The new function of auxin
It is reported that the annual meeting of the Diet Behavior Research Society was held in the Netherlands in early 20 19. At the meeting, neuroscientists from the University of Southern California put forward a new function of Ghrelin-participating in controlling brain memory, especially situational memory.
Previously, scientists believed that auxin played a special role in sending hunger signals from the intestine to the brain. In this study, the researchers found that auxin is also involved in brain memory.
Ghrelin, translated as ghrelin and brain-gut peptide, is a kind of brain-gut peptide, which is secreted in the gastrointestinal tract and acts on the brain. Specifically produced by endocrine cells at the bottom of the stomach, it is a brain-gut peptide recently discovered and the first hormone that can stimulate appetite. It is secreted before eating and is famous for increasing hunger.
Dr Elizabeth Davis, the author of the article, said at the meeting: Ghrelin is secreted into the blood by secretory cells at the bottom of the stomach, and binds to special receptors of vagus nerve to transmit signals from the intestine to the brain. It will not only increase the hunger and food intake when eating, but also affect people's memory function. This function is mainly realized through the intestinal brain axis.
They designed a series of mouse experiments for this purpose. The experimental design is to make mice need to remember specific objects in specific places.
In the experiment, they first used RNA interference technology to reduce the number of auxin receptors, thus blocking the auxin signal in the vagus nerve of experimental rats. Compared with the control group, the rats with reduced Ghrelin signal in vagus nerve were obviously damaged in "situational memory"
So what is episodic memory?
It refers to consciously recalling memories about personal experiences. Such as dialogue, storage location, movie plot, face, sense of smell. Simply put, it's like "three elements of news writing": what happened, when and where.
Image source: Nature Review Gastroenterology &; Hepatology
Vagus nerve is a "highway" connecting gastrointestinal tract and brain.
Scott Kanoski, one of the researchers of this discovery, clearly put forward the concept of gut-brain axis in an article published in Nature Communications last year. It is pointed out that vagus nerve is the key to nerve communication between gastrointestinal tract and brain.
Vagus nerve is a highway connecting what scientists call "two brains", one in your head and the other in your gastrointestinal tract.
Image source: Natural News
In this paper, experiments in mice show that the spatial and situational memory dependent on hippocampus can be damaged by vagotomy in gastrointestinal tract or selective elimination of most signals input to brain, which is related to the decrease of neurogenesis and the expression of neurotrophic biomarkers (such as ghrelin) in gastrointestinal tract.
The more profound contents of this paper include: the medial septal nucleus (MS) is the transition region connecting the medial subnucleus of the nucleus tractus solitarius and the glutamate neurons in the dorsal hippocampus; The first stop for the brain to receive gastrointestinal vagus nerve sensory signals is the medial subnucleus of the nucleus tractus solitarius.
At this time, the conclusion of the article has come out: vagus nerve signals from the digestive tract can promote hippocampus-mediated memory function.
Image source: Natural News
In fact, this may be related to the evolution of our ancestors.
Scott Kanoski, the author of the article, said, "In the distant primitive times, we still collected tribes, not planted them. Ancestors need to remember where they found and collected food so that they can go there again and again. 」
For example, whenever I am hungry, my ancestors' brains will think of an apple orchard on the other side of the river. I had a good time last time, and I will go again today.
This links ghrelin with "situational memory".
Scott Kanoski also gave an example: "At that time, the interaction between the intestine and the brain was as important as the Google Maps navigation application. 」
If the human body really has a "second brain", it must be a "gut brain".
The intricate nervous system in the gastrointestinal tract is often regarded by scientists as the second "brain" and the second command system of the human body.
Emmmm, maybe this is another way to develop "weight loss surgery"?
Cover source: Station Cool Luo Haijia Image taken from freepik
Subject: ghrelin, RNA, brain memory, bariatric surgery, gut brain, ghrelin, ghrelin.