A Short Read On The Neuroendocrine Response Of Adrenocorticotropic Hormone In Shock
By C.M Diaz
Introduction: Severe pain or acute stress causes the hypothalamic activation and release of adrenocorticotropic hormone (ACTH). Our natural response is to counteract this stress with some sort of physiologic compensation in order to return or maintain homeostasis.
Today I want to discuss briefly the neuroendocrine response of ACTH to the clinical syndrome of shock (which is defined by Harrison’s 18th Edition; as the clinical syndrome that results from inadequate tissue perfusion – irrespective of the cause).
Physiology: ACTH stimulates cortisol secretion from the adrenal glands (more specifically from the zona fasciculata) which secretes a basal level of cortisol but can also produce bursts of the hormone in response to the level of provocation relayed by ACTH from the anterior pituitary.
This stimulates cortisol secretion that contributes to decreased peripheral uptake of glucose and amino acids, while enhancing lipolysis and increasing gluconeogenesis.
Also, with the increased pancreatic secretion of glucagon during stress – these work to accelerate hepatic gluconeogenesis and further elevating the blood glucose concentration. This increase in gluconeogenesis is important because the need for available energy is important to sustain life.
NOTE – A decrease in ATP along with sustained hypoxia will lead to cell apoptosis along with and increase of proinflammatory mediators and eventually organ failure; thus a shock induced “vicious cycle”
INCREASE MORTALITY: Many critically ill patients have recently been shown to exhibit low plasma cortisol levels and an impaired response to ACTH stimulation, which is linked to a decrease in survival – initially documented by Rothwell et al. which was the largest study examining the response of high dose Synacthen test in Septic patients and was performed by Annane and co-workers.
Reflection: Can you imagine all of these hormones acting synergistically to increase blood glucose for both selective tissue metabolism as well as the maintenance of blood volume? It truly is amazing! Psalm 139:14 says, I praise you because I am fearfully and wonderfully made; your works are wonderful, I know that full well.