With the increase in population and industrialization, the environment gets contaminated from the release of harmful wastes into the atmosphere, disruption of natural habitats, and an increase in the production of domestic wastes. Thus, there is a need to ensure environmental health and reduce population growth. All these and more, like personal harmful habits and chronic diseases, can predispose a person to infections and health hazards.
Sepsis
The body, however, has ways of identifying and combating these diseases. One of these is inflammation. Inflammation is part of the body’s response to injury or disease. Here, there is swelling, redness, pain, and loss of function at the level of the tissues.
Inflammation and homeostasis
Since the body aims at maintaining homeostasis and balance, the inflammatory response is also regulated so there will be minimal tissue destruction. Hyperinflammatory states may cause a myriad of inflammatory diseases like autoimmune pathologies and metabolic syndromes. It can also contribute to chronic diseases like atherosclerosis, cardiovascular diseases, cancers, and Alzheimer’s disease.
Two pathways help the brain detect inflammation and thus lead to inflammation regulation. The neural pathway involves the sensory afferents of nerves that send signals to the brain of local inflammation, and the humoral pathway, which deals with the entrance of inflammatory mediators into the brain.
The brain integrates the signals from both pathways, and it gives its regulatory response through the hypothalamo-pituitary-adrenal pathway (neuroendocrine), autonomic and limbic response, and behavioral elements.
The neuroendocrine response involves the release of cortisol, which subserves anti-inflammatory responses. Cortisol is the major stress hormone.
The autonomic response involves the vagal system, which subserves local anti-inflammatory properties, and the sympathetic nervous system. Mood, sleep, appetite, and attention are also affected. Thus, homeostasis is maintained. However, psychological and immunological disorders may arise when these responses are ill-fitted.
The neural circuit
To study this relationship between anti-inflammatory response and psychological disorders, research was carried out by Professor Pierre-Marie Lledo and his team on mice that had sepsis.
Sepsis is a severe infection that can induce the body’s anti-inflammatory response. In addition to being a leading cause of death across the globe, chronic psychological disorders like depression, anxiety, and post-traumatic stress disorder have also been associated with sepsis. Hence, the study was carried out by Professor Lledo and his team.
In this study, a dedicated neural circuit made up of the bed nucleus of the stria terminalis and the central nucleus of the amygdala, discovered through pharmacogenetic techniques, was activated within the first few hours of sepsis in mice. This circuit, in turn, induced anxious behavior which mimicked the post-traumatic stress disorder seen in patients recuperating from sepsis. This anxious behavior in the mice was observed after two weeks of infection clearance.
Clinical significance
Since psychological disorders affect the lives of patients and can lead to suicidal tendencies, it is important to study the various pathways of the disease and proffer solutions.
This study reveals a relationship between psychiatric disorders and sepsis, which is an inducer of anti-inflammatory response. With this knowledge, there is a better understanding of post-traumatic stress disorder among patients recovering from sepsis. Pharmacologic treatments can also be developed. Hence, there is a need for further research.
Conclusion
Professor Pierre-Marie Lledo and his team’s research offers hope for a reduction in the incidence of psychiatric disorders among patients.
References
Silencing of amygdala circuits during sepsis prevents the development of anxiety-related behaviours