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Review
. 2020 Apr 19;21(8):2850.
doi: 10.3390/ijms21082850.

Endocannabinoid-Mediated Neuromodulation in the Olfactory Bulb: Functional and Therapeutic Significance

Affiliations
Review

Endocannabinoid-Mediated Neuromodulation in the Olfactory Bulb: Functional and Therapeutic Significance

Naina Bhatia-Dey et al. Int J Mol Sci. .

Abstract

Endocannabinoid synthesis in the human body is naturally occurring and on-demand. It occurs in response to physiological and environmental stimuli, such as stress, anxiety, hunger, other factors negatively disrupting homeostasis, as well as the therapeutic use of the phytocannabinoid cannabidiol and recreational use of exogenous cannabis, which can lead to cannabis use disorder. Together with their specific receptors CB1R and CB2R, endocannabinoids are major components of endocannabinoid-mediated neuromodulation in a rapid and sustained manner. Extensive research on endocannabinoid function and expression includes studies in limbic system structures such as the hippocampus and amygdala. The wide distribution of endocannabinoids, their on-demand synthesis at widely different sites, their co-existence in specific regions of the body, their quantitative differences in tissue type, and different pathological conditions indicate their diverse biological functions that utilize specific and overlapping pathways in multiple organ systems. Here, we review emerging evidence of these pathways with a special emphasis on the role of endocannabinoids in decelerating neurodegenerative pathology through neural networks initiated by cells in the main olfactory bulb.

Keywords: Alzheimer’s Disease; endocannabinoids; neural dysfunction; neurodegeneration; neuromodulation; odor; olfactory bulb; olfactory system; synaptic plasticity.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic representation of stimuli that can activate the endocannabinoid system (ECS) and their impact through endocannabinoid receptors CB1R and CB2R, some pathways of neuromodulation are known, newer research studies are constantly revealing newer pathways.
Figure 2
Figure 2
The endocannabinoid system (ECS) and the olfactory bulb as a site of therapeutic intervention for a functional olfactory pathway and neuronal homeostasis. ECS activation in response to diverse stimuli and environmental insults to the olfactory bulb affects overlapping physiological pathways and gene regulatory networks (top part of the figure) resulting in perturbed gene regulatory networks (shaded olfactory bulb in the lower half), a probable cause of onset and progression of olfactory deficits. The olfactory bulb and components of ECS can be used as therapeutic targets to restore homeostasis and physiological pathways as well as functional gene regulatory networks at a normal level. Just as there are multiple therapeutic targets, there could be at least two broader sets of therapeutic drugs: one set modulating ECS and the other set regulating olfactory bulb specific pathways at single cell level.

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