Most people are aware of various symptoms caused by the stress that we experience on a day-to-day basis. However, there are a variety of physiological reactions that affect our peripheral and central systems.
According to a recent article in Science Magazine, scientists at Cold Spring Harbor Laboratory have zeroed in on the neural circuit’s reaction to stress. In addition, the scientists determined that the neural circuit affects the immune system.
Reaction to stress is not only biological but also psychological. When the stress circuitry is activated, it creates the well-known “flight or fight” response.
This leads to responses such as glucocorticoid secretion via activation of the HPA (hypothalamic-pituitary-adrenal) axis. HPA is the central stress response system that interconnects with the endocrine system and the central nervous system.
The HPA axis produces cortisol when it is confronted with a stressor. The body reacts to threatening situations by activating neural mechanisms that are regulated through the mid-brain. Ultimately, epinephrine and cortisol, known as stress hormones, are released.
Epinephrine produces activity in the nervous system. This encourages our ability to distance ourselves from threats.
Cortisol secretion follows but when the threat no longer exists cortisol’s activation abates. Physicians emphasize the importance of maintaining healthy cortisol levels. This ensures that the pituitary and hypothalamus glands have the requisite level of sensitivity when confronted with feedback from cortisol.
A complete description of the process is available here.
It may be noted that the pituitary and hypothalamus become less sensitive to feedback from cortisol as a person ages. It is also interesting that older females will secrete more cortisol when in stressful situations than older males. The reverse occurs with young females producing lower levels of cortisol than young males.
About Neurons, Stress, and Insomnia
Scientists have discovered that there is a correlation between neurons that react to stress through the release of cortisol and neurons in the same region that cause insomnia. It appears that signals sent out by hormone-releasing brain cells strongly affect the neurons that cause insomnia.
The researchers tested this theory on animal models. They interrupted the connection allowing mice to sleep undisturbed even after the mice had been exposed to stress.
The team observed that the switch was very sensitive, and even a weak stimulus could cause insomnia. This theory also applied to the immune system when the researchers found that they were able to make changes to cell distribution via that same connection. For example, the same neurons linking stress to insomnia.
Looking Forward
The aforementioned discoveries have created an interest in whether the brain’s circuits that are associated with whole-body (systemic) inflammation, such as cancer and IBD, can also be manipulated.
