Cannabinoid Receptor Modulation of Neurogenesis: ST14A Striatal Neural Progenitor Cells as a Simplified In Vitro Model.

Erika Cottone,Valentina Pomatto,Stefania Rapelli,Patrizia Bovolin,Rosaria Scandiffio,Ken Mackie

doi:10.3390/molecules26051448

Erika Cottone, Valentina Pomatto + Show 4 more

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https://doi.org/10.3390/molecules26051448

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Abstract

The endocannabinoid system (ECS) is involved in the modulation of several basic biological processes, having widespread roles in neurodevelopment, neuromodulation, immune response, energy homeostasis and reproduction. In the adult central nervous system (CNS) the ECS mainly modulates neurotransmitter release, however, a substantial body of evidence has revealed a central role in regulating neurogenesis in developing and adult CNS, also under pathological conditions. Due to the complexity of investigating ECS functions in neural progenitors in vivo, we tested the suitability of the ST14A striatal neural progenitor cell line as a simplified in vitro model to dissect the role and the mechanisms of ECS-regulated neurogenesis, as well as to perform ECS-targeted pharmacological approaches. We report that ST14A cells express various ECS components, supporting the presence of an active ECS. While CB1 and CB2 receptor blockade did not affect ST14A cell number, exogenous administration of the endocannabinoid 2-AG and the synthetic CB2 agonist JWH133 increased ST14A cell proliferation. Phospholipase C (PLC), but not PI3K pharmacological blockade negatively modulated CB2-induced ST14A cell proliferation, suggesting that a PLC pathway is involved in the steps downstream to CB2 activation. On the basis of our results, we propose ST14A neural progenitor cells as a useful in vitro model for studying ECS modulation of neurogenesis, also in prospective in vivo pharmacological studies.

Highlights

The endocannabinoid system (ECS) is comprised of several different components: (a) the cannabinoid receptors, the best characterized being CB1 and CB2 receptors; (b) the endogenous cannabinoids, called endocannabinoids, among which anandamide (AEA) and 2-arachidonoylglycerol (2-AG); (c) the enzymes involved in eCB biosynthesis “on demand”, e.g., N-acylphosphatidylethanolamine-specific phospholipase D-like hydrolase (NAPE-PLD) and diacylglycerol lipase (DAGL); (d) the enzymes involved in eCB degradation, e.g., fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL); (e) the molecules involved in eCB transport across the membrane [1,2,3]
CB receptor cellular localization was assessed by means of immunofluorescence (Figure 1C); CB1 and CB2 immunoreactivities were abundantly found in the cytoplasm, especially around the nucleus
The involvement of CB2 receptor in neurogenesis, as well as neurodegenerative and neuroinflammatory disorders, open to new possible pharmacological strategies based on the use of CB2-specific therapeutic drugs, possibly overcoming the neuropsychiatric adverse effects of CB1-targeted therapies [2,8]

Summary

Introduction

The endocannabinoid system (ECS) is comprised of several different components: (a) the cannabinoid receptors, the best characterized being CB1 and CB2 receptors; (b) the endogenous cannabinoids, called endocannabinoids (eCBs), among which anandamide (AEA) and 2-arachidonoylglycerol (2-AG); (c) the enzymes involved in eCB biosynthesis “on demand”, e.g., N-acylphosphatidylethanolamine-specific phospholipase D-like hydrolase (NAPE-PLD) and diacylglycerol lipase (DAGL); (d) the enzymes involved in eCB degradation, e.g., fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL); (e) the molecules involved in eCB transport across the membrane [1,2,3]. Considering that marijuana is one of the most abused substances in the world and it is becoming legal in many countries, a particular concern is on the fact that acute and chronic use of cannabis could lead to cognitive impairments; interestingly, chronic treatment with THC, and the administration of a single ultra-low dose of THC was shown to lead to long-term cognitive impairments, possibly resulting from deficits in attention or motivation [5]. CB1 and CB2 cannabinoid receptors are seven-transmembrane G protein-coupled receptors [8]; they primarily signal through Gi/o proteins, leading to the inhibition of adenylyl cyclase and activation of Mitogen-activated protein kinases (MAPKs). In response to CB1 stimulation, MAPKs such as ERK1/2, c-Jun N-terminal kinase (JNK) and p38 are activated; CB1 was shown to activate the Phosphoinositide 3-kinases (PI3K) pathway, leading to the regulation of neuronal survival. Different ligands can elicit different signaling pathways mediated by cannabinoid receptors [1]

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