In dieser Arbeit wurde ein Verfahren zur effizienten Herstellung von (−)-trans-Cannabidiol (CBD, 10), (−)-trans-Δ9-Tetrahydrocannabinol (Dronabinol, 21) und (−)-trans-Cannabidivarin (CBDV, 30) durch kontinuierliche Synthese untersucht und entwickelt. CBD konnte durch kontinuierliche Synthese in drei Schritten aus Olivetolcarbonsäuremethylester (OM, 6) und Menthadienol G (3) mit einer Ausbeute von 41 % synthetisiert werden. Bei optimierten Bedingungen betrug die Reinheit nach Kristallisation > 99 %. Die Stereochemie konnte durch Röntgenstrukturanalyse eindeutig als 1R,6R bestimmt werden. Vorteilhaft war dabei, dass Toluol anstatt eines chlorierten Lösungsmittels verwendet werden konnte. Weitere Vorteile waren die kurze Reaktionszeit und die Tatsache, dass die Synthese bei Raumtemperatur durchgeführt werden konnte. Es konnten fünf Nebenprodukte detektiert und identifiziert werden, wovon eines Dronabinol war. Bei optimierten Reaktionsparametern konnte eine Ausbeute an Dronabinol von 64,5 % erreicht werden. Durch Simulated Moving Bed (SMB)-Chromatographie konnte Dronabinol kontinuierlich mit einem Gehalt von > 95 % hergestellt werden. Nach der Synthese waren vier Verunreinigungen detektierbar, und zwar Olivetol (17), CBD, Exo-Tetrahydrocannabinol (Exo-THC, 23) und Δ8-Tetrahydrocannabinol (Δ8-THC, 22). Durch die SMB-Aufreinigung konnten alle Verunreinigungen auf einen monographiekonformen (USP 37) Gehalt abgereichert werden. Nach der finalen destillativen Aufarbeitung trat eine noch nicht identifizierte Verunreinigung in einem Gehalt von ca. 0,4 Flächen-% auf. CBDV konnte durch kontinuierliche Synthese in drei Schritten aus Divarincarbonsäuremethylester (DM, 25) und Menthadienol G synthetisiert werden. Die Ausbeute betrug ca. 30 %, die Reinheit nach Kristallisation > 99 %. Es konnten fünf Nebenprodukte detektiert werden, die im Rahmen dieser Arbeit nicht weiter charakterisiert wurden. Der Syntheseweg bietet durch Modifikation der Seitengruppen an Position 6 (R1) und Position 5 (R2) der Alkylbenzol-Gruppe Zugang zu synthetischen Cannabinoiden mit einem CBD- oder CBDV-Grundgerüst. Es wurden neun neue Cannabinoide hergestellt: 2-Hydroxyethylcannabidiolat (2-HEC, 31), 2-Hydroxypentylcannabidiolat (2 HPC, 32), Glycerylcannabidiolat (GCBD, 33), Cyclohexylcannabidiolat (CHC, 34), Hexylcannabidiolat (HC, 35), N-Methylsulfonylcannabidiolat (NMSC, 36), 2 Hydroxyethylcannabidivarinolat (2-HECBDV, 37), Cyclohexylcannabidivarinolat (CHCBDV, 38) und Hexylcannabidivarinolat (HCBDV, 39). Die Bindungsaffinität wurde in Cannabinoid-Rezeptor-transfizierten HEK293EBNA-Zellen untersucht, die intrinsische Aktivität in CHO-Zellen, die Induktion von NF-κB (nuclear factor kappa B) sowie von NFAT (nuclear factor of activated T cells) in Jurkat-T Zellen, die Induktion proinflammatorischer Zytokine und Chemokine (Interleukin(IL)-6, IL-1β, CC Chemokinligand 2' (CCL2) und Tumornekrosefaktor(TNF)-α) auf mRNA-Ebene in RAW264.7-Makrophagen und die Expression von proinflammatorischen Zytokinen (IL-1β, IL-6, IL-8, TNF-α) und Prostaglandin E2 (PGE2) auf Proteinebene in primären humanen Monozyten. Die CBD-Derivate zeigten eine höhere Selektivität für CB2-Rezeptoren. Die CBDV-Derivate HCBDV und CHCBDV zeigten eine spezifische Bindung an CB1- und CB2-Rezeptoren im nanomolaren Bereich. 2-HEC, 2-HPC, GCBD und NMSC wirkten als Agonisten an CB2- und als Antagonisten am CB1-Rezeptor. CHC band an CB1 und CB2 im submikromolaren Bereich und schien ein Agonist für beide Rezeptoren zu sein. 2- HECBD wirkte als Agonist auf CB2-Rezeptoren und als Antagonist auf CB1-Rezeptoren. In Jurkat-T Zellen hemmte NMSC dosisabhängig die Aktivität von NF-κB sowie von NFAT. 2-HEC, 2-HPC und GCBD hemmten die Expression von NFAT ebenfalls dosisabhängig. CHC und HC reduzierten dosisabhängig die Expression von IL-1β- und CCL2-mRNA in RAW264.7-Makrophagen. NMSC hemmte in geringeren Dosen IL-1β, CCL2 sowie TNF-α und induzierte in höheren Dosen einen starken Anstieg der IL-6-mRNA. In primären humanen Monozyten hemmten 2 HEC und GCBD konzentrationsabhängig die Synthese von IL-1β, IL-6 und TNF-α. 2-HPC hemmte dosisabhängig die Bildung von TNF-α und IL-6. HC verminderte dosisabhängig die Freisetzung von TNF-α und IL-6. NMSC steigerte die durch LPS erhöhte Freisetzung von IL-1β noch weiter, hemmte aber TNF-α, IL-8 und PGE2. Die hier untersuchten CBD- und CBDV-Derivate sind geeignet, gezielt an Cannabinoid-Rezeptoren zu wirken. Einige der Derivate könnten als selektive CB2-Agonisten genutzt werden. Die Länge des aliphatischen Rests an R2 von CBD (Pentyl-Cannabinoiden) und CBDV (Propyl-Cannabinoiden) korrelierte nicht mit der Bindungsaffinität. Eine höhere Polarität an R1 (2-HECBDV > NMSC > GCBD > 2-HEC) schien demgegenüber die agonistische Aktivität an CB2 zu begünstigen. Um den Ergebnissen zur Beziehung zwischen Struktur und Wirkung noch mehr Bedeutung zu geben, wären weitere synthetische Derivate und deren Testung notwendig. / In this thesis a process for the efficient production of (−)-trans-cannabidiol (CBD, 10), (−)-trans-Δ9-tetrahydrocannabinol (dronabinol, 21) und (−)-trans-cannabidivarin (CBDV, 30) by means of continuous synthesis was researched and developed. CBD was synthesized in three steps using a continuous synthesis process from olivetol-carboxylic acid methyl ester (OM, 6) and Menthadienol G (3) with a yield of 41%. With optimized conditions, the purity after crystallization was >99%. The stereochemistry was distinctly determined as 1R,6R by X-ray crystal analysis. Beneficial was the fact that toluene was used instead of a chlorinated solvent. Further advantages comprised a short reaction time and the fact that the synthesis can be carried out at room temperature. Five by-products were detected and identified, one of them being dronabinol. With optimized reaction parameters, a yield of up to 64.5% of dronabinol was achieved. By simulated moving bed (SMB) chromatography, dronabinol was produced repeatedly with a purity of >95%. After the synthesis process, four impurities were detectable, namely olivetol (17), CBD, exo-tetrahydrocannabinol (exo-THC, 23) and Δ8-tetrahydrocannabinol (Δ8-THC, 22). All impurities were depleted to a monograph (USP 37) conforming level through SMB purification. After the final distillation, one further unidentified impurity occurred with a content of about 0.4 area%. CBDV was synthesized through continuous synthesis in three steps from divarin-carboxylic acid methyl ester (DM, 25) und Menthadienol G. The yield was approximately 30%, the purity after crystallization >99%. Five by-products were detected which were not further characterized within the scope of this thesis. Through modification of the side groups at position 6 (R1) and position 5 (R2) of the alkyl benzene moiety, the synthesis route offers access to synthetic cannabinoids with a CBD or CBDV scaffold. Nine new cannabinoids have been produced: 2-hydroxyethyl cannabidiolate (2-HEC, 31), 2-hydroxypentyl cannabidiolate (2-HPC, 32), glyceryl cannabidiolate (GCBD, 33), cyclohexyl cannabidiolate (CHC, 34), hexyl cannabidiolate (HC, 35), N-methyl-sulfonyl cannabidiolate (NMSC, 36), 2-hydroxyethyl cannabidivarinolate (2-HECBDV, 37), cyclohexyl cannabidivarinolate (CHCBDV, 38), hexyl cannabidivarinolate (HCBDV, 39). Binding affinity was studied in CB receptor-transfected HEK293EBNA cells, the intrinsic activity in CHO cells, the induction of nuclear factor kappa B (NF-κB) and nuclear factor of activated T cells (NFAT) in Jurkat T cells, the induction of pro-inflammatory cytokines and chemokines (interleukin (IL)-6, IL 1β, CC chemokine ligand 2 (CCL2) and tumor necrosis factor (TNF)-α) on the mRNA level in RAW264.7 macrophages and the expression of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) and prostaglandin E2 (PGE2) on the protein level in primary human monocytes. The CBD derivatives showed higher selectivity for CB2. The CBDV derivatives HCBDV and CHCBDV showed specific binding at CB1 and CB2 receptors in the nanomolar range. 2-HEC, 2-HPC, GCBD and NMSC acted as agonists at CB2 and as antagonists at CB1 receptors. CHC bound CB1 and CB2 at the submicromolar range, and acted as an agonist for both receptors. 2-HECBDV was demonstrated to be an agonist at CB2 and an agonist at CB1. In Jurkat T cells, NMSC inhibited both NF-κB and NFAT activity in a dose-dependent fashion. 2-HEC, 2-HPC and GCBD inhibited the expression of NFAT, also in a dose-dependent manner. CHC and HC dose-dependently reduced the expression of IL-1β and CCL2 mRNA in RAW264.7 macrophages. NMSC inhibited at lower doses IL-1β, CCL2 and TNF-α and at higher doses induced a pronounced increase in IL-6 mRNA. In human primary monocytes, 2-HEC and GCBD inhibited IL-1β, IL-6 and TNF-α synthesis in a dose-dependent fashion. 2-HPC dose-dependently prevented the expression of TNF-α and IL-6 in high concentrations. HC decreased TNF-α and IL-6 release in a dose-dependent fashion. NMSC further increased LPS-elevated IL-1β release but inhibited TNF-α, IL-8 und PGE2. The CBD and CBDV derivatives studied here are suitable for targeting CB receptors. Some of the derivatives might be used as selective CB2 agonists. The length of the aliphatic rest at R2 of CBD (pentyl) and CBDV (propyl) did not correlate with binding affinity. Higher polarity at R1 (2-HECBDV > NMSC > GCBD > 2 HEC) however appeared to favor the agonistic activity at CB2 receptors. To give the results on the relationship between structure and effect more significance, further synthetic derivatives and their testing would be necessary.

Frankfurt (Main), University, Diss., 2007.

Frankfurt (Main), Universiẗat, Diss., 2007.

Ulm, Univ., Diss., 2008.

Regensburg, Univ., Diss., 2008

Thesis (doctoral)--Albert-Ludwigs-Universität Freiburg im Breisgau, 2005.

München, Techn. Univ., Diss., 2004.

La cirrosi és una malaltia crònica, difusa i considerada irreversible, caracteritzada per l’alteració de l’arquitectura vascular hepàtica provocada pel reemplaçament del teixit parenquimàtic per teixit fibròtic, així com per l’aparició de nòduls de regeneració. Aquesta destrucció del teixit hepàtic i la seva substitució per teixit fibrós provoca un augment marcat de la resistència al flux de la vena porta, així com una greu alteració de la funció hepàtica. A més d’un risc augmentat d’aparició de càncer hepàtic, les complicacions més freqüents i potencialment mortals de la cirrosi, associades a la hipertensió portal, són l’hemorràgia digestiva, l’ascites i trastorns de la funció renal, les infeccions bacterianes i l’encefalopatia hepàtica. S’han utilitzat diverses estratègies terapèutiques per evitar o disminuir la gravetat de les complicacions de la cirrosi, tot i que en la majoria de casos la seva eficàcia és escassa o presenten contraindicacions. És important doncs desenvolupar altres estratègies dirigides a evitar o revertir el dany hepàtic. Considerem, en aquesta línia, que el sistema endocannabinoide de senyalització podria ser una bona diana terapèutica. Aquest sistema està format per cannabinoides endògens, així com pels seus receptors específics (CB1, CB2 i altres) i els seus enzims de síntesi i degradació. El desenvolupament de molècules agonistes i antagonistes selectives d’aquests mediadors ha permès conèixer la seva acció biològica i assajar possibles tractaments de diverses malalties, entre elles les complicacions associades a la cirrosi. Concretament el bloqueig del receptor CB1 mitjançant l’antagonista rimonabant ha mostrat, en diversos estudis, efectes beneficiosos en la progressió de la fibrosi, alteracions hemodinàmiques i formació d’ascites, sobretot en administració aguda o pretractament a llarg termini. A més, en estudis experimentals d’encefalopatia hepàtica per dany hepàtic fulminant, s’han observat millores a les funcions neurològiques, dosi-depenents de l’administració d’antagonistes del receptor CB1. Tot i que l’expressió de CB1 de cèl·lules de Kupffer i estelades està augmentada en fetges cirròtics, podria ser que els hepatòcits també estiguessin implicats de manera rellevant a través de l’activació dels seus receptors CB1 a la progressió de la fibrosi. Així doncs, l’objectiu principal d’aquesta tesi fou investigar l’efecte del tractament a llarg termini amb rimonabant en un model de cirrosi avançada, sobre la fibrosi i la cirrosi, avaluar el seu efecte sobre l’incidència de translocació bacteriana, l’hemodinàmica sistèmica i en el desenvolupament d’encefalopatia hepàtica en rates cirròtiques ascítiques, així com establir el paper del receptor CB1 dels hepatòcits sobre la progressió de la fibrosi. Per aquest motiu es va dissenyar un primer estudi experimental in vivo en el que es va administrar rimonabant a llarg termini a rates cirròtiques amb ascites per tal de valorar l’efecte sobre la progressió de la cirrosi, i sobre les complicacions associades, com les alteracions hemodinàmiques, la translocació bacteriana i l’encefalopatia hepàtica. Un segon estudi in vitro amb cultius primaris de hepatòcits de rates cirròtiques ens va permetre avaluar el paper dels hepatòcits i la seva relació amb el sistema endocannabinoide de senyalització en la progressió de la cirrosi. D’acord amb els resultats obtinguts d’aquests dos estudis vam poder concloure que el tractament a llarg termini amb rimonabant disminueix la fibrosi i millora l’hemodinàmica esplàcnica i sistèmica així com alguns paràmetres de funció hepàtica. Això s’associa amb una reducció de la translocació bacteriana. A més, redueix l’amoni cerebral i l’edema cerebral de baix grau. Rimonabant podria ser útil per algunes de les complicacions associades a la cirrosi com les infeccions bacterianes i l’encefalopatia hepàtica. Pel que fa al paper dels hepatòcits a la cirrosi experimental per tetraclorur de carboni, sembla que aquest seria limitat. / Cirrhosis is a chronic disease characterized for the alteration of hepatic vascular architecture due to the replacement of parenchymal tissue with fibrotic tissue. This hepatic tissue destruction and its substitution with fibrotic tissue leads to the increased resistance to portal vein flow and to serious alteration of hepatic function. Aside from development of hepatic cancer, the most common complications of cirrhosis, associated to portal hypertension, are gastrointestinal bleeding, ascites and renal malfunction, bacterial infections and hepatic encephalopathy. Several therapeutic strategies had been used to avoid or decrease severity of cirrhosis complications, although its effectiveness is low or they present contraindications. Therefore, there is a need of new strategies than avoid or revert hepatic damage. Considering this, the endocannabinoid system of signaling could represent a new therapeutic target. This system is composed by endogen cannabionids, their specific receptors (CB1, CB2 and others) as well as by the respective synthesis and degradation enzymes. The development of selectives agonists and antagonists for these molecules enabled to learn about their biological activity as well as to test their use as a treatment on different diseases, among them cirrhosis. Specifically the blockade of CB1 receptor by its antagonist rimonabant has show to be beneficial in the progression of fibrosis, hemodynamic alterations and ascites formation, mainly in acute administration or long term pretreatment experimental studies. Further, in hepatic encephalopathy experimental studies by means of fulminant liver damage, improvement on neurological functions when administering CB1 receptor antagonists has been reported. Even if CB1 expression on Kupffer cells and stellate cells is increased in cirrhotic livers, hepatocytes may as well be involved in fibrosis progression through CB1 receptor activation. So, the aim of the present thesis was assess the effect of Rimonabant long-term administration on fibrosis and cirrhosis, bacterial translocation, hemodynamic alterations and hepatic encephalopathy development in ascitic cirrhotic rats, as well as to establish the role of hepatocyte receptor CB1 on progression of fibrosis. To do so, firstly an in vivo experimental study was designed. In this study we administered rimonabant for a ten days to cirrhotic ascitic rats in order to assess its effect on cirrhosis progression and its associated complications. Secondly, an in vitro study with primary cultured hepatocytes from cirrhotic rats allowed as to assess the role of hepatocytes and their relations with the endocannabinoid system regarding progression of cirrhosis. According to our results, long-term rimonabant administration improves fibrosis, splachnic and systemic vasodilatation and some liver function parameters. This is associated with a reduction in bacterial translocation incidence. Moreover, long-term treatment reduces brain ammonia leading to a decrease of low grade brain edema. Rimonabant could be a useful therapy for some complications associated with cirrhosis such as bacterial infections and hepatic encephalopathy. In terms of the role of hepatocytes on experimental cirrhosis by carbon tetrachloride, it seems it is not relevant.

Con la finalidad de explorar con profundidad las bases neurobiológicas de la adicción a cannabinoides hemos llevado a cabo diferentes estudios farmacológicos y moleculares. El sustrato neuroanatómico de la dependencia física de cannabinoides ha sido investigado en ratones que recibieron un tratamiento crónico con el agonista WIN55,212-2. En este estudio, se observó que el cerebelo y en menor grado el hipocampo y la amígdala, participan en la manifestación comportamental del síndrome de abstinencia de cannabinoides. Estas tres áreas se caracterizan por presentar una alta densidad de receptores cannabinoides CB1. Además, hemos evaluado la participación de diversos sistemas de neurotransmisión como son los sistemas opioide y purinérgico endógenos, en las respuestas comportamentales inducidas tras la administración de cannabinoides. Especialmente, nos hemos interesado por aquellas respuestas que están estrechamente relacionadas con las propiedades adictivas de dichos compuestos, como son los efectos reforzantes y aversivos y el desarrollo de dependencia física. Para ello hemos utilizado ratones modificados genéticamente. El sistema opioide endógeno ha sido relacionado con la manifestación de las propiedades adictivas de los cannabinoides. En este trabajo, mediante la utilización de ratones dobles mutantes MOR/DOR, hemos demostrado que se requiere una acción cooperativa entre ambos tipos de receptores opioides para que el síndrome de abstinencia cannabinoide se exprese enteramente. Por otro lado, los ratones con una supresión del gen que codifica para el receptor de adenosina A2A no mostraron ni preferencia de plaza ni aversión de plaza condicionadas a la administración de THC. Además, estos ratones presentaron un síndrome de abstinencia de THC de menor severidad, lo que sugiere una participación específica de los receptores A2A en efectos de los cannabinoides relacionados con sus propiedades adictivas. Finalmente, teniendo en cuenta que el sistema cannabinoide parece estar implicado en la modulación de las propiedades adictivas de otras drogas de abuso como opiáceos, etanol, cocaína y MDMA, hemos investigado la posible implicación del sistema cannabinoide en las propiedades adictivas de la nicotina. Para ello, hemos evaluado las respuestas comportamentales inducidas tras la administración aguda y crónica de nicotina en ratones deficientes del receptor cannabinoide CB1. En este sentido, nuestro principal hallazgo ha sido que las propiedades gratificantes de la nicotina no se manifiestan en los ratones mutantes sin el receptor cannabinoide CB1. Este hecho resulta de especial interés para la búsqueda de nuevas alternativas terapéuticas que faciliten el abandono del hábito tabáquico. / Cannabinoid addiction includes complex neurobiological and behavioural processes. Recently, several animal models allowing the exploration of the neurobiological basis of cannabinoid addiction have been developed. Acute cannabinoid reinforcing effects play a major role in the initiation of cannabinoid addiction, whereas the negative consequences of drug abstinence have a crucial motivational significance for relapse and maintenance of the addictive process. To further explore the neurobiological basis of cannabinoid addiction, we have conducted several pharmacological and molecular studies. The neuroanatomical substrate of cannabinoid physical dependence has been investigated in mice chronically receiving the cannabinoid agonist WIN 55,212-2. Interestingly, the cerebellum and in a lesser extent the hippocampus and the amygdala are shown to participate in the behavioural expression of cannabinoid withdrawal. All these brain areas have a high density of CB1 cannabinoid receptors. Moreover, we have evaluated the involvement of various neurotransmitter systems, such as the purinergic and opioid systems, in the behavioural responses of cannabinoids related to their addictive properties, including rewarding effects and the development of physical dependence. For this purpose, we have used genetically modified mice. Mice lacking A2A adenosine receptors reveal lower motivational responses to cannabinoids and a decreased cannabinoid withdrawal syndrome, suggesting a specific involvement of these receptors in the addictive-related properties of cannabinoids. On the other hand, the opioid system has also been implicated in the addictive properties of cannabinoids. Here, by using double mutants for mu- and delta-opioid receptors, we show that a cooperative action of both receptors is required for the entire expression of cannabinoid dependence. Finally, taking into account that the cannabinoid system has been reported to participate in the addictive properties of other drugs of abuse, such as ethanol, cocaine and MDMA, we have investigated the possible role of the cannabinoid system in the addictive properties of nicotine. We have evaluated nicotine behavioural responses in mice lacking CB1 cannabinoid receptors. In this regard, our main findings are that some acute effects and motivational responses of nicotine can be modulated by the endogenous cannabinoid system which could be of interest in order to find new therapies to facilitate tobacco smoking cessation.

Background: Background of this work was the investigation of the endocannabinoid system (ECS) in the Fmr1 knock- out (KO) mouse. The Fmr1- KO mouse is a mouse model for fragile X syndrome (FXS). FXS is the leading monogenic cause for autism spectrum disorders (ASD) in humans. The Fmr1- KO mouse displays autistic behavior such as an impaired social interaction, repetitive behavior, cognitive deficits, increased anxiety and aggressiveness. Alterations of the ECS have been suggested to play a key role in the etiopathology of a variety of neuropsychiatric disorders. Until today, little has been described about the involvement of the ECS in ASD. Interrogation: 1. Evaluating the manifestation of typical cannabinoid- induced effects in the Fmr1- KO mouse 2. Investigating the influenceability of autistic symptoms with THC treatment in the Fmr1- KO mouse 3. Analyzing the signaling cascade of the stimulated and unstimulated ECS in different brain regions of the Fmr1- KO mouse Material and Methods: Experiments were carried out on adult (12±1 weeks old) male Fmr1- KO and Fmr1- wild- type (WT) mice from the C57BL/6J- (B6)- background. N= 15 mice received THC (10mg/kg bodyweight) and N= 16 received WIN55,212 (3mg/kg bodyweight). 30min after injection, the body temperature was measured and the distance animals moved in an open field during 15min was recorded (locomotion). Then, animals were placed with their forepaws onto a horizontally fixed bar and the time remaining in this position (catalepsy) was measured. Finally animals were placed on a preheated plate and the temperature at which a pain stimulus occurred was determined (testing analgesia). All 4 experiments are called tetrad experiment. Afterwards changes in body temperature, locomotion, catalepsy and analgesia of the animals was evaluated. To explore long-term effects of THC after the tetrad, N= 15 animals were tested in a social interaction test with a female contact mouse, 10 and 20 days after THC treatment. Therefore, the tested mouse and the contact mouse were placed together into a cage and the time mice spent in social interaction (nose, body and anogential sniffing, allogrooming and body contact) was manually quantified during 6min of recorded testing time. Another group of N= 19 received a premedication of rimonabant (Cannabinoid- receptor 1 (CB1) antagonist, 3mg/kg bodyweight) 30min prior to THC treatment. Rimonabant prevents THC from binding to CB1 and therefore allows the assessment of the involvement of CB1 in mediating social behavior. Furthermore the suggestibility of context-dependent fear conditioning with THC treatment has been tested on N= 13 mice. Animals were placed into a conditioning chamber that delivered 6 short electric shocks with a 30sec pause to their paws (conditioning phase). Immediately afterwards mice received THC or placebo. 24h later contextdependent fear was evaluated by quantification of the time mice spent freezing in the conditioning-chamber (fear) without receiving foot shocks. Intraneuronal signaling of the ECS was analyzed with N= 29 animals using western blots. Quantities of phosphorylated (“activated”) protein kinases (ERK, AKT and S6) from different brain homogenates (hippocampus, striatum, cortex and cerebellum) were therefore measured after THC or placebo injection (30 minutes prior to sacrificing). Results: Cannabinoids induced hypothermia, hypolocomotion, analgesia and catalepsy in WTmice. These effects were significantly less detectable in Fmr1- KO mice. Effects of both cannabinoids, THC and WIN55,212, were comparable with a slightly greater but not significant efficiency of THC. THC treated WT- mice exhibited further reduced social interaction 10 days after treatment, an effect that was partially prevented by premedication with rimonabant. THC increased social interaction in Fmr1- KO mice comparable to the level of untreated WT- mice. THC had no effect on behavior of WT- mice in context-dependent fear conditioning. Fmr1- KO mice showed significant less contextdependent fear conditioning compared to WT- mice. THC facilitated the recognition of an anxiety-correlated context in Fmr1- KO mice comparable to untreated WT- mice. In western blots significant changes in the THC- induced signaling cascade were detectable and depending on genotype, brain-region and analyzed protein-kinase. In the hippocampus there were no changes in untreated Fmr1- KO mice compared to WT- mice. THC had no effect on activation of protein-kinases in WT- and Fmr1- KO mice. In the striatum there were no changes in untreated Fmr1- KO mice compared to WTmice. THC significantly increased activity of ERK, AKT and S6 in WT-mice and not in Fmr1- KO mice. In the cortex of untreated Fmr1- KO mice AKT showed a significantly increased activity compared to WT- mice. THC significantly increased AKT activity in WT- mice without having an effect on KO- mice. In the cerebellum there were no changes in untreated Fmr1- KO mice compared to WT- mice. THC significantly increased ERK- activity in Fmr1- KO mice but had no effect on protein kinase activity in WT- mice. Conclusion: We observed physiological cannabinoid effects in WT- mice after treatment with THC and WIN55,212. These effects are significantly attenuated in Fmr1- KO mice. This may be interpreted as a desensitization of the ECS in the Fmr1- KO mouse. At the same time it was demonstrated that THC has the potential to improve context dependent memory consolidation and to increase social interaction in the Fmr1- KO mouse. In particular the influence of THC on impaired social interaction should be a target of further investigations to find possible therapeutic options for this typical symptom of Autism. Underlying molecular mechanisms remain unclear and the analysis of THC stimulated intraneuronal signaling gave no clear indication of possible molecular alterations in the Fmr1- KO mouse.