A physiological role for the granins as prohormones for homeostatically important regulatory peptides? A working hypothesis for future research.

Abstract

The concept of stress (Selye 1936) describes a state of threatened homeostasis. The main purpose of the stress response is to regain equilibrium via a chain of reactions co-ordinated by the brain and effected via the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis. As amply documented in the chapters of this volume, the chromogranins and secretogranin II are co-released with the respective hormones from the sympathoadrenomedullary division and other elements of the diffuse neuroendocrine system. Accordingly, there is an overflow to the circulation of both catecholamines and chromogranins in similar, low nanomolar ranges, reflecting the intensity of activation. However, while the catecholamines have long since been recognised as primary stress hormones, the implications of the co-released chromogranins in the stress response have proved difficult to envisage. In view of the wealth of information accumulated in this volume, the chromogranins now deserve attention as potential stress signals. The main emphasis of this concluding chapter is to discuss a unifying concept for the chromogranins and their derived peptides as physiologically important regulators, based on the current evidence of their biological activities.