Non-neuronal acetylcholine, a signalling molecule synthezised by surface cells of rat and man

Abstract

Acetylcholine acts as a prominent transmitter in the central and peripheral nervous system. The aim of the present study was to investigate whether mammalian non-neuronal cells can synthesize and store acetylcholine. A cotton tipped applicator (Q-tip) was used to collect surface cells from airways and alimentary tract. Histological inspection indicated that rubbing of the luminal surface of human bronchi did not penetrate the basal membrane. Acetylcholine was measured by an HPLC-method using substrate-specific enzyme reactor-columns. Non-neuronal acetylcholine was found in cells covering inner and outer surfaces of rat and man. For example, acetylcholine was detected in the surface epithelium of human bronchi (33 pmol/g), mouth (female 0.7 and male 8 pmol/sample), small and large intestine (800 and 16 pmol/g, respectively), gall bladder (12 pmol/g), vagina (6 pmol/sample), skin 1000 (pmol/g) and in pulmonary pleura (5 pmol/sample). Somewhat higher amounts of acetylcholine were found in rat tracheal and intestinal epithelium and in rat skin. The synthesizing enzyme choline acetyltransferase (ChAT) was demonstrated in human surface epithelium by immunohistochemistry and by Western blot analysis. Enzymatic ChAT activity was demonstrated in isolated epithelial cells of human bronchi and small intestine (3.5 and 28 nmol/mg protein/h, respectively). Applied acetylcholine (in nM concentrations) increased, whereas inhibition of ChAT activity by bromoacetylcholine (10 microM) reduced the growth of cultured human bronchial epithelial cells. Inhibition of cell growth occurred also in the presence of atropine (1 microM) together with (+/-)-tubocurarine (30 microM). In conclusion, the present experiments demonstrate a widespread existence of non-neuronal acetylcholine in surface cells of man. Non-neuronal acetylcholine may act as a local signalling molecule.

Donepezil, an acetylcholinesterase inhibitor against Alzheimer's dementia, promotes angiogenesis in an ischemic hindlimb model

“…Kawashima and Wessler [30,31] speculated that non-neuronal and non-central cells synthesize ACh. Our recent study has demonstrated for the first time that cardiomyocytes also possess the intracellular ACh synthesis system, which is transcriptionally activated in a positive feedback manner, and donepezil also elevates ACh level in cardiomyocytes, which was partly independent of muscarinic receptors [29].…”

Neonatal maternal separation of rat pups results in abnormal cholinergic regulation of epithelial permeability

“…ChAT was used to indicate the presence of acetylcholine, since it is essential in the synthesis of the neurotransmitter and is a specific marker of cholinergic nerves and acetylcholine-containing cells. ChAT has been identified by immunohistochemisty in the cell bodies and nerve terminals of both submucosal and myenteric plexus neurons (27); in addition, the cell membrane, endosomes, cytoskeleton, nucleus, and mitochondria of epithelial cells have also been shown to be immunoreactive (16). In our study, densitometry analysis of Western blots revealed a significant increase in the expression of ChAT relative to the expression of PGP9.5, a neuronal marker, suggesting that increased enzyme levels were present in the enteric nerves of MS pups.…”

Blocking M2 muscarinic receptor signaling inhibits tumor growth and reverses epithelial-mesenchymal transition (EMT) in non-small cell lung cancer (NSCLC)

“…The recent discovery that lung cancers synthesize and secrete acetylcholine (ACh) that acts as an autoparacrine growth factor provides potential new targets to inhibit lung cancer growth. 3,4 It is well established that ACh is an important neurotransmitter in the central and peripheral nervous systems and acts via activation of ACh receptors (AChRs).Recently, it has been found that ACh is also widely synthesized by a variety of non-neuronal cell types including airway epithelial cells, 5,6 keratinocytes, 7 small and large intestine, gall bladder, 8 glial, 9 vascular endothelial, 10 immune cells and most common cancer cells such as NSCLC, SCLC, colon, glial and ovarian carcinomas. [11][12][13][14][15][16] Although the primary function has not yet been completely elucidated, the expression of ACh in many different cell types suggests that its roles will be fundamental and will present novel therapeutic targets.…”