Prenatal downregulation of CB₁ cannabinoid receptors in the mouse prefrontal cortex disrupts cortical lamination and induces a transcriptional signature associated with social interaction deficits

Endocannabinoid signaling exerts a neurodevelopmental regulatory role via CB 1 cannabinoid receptors (CB 1 Rs), which control pyramidal neuron differentiation, migration, and axonal guidance. Here, we investigated the long-lasting consequences of transient prenatal CB 1 R downregulation within the mouse prefrontal cortex by assessing its impact on gene expression, neuronal electrophysiological properties, and animal behavioral traits. Transient loss of CB 1 Rs as induced by in-utero small-interference (si) RNA electroporation at E14.5, when upper-layer neurons are generated, arrested cell migration leading to ectopic neurons that populated deep layers. Whole cell-current clamp recordings showed that ectopic neurons are less excitable (increased afterhyperpolarization amplitude, decreased sag, lowe firing frequency) than deep layer-native pyramidal neurons. Differentially expressed genes (DEGs), identified by microarray characterization of FACS-sorted electroporated neurons were significantly enriched in pathways related to cortical development, regulation of cell migration, neurotransmitter secretion, and cytoskeletal organization. Gene set enrichment analysis also supported enrichment in pathways associated with neurodegenerative disorders and synaptic function. The gene expression profile of siCB 1 R-derived neurons showed DEGs that had been previously associated with intellectual disability, schizophrenia, and autism. Venn diagrams unveiled one common DEG for neuropsychiatric risk databases and CB 1 R expression manipulation, namely the transcription factor ZBTB20. Prenatal knockdown of CB 1 Rs induced long-lasting behavioral alterations in the adult offspring of either sex, with an impairment of social interaction and motor behavior in siCB 1 R-derived adult mice. Taken together, these findings highlight the role of CB 1 Rs in controlling the development of pyramidal neurons in the prefrontal cortex and support the contribution of altered endocannabinoid signaling to neuropsychiatric vulnerability. Significance statement Transient loss of function of CB 1 cannabinoid receptors (CB 1 Rs) during prenatal development of the mouse prefrontal cortex leads to pyramidal neuron migration arrest, altered gene expression program, abnormal intrinsic electrophysiological properties, and deficits in social interaction. These findings underscore the critical role of the endocannabinoid system in cortical pyramidal neuron development and highlight similarities between the molecular signature induced by a prenatal transient loss of CB 1 Rs and the vulnerability to neuropsychiatric disorders. Given that Δ 9 -tetrahydrocannabinol, the primary psychoactive compound in Cannabis preparations, acts in the brain via CB 1 Rs, these results also provide important insights into the neuronal alterations associated with prenatal cannabinoid exposure.