title: Innervation patterns of autonomic axons in the human endocrine pancreas.
abstract: The autonomic nervous system regulates hormone secretion from the endocrine pancreas, the islets of Langerhans, thus impacting glucose metabolism. The parasympathetic and sympathetic nerves innervate the pancreatic islet, but the precise innervation patterns are unknown, particularly in human. Here we demonstrate that the innervation of human islets is different from that of mouse islets and does not conform to existing models of autonomic control of islet function. By visualizing axons in three dimensions and quantifying axonal densities and contacts within pancreatic islets, we found that, unlike mouse endocrine cells, human endocrine cells are sparsely contacted by autonomic axons. Few parasympathetic cholinergic axons penetrate the human islet, and the invading sympathetic fibers preferentially innervate smooth muscle cells of blood vessels located within the islet. Thus, rather than modulating endocrine cell function directly, sympathetic nerves may regulate hormone secretion in human islets by controlling local blood flow or by acting on islet regions located downstream.
authors: Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
authors: Rayner
authors: R
authors: Rodriguez-Diaz
authors: Midhat H
authors: MH
authors: Abdulreda
authors: Alexander L
authors: AL
authors: Formoso
authors: Itai
authors: I
authors: Gans
authors: Camillo
authors: C
authors: Ricordi
authors: Per-Olof
authors: PO
authors: Berggren
authors: Alejandro
authors: A
authors: Caicedo
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D006801:Humans; D007515:Islets of Langerhans / Q000294:innervation* / Q000502:physiology; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D016704:Synapsins / Q000378:metabolism
chemical_list: D016704:Synapsins