quieting nerves; the test didn't measure calmer behavior.
You can compare these peptides by the animals and people actually tested. Chemical changes help explain further research, but don't settle your treatment choices.
Personal accounts do not prove what caused a change
Most papers come from a few Russian centers, and human tests remain limited. The references list gives the papers behind the numbered study links.
A review brings earlier findings together instead of testing another group of people. Repeated accounts of one test don't make the test larger or longer.
People who try Semax or Selank on their own sometimes describe changes they felt in daily life, but those accounts do not mean the writers took part in a medical study. A personal experiment gives no fair comparison with another kind of care.
Their accounts haven't been checked by comparing similar people receiving different care. You cannot tell whether the compound, another medicine or something else caused a change.
Feeling better matters to the person who reports feeling better. The account still cannot prove a benefit or show that serious harms won't occur.
Your strongest clue is what researchers measured in the people or animals tested. When a study measured only tissue changes, improved daily life remains unproved.
Semax
Most Semax tests over two decades used rats or mice. Researchers checked memory after injury and proteins that help nerve cells survive.
Read what happened ›
Selank
Selank was tested for anxiety, or worry that won't settle down. Rat tests and small human studies also examined the immune system, your body's defenses.
Look at the worry tests ›