CB2 cannabinoid receptor expression is increased in 129S1/SvImJ mice: behavioral consequences

Area of Science:

• Neuroscience
• Genetics
• Pharmacology

Background:

• Neuropsychiatric diseases arise from genetic and environmental factors.
• Inbred mouse strains, like 129S1/SvImJ (S1), serve as models for studying genetic influences on these conditions.
• S1 mice exhibit anxiogenic-like behavior, impaired fear extinction, and increased prepulse inhibition (PPI) compared to C57BL/6J mice.

Purpose of the Study:

• To investigate the role of the endocannabinoid system (ECS) in the behavioral alterations observed in S1 mice.
• To evaluate the expression of ECS components in different brain regions of S1 mice.
• To determine the involvement of cannabinoid type-2 receptor (CB2R) in neuropsychiatric-like phenotypes.

Main Methods:

• Assessed gene expression of cannabinoid receptors (CB1R, CB2R) and metabolizing enzymes in various brain regions of S1 mice.
• Administered CB2R antagonist SR144528 and agonist JWH133 to S1 mice.
• Evaluated behavioral responses including anxiogenic-like behavior, fear extinction, and PPI of the startle reflex.

Main Results:

• CB2R expression was significantly elevated in the amygdala, prefrontal cortex, and hippocampus of S1 mice.
• CB2R blockade partially ameliorated the anxiogenic-like phenotype in S1 mice.
• CB2R activation exacerbated deficits in fear extinction and PPI in S1 mice.

Conclusions:

• CB2R plays a significant role in the observed behavioral alterations in S1 mice.
• The findings highlight CB2R's importance in regulating central nervous system functions relevant to neuropsychiatric disorders.
• Targeting CB2R may offer therapeutic potential for certain neurological and psychiatric conditions.