Long-term aberrations to cerebellar endocannabinoids induced by early-life stress

Studies of early-life stress traditionally focus on glucocorticoid signaling as a modulator of neurodevelopmental risk, but emerging evidence points to the role of the endocannabinoid system in long-term stress-induced neural remodeling. Existing studies on stress-induced endocannabinoid dysregulation have focused on changes to cerebrum that are temporally proximal to stressors, but little is known about temporally distal effects, especially in cerebellum, which is vulnerable to early developmental stress and is dense with cannabinoid receptors. Further, sex-specific effects of stress on cerebellar endocannabinoid tone are understudied. Following a naturalistic rodent model of early-life stress, limited bedding at postnatal days 2-9, adult (postnatal day 70) cerebellar and hippocampal endocannabinoids and related lipids and mRNA were assessed, and behavioral performance was evaluated. Regional and sex-specific effects were present at baseline and following early-life stress. Limited bedding impaired peripherally-measured basal corticosterone in adult males only. In the CNS, early-life stress (1) decreased 2-arachidonoyl glycerol and arachidonic acid in the cerebellar deep nuclei in males only; (2) decreased 2-arachidonoyl glycerol in females only in cerebellar Crus I; and (3) increased dorsal hippocampus prostaglandins in males only. Transcriptomics for cerebellar interpositus nucleus revealed substantial sex effects, with minimal effects of stress. Stress did impair novel object recognition in both sexes and social preference in females. Taken together, the cerebellar endocannabinoids system exhibits robust sex-specific differences, malleable through early-life stress and perhaps also contributing to sexual differentiation of the brain. The current study may foster future research into stress as a risk factor for cerebellar-related dysfunctions.