Cannabinoid CB1 receptor gene inactivation in oligodendrocyte precursors disrupts oligodendrogenesis and myelination in mice

[EN] Cannabinoids are known to modulate oligodendrogenesis and developmental CNS myelination. However, the cell-autonomous action of these compounds on oligodendroglial cells in vivo, and the molecular mechanisms underlying these effects have not yet been studied. Here, by using oligodendroglial precursor cell (OPC)-targeted genetic mouse models, we show that cannabinoid CB1 receptors exert an essential role in modulating OPC differentiation at the critical periods of postnatal myelination. We found that selective genetic inactivation of CB1 receptors in OPCs in vivo perturbs oligodendrogenesis and postnatal myelination by altering the RhoA/ROCK signaling pathway, leading to hypomyelination, and motor and cognitive alterations in young adult mice. Conversely, pharmacological CB1 receptor activation, by inducing E3 ubiquitin ligase-dependent RhoA proteasomal degradation, promotes oligodendrocyte development and CNS myelination in OPCs, an effect that was not evident in OPC-specific CB1 receptor-deficient mice. Moreover, pharmacological inactivation of ROCK in vivo overcomes the defects in oligodendrogenesis and CNS myelination, and behavioral alterations found in OPC-specific CB1 receptor-deficient mice. Overall, this study supports a cell-autonomous role for CB1 receptors in modulating oligodendrogenesis in vivo, which may have a profound impact on the scientific knowledge and therapeutic manipulation of CNS myelination by cannabinoids.This work was supported by the MINECO grants SAF2017-83516 and PID2020-112640RB-I00, and the Comunidad de Madrid grants 2016-T1/BMD-1060 and 2020-5 A/BMD-19728, Atraccion del Talento Investigador Program, to JP. AHG and TA. AHG was also supported by the Comunidad de Madrid contract PEJD-2017PRE/BMD-3703, and A.S.T by Fundacion Tatiana Perez de Guzman el Bueno. Support was also provided by MINECO (grants RTI2018-095311-B-I00 to MG. and SAF2016-75292-R to CM), CIBERNED (grants CB06/05/0005 to M.G. and CB06/0005/0076 to C.M.), FEDER and ISCIII (AES 2018 grants PI18-00941 to IG-R and PI18/00513 to SM), Basque Government (grants IT1203-19 to C.M. and PIBA19-0059 to SM), and ARSEP Foundation (grant to SM)