TY - JOUR
T1 - Role of the endocannabinoid system in fragile X syndrome
T2 - potential mechanisms for benefit from cannabidiol treatment
AU - Palumbo, Joseph M.
AU - Thomas, Brian F.
AU - Budimirovic, Dejan
AU - Siegel, Steven
AU - Tassone, Flora
AU - Hagerman, Randi
AU - Faulk, Christopher
AU - O’Quinn, Stephen
AU - Sebree, Terri
N1 - Publisher Copyright:
© 2023, The Author(s).
PY - 2023/12
Y1 - 2023/12
N2 - Multiple lines of evidence suggest a central role for the endocannabinoid system (ECS) in the neuronal development and cognitive function and in the pathogenesis of fragile X syndrome (FXS). This review describes the ECS, its role in the central nervous system, how it is dysregulated in FXS, and the potential role of cannabidiol as a treatment for FXS. FXS is caused by deficiency or absence of the fragile X messenger ribonucleoprotein 1 (FMR1) protein, FMRP, typically due to the presence of >200 cytosine, guanine, guanine sequence repeats leading to methylation of the FMR1 gene promoter. The absence of FMRP, following FMR1 gene-silencing, disrupts ECS signaling, which has been implicated in FXS pathogenesis. The ECS facilitates synaptic homeostasis and plasticity through the cannabinoid receptor 1, CB1, on presynaptic terminals, resulting in feedback inhibition of neuronal signaling. ECS-mediated feedback inhibition and synaptic plasticity are thought to be disrupted in FXS, leading to overstimulation, desensitization, and internalization of presynaptic CB1 receptors. Cannabidiol may help restore synaptic homeostasis by acting as a negative allosteric modulator of CB1, thereby attenuating the receptor overstimulation, desensitization, and internalization. Moreover, cannabidiol affects DNA methylation, serotonin 5HT1A signal transduction, gamma-aminobutyric acid receptor signaling, and dopamine D2 and D3 receptor signaling, which may contribute to beneficial effects in patients with FXS. Consistent with these proposed mechanisms of action of cannabidiol in FXS, in the CONNECT-FX trial the transdermal cannabidiol gel, ZYN002, was associated with improvements in measures of social avoidance, irritability, and social interaction, particularly in patients who are most affected, showing ≥90% methylation of the FMR1 gene.
AB - Multiple lines of evidence suggest a central role for the endocannabinoid system (ECS) in the neuronal development and cognitive function and in the pathogenesis of fragile X syndrome (FXS). This review describes the ECS, its role in the central nervous system, how it is dysregulated in FXS, and the potential role of cannabidiol as a treatment for FXS. FXS is caused by deficiency or absence of the fragile X messenger ribonucleoprotein 1 (FMR1) protein, FMRP, typically due to the presence of >200 cytosine, guanine, guanine sequence repeats leading to methylation of the FMR1 gene promoter. The absence of FMRP, following FMR1 gene-silencing, disrupts ECS signaling, which has been implicated in FXS pathogenesis. The ECS facilitates synaptic homeostasis and plasticity through the cannabinoid receptor 1, CB1, on presynaptic terminals, resulting in feedback inhibition of neuronal signaling. ECS-mediated feedback inhibition and synaptic plasticity are thought to be disrupted in FXS, leading to overstimulation, desensitization, and internalization of presynaptic CB1 receptors. Cannabidiol may help restore synaptic homeostasis by acting as a negative allosteric modulator of CB1, thereby attenuating the receptor overstimulation, desensitization, and internalization. Moreover, cannabidiol affects DNA methylation, serotonin 5HT1A signal transduction, gamma-aminobutyric acid receptor signaling, and dopamine D2 and D3 receptor signaling, which may contribute to beneficial effects in patients with FXS. Consistent with these proposed mechanisms of action of cannabidiol in FXS, in the CONNECT-FX trial the transdermal cannabidiol gel, ZYN002, was associated with improvements in measures of social avoidance, irritability, and social interaction, particularly in patients who are most affected, showing ≥90% methylation of the FMR1 gene.
KW - Cannabidiol
KW - Cannabinoid receptors
KW - Endocannabinoid system
KW - Fragile X syndrome
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U2 - 10.1186/s11689-023-09475-z
DO - 10.1186/s11689-023-09475-z
M3 - Review article
C2 - 36624400
AN - SCOPUS:85145957630
SN - 1866-1947
VL - 15
JO - Journal of Neurodevelopmental Disorders
JF - Journal of Neurodevelopmental Disorders
IS - 1
M1 - 1
ER -