Histamine Could Be Bridge Between Inflammation and Depression

Histamine could be the key for us to understand why some individuals are not affected by drugs with antidepressant properties.

Through the help of mouse subjects and a series of examinations, it was determined that the process of inflammation-induced histamine in our brain can influence the production of serotonin.

In the new study, experts theorized that the link between serotonin and histamine holds the solution that will allow us to specify the origins of depression.

Inflammation and Depression

(Photo: Andrew Neel from Pexels)

Inflammation and depression are two separate conditions that attack different systems of our bodies. However, the combined efforts of scientists throughout the years of medicinal studies have given them an opportunity to discover the link between the two problems.

One example of autoimmune disease that affects brain activities is inflammatory bowel syndrome. Based on previous studies, the patients with this bowel disease also suffer irritation and mood disorders.

Inflammation and depression, although potentially correlated to each other, are still a great topic for scientific theories and debates. With that said, a group of experts took the first comprehensive investigation on how inflammation can cause emotional distress, resulting in depression.

The research about inflammation and depression correlation required experiments that could read and measure moods of a body that experiences inflammation. The trials were possible with the help of the hippocampi models in mouse subjects.

New Atlas reported that through the experiments, researchers were able to observe the changing rates of serotonin via the microelectrode implanted in the subjects' brains.

Serotonin is a crucial part of the brain that is responsible for mood regulation. It is also subject to studies as well as treatments to fight depression.

The inflammatory responses in the brain of subjects were triggered through the use of toxins injected. By going through this process, experts pinpoint the influences of inflammation on serotonin levels, and within minutes, the results showed that serotonin in the hippocampus significantly decreased.

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Escitalopram Efficacy Blocked by Inflammation-Induced Histamine

However, the researchers observed that the toxins injected into the hippocampus were not able to cross the blood-brain barrier. This means that inflammation alone is not the only factor at work.

In the following trials, the scientists were able to see that the animal's response causes a massive production of histamine in their brains. In conclusion, the high rates of histamine are relative to the drop of serotonin.

Selective serotonin reuptake inhibitors or SSRIs are the formulations used during the next experiment. SSRIs are among the family that contains antidepressant properties commonly found in escitalopram.

When treated with the SSRIs, the subjects under inflammatory conditions were not seen with an increase of their serotonin levels. The reason was that the antidepressant itself blocks the histamine clearance, therefore stopping the serotonin activities.

For the final step, the subjects under inflammatory conditions were once again given an antidepressant, but this time, it is relayed along with a separate drug with histamine reduction properties.

The combined effects of both drugs were able to successfully bring back and increase serotonin levels again. The study was published in The Journal of Neuroscience, titled "Inflammation-Induced Histamine Impairs the Capacity of Escitalopram To Increase Hippocampal Extracellular Serotonin."

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