The Enteric Glia and Its Modulation by the Endocannabinoid System, a New Target for Cannabinoid-Based Nutraceuticals?

The enteric nervous system (ENS) is a part of the autonomic nervous system that intrinsically innervates the gastrointestinal (GI) tract. Whereas enteric neurons have been deeply studied, the enteric glial cells (EGCs) have received less attention. However, these are immune-competent cells that contribute to the maintenance of the GI tract homeostasis through supporting epithelial integrity, providing neuroprotection, and influencing the GI motor function and sensation. The endogenous cannabinoid system (ECS) includes endogenous classical cannabinoids (anandamide, 2-arachidonoylglycerol), cannabinoid-like ligands (oleoylethanolamide (OEA) and palmitoylethanolamide (PEA)), enzymes involved in their metabolism (FAAH, MAGL, COX-2) and classical (CB1 and CB2) and non-classical (TRPV1, GPR55, PPAR) receptors. The ECS participates in many processes crucial for the proper functioning of the GI tract, in which the EGCs are involved. Thus, the modulation of the EGCs through the ECS might be beneficial to treat some dysfunctions of the GI tract. This review explores the role of EGCs and ECS on the GI tract functions and dysfunctions, and the current knowledge about how EGCs may be modulated by the ECS components, as possible new targets for cannabinoids and cannabinoid-like molecules, particularly those with potential nutraceutical use.

Nutraceuticals and peripheral glial cells: a possible link?

A nutraceutical is a food-derived molecule that provides medical or health benefits beyond its basic nutritional role, including the prevention and treatment of disease and its symptoms. In the peripheral nervous system, satellite glial cells are found in close relationship with neurons, mainly in peripheral sensory ganglia, but, compared with other glial cells, the relationship between these cells and nutraceuticals has received little attention. After describing satellite glial cells and their role and changes in physiology and pathology, we review the studies on the effects of nutraceuticals as modulators of their functions. Maybe due to the difficulties in selectively labeling these cells, only a few studies, performed mainly in rodent models, have analyzed nutraceutical effects, showing that N-acetylcysteine, curcumin, quercetin, osthole and resveratrol may palliate neuropathic pain through satellite glial cells-dependent pathways, namely antioxidant mechanisms and/or interference with purinergic signaling. Neither other conditions in which satellite glial cells are involved (visceral pain, nerve regeneration) nor other nutraceuticals or mechanisms of action have been studied. Although more preclinical and clinical research is needed, the available reports support the general notion that nutraceuticals may become interesting alternatives in the prevention and/or treatment of peripheral gliopathies and their associated conditions, including those affecting the satellite glial cells.

Nutraceuticals and Enteric Glial Cells.

Until recently, glia were considered to be a structural support for neurons, however further investigations showed that glial cells are equally as important as neurons. Among many different types of glia, enteric glial cells (EGCs) found in the gastrointestinal tract, have been significantly underestimated, but proved to play an essential role in neuroprotection, immune system modulation and many other functions. They are also said to be remarkably altered in different physiopathological conditions. A nutraceutical is defined as any food substance or part of a food that provides medical or health benefits, including prevention and treatment of the disease. Following the description of these interesting peripheral glial cells and highlighting their role in physiological and pathological changes, this article reviews all the studies on the effects of nutraceuticals as modulators of their functions. Currently there are only a few studies available concerning the effects of nutraceuticals on EGCs. Most of them evaluated molecules with antioxidant properties in systemic conditions, whereas only a few studies have been performed using models of gastrointestinal disorders. Despite the scarcity of studies on the topic, all agree that nutraceuticals have the potential to be an interesting alternative in the prevention and/or treatment of enteric gliopathies (of systemic or local etiology) and their associated gastrointestinal conditions.