Histamine may be a key factor in depression

If repeated in humans, this discovery-identifying histamine as a "new interest molecule" in depression-may open up new avenues for the treatment of depression

Inflammation-a broad term describing the immune response-triggers the release of histamine in the body

Lead author Dr.

"Our research focuses on histamine as a potentially key factor in depression

Chemical messenger

Serotonin, often referred to as the "feel-good molecule", is a key target of drugs for treating depression

However, although SSRIs have brought relief to many users, more and more people are resistant to their effects

With this in mind, researchers began to investigate the relationship between histamine, serotonin, and SSRIs

They made microelectrodes that can measure serotonin and put them in the hippocampus of the brains of living mice, which is the area that regulates emotions

After placing the microelectrodes, they injected lipopolysaccharide (LPS), an inflammation-causing toxin found in certain bacteria, into half of the mice, and injected saline into the other half of the mice as a control

Within a few minutes after the injection of LPS, the serotonin level in the brain decreased, while the serotonin level in the control mice remained unchanged, indicating how quickly the inflammatory response in the body was transformed into the brain and affected serotonin

In further research, they found that histamine in the brain is triggered by an inflammatory response, and directly inhibits the release of serotonin through inhibitory receptors attached to serotonin neurons

To solve this problem, researchers injected mice with SSRIs, but their ability to increase serotonin levels was far less than that of control mice

Then, the researchers took histamine reducing drugs while taking SSRIs to counter the inhibitory effects of histamine, and found that the serotonin level returned to a controlled level

A new interest

Researchers say that if their research results are applied to humans, it can help us ultimately diagnose depression by measuring chemicals such as serotonin and histamine in the human brain

They also said that this discovery opens up new avenues for studying histamine as a trigger for depression, including the possible development of new drugs that reduce histamine in the brain

Because this research was conducted on animals, more research is needed to know whether these concepts are applicable to humans

The pain that accompanies inflammation can also change neurotransmitter levels-but previous studies have shown that in similar models, these changes last for a few minutes, while the serotonin decline shown in this study lasts longer, excluding Pain is the cause of the decline in serotonin
.

Dr.
Hashmi added: "Inflammation is a systemic response, so it is very complex
.
Depression is also complex, and the chemicals in it are affected by multiple genetic and environmental factors
.
Therefore, we need to study more complex mice and A behavioral model of human depression to better understand the role of histamine and serotonin in depression
.
"

Journal Reference :

1. Melinda Hersey, Srimal Samaranayake, Shane N.
   Berger, Navid Tavakoli, Sergio Mena, H.
   Frederik Nijhout, Michael C.
   Reed, Janet Best, Randy D.
   Blakely, Lawrence P.
   Reagan, Parastoo Hashemi.
   Inflammation-Induced Histamine Impairs the Capacity of Escitalopram to Increase Hippocampal Extracellular Serotonin .
   The Journal of Neuroscience , 2021; 41 (30): 6564 DOI: 10.
   1523/JNEUROSCI.
   2618-20.
   2021