Cannabidiol (CBD) potentiates physiological and behavioral markers of hypothalamic-pituitary-adrenal (HPA) axis responsivity in female and male mice
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Rationale
Clinical literature indicates there may be a therapeutic use of cannabidiol (CBD) for stress-related disorders. Preclinical literature remains conflicted regarding the underlying neurobehavioral mechanisms, reporting mixed effects of CBD (increased, decreased, or no effect) on anxiety- and fear-related behaviors. Preclinical data demonstrated that CBD modulates hypothalamus-pituitary-adrenal (HPA) axis gene expression; it is unknown whether CBD changes HPA axis responsivity and how this relates to altered behavior.
Objectives
We aimed to evaluate whether acute or chronic CBD administration would alter physiological and behavioral measures of HPA axis responsivity in male or female mice.
Methods
C57BL/6 mice of both sexes were injected with vehicle or CBD (30 mg/kg, i.p.) daily for 26 days. Plasma corticosterone (CORT) levels were evaluated following dexamethasone suppression and adrenocorticotropin hormone stimulation tests after acute and chronic CBD exposure. After chronic CBD, mice were tested for anxiety-like behavior using an elevated plus maze (EPM) and associative fear learning and memory using a trace fear conditioning (FC) protocol.
Results
Compared to vehicle, CBD induced a state of HPA axis hyperactivation, an effect which was significant in males; it also normalized anxiety-like behavior in female mice classified as having HPA axis hypofunction and primed all female mice for enhanced conditioned responding. Significant sex differences were also detected: females had greater plasma CORT levels and HPA axis responsivity than males, exhibited less EPM anxiety-like behavior, and were more responsive during FC.
Conclusions
CBD potentiated physiological and behavioral markers of HPA axis function and normalized anxiety-like behavior in a sex-specific manner. This observation has implications for cannabinoid-based drug development targeting individuals with stress-related disorders involving HPA axis hypofunction pathology.
