Chap3 Amygdala Injury, Stress Causes Brain Injury and Muscle Stiffness
Amygdala of the brain
Stress creates injury in the amygdala of the brain, which becomes depression.At the same time, stress makes muscle stiffness in the body.
This theme “Stress Causes Brain Injury and Muscle Stiffness” has two stories:
1. Chap3: Relationship between stress and brain Amygdala injury in simple words using information from the latest brain neuroscience papers. Here is this story.
2. Chap3B: Relationship between stress and muscle stiffness in a simple and straightforward manner. Please read the next story about Chap3B.
Figure 1: Injured Almonds
The shape of the amygdala in the brain resembles an almond.
Mechanism of Brain Injury in Depression
Dr. Taiju Matsuzawa, a former professor at Tohoku University, analyzed MRI imagery of the brain and made clear that depression is a brain injury.This was around the time of the 1990s. At that time, the mechanism of brain injury in depression was not known. Thirty years have passed since then, we have got some important things while we have not known all of the details.
The phenomenon that appeared in the amygdala of the brain caused by stress has been made clear. It is that the keywords related to stress, amygdala, cortisol, and receptors.
The Amygdala
The amygdala is an almond-shaped structure located at the end of the bottom of the hippocampus.The amygdala of the brain is overexcited by continuous stress. This causes the amygdala to become enlarged. The amygdala is where sensations and emotions are bound together and act on memory.
This causes hypersensitivity in perception and emotion. The injured holes in the amygdala are made that causes depression.
Cortisol
Cortisol is a hormone produced by the body to protect itself from stress. Short-time cortisol secretion protects the body.When the secretion of cortisol continues for a long time, it is a case of continuous stress. When this happens, cortisol will now start to harm the body.
It has been shown to atrophy the nerve cells in the periphery of the hippocampus (we think that includes the amygdala) and create cell death. This is brain damage. Injury to the amygdala causes depression.*1),2),3),4)
Receptors are the switches of household appliances
Receptors are like switches in a cell. It is similar to the switches of various household appliances.There are various switches in home appliances, such as the switch for your phone, the switch for your electric bot, and the switch for your TV.
In the same way, there are various switches in cells. In addition, the location of the switches varies. Some switches are on the surface of the cell, and some are inside the cell.
Cortisol receptors in the amygdala
The hippocampus and amygdala secrete particularly large numbers of cortisol receptors in their cells.Cortisol is a fat-soluble hormone. The outer membrane of the cells is also fat-soluble. The components of water and oil repel each other. Other hand, cortisol is made of the same oil as the cell membrane.
This allows cortisol to enter the cell.
Cortisol enters the cells of the hippocampus and amygdala. (*5) If the cortisol stays in the cell for a long time, It is created cell death.
Mechanism of amygdala injury (my opinion)
When the amygdala is injured, its injury becomes large, a hole is made there. This causes depression. The hole in the cell is made by cell death.The mechanism of cell death is my personal opinion, which I just have come up with. I will explain it as follows.
When cortisol stays in the cells of the amygdala for a long time, the cortisol gradually produces reactive oxygen. This makes killing the cells in the amygdala.
The reactive oxygen species (ROS) produced by cortisol are created by the combination of intracellular chloride ions (Cl-) and the OH group produced during the breakdown of cortisol.
To understand this, think of sodium hypochlorite, which has become famous for disinfecting coronaviruses. Sodium hypochlorite is a kind of chlorine. If we say chlorine, then we image disinfection. Its chlorine disinfects by killing the protein genes of the coronavirus on the surface of the hand.
Cortisol similarly activates the chlorine in the cells, and the reactive oxygen produced by the chlorine kills the cells.
I think it may destroy the cells in the hippocampus and amygdala and make holes in them.
GABA and benzodiazepines also kill brain cells when they stay in the body for a long time.
In addition, GABA and Benzodiazepines inject chlorine ions from outside the cell into the cell. They stay in the cell for a long time, which makes active the chlorine ions (Cl-), which also causes cell death. In this case, I believe it is the action of the chloride ion alone, regardless of cortisol.I have could not find any research results for this part, apparently, it’s not scientifically known, so I thought of it myself. I created something out of nothing, so I believe it is the latest theory.
Maybe if I take the time to look for it, I might find such a theory, but no so far. I did my best, but I am just an acupuncturist in town. I ask for your kindly understanding about my opinion.
I would like to do some more research on this receptor behavior and write a detailed article about it sooner or later.
Academic papers on cortisol damage to brain cells
In the last 10 years or so, it has been an established fact in neuroscience papers that excessive secretion of this hormone causes brain cell damage.1)According to an article in the Journal of the Japanese Pharmacological Society by Prof. Shigenobu Kamba of Kyushu University (as of 2006),
“Severe psychological stress causes hippocampal neuronal loss or atrophy”, which was first reported by Dr. Ryosuke Tada in 2003 and Dr. Youji Hirano in 2004. *2),3),4)
A little more about cortisol
When we are stressed, the body produces anti-stress hormones to protect itself. Excessive stress, or continuous and uninterrupted stress, causes excessive anti-stress hormones to be released into the bloodstream. The main one is cortisol. *6)The function of cortisol is described in “Basic Knowledge of Health Terms” by Yakult Central Institute in Japan.
The main functions of cortisol are to promote metabolisms, such as sugar production in the liver, protein metabolism in muscles, and fat breakdown in adipose tissue, as well as anti-inflammation and immune suppression.
For example, because of its ability to reduce inflammation, it is widely used in therapy as a steroidal inflammatory drug.
As you can read from the above explanation, cortisol is used as a steroid. When steroids are used to treat atopic symptoms on the skin, they work very well at first and reduce inflammation, but long-term use of steroids worsens the atopic symptoms.
The same thing can happen with cortisol in the brain. At first, cortisol protects the brain from stress, but when the secretion of cortisol becomes prolonged and excessive cortisol is constantly present in the brain, it starts to damage the brain.
Preface
1) Long-term exposure to cortisol causes neuronal atrophy
Excerpts from the Brain Science Dictionary
The hippocampus is a part of the limbic system, a brain region involved in memory and learning abilities.
The hippocampus is considered to be highly vulnerable to stress, and prolonged exposure to cortisol due to psychological and physical stress loads causes neuronal atrophy.
2) Hippocampal neurogenesis and mental function,
Folia Pharmacologica Japonica. 128, 3・ (2006),
r Professor Shigenobu Kamba, Kyushu University Japan,
Neurogenesis of the hippocampus and mental function division,
It has been reported that hippocampal neuronal loss or atrophy occurs when severe psychological stress is applied (3, 4). These changes are presumably due to an increase in glucocorticoids caused by an overreaction of the HPA system.
3) Liangsuke Tian , et al. Molecular Psychiatry. 2003;3:32-7.
4) Hirano Yotsugu , et al. Molecular Psychiatry. 2004;4:22-1.
5) Tokyo Medical and Dental University Net Data 4. Mechanism of action of liposoluble hormones. Updated: Aug. 23, 2001
6) Wikipedia Chemical structure of cortisol