What is the point of the adrenal cortex?
I first developed a research interest in the adrenal cortex about 50 years ago. As for many others, these studies gave a detailed insight into several important, though necessarily focused aspects. Teaching endocrinology to undergraduates, it was easy to explain the functions of the gland by following the usual well-trodden paths. Over several years, however, I have come to realize that, despite all that, I still dont actually know what the adrenal cortex is for. Ill qualify that, aldosterone has a very clear function, essential for life. But what about the so-called glucocorticoids, secreted in amounts 1000 times greater than aldosterone?
As it seems to me now, glucocorticoids are best understood for their damaging effects in disease. Their roles in normal physiology remain quite obscure, though many have attempted to explain them. In normal animals or subjects, two things cause massive changes in glucocorticoid secretion. These are stress (which can be quite mild), and the clock. Why? Is it to induce gluconeogenesis, to oppose insulin, to inhibit inflammation or the immune response, to increase membrane permeability, to increase GFR or to act on the CNS to increase appetite, or depression? Even supposing that all of these functions occur in normal physiology (the evidence on carbohydrate metabolism for example is pretty inconclusive), it is hard to see why both stress (and it doesnt matter what sort of stress) and the clock demand the same responses, particularly when some of them seem to be positively damaging.
I think theres still a long way to go. Perhaps, like David Anderson, Im somewhat jaded (but I wont be showing any erotic art).