The non-neuronal cholinergic system, phylogenetically an extremely old system, is more widely distributed in biological systems than the neuronal system. The majority of human cells synthesize acetylcholine . . . We postulate that a picture will emerge showing that ACh plays an important role in the regulation of cellular homeostasis, comparable with its dominant role within the nervous system. The scientists are saying, in short, that we have long been overlooking a fundamentally important aspect of acetylcholine's role in our physiology - a role that runs deeper and broader than we imagined. Before getting to some of the evidence supporting the authors' conclusion, let's look at its implications.
Homeostasis is one of the key concepts of biology.
It is the process by which an organism, or an organ, or a single cell, maintains equilibrium by adjusting its physiological processes to compensate for the effects of disruptive outside forces, such as changes in temperature or chemical composition, or assault by hostile microorganisms. Since homeostasis is necessary for the proper functioning, and ultimately the survival, of our cells, it's fair to say that anything, such as acetylcholine, that plays an important role in that process is very important indeed. An intriguing clue regarding the importance of acetylcholine is its ubiquity in nature. Although we think of it primarily as a neurotransmitter, ACh is found, more than any other such type of molecule, in a wide variety of creatures - including those that do not even have a nervous system. It has been detected in bacteria and in primitive organisms, such as blue-green algae, yeasts, fungi, protozoa, worms, and sponges.