A novel enteric neuron–glia coculture system reveals the role of glia in neuronal development

Abstract

In the nervous system, the formation of neuronal circuitry results from a complex and coordinated action of intrinsic and extrinsic factors. In the CNS, extrinsic mediators derived from astrocytes have been shown to play a key role in neuronal maturation, including dendritic shaping, axon guidance and synaptogenesis. In the enteric nervous system (ENS), the potential role of enteric glial cells (EGCs) in the maturation of developing enteric neuronal circuit is currently unknown. A major obstacle in addressing this question is the difficulty in obtaining a valuable experimental model in which enteric neurons could be isolated and maintained without EGCs. We adapted a cell culture method previously developed for CNS neurons to establish a neuron-enriched primary culture from embryonic rat intestine which was cultured in indirect coculture with EGCs. We demonstrated that enteric neurons grown in such conditions showed several structural, phenotypic and functional hallmarks of proper development and maturation. However, when neurons were grown without EGCs, the complexity of the axonal arbour and the density of synapses were markedly reduced, suggesting that glial-derived factors contribute strongly to the formation of the neuronal circuitry. We found that these effects played by EGCs were mediated in part through purinergic P2Y receptor- and glial cell line-derived neurotrophic factor-dependent pathways. Using a novel and valuable culture model to study enteric neuron-glia interactions, our study identified EGCs as a key cellular actor required for neuronal network maturation.

Maternal protein restriction induces gastrointestinal dysfunction and enteric nervous system remodeling in rat offspring

“…We next examined the consequences of reduced autophagy on the vulnerability of enteric neurons from control or MPR animals to a stress. To address this issue, we used a noncontact primary coculture model of enteric neurons and EGCs (26) (Fig. 5A).…”

Enteric glial cell activation protects enteric neurons from damage due to diabetes in part via the promotion of neurotrophic factor release

“…Increasing evidence has confirmed that EGCs are major contributors to the GI complications of diabetes, which provides insight into the role of EGCs in enteric neuropathies. Indeed, EGCs have been shown to play a directly supportive role in the survival of enteric neurons . In this context, interestingly, the expression of GFAP and S‐100β was found to increase 1 week after STZ injection and was followed by further up‐regulation 4 weeks after injection.…”

“…Nevertheless, the changes to ileum neurons that occur during the acute stage of the disease are contradictory and poorly understood. Enteric glial cells can support enteric neurons by secreting neurotrophic factors such as GDNF, NGF, and NT‐3 . Therefore, this investigation was aimed at clarifying how the dynamic changes of enteric neurons correlate with EGC expression and to further illuminate the role and mechanisms of EGCs in regulating the survival and maintenance of enteric neurons in diabetes.…”

“…An increasing amount of evidence has shown that EGCs provide crucial supportive functions to enteric neurons and contribute to their survival and maintenance . Moreover, the release of nerve growth factor (NGF), neurotrophin 3 (NT‐3), and glial cell‐derived neurotrophic factor (GDNF) by EGCs appear to be responsible for regulating and maintaining the functional and structural integrity of the ENS . However, the exact alterations that EGCs undergo and their neuroprotective role in the different stages of diabetes have not yet been elucidated.…”

“…[14][15][16] Moreover, the release of nerve growth factor (NGF), neurotrophin 3 (NT-3), and glial cell-derived neurotrophic factor (GDNF) by EGCs appear to be responsible for regulating and maintaining the functional and structural integrity of the ENS. 17,18 However, the exact alterations that EGCs undergo and their neuroprotective role in the different stages of diabetes have not yet been elucidated. Therefore, our aim was to evaluate the relationships between EGC expression/activation and the alteration of enteric neurons in the ilea of diabetic rats 1, 4, 8, and 16 weeks after streptozotocin (STZ) injection.…”