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We identified three types of monosynaptic cholinergic inputs spatially arranged onto medial substantia nigra dopaminergic neurons in male and female mice: cotransmitted acetylcholine (ACh)/GABA, GABA-only, and ACh only. There was a predominant GABA-only conductance along lateral dendrites and soma-centered ACh/GABA cotransmission. In response to repeated stimulation, the GABA conductance found on lateral dendrites decremented less than the proximally located GABA conductance, and was more effective at inhibiting action potentials. While soma-localized ACh/GABA cotransmission showed depression of the GABA component with repeated stimulation, ACh-mediated nicotinic responses were largely maintained. We investigated whether this differential change in inhibitory/excitatory inputs leads to altered neuronal excitability. We found that a depolarizing current or glutamate preceded by cotransmitted ACh/GABA was more effective in eliciting an action potential compared with current, glutamate, or ACh/GABA alone. This enhanced excitability was abolished with nicotinic receptor inhibitors, and modulated by T- and L-type calcium channels, thus establishing that activity of multiple classes of ion channels integrates to shape neuronal excitability.SIGNIFICANCE STATEMENTOur laboratory has previously discovered a population of substantia nigra dopaminegic neurons (DA) that receive cotransmitted ACh and GABA. This study used subcellular optogenetic stimulation of cholinergic presynaptic terminals to map the functional ACh and GABA synaptic inputs across the somatodendritic extent of substantia nigra DA neurons. We determined spatially clustered GABA-only inputs on the lateral dendrites while cotransmitted ACh and GABA clustered close to the soma. We have shown that the action of GABA and ACh in cotransmission spatially clustered near the soma play a critical role in enhancing glutamate-mediated neuronal excitability through the activation of T- and L-type voltage-gated calcium channels.

The alteration of the endocannabinoid tone usually associates with changes in the expression and/or function of the cannabinoid CB

The use and abuse of cannabis can be associated with significant pathophysiology, however, it remains unclear whether (1) acute administration of Δ-9-tetrahydrocannabinol (THC) during early adulthood alters the cannabinoid type 1 (CB1 ) receptor localization and expression in cells of the brain, and (2) THC produces structural brain changes. Here we use electron microscopy and a highly sensitive pre-embedding immunogold method to examine CB1 receptors in the hippocampus cornu ammonis subfield 1 (CA1) 30 min after male mice were exposed to a single THC injection (5 mg/kg). The findings show that acute exposure to THC can significantly decrease the percentage of CB1 receptor immunopositive terminals making symmetric synapses, mitochondria, and astrocytes. The percentage of CB1 receptor-labeled terminals forming asymmetric synapses was unaffected. Lastly, CB1 receptor expression was significantly lower at terminals of symmetric and asymmetric synapses as well as in mitochondria. Structurally, CA1 dendrites were significantly larger, and contained more spines and mitochondria following acute THC administration. The area of the dendritic spines, synaptic terminals, mitochondria, and astrocytes decreased significantly following acute THC exposure. Altogether, these results indicate that even a single THC exposure can have a significant impact on CB1 receptor expression, and can alter CA1 ultrastructure, within 30 min of drug exposure. These changes may contribute to the behavioral alterations experienced by young individuals shortly after cannabis intoxication.

Omega-3 fatty acids (FA) are essential long-chain polyunsaturated FA, amongst others, α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The main food source of omega-3 is the oily fish which is found in salmon, anchovy or tuna. A diet enriched with omega-3 is known to favour healthy states by promoting molecular and functional changes during brain damage recovery, membranes fluidity, energy metabolism regulation, release of signalling molecules or gene expression. Likewise, the activation of signalling pathways by omega-3 improves neural transmission and plasticity and decreases oxidative stress and inflammation in cells, particularly in neurons. Therefore, omega-3 supplements have been used to prevent or treat many human disorders. This review is intended to provide the stateof- the art of omega-3 as a natural component with beneficial therapeutic properties in cardiovascular and neurodegenerative diseases (Alzheimer and Parkinson), cancer, alcoholism and overweight. Lastly, some insights into the potential benefits of omega-3 supplementation to dodge or treat some other diseases in the future are also considered.; Kate luzeko omega-3 mantenugaiak, azido α-linolenikoa (ALA), azido eikosapentaenoikoa (EPA) eta azido dokosahexaenoikoa (DHA), dietaren bitartez bereganatzen diren gantz-azido (GA) poliasegabeak dira. Propietate antioxidatzaileak barne hartzen dituzten hiru osagai horien elikagai-iturri nagusia arrain koipetsua (izokina, antxoa, hegalaburra…) eta horretatik eratorritako arrain-olioa dira batez ere. Omega-3 GA osagarriaz aberastutako dietak aldaketa molekular zein funtzional mesedegarriak eragiten ditu garunaren garapen prozesuan, zenbait garun lesioren berreskurapenean parte hartzen. Gehigarri horrek mintz zelularraren fluidotasuna areagotzen du, eta metabolismoaren erregulazioan parte hartzen du, seinaleztapen molekulen askapena sustatuz eta gene espresioan eraginez. Bi ekintza horien bidez seinaleztapen bideak aktibatzen dira, eta ondorioz garun plastikotasuna eta transmisio sinaptikoa suspertu. Areago, omega-3 GAk zeluletan oro har, eta neuronetan bereziki, oxidazio-estresak eta hanturak eragindako kalteak murriztu ditzake. Horregatik guztiagatik, omega-3 osagarria hainbat patologietan prebentzioan edo tratamenduan erabili da. Berrikuspen honek laburbiltzen ditu kate luzeko omega-3 GAetan aberastutako tratamenduak bihotz hodietako gaixotasunetan, minbizian, neuroendekapenezko gaixotasunetan (Alzheimer eta Parkinson), alkoholismoan eta gainpisuan, oinarrizko ikerkuntzan eta ikerketa klinikoan frogatu eta egiaztatu diren aurrerapen terapeutiko berriak; eta etorkizunera begira beste hainbat gaixotasuni aurrea hartzeko edo haiek tratatzeko potentzialtasun handiko eta albo ondoriorik gabeko osagarri ez-inbaditzaile aproposa izan daitekeela iradokitzen du.

Astrocytes take up glucose from the bloodstream to provide energy to the brain, thereby allowing neuronal activity and behavioural responses1,2,3,4,5. By contrast, astrocytes are under neuronal control through specific neurotransmitter receptors5,6,7. However, whether the activation of astroglial receptors can directly regulate cellular glucose metabolism to eventually modulate behavioural responses is unclear. Here we show that activation of mouse astroglial type-1 cannabinoid receptors associated with mitochondrial membranes (mtCB1) hampers the metabolism of glucose and the production of lactate in the brain, resulting in altered neuronal functions and, in turn, impaired behavioural responses in social interaction assays. Specifically, activation of astroglial mtCB1 receptors reduces the phosphorylation of the mitochondrial complex I subunit NDUFS4, which decreases the stability and activity of complex I. This leads to a reduction in the generation of reactive oxygen species by astrocytes and affects the glycolytic production of lactate through the hypoxia-inducible factor 1 pathway, eventually resulting in neuronal redox stress and impairment of behavioural responses in social interaction assays. Genetic and pharmacological correction of each of these effects abolishes the effect of cannabinoid treatment on the observed behaviour. These findings suggest that mtCB1 receptor signalling can directly regulate astroglial glucose metabolism to fine-tune neuronal activity and behaviour in mice., This work was funded by: INSERM, the European Research Council (Endofood, ERC–2010–StG–260515 and CannaPreg, ERC-2014-PoC-640923, MiCaBra, ERC-2017-AdG-786467), Fondation pour la Recherche Medicale (FRM, DRM20101220445), the Human Frontiers Science Program, Region Nouvelle Aquitaine and Agence Nationale de la Recherche (ANR; NeuroNutriSens ANR-13-BSV4-0006, CaCoVi ANR 18-CE16-0001-02, MitObesity ANR 18-CE14-0029-01, ORUPS ANR-16-CE37-0010-01 and BRAIN ANR-10-LABX-0043) (to G.M.); NIH/NIDA (1R21DA037678-01), Spanish Ministry of Science, Innovation and Universities (MCINU/FEDER; grants SAF2016-78114-R and RED2018-102576-T), Instituto de Salud Carlos III (CB16/10/00282), an EU BATCure grant (666918), Junta de Castilla y León (Escalera de Excelencia CLU-2017-03), Ayudas Equipos Investigación Biomedicina 2017 Fundación BBVA and Fundación Ramón Areces (to J.P.B.); Instituto de Salud Carlos III (PI18/00285; RD16/0019/0018), the European Regional Development Fund, the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement 686009), Junta de Castilla y León (IES007P17) and Fundación Ramón Areces to (A.A.); French State/ANR/IdEx (ANR-10-IDEX-03-02), Eu-Fp7 (FP7-PEOPLE-2013-IEF-623638) and Ramon y Cajal Investigator Program (RYC-2017-21776) (to A.B.-G.); FRM (SPF20121226369) (to R.S.); FRM (ARF20140129235) (to L.B.); Spanish Ministry of Science, Innovation and Universities (MCINU/FEDER; grants SAF2015-64945-R and RTI2018-095311-B-I00) (to M.G.); Canada Research Chair, Alzheimer Society of Canada—Brain Canada (17-09), Natural Sciences and Engineering Research Council (RGPIN-2015-05880), Canadian Breast Cancer Foundation (2015-317342), Canadian Health Research Institute (CIHR, 388808), New Brunswick Innovation Foundation, New Brunswick Health Research Foundation and Université de Moncton (to E.H.-C.); Basque Government (IT1230-19), Red de Trastornos Adictivos, Instituto de Salud Carlos III (ISC-III), European Regional Development Funds-European Union (ERDF-EU; RD16/0017/0012) and MINECO/FEDER, UE (SAF2015-65034-R) (to P.G.); University of the Basque Country PhD contract (PIF 16/251) (to S.A.); POP contract (BES-2016-076766, BES-C-2016-0051) (to I.B.-D.R.); French State/ANR (ANR-10-IDEX and TRAIL ANR-10-LABX-57); French-Swiss ANR-FNS (ANR-15- CE37-0012) (to A.-K.B.-S.); SFB/TRR 58 ‘Fear, anxiety, anxiety disorders’ (subproject A04); and CRC 1193 ‘Neurobiology of resilience’ (subproject B04) (to B.L.).

The cannabinoid CB1 receptor localizes to the glutamatergic parallel fiber (PF) terminals of the cerebellar granule cells and participates in synaptic plasticity, motor control and learning that are impaired in CB1 receptor knockout (CB 1 -KO) mice. However, whether ultrastructural changes at the PF-Purkinje cell (PC) synapses occur in CB 1 -KO remains unknown. We studied this in the vermis of the spinocerebellar lobule V and the vestibulocerebellar lobule X of CB 1 -KO and wild-type (CB 1 -WT) mice by electron microscopy. Lobule V, but not lobule X, of CB 1 -KO had significantly less and longer synapses than in CB 1 -WT. PF terminals were significantly larger in both lobules of CB 1 -KO with no changes in PC dendritic spines. The PF terminals in lobule V of CB 1 -KO contained less synaptic vesicles and lower vesicle density; by contrast, vesicle density in lobule X of CB 1 -KO remained unchangeable relative to CB 1 -WT. There were as many vesicles in lobule V of CB 1 -KO as in CB 1 -WT, but their distribution decreased drastically at 300 nm of the active zone. In lobule X of CB 1 -KO, less vesicles were found within 150 nm from the presynaptic membrane; however, no vesicles were at 450-600 nm of the active zone. A significant higher amount of synaptic vesicles close to the active zone in lobule V and X of CB 1 -KO was observed. In conclusion, the absence of CB1 receptors strikingly and distinctively impacts on the ultrastructural architecture of the PF-PC synapses located in cerebellar lobules that differ in vulnerability to damage and motor functions.

The use and abuse of alcohol (EtOH) is one of the world’s main health issues that strikingly impacts on our society, as heavy episodic drinking is becoming more and more common in the adolescence when the brain is particularly vulnerable to EtOH. However, molecular, anatomical, functional and behavioral alterations improve inyoung adult mice brains by an enriched environment (EE) exposure after adolescence EtOH consumption [21]. It remains unknown whether these beneficial effects are maintained over a long period of time after cessation of EtOH consumption. The aim of this study was to measure the long-term behavioral consequences of EtOH consumption and to explore the effects of EE in adulthood. For this goal, we treated C57BL/6J male mice with 20% EtOH or water during the 4 weeks of adolescence (p32-p56) followed by an abstinence period (p56-p90). Finally, they were exposed to EE for two weeks (p90-p104) and behavioral tests were conducted at their full adulthood: thigmotaxis for anxiety-like behaviour; novel object recognition test (NORT) for object recognition memory; novel object location test (NOLT) for location memory and beam walking balance test (BWBT) for motor coordination and balance. Object and spatial recognition memory were significantly lower in EtOH-treated mice. Also, motor coordination and balance were impaired after EtOH intake. Noticeably, memory and motor deficits reversed to control values after EE. In conclusion, we show that EE recovers the long-term behavioral and motor deficits after abusive EtOH consumption during adolescence. These results point to the beneficial effects EE have in EtOH addiction.; Alkohola (EtOH) munduan gehien kontsumitzen den substantzia psikoaktiboa da eta nerabezaroko alkoholaren kontsumo intentsiboa geroz eta ohikoagoa da. Adin tarte horretan burmuina garatzen ari da eta hainbat garun-atal zaurgarriagoak dira neurotoxikoen kalteen aurrean; hipokanpoa eta garuntxoa, esaterako. Ingurune aberastuak (IAk), aldaketa molekular, anatomiko zein funtzionalak eragiten ditu garunaren garapen prozesuan eta alkoholaren ondorioz helduaro goiztiarreko saguek galdutako portaera gaitasunen berreskurapena sustatzen du. Hala ere, IAk eragindako efektu mesedegarri horiek epe luzerago batean mantentzen diren aztertzeke dago. Ikerketa honen helburuak hurrengoak dira: nerabezaroko gehiegizko alkohol kontsumoak helduaroan eragiten dituen portaera aldaketak ikertzea eta parametro hauetan IAk izan ditzakeen onurak aztertzea. Horretarako, C57BL/6J sagu arrei nerabezaroko 4 astetan zehar (p32-p56) alkohol edo ur tratamendua eman zaie. Ondoren, helduaro goiztiarrean (p56-p90) animaliak abstinentzia egoeran mantendu dira eta helduaroan (p90-p104) saguen kumaldi erdia IAko baldintzetan jarri da 2 astez. Abstinentzia tarte horren azken egunetan portaera probak burutu dira: eremu irekiaren proba, antsietate maila neurtzeko; objektu berrien ezagutze proba, ezagutze oroimenerako; objektuen kokaleku berriaren ezagutze proba, oroimen espazialerako eta oreka proba, oreka eta koordinazio motorrerako. Alkohol taldeko saguek bereizketa indize baxuagoak erakutsi dituzte bai ezagutze oroimen proban baita oroimen espazialean ere, alkohol kontsumoaren ondoriozko narriadura kognitibo adierazgarria iradokiz. Antzeko emaitzak behatu dira oreka proban ere, non alkohol taldeko saguek (EtOH) oreka eta koordinazio motorra kaltetuta erakutsi duten. Interesgarriki, animaliak IAko baldintzapean jartzean objektuak eta kokalekuak bereizteko gaitasuna berreskuratzen dute eta oreka eta koordinazio maila hobetzen dute helduaroan, kontrol taldekoen (H2O) antzeko balioetaraino. IAk alkoholaren ondoriozko helduaroko efektu kaltegarriak leheneratzeko gaitasuna duela erakutsi du.

Binge drinking (BD) is a serious health concern in adolescents as high ethanol (EtOH) consumption can have cognitive sequelae later in life. Remarkably, an enriched environment (EE) in adulthood significantly recovers memory in mice after adolescent BD, and the endocannabinoid, 2-arachydonoyl-glycerol (2-AG), rescues synaptic plasticity and memory impaired in adult rodents upon adolescent EtOH intake. However, the mechanisms by which EE improves memory are unknown. We investigated this in adolescent male C57BL/6J mice exposed to a drinking in the dark (DID) procedure four days per week for a duration of 4 weeks. After DID, the mice were nurtured under an EE for 2 weeks and were subjected to the Barnes Maze Test performed the last 5 days of withdrawal. The EE rescued memory and restored the EtOH-disrupted endocannabinoid (eCB)-dependent excitatory long-term depression at the dentate medial perforant path synapses (MPP-LTD). This recovery was dependent on both the cannabinoid CB1 receptor and group I metabotropic glutamate receptors (mGluRs) and required 2-AG. Also, the EE had a positive effect on mice exposed to water through the transient receptor potential vanilloid 1 (TRPV1) and anandamide (AEA)-dependent MPP long-term potentiation (MPP-LTP). Taken together, EE positively impacts different forms of excitatory synaptic plasticity in water- and EtOH-exposed brains. This research was funded by ISCIII (“RD16/0017/0012” to P.G.), co-funded by ERDF/ESF, “Investing in your future”; The Basque Government (IT1230-19 to P.G.); Ministry of Science and Innovation (PID2019-107548RB-I00 to P.G.); Ph.D. contract from MINECO (BES-2013-065057 to S.P.); Ph.D. contract from UPV/EHU (PIF 18/315 to L.L.), and Ph.D. contract from UPV/EHU (PIF 19/164 to M.S.).

The use and abuse of cannabis can be associated with significant pathophysiology, however, it remains unclear whether (1) acute administration of Δ-9-tetrahydrocannabinol (THC) during early adulthood alters the cannabinoid type 1 (CB

SUMMARYThe idea that the effects of drugs largely depend on subcellular target location is emerging as a novel predictive factor of their beneficial or adverse outcomes. G protein-coupled type-1 cannabinoid receptors (CB1) are regulators of several brain functions as well as the main targets of cannabinoid-based medicines.Besides their classical location at plasma membranes, CB1receptors are present at different locations within cells, including in association to mitochondrial membranes (mtCB1). Here we report the generation and characterization of a mutant mouse line, which lack mtCB1receptors.

Binge drinking (BD) is a common pattern of ethanol (EtOH) consumption by adolescents. The brain effects of the acute EtOH exposure are well-studied; however, the long-lasting cognitive and neurobehavioral consequences of BD during adolescence are only beginning to be elucidated. Environmental enrichment (EE) has long been known for its benefits on the brain and may serve as a potential supportive therapy following EtOH exposure. In this study, we hypothesized that EE may have potential benefits on the cognitive deficits associated with BD EtOH consumption. Four-week-old C57BL/6J male mice were exposed to EtOH following an intermittent 4-day drinking-in-the-dark procedure for 4 weeks. Then they were exposed to EE during EtOH withdrawal for 2 weeks followed by a behavioral battery of tests including novel object recognition, novel location, object-in-place, rotarod, beam walking balance, tail suspension, light-dark box and open field that were run during early adulthood. Young adult mice exposed to EE significantly recovered recognition, spatial and associative memory as well as motor coordination skills and balance that were significantly impaired after adolescent EtOH drinking with respect to controls. No significant permanent anxiety or depressive-like behaviors were observed. Taken together, an EE exerts positive effects on the long-term negative cognitive deficits as a result of EtOH consumption during adolescence.

Cannabinoid type-1 (CB1 ) receptors are widely distributed in the brain and play important roles in astrocyte function and the modulation of neuronal synaptic transmission and plasticity. However, it is currently unknown how CB1 receptor expression in astrocytes is affected by long-term exposure to stressors. Here we examined CB1 receptors in astrocytes of ethanol (EtOH)-exposed adolescent mice to determine its effect on CB1 receptor localization and density in adult brain. 4-8-week-old male mice were exposed to 20 percent EtOH over a period of 4 weeks, and receptor localization was examined after 4 weeks in the hippocampal CA1 stratum radiatum by pre-embedding immunoelectron microscopy. Our results revealed a significant reduction in CB1 receptor immunoparticles in astrocytic processes of EtOH-exposed mice when compared with controls (positive astrocyte elements: 21.50 ± 2.80 percent versus 37.22 ± 3.12 percent, respectively), as well as a reduction in particle density (0.24 ± 0.02 versus 0.35 ± 0.02 particles/μm). The majority of CB1 receptor metal particles were in the range of 400-1200 nm from synaptic terminals in both control and EtOH. Altogether, the decrease in the CB1 receptor expression in hippocampal astrocytes of adult mice exposed to EtOH during adolescence reveals a long lasting effect of EtOH on astrocytic CB1 receptors. This deficiency may also have negative consequences for synaptic function.

Binge drinking is a significant problem in adolescent populations, and because of the reciprocal interactions between ethanol (EtOH) consumption and the endocannabinoid (eCB) system, we sought to determine if adolescent EtOH intake altered the localization and function of the cannabinoid 1 (CB(1)) receptors in the adult brain. Adolescent mice were exposed to a 4-day-per week drinking in the dark (DID) procedure for a total of 4 weeks and then tested after a 2-week withdrawal period. Field excitatory postsynaptic potentials (fEPSPs), evoked by medial perforant path (MPP) stimulation in the dentate gyrus molecular layer (DGML), were significantly smaller. Furthermore, unlike control animals, CB(1) receptor activation did not depress fEPSPs in the EtOH-exposed animals. We also examined a form of excitatory long-term depression that is dependent on CB(1) receptors (eCB-eLTD) and found that it was completely lacking in the animals that consumed EtOH during adolescence. Histological analyses indicated that adolescent EtOH intake significantly reduced the CB(1) receptor distribution and proportion of immunopositive excitatory synaptic terminals in the medial DGML. Furthermore, there was decreased binding of [(35)S]guanosine-5*-O-(3-thiotriphosphate) ([(35)S] GTPγS) and the guanine nucleotide-binding (G) protein Gαi2 subunit in the EtOH-exposed animals. Associated with this, there was a significant increase in monoacylglycerol lipase (MAGL) mRNA and protein in the hippocampus of EtOH-exposed animals. Conversely, deficits in eCB-eLTD and recognition memory could be rescued by inhibiting MAGL with JZL184. These findings indicate that repeated exposure to EtOH during adolescence leads to long-term deficits in CB(1) receptor expression, eCB-eLTD, and reduced recognition memory, but that these functional deficits can be restored by treatments that increase endogenous 2-arachidonoylglycerol.

Snoezelen terapia, zentzumen anitzeko terapia (ZAT) ez-farmakologiko eta psikosoziala da; zazpi funtsezko zentzumenen estimulazioan edo erlaxazioan oinarritzen dena, hain zuzen ere. Pertsonon ongizatea eta norberaren bizi-kalitatea hobetzea du helburu nagusia.Ikusmen, entzumen, ukimen, dastamen, oreka, propriozepzio eta usaimen zentzumenak hainbat objekturen bitartez kitzikatzen dira: argiztapen artifizialaren, musika lasaigarri edo terapeutikoaren, ehundura ezberdinen eta hainbat lurrinen eta elikagaien bidez, besteak beste. Terapia honen erabilera dementziaren sintoma fisiologikoak eta portaera-aldaketak arintzeko hautabide eraginkor gisa bistaratu da azken hamarkadan. Dementziaetengabeko narriadura kognitiboa eragiten duen gaixotasun kronikoa eta atzeraezina da; baita sintoma fisiko, fisiologiko eta portaera-aldaketa nabarmenak eragiten dituen gaitz neurologikoa ere. Oldarkortasuna, depresioa, antsietatea, gogogabezia, loezina eta elikadura-nahasmendua dira dementzia gaixotasunean deskribatu izan diren eta Snoezelen terapiak hobetzen dituen sintoma fisiologiko eta portaera-aldaketa ohikoenak. Horrez gain, aipatzekoak dira Rett sindromean, garun-lesio traumatikoan, zainketa aringarrietako programetan eta garun-paralisian Snoezelen terapiak eragiten dituen onura nabarmenak. Azterlan honek Snoezelen terapiaren inguruko hainbat ikerketa biltzen ditu. Kontzeptuaren deskribapen zehaztua eta Euskal Herriko udalerrietan azken urteotan terapia honi eman zaion erabilera terapeutikoaren zein pedagogikoaren azalpen orokorra azaltzen dira. Horrez gain, hainbat gaixotasunen aurrean terapia honek ekar ditzakeen efektu mesedegarrien edo mugen eta gabezien deskribapena jorratuko da ikuspuntu kritiko batetik.

The cannabinoid CB

International audience; Recent advances in neuroscience have positioned brain circuits as key units in controlling behavior, implying that their positive or negative modulation necessarily leads to specific behavioral outcomes. However, emerging evidence suggests that the activation or inhibition of specific brain circuits can actually produce multimodal behavioral outcomes. This study shows that activation of a receptor at different subcellular locations in the same neuronal circuit can determine distinct behaviors. Pharmacological activation of type 1 cannabinoid (CB1) receptors in the striatonigral circuit elicits both antinociception and catalepsy in mice. The decrease in nociception depends on the activation of plasma membrane-residing CB1 receptors (pmCB1), leading to the inhibition of cytosolic PKA activity and substance P release. By contrast, mitochondrial-associated CB1 receptors (mtCB1) located at the same terminals mediate cannabinoid-induced catalepsy through the decrease in intra-mitochondrial PKA-dependent cellular respiration and synaptic transmission. Thus, subcellular-specific CB1 receptor signaling within striatonigral circuits determines multimodal control of behavior.

Type 1 cannabinoid (CB1 ) receptors are widely distributed in the brain. Their physiological roles depend on their distribution pattern, which differs remarkably among cell types. Hence, subcellular compartments with little but functionally relevant CB1 receptors can be overlooked, fostering an incomplete mapping. To overcome this, knockin mice with cell-type-specific rescue of CB1 receptors have emerged as excellent tools for investigating CB1 receptors' cell-type-specific localization and sufficient functional role with no bias. However, to know whether these rescue mice maintain endogenous CB1 receptor expression level, detailed anatomical studies are necessary. The subcellular distribution of hippocampal CB1 receptors of rescue mice that express the gene exclusively in dorsal telencephalic glutamatergic neurons (Glu-CB1 -RS) or GABAergic neurons (GABA-CB1 -RS) was studied by immunoelectron microscopy. Results were compared with conditional CB1 receptor knockout lines. As expected, CB1 immunoparticles appeared at presynaptic plasmalemma, making asymmetric and symmetric synapses. In the hippocampal CA1 stratum radiatum, the values of the CB1 receptor-immunopositive excitatory and inhibitory synapses were Glu-CB1 -RS, 21.89% (glutamatergic terminals); 2.38% (GABAergic terminals); GABA-CB1 -RS, 1.92% (glutamatergic terminals); 77.92% (GABAergic terminals). The proportion of CB1 receptor-immunopositive excitatory and inhibitory synapses in the inner one-third of the dentate molecular layer was Glu-CB1 -RS, 53.19% (glutamatergic terminals); 2.30% (GABAergic terminals); GABA-CB1 -RS, 3.19% (glutamatergic terminals); 85.07% (GABAergic terminals). Taken together, Glu-CB1 -RS and GABA-CB1 -RS mice show the usual CB1 receptor distribution and expression in hippocampal cell types with specific rescue of the receptor, thus being ideal for in-depth anatomical and functional investigations of the endocannabinoid system. J. Comp. Neurol. 525:302-318, 2017. © 2016 Wiley Periodicals, Inc.

Activation of type 1 cannabinoid (CB(1)) receptors by endogenous, exogenous (cannabis derivatives) or synthetic cannabinoids (i.e., CP 55.940, Win-2) has a wide variety of behavioral effects due to the presence of CB(1) receptors in the brain. In situ hybridization and immunohistochemical techniques have been crucial for defining the CB(1) receptor expression and localization at the cellular level. Nevertheless, more advanced methods are needed to reveal the precise topography of CB(1) receptors in the brain, especially in unsuspected sites such as other cell types and organelles with low receptor expression (e.g., glutamatergic neurons, astrocytes, mitochondria). High-resolution immunoelectron microscopy provides a more precise detection method for the subcellular localization of CB(1) receptors in the brain. Herein, we describe a single pre-embedding immunogold method for electron microscopy based on the use of specific CB(1) receptor antibodies and silver-intensified 1.4 nm gold-labeled Fab' fragments, and a combined pre-embedding immunogold and immunoperoxidase method that employs biotinylated secondary antibodies and avidin-biotin-peroxidase complex for the simultaneous localization of CB(1) receptors and protein markers of specific brain cells or synapses (e.g., GFAP, GLAST, IBA-1, PSD-95, gephyrin). In addition, a post-embedding immunogold method is also described and compared to the pre-embedding labeling procedure. These methods provide a relatively easy and useful approach for revealing the subcellular localization of low amounts of CB(1) receptors in glutamatergic synapses, astrocytes, neuronal and astrocytic mitochondria in the brain.

The endocannabinoid system modulates synaptic plasticity in the hippocampus, but a link between long-term synaptic plasticity and the type 1 cannabinoid (CB1) receptor at medial perforant path (MPP) synapses remains elusive. Here, immuno-electron microscopy in adult mice showed that similar to 26% of the excitatory synaptic terminals in the middle 1/3 of the dentate molecular layer (DML) contained CB1 receptors, and field excitatory postsynaptic potentials evoked by MPP stimulation were inhibited by CB1 receptor activation. In addition, MPP stimulation at 10 Hz for 10 min triggered CB, receptor-dependent excitatory long-term depression (eCB-eLTD) at MPP synapses of wild-type mice but not on CB1-knockout mice. This eCB-eLTD was group I mGluR-dependent, required intracellular calcium influx and 2-arachydonoyl-glycerol (2-AG) synthesis but did not depend on N-methyl-d-aspartate (NMDA) receptors. Overall, these results point to a functional role for CB1 receptors with eCB-eLTD at DML MPP synapses and further involve these receptors in memory processing within the adult brain. We thank all members of P. Grandes laboratory for their helpful comments, suggestions, and discussions during the performance of this study. The authors thank Giovanni Marsicano (INSERM, U1215 Neurocentre Magendie, Endocannabinoids and Neuroadaptation, Bordeaux, France. University de Bordeaux, France), Beat Lutz (Institute of Physiological Chemistry and German Resilience Center, University Medical Center of the Johannes Gutenberg University Mainz, Germany) and Susana Mato (Achucarro Basque Center for Neuroscience, Science Park of the UPV/EHU, Leioa, Vizcaya, Spain) for providing the CB1 receptor knock-out mice. This work was supported by MINECO/FEDER, UE (grant number SAF2015-65034-R to PG); The Basque Government (grant number BCG IT764-13 to PG); Red de Trastornos Adictivos, Instituto de Salud Carlos III (ISC-III) and European Regional Development Funds-European Union (ERDF-EU; grant RD16/0017/0012 to PG); PhD contract from MINECO (BES-2013-065057 to SP); Vanier Canada Graduate Scholarship (NSERC to CJF).

International audience; The retrieval of odor-related memories shapes animal behavior. The anterior piriform cortex (aPC) is the largest part of the olfactory cortex, and it plays important roles in olfactory processing and memory. However, it is still unclear whether specific cellular mechanisms in the aPC control olfactory memory, depending on the appetitive or aversive nature of the stimuli involved. Cannabinoid-type 1 (CB1) receptors are present in the aPC (aPC-CB1), but their potential impact on olfactory memory was never explored. Here, we used a combination of behavioral, genetic, anatomical, and electrophysiological approaches to characterize the functions of aPC-CB1 receptors in the regulation of appetitive and aversive olfactory memory. Pharmacological blockade or genetic deletion of aPC-CB1 receptors specifically impaired the retrieval of conditioned odor preference (COP). Interestingly, expression of conditioned odor aversion (COA) was unaffected by local CB1 receptor blockade, indicating that the role of aPC endocannabinoid signaling is selective for retrieval of appetitive memory. Anatomical investigations revealed that CB1 receptors are highly expressed on aPC GABAergic interneurons, and ex vivo electrophysiological recordings showed that their pharmacological activation reduces miniature inhibitory post-synaptic currents (mIPSCs) onto aPC semilunar (SL), but not pyramidal principal neurons. COP retrieval, but not COA, was associated with a specific CB1-receptor-dependent decrease of mIPSCs in SL cells. Altogether, these data indicate that aPC-CB1 receptor-dependent mechanisms physiologically control the retrieval of olfactory memory, depending on odor valence and engaging modulation of local inhibitory transmission.

Astroglial type‐1 cannabinoid (CB1) receptors are involved in synaptic transmission, plasticity and behavior by interfering with the so‐called tripartite synapse formed by pre‐ and post‐synaptic neuronal elements and surrounding astrocyte processes. However, little is known concerning the subcellular distribution of astroglial CB1 receptors. In particular, brain CB1 receptors are mostly localized at cells' plasmalemma, but recent evidence indicates their functional presence in mitochondrial membranes. Whether CB1 receptors are present in astroglial mitochondria has remained unknown. To investigate this issue, we included conditional knock‐out mice lacking astroglial CB1 receptor expression specifically in glial fibrillary acidic protein (GFAP)‐containing astrocytes (GFAP‐CB1‐KO mice) and also generated genetic rescue mice to re‐express CB1 receptors exclusively in astrocytes (GFAP‐CB1‐RS). To better identify astroglial structures by immunoelectron microscopy, global CB1 knock‐out (CB1‐KO) mice and wild‐type (CB1‐WT) littermates were intra‐hippocampally injected with an adeno‐associated virus expressing humanized renilla green fluorescent protein (hrGFP) under the control of human GFAP promoter to generate GFAPhrGFP‐CB1‐KO and ‐WT mice, respectively. Furthermore, double immunogold (for CB1) and immunoperoxidase (for GFAP or hrGFP) revealed that CB1 receptors are present in astroglial mitochondria from different hippocampal regions of CB1‐WT, GFAP‐CB1‐RS and GFAPhrGFP‐CB1‐WT mice. Only non‐specific gold particles were detected in mouse hippocampi lacking CB1 receptors. Altogether, we demonstrated the existence of a precise molecular architecture of the CB1 receptor in astrocytes that will have to be taken into account in evaluating the functional activity of cannabinergic signaling at the tripartite synapse.

Drug addiction is a chronic relapsing disorder that produces a dramaticglobal health burden worldwide. Not effective treatment of drug addiction is currently available probably due to the difficulties to find an appropriate target to manage this complex disease raising the needs for further identification of novel therapeutic approaches. The endocannabinoid system has been found to play a crucial role in the neurobiological substrate underlying drug addiction. Endocannabinoids and cannabinoid receptors are widely expressed in the main areas of the mesocorticolimbic system that participate in the initiation and maintenance of drug consumption and in the development of compulsion and loss of behavioral control occurring during drug addiction. The identification of the important role played by CB1 cannabinoid receptors in drug addiction encouraged the possible used of an early commercialized CB1 receptor antagonist for treating drug addiction. However, the incidence of serious psychiatric adverse events leaded to the sudden withdrawal from the market of this CB1 antagonist and all the research programs developed by pharmaceutical companies to obtain new CB1 antagonists were stopped. Currently, new research strategies are under development to target the endocannabinoid system for drug addiction avoiding these side effects, which include allosteric negative modulators of CB1 receptors and compounds targeting CB2 receptors. Recent studies showing the potential role of CB2 receptors in the addictive properties of different drugs of abuse have open a promising research opportunity to develop novel possible therapeutic approaches. We acknowledge the financial support of the Spanish MINECO (#SAF2017-84060-R-AEI/FEDER-UE), Instituto de Salud Carlos III-RETICS(##RD16/0017/0020), Ministerio de Sanidad, Servicios Sociales e Igualdad-Plan Nacional Sobre Drogas (#PNSD-2017I068), and the Generalitat de Catalunya-AGAUR ((#2017-SGR-669 and #ICREA Acadèmia2015) and the European Commission-DG RTD (#FP7-HEALTH-F2-2013-602891-NeuroPain) to RM. FEDER funding support is also acknowledged. This work was supported by Red de Trastornos Adictivos, Instituto de Salud Carlos III (ISC-III) and European Regional Development Funds-European Union (ERDF-EU) (RD16/0017/0012), The Basque Government (BCG IT764-13) and MINECO/FEDER, UE(SAF2015-65034-R) to PG. This research was supported by Instituto de Salud Carlos III (RETICS, RD12/0028/0019, RD16/0017/0014 and RD06/0001/1004), Plan Nacional Sobre Drogas (PNSD 2016/016 and 2007/061), Ministerio de Economía y Competitividad (FIS, PI14/00438) and Ministerio de Ciencia e Innovación (SAF2008-01106) to JM

The dorsal striatum is a key node for many neurobiological processes such as motor activity, cognitive functions, and affective processes. The proper functioning of striatal neurons relies critically on metabotropic receptors. Specifically, the main adenosine and endocannabinoid receptors present in the striatum, ie, adenosine A(2A) receptor (A(2A)R) and cannabinoid CB1 receptor (CB1R), are of pivotal importance in the control of neuronal excitability. Facilitatory and inhibitory functional interactions between striatal A(2A)R and CB1R have been reported, and evidence supports that this cross-talk may rely, at least in part, on the formation of A(2A)R-CB1R heteromeric complexes. However, the specific location and properties of these heteromers have remained largely unknown. Here, by using techniques that allowed a precise visualization of the heteromers in situ in combination with sophisticated genetically modified animal models, together with biochemical and pharmacological approaches, we provide a high-resolution expression map and a detailed functional characterization of A(2A)R-CB1R heteromers in the dorsal striatum. Specifically, our data unveil that the A(2A)R-CB1R heteromer (i) is essentially absent from corticostriatal projections and striatonigral neurons, and, instead, is largely present in striatopallidal neurons, (ii) displays a striking G protein-coupled signaling profile, where co-stimulation of both receptors leads to strongly reduced downstream signaling, and (iii) undergoes an unprecedented dysfunction in Huntington's disease, an archetypal disease that affects striatal neurons. Altogether, our findings may open a new conceptual framework to understand the role of coordinated adenosine-endocannabinoid signaling in the indirect striatal pathway, which may be relevant in motor function and neurodegenerative diseases. This work was supported by grants from the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER; grant SAF2015-64945-R to MG; grant SAF-2014-54840-R to EIC and VC; grant SAF2015-65034-R to PG; grant SAF2015-67474-R to SG; grants SAF2014-55700-P and PCIN-2013-019-C03-03 to FC); Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED; grant PI2013/05 to MG, PJM and EIC); Comunidad de Madrid (grant S2010/BMD-2308 to MG); Generalitat de Catalunya (grant 2014-SGR-1236 to EIC); 'La Marato de TV3' Foundation (grant 20140610 to EIC; grant 20152031 to FC); Agentschap voor Innovatie door Wetenschap en Technologie (grant SBO-140028 to FC); BBSRC DTP studentship (to PJM and LB); EPSRC (grant EP/M006379/1 to LAH); Deutsche Forschungsgemeinschaft (DFG; grant MO 1920/1-1 to KM; grant CRC-TRR 58 to BL); Institute of Health Carlos III from the Spanish Ministry of Economy and Competitiveness (grant PIE14/00034 to FC; grant PI10/00172 and funding from FEDER grants to MJC and JP); The Basque Government (grant IT764-13 to PG); University of the Basque Country UPV/EHU (grant UFI11/41 to PG); Red de Trastornos Adictivos-Institute of Health Carlos III (grant RD12/0028/0004 to PG). AC is supported by the Spanish Ministry of Economy and Competitiveness (Juan de la Cierva Program). MM is supported by the Spanish Ministry of Education, Culture and Sport (FPU Program). The authors declare no conflict of interest.

Binge drinking (BD) is a common pattern of ethanol (EtOH) consumption by adolescents. The brain effects of the acute EtOH exposure are well-studied; however, the long-lasting cognitive and neurobehavioral consequences of BD during adolescence are only beginning to be elucidated. Environmental enrichment (EE) has long been known for its benefits on the brain and may serve as a potential supportive therapy following EtOH exposure. In this study, we hypothesized that EE may have potential benefits on the cognitive deficits associated with BD EtOH consumption. Four-week-old C57BL/6J male mice were exposed to EtOH following an intermittent 4-day drinking-in-the-dark procedure for 4 weeks. Then they were exposed to EE during EtOH withdrawal for 2 weeks followed by a behavioral battery of tests including novel object recognition, novel location, object-in-place, rotarod, beam walking balance, tail suspension, light-dark box and open field that were run during early adulthood. Young adult mice exposed to EE significantly recovered recognition, spatial and associative memory as well as motor coordination skills and balance that were significantly impaired after adolescent EtOH drinking with respect to controls. No significant permanent anxiety or depressive-like behaviors were observed. Taken together, an EE exerts positive effects on the long-term negative cognitive deficits as a result of EtOH consumption during adolescence.

Recent evidence indicates that, besides its canonical localization at cell plasma membranes, the type-1 cannabinoid receptor, CB1 is functionally present at brain and muscle mitochondrial membranes (mtCB1). Through mtCB1 receptors, cannabinoids can directly regulate intramitochondrial signaling and respiration. This new and surprising discovery paves the way to new potential fields of research, dealing with the direct impact of G protein-coupled receptors on bioenergetic processes and its functional implications. In this chapter, we summarize some key experimental approaches established in our laboratories to identify anatomical, biochemical, and functional features of mtCB1 receptors in the brain. In particular, we describe the procedures to obtain reliable and controlled detection of mtCB1 receptors by immunogold electromicroscopy and by immunoblotting methods. Then, we address the study of direct cannabinoid effects on the electron transport system and oxidative phosphorylation. Finally, we present a functional example of the impact of mtCB1 receptors on mitochondrial mobility in cultured neurons. Considering the youth of the field, these methodological approaches will very likely be improved and refined in the future, but this chapter aims at presenting the methods that are currently used and, in particular, at underlining the need of rigorous controls to obtain reliable results. We hope that this chapter might help scientists becoming interested in this new and exciting field of research.