Electrophysiology of porcine myenteric neurons revealed after vital staining of their cell bodies. A preliminary report

Abstract

Due to practical limitations in visualizing and getting access to the ganglionic components of large mammals, electrophysiology of the enteric nervous system has been restricted mainly to small laboratory animals, more particularly the guinea-pig. The use of the vital dye 4-(4-diethylaminostyry1)-N-methylphyridinium iodide (4-Di-2-ASP), however, overcomes some of these difficulties. A 20-min incubation period with this dye, followed by a minimum period of 4 h in Krebs solution, suffices to stain the neuronal cell bodies, permitting selection of a neuron and positioning of the microelectrode for impalement and recording. The method has been applied to pig ileum and guinea-pig large and small bowel myenteric neurons. Impalements of untreated guinea-pig myenteric neurons were compared with those of 4-Di-2-ASP-pretreated ones. According to our preliminary data, the staining did not suppress the expression of apparently normal electrophysiological activity. Moreover, the procedure permitted impalement and recording of myenteric plexus neurons in pig ileal tissue with a rate of success equalling blind impalement on guinea-pig tissue. In contrast with formerly published results whereby staining of the neuronal cell bodies only occurred when the cells had been chemically damaged, our experiments suggest a possible correlation between fluorescence and cell viability.

Neural Control of the Gallbladder: An Intracellular Study of Human Gallbladder Neurons

“…A previous study had shown that 4-Di-2-ASP did not affect the viability of cells in different kinds of tissue in several species [12]. A recent paper demonstrated that the normal electrophysiological activity of porcine myenteric neurons was not altered by long-term incubation with 4-Di-2-ASP [14]. In the present study, the electrical properties of guinea pig gallbladder neurons were similarly not affected by 4-Di-2-ASP.…”

“…This is due to the diffuse nature of the ganglia in the human gallbladder, as the ganglia are not found in a discrete layer, but are found at any level within the smooth muscle. In comparison, as the porcine myenteric plexus is in a discrete layer, once the ganglia could be identified electrophysiology was possible with a rate of success equivalent to that in the guinea pig [14]. Another study involving electrical recordings from neurons of the human gut tube did not utilize any vital dyes [15].…”

Outer submucous plexus: An intrinsic nerve network involved in both secretory and motility processes in the intestine of large mammals and humans

“…Furthermore, it should be stressed that, despite a large degree of similarity between the neurochemically and morphologically identified neuron populations of the OSP and MP, both nerve networks are not identical, as illustrated by the absence of the Dogiel type I cell type in the OSP and the different proportions of particular neuron classes in both networks. In addition, the difference in proportion of neurons with the electrophysiological AH phenotype between the OSP (70%) and the MP (3-17%) (Cornelissen et al, 1996(Cornelissen et al, , 1999(Cornelissen et al, , 2000Thomsen et al, 1997a,b) is not in support of a hypothesis that the OSP has to be regarded as just a topographical subdivision of the MP.…”

“…Electrophysiological Kunze et al, 1997Kunze et al, , 1998Furness et al, 1998), tracing (Song et al, 1991;Kirchgessner et al, 1996), and c-fos (Kirchgessner et al, 1992) experiments have led to the assumption that the cell bodies of intrinsic mucosal mechanosensitive neurons are located in the submucosa, whereas the myenteric plexus (MP) harbours chemo-and stretch-sensitive neurons (Furness et al, 1999). Though differing in neurochemical content (Timmermans et al, 1990(Timmermans et al, , 1992b(Timmermans et al, , 1997 and electrophysiological properties (Brookes et al, 1987;Cornelissen et al, 1996Cornelissen et al, , 1999, some neurons in both the submucous and the myenteric plexuses of pig and human intestine were found to exhibit a similar type II morphology (Scheuermann et al, 1987a;Timmermans et al, 1992a).…”

Postnatal development of the mucosal plexus in the porcine small and large intestine

“…Pigs are one of the few common and readily available mammals that are omnivorous. Both with regard to the anatomic organisation of the intrinsic nerve networks and to the morphologic and electrophysiological features of distinct subclasses of enteric neurons, the pig model seems to resemble more closely the human situation than the guinea pig model does [15][16][17][18]. The aim of our study was to establish the age-related development of the mucosal innervation in porcine small and large bowel from foetal to adult life.…”