Nature of Islet-cell Innervation in the Cat Pancreas

Abstract

Enzyme histochemical and autoradio graphic methods provided evidence for adrenergic and cholinergic innervation of both alpha and beta cells in the islets of Langerhans of the cat. DIABETES 17:33-36, January, 1968.

Autonomic regulation of islet hormone secretion - Implications for health and disease

“…They enter the pancreas along the vessels and terminate at intrapancreatic ganglia, from which the postganglionic nerves pass to the islets; these nerves penetrate the islets to terminate close to the endocrine cells [7±9]. That parasympathetic nerves innervate the islets has been verified in a number of species by light and electron microscopy after staining pancreatic sections with cholinesterase [3,5,7,8]. The relative abundance of the islet cholinergic innervation is evident because isolated islet tissue has a tenfold higher concentration of choline acetyltransferase than pancreatic tissue as a whole [11].…”

“…A rich supply of nerve endings containing amine in close connection with the islet endocrine cells was made visible in several species [6]. Furthermore, islet innervation of adrenergic nerves has also been supported by the localisation in islets of labelled noradrenaline or 5-hydroxytryptophan from intact animals that had been given these neurotransmitters in vivo [3]. Moreover, by electron microscopic studies adrenergic nerve terminals in close association with islet endocrine cells have been made visible [54].…”

“…Sometimes more than three nerve terminals were found to approach a single endocrine cell [3,4]. The nature of these islet nerves was studied using histochemical and fluorescene staining techniques during the 1950 s and 1960 s. These techniques revealed localisation of cholinesterase to some of the islet nerves and catecholamines to other nerves, indicating that both cholinergic and adrenergic nerves innervate the islets [5,6].…”

An Examination of Adrenergic Axons Around Pancreatic Arterioles of the Cat for the Presence of Acetylcholinesterase by High Resolution Autoradiographic and Histochemical Methods

“…The tenability of this concept in the context of the technique used for ACHE " staining " in this work has been presented earlier (Esterhuizen et al, 1968). The most important criticism of this " staining " is the possibility of the substrate being hydrolysed by non-specific esterases.…”

“…Outside the arteriolar adventitial fibroblast sheath nerve bundles may contain only cholinergic or only adrenergic axons or a mixture of discrete adrenergic and cholinergic axons. The adrenergic axons in the " mixed " nerve bundles may dissociate from the cholinergic axons to penetrate the arteriolar adventitia more peripherally and thus become vasomotor, or they may continue the association and ultimately provide the adrenergic innervation of the endocrine cells of the islets of Langerhans (Esterhuizen, Spriggs & Lever, 1968). Similar " mixed " nerve bundles have been found in the toad bladder (Robinson & Bell, 1967) and, although rarely, in the nictitating muscle of the cat (Esterhuizen et al, 1967(Esterhuizen et al, , 1968, and if they occur in other autonomically innervated tissues may provide an alternative explanation for results which have hitherto been interpreted as evidence of a cholinergic link in adrenergic transmission.…”