Intercellular calcium waves in cultured enteric glia from neonatal guinea pig

Abstract

Enteric glia are important participants in information processing in the enteric nervous system. However, intercellular signaling mechanisms in enteric glia remain largely unknown. We postulated that intercellular calcium waves exist in enteric glia. Primary cultures of enteric glia were isolated from neonatal guinea pig taenia coli. Intracellular calcium in individual cells was quantified with fura-2 AM microfluorimetry. Single-cell stimulation was performed with a micromanipulator-driven glass pipette. Data were expressed as mean +/- SEM and analyzed by Student's t-test. Mechanical stimulation of a single enteric glial cell resulted in an increase in intracellular calcium, followed by concentric propagation to 36% +/- 3% of neighboring cells. Intercellular calcium waves were blocked by depletion of intracellular calcium stores with thapsigargin (1 microM). Pretreatment of enteric glia with the phospholipase C inhibitor U73122 (1 microM) significantly decreased the percentage of cells responding to mechanical stimulation (6% +/- 4%), but had no effect on waves induced by microinjection of the inositol trisphosphate (67% +/- 13% vs. 60% +/- 4% for control). Antagonism of inositol trisphosphate receptor attenuated intercellular calcium waves induced by both mechanical stimulation and microinjection of inositol trisphosphate. Uncoupling of gap junctions with octanol or heptanol significantly inhibited intercellular calcium wave propagation. Pretreatment of enteric glia with apyrase partially attenuated intercellular calcium waves. Our data demonstrate that enteric glial cells are capable of transmitting increases in intracellular calcium to surrounding cells, and that intercellular calcium waves involve a sequence of intracellular and extracellular steps in which phospholipase C, inositol trisphosphate, and ATP play roles.

Enteric Glia Are Targets of the Sympathetic Innervation of the Myenteric Plexus in the Guinea Pig Distal Colon

“…Much like in CNS astrocytes, propagating calcium waves have been reported in cultured enteric glia in response to mechanical stimulation (Zhang et al, 2003). Furthermore, guinea pig enteric glia express mGluR5 receptors, raising the possibility that they may respond to glutamate (Nasser et al, 2007).…”

Colonic neuropathological aspects in patients with intractable constipation due to obstructed defecation

“…44 In fact, experimental human and animal studies have shown that enteric glial cells may also be involved in intestinal inflammation, 45,46 enteric neurotransmission [47][48][49] and, importantly, are essential for the homeostasis of enteric neurons. 50 With respect to this last aspect, a recent study showed that enteric glia disruption may alter the neurochemical coding of enteric neurons in an experimental animal model.…”

Clostridium difficile-related postinfectious IBS: a case of enteroglial microbiological stalking and/or the solution of a conundrum?

“…Most EGC within enteric ganglia are contacted by vesiculated nerve processes with presynaptic specializations [35], and respond to transmitters released by these terminations by expressing a series of receptors for neurotransmitters and neuromodulators [36][37][38][39]. Thus, EGC can modulate enteric neural circuits in several ways, such as by supplying neurotransmitters precursors to neurons [40,41], terminating the actions of neurotransmitters from synapses [42,43], and through the generation of neuroactive compounds [44]. In addition, EGC are needed to assure survival of the enteric neurons, as demonstrated by the experimental ablation of the intestinal glial network [45].…”