Is Cortisol the Aging Hormone?

Abstract

The “Dorian Gray” senescence of several fish species and a small Australian marsupial mouse (Antechinus), is well documented to be caused by a large increase of cortisol triggered by stress. While cortisol is important in response to trauma, infection, exercise, anxiety, depression and up to 10-fold during surgery, it may also cause involution of the thymus, depression of immune response, tissue damage, fat deposition, confusion and dementia. Excess cortisol is transported by the cortisol binding globulin (CBG) and by albumin. The specific affinity for albumin is lower, but the total binding capacity over 1000-fold higher (42g/L = >200,000ug/L), than CBG (0.037g/L = 250ug/L). With increasing cortisol levels, CBG becomes saturated and a larger proportion of cortisol is carried by albumin. Synthetic glucocorticoids and other hormones are also albumin-bound. In fish and Antechinus the level of albumin is low, perhaps explaining why excess cortisol can cause rapid aging, associated with immune depression. In premature infants, hypoal-buminemia and in the elderly, albumin is decreased and the proportion of free steroid increased during stress. This factor may help explain why the level of serum albumin has emerged in major studies as an important biochemical factor in determining all-cause mortality and morbidity. One area that has shown the possibility of achieving high albumin profiles (55g/L, A/G ratio 2.75), is a hygiene regimen. Hygiene reduces globulin levels, allowing higher albumin levels, while maintaining total protein. We have observed very high albumin profiles (59g/L and an A/G ratio 4.13), associated with the use of a hygiene regime in a few cases.