Prenatal exposure to cannabinoids evokes long-lasting functional alterations by targeting CB1 receptors on developing cortical neurons

The CB1 cannabinoid receptor, the main target of Δ9 -tetrahydrocannabinol (THC), the most prominent psychoactive compound of marijuana, plays a crucial regulatory role in brain development as evidenced by the neurodevelopmental consequences of its manipulation in animal models. Likewise, recreational cannabis use during pregnancy affects brain structure and function of the progeny. However, the precise neurobiological substrates underlying the consequences of prenatal THC exposure remain unknown. As CB1 signaling is known to modulate long-range corticofugal connectivity, we analyzed the impact of THC exposure on cortical projection neuron development. THC administration to pregnant mice in a restricted time window interfered with subcerebral projection neuron generation, thereby altering corticospinal connectivity, and produced long-lasting alterations in the fine motor performance of the adult offspring. Consequences of THC exposure were reminiscent of those elicited by CB1 receptor genetic ablation, and CB1-null mice were resistant to THC-induced alterations. The identity of embryonic THC neuronal targets was determined by a Cre-mediated, lineage-specific, CB1 expression-rescue strategy in a CB1-null background. Early and selective CB1 reexpression in dorsal telencephalic glutamatergic neurons but not forebrain GABAergic neurons rescued the deficits in corticospinal motor neuron development of CB1-null mice and restored susceptibility to THC-induced motor alterations. In addition, THC administration induced an increase in seizure susceptibility that was mediated by its interference with CB1-dependent regulation of both glutamatergic and GABAergic neuron development. These findings demonstrate that prenatal exposure to THC has long-lasting deleterious consequences in the adult offspring solely mediated by its ability to disrupt the neurodevelopmental role of CB1 signaling

Sustained Gq-Protein Signaling Disrupts Striatal Circuits via JNK

International audienceThe dorsal striatum is a major input structure of the basal ganglia and plays a key role in the control of vital processes such as motor behavior, cognition, and motivation. The functionality of striatal neurons is tightly controlled by various metabotropic receptors. Whereas the G s /G i-protein-dependent tuning of striatal neurons is fairly well known, the precise impact and underlying mechanism of G q-protein-dependent signals remain poorly understood. Here, using different experimental approaches, especially designer receptor exclusively activated by designer drug (DREADD) chemogenetic technology, we found that sustained activation of G q-protein signaling impairs the functionality of striatal neurons and we unveil the precise molecular mechanism underlying this process: a phospholipase C/Ca 2ϩ /proline-rich tyrosine kinase 2/cJun N-terminal kinase pathway. Moreover, engagement of this intracellular signaling route was functionally active in the mouse dorsal striatum in vivo, as proven by the disruption of neuronal integrity and behavioral tasks. To analyze this effect anatomically, we manipulated G q-protein-dependent signaling selectively in neurons belonging to the direct or indirect striatal pathway. Acute G q-protein activation in direct-pathway or indirect-pathway neurons produced an enhancement or a decrease, respectively , of activity-dependent parameters. In contrast, sustained G q-protein activation impaired the functionality of direct-pathway and indirect-pathway neurons and disrupted the behavioral performance and electroencephalography-related activity tasks controlled by either anatomical framework. Collectively, these findings define the molecular mechanism and functional relevance of G q-protein-driven signals in striatal circuits under normal and overactivated states

Prenatal exposure to cannabinoids evokes long-lasting functional alterations by targeting CB1 receptors on developing cortical neurons

The CB1 cannabinoid receptor, the main target of Δ9 -tetrahydrocannabinol (THC), the most prominent psychoactive compound of marijuana, plays a crucial regulatory role in brain development as evidenced by the neurodevelopmental consequences of its manipulation in animal models. Likewise, recreational cannabis use during pregnancy affects brain structure and function of the progeny. However, the precise neurobiological substrates underlying the consequences of prenatal THC exposure remain unknown. As CB1 signaling is known to modulate long-range corticofugal connectivity, we analyzed the impact of THC exposure on cortical projection neuron development. THC administration to pregnant mice in a restricted time window interfered with subcerebral projection neuron generation, thereby altering corticospinal connectivity, and produced long-lasting alterations in the fine motor performance of the adult offspring. Consequences of THC exposure were reminiscent of those elicited by CB1 receptor genetic ablation, and CB1-null mice were resistant to THC-induced alterations. The identity of embryonic THC neuronal targets was determined by a Cre-mediated, lineage-specific, CB1 expression-rescue strategy in a CB1-null background. Early and selective CB1 reexpression in dorsal telencephalic glutamatergic neurons but not forebrain GABAergic neurons rescued the deficits in corticospinal motor neuron development of CB1-null mice and restored susceptibility to THC-induced motor alterations. In addition, THC administration induced an increase in seizure susceptibility that was mediated by its interference with CB1-dependent regulation of both glutamatergic and GABAergic neuron development. These findings demonstrate that prenatal exposure to THC has long-lasting deleterious consequences in the adult offspring solely mediated by its ability to disrupt the neurodevelopmental role of CB1 signaling

Interaction between anandamide and sphingosine-1-phosphate in mediating vasorelaxation in rat coronary artery

<b>BACKGROUND AND PURPOSE</b> Anandamide and sphingosine-1-phosphate (S1P) both regulate vascular tone in a variety of vessels. This study aimed to examine the mechanisms involved in the regulation of coronary vascular tone by anandamide and S1P, and to determine whether any functional interaction occurs between these receptor systems. <br></br> <b>EXPERIMENTAL APPROACH</b> Mechanisms used by anandamide and S1P to regulate rat coronary artery (CA) reactivity were investigated using wire myography. Interactions between S1P and the cannabinoid (CB)2 receptor were determined using human embryonic kidney 293 (HEK293) cells that stably over-express recombinant CB2 receptor. <br></br> <b>KEY RESULTS</b> Anandamide and S1P induced relaxation of the rat CA. CB2 receptor antagonists attenuated anandamide-induced relaxation, while S1P-mediated relaxation was dependent on the vascular endothelium and S1P3. Anandamide treatment resulted in an increase in the phosphorylation of sphingosine kinase-1 within the CA. Conversely, anandamide-mediated relaxation was attenuated by inhibition of sphingosine kinase. Moreover, S1P3, specifically within the vascular endothelium, was required for anandamide-mediated vasorelaxation. In addition to this, S1P-mediated relaxation was also reduced by CB2 receptor antagonists and sphingosine kinase inhibition. Further evidence that S1P functionally interacts with the CB2 receptor was also observed in HEK293 cells over-expressing the CB2 receptor. <br></br> <b>CONCLUSIONS AND IMPLICATIONS</b> In the vascular endothelium of rat CA, anandamide induces relaxation via a mechanism requiring sphingosine kinase-1 and S1P/S1P3. In addition, we report that S1P may exert some of its effects via a CB2 receptor- and sphingosine kinase-dependent mechanism, where subsequently formed S1P may have privileged access to S1P3 to induce vascular relaxation

Mutations in the 'DRY' motif of the CB1 cannabinoid receptor result in biased receptor variants.

The role of the highly-conserved 'DRY' motif in the signaling of the CB1 cannabinoid receptor (CB1R) was investigated by introducing single, double and triple alanine mutations into this site of the receptor. We found that the CB1R-R3.50A mutant displays a partial decrease in its ability to activate heterotrimeric Go proteins (~85% of wild-type CB1R (CB1R-WT)). Moreover, this mutant showed impaired beta-arrestin binding in response to agonist stimulus, although its basal beta-arrestin binding was enhanced. More strikingly, the double mutant CB1R-D3.49A/R3.50A was biased toward beta-arrestins, as it gained a robustly increased beta-arrestin1 and beta-arrestin2 binding ability compared to the wild-type receptor, while its G protein activation was decreased. In contrast, the double mutant CB1R-R3.50A/Y3.51A proved to be G protein-biased, as it was practically unable to recruit beta-arrestin2 in response to agonist stimulus, while still activating G proteins, although at a reduced level (~75% of CB1R-WT). Agonist-induced ERK1/2 activation of the CB1R mutants showed good correlation with their beta-arrestin binding ability but not with their G protein activation or inhibition of cAMP accumulation. Our results suggest that G protein-activation and beta-arrestin-binding of the CB1R are mediated by distinct receptor conformations and the conserved 'DRY' motif plays different roles in the stabilization of these conformations, thus mediating both G protein- and beta-arrestin2-mediated functions of CB1R

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)

Long-term hippocampal interneuronopathy drives sex-dimorphic spatial memory impairment induced by prenatal THC exposure

Prenatal exposure to Delta(9)-tetrahydrocannabinol (THC), the most prominent active constituent of cannabis, alters neurodevelopmental plasticity with a long-term functional impact on adult offspring. Specifically, THC affects the development of pyramidal neurons and GABAergic interneurons via cannabinoid CB1 receptors (CB1R). However, the particular contribution of these two neuronal lineages to the behavioral alterations and functional deficits induced by THC is still unclear. Here, by using conditional CB1R knockout mice, we investigated the neurodevelopmental consequences of prenatal THC exposure in adulthood, as well as their potential sex differences. Adult mice that had been exposed to THC during embryonic development showed altered hippocampal oscillations, brain hyperexcitability, and spatial memory impairment. Remarkably, we found a clear sexual dimorphism in these effects, with males being selectively affected. At the neuronal level, we found a striking interneuronopathy of CCK-containing interneurons in the hippocampus, which was restricted to male progeny. This THC-induced CCK-interneuron reduction was not evident in mice lacking CB1R selectively in GABAergic interneurons, thus pointing to a cell-autonomous THC action. In vivo electrophysiological recordings of hippocampal LFPs revealed alterations in hippocampal oscillations confined to the stratum pyramidale of CA1 in male offspring. In addition, sharp-wave ripples, a major high-frequency oscillation crucial for learning and memory consolidation, were also altered, pointing to aberrant circuitries caused by persistent reduction of CCK+ basket cells. Taken together, these findings provide a mechanistic explanation for the long-term interneuronopathy responsible for the sex-dimorphic cognitive impairment induced by prenatal THC.The authors declare no conflict of interest. This work was supported by grants PI18-00941 to IG-R cofinanced by the European Development Regional Fund "A way to achieve Europe"; RTI2018-095311-B-100 to MG, BFU2015-66887-R to LM-P, and 2017-SGR-138 to MP from the Generalitat de Catalunya. DG-R was supported by Fundacion Tatiana Perez de Guzman; DG-D was supported by a PhD fellowship from the Spanish Ministry of Economy and Competitiveness (BES-2013-064171). JP-L and JA were supported by FPI and FPU program fellowships, respectively (Ministerio de Educacion, Cultura y Deporte) and S. S-S. was supported by Fondo Social Europeo-YEI (CT101/18-CT102/18PEJD-2018-PRE/BMD-7933). CM is recipient of a Marie Curie program fellowship (747487)