Targeting dysregulated CB1 receptors in a Down syndrome mouse model improves neurological outcomes.

INTRODUCTION

Down syndrome (DS) is the most common genetic cause of intellectual disability, affecting cognitive function and increasing the risk of early-onset Alzheimer's disease (AD). The endocannabinoid system may serve as a therapeutic target for cognitive deficits by inhibiting cannabinoid type-1 receptor (CB1R) function.

METHODS

CB1R expression was analyzed in the hippocampi of aged DS-associated AD (DSAD) individuals and middle-aged Ts65Dn mice. Long-term oral treatment with the CB1R antagonist rimonabant was used to assess its effects on memory and neuroinflammation in the Ts65Dn mouse model of DS.

RESULTS

CB1R expression was significantly increased in both aged DSAD subjects (specifically in the dentate gyrus and CA2 posterior hippocampal subregions) and Ts65Dn mice. Long-term rimonabant treatment improved memory performance, normalized microglial morphology, and reduced plasma inflammatory markers in trisomic mice without preventing neuron decline.

DISCUSSION: These findings suggest that sustained CB1R inhibition may enhance cognitive function by modulating neuroinflammation, highlighting its therapeutic potential for cognitive impairments in DS.

HIGHLIGHTS: Cannabinoid type-1 receptor (CB1R) expression is increased in the posterior hippocampus of aged Down syndrome (DS) subjects and Ts65Dn mice. Long-term rimonabant treatment enhances memory in middle-aged Ts65Dn mice. CB1R inhibition shifts neuroinflammatory features in Ts65Dn mice. CB1R inhibition does not halt noradrenergic/cholinergic neurodegeneration in Ts65Dn. CB1R inhibition presents potential for memory improvement in DS-related deficits.