Genetic deletion or pharmacological blockade of the CB1 receptor has been reported to impair extinction learning in aversive conditioning (i.e., conditioned fear and Morris water maze) paradigms, but not in operant procedures in which food reinforcement is earned. It is difficult to discern whether the differential effects caused by CB1 receptor disruption on extinction result from the hedonics (i.e., aversive vs. appetitive) or is related to the required responses associated with these disparate tasks. In order to evaluate whether the hedonics is the determining factor, we used either aversive (i.e., escape from bright lights and air turbulence) or appetitive (i.e., to gain access to water) motivators in the Barnes maze task, a model in which mice are required to enter a hidden goal box. Administration of the CB1 receptor antagonist, rimonabant, disrupted extinction learning under aversive conditions, but not under appetitive conditions. This is the first study to show a differential effect of rimonabant on extinction in a task that required identical motor behaviors, but only differed in hedonic nature of the reinforcer. In addition, genetic ablation of CB1 receptor signaling impaired acquisition of the task under both aversive and appetitive conditioning procedures. Conversely, enhancing endocannabinoid signaling, via genetic deletion of the FAAH enzyme, accelerated acquisition of the task under aversive, but not appetitive, conditioning procedures. Accordingly, these data strongly support the hypothesis that the endogenous cannabinoid system plays a necessary role in the extinction of aversively motivated behaviors, but is expendable in appetitively motivated behaviors. While these findings underscore concerns over potential side effects associated with CB1 receptor antagonists, they also suggest that stimulating the endogenous cannabinoid system may be a promising pharmacological approach to treat maladaptive behaviors that arise from stress or trauma.

Animal models are crucial to improve the knowledge of the mechanisms underlying the different pathological processes. These models are also excellent tools to facilitate the research of new targets for the treatment of different diseases and to evaluate the benefit/risk ratio of the potential new treatments. We have focussed this research work in the study of a new potential targets for pain, cognitive and eating disorders using new animal models developed in our laboratory. We first investigated the effects of the interaction between cannabinoids and nicotine on cognitive processes and metabolism using different behavioural models and new experimental devices. In a second part of this work, we investigated new therapeutic targets for neuropathic pain and for this purpose we developed a new behavioural model to improve the study of the therapeutic potential and possible side-effects of novel compounds. / Los modelos animales son cruciales para mejorar el conocimiento sobre los mecanismos que constituyen la base de los diversos procesos patológicos. Estos modelos representan también excelentes herramientas para facilitar la investigación de nuevas dianas para el tratamiento de estas enfermedades y para evaluar el cociente beneficio/riesgo de los nuevos tratamientos potenciales. Este trabajo de investigación se encuentra centrado en el estudio de nuevos dianas terapéuticas para el dolor, los procesos cognitivos y los desórdenes alimentarios utilizando nuevos modelos animales desarrollados en nuestro laboratorio. En primer lugar, hemos investigado los efectos de la interacción entre los cannabinoinoides y la nicotina a nivel los procesos cognitivos y del metabolismo usando diversos modelos comportamentales y nuevos dispositivos experimentales. En una segunda parte de este trabajo, hemos estudiado nuevas dianas terapéuticas para el dolor neuropático y hemos desarrollado para este propósito un nuevo modelo comportamental que permite evaluar el potencial terapéutico y los posibles efectos secundarios de nuevos compuestos.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Rimonabant is a selective antagonist of the cannabinoid type 1 (CB1) receptor indicated as an adjunct to diet and exercise for the treatment of obese patients (BMI ≥ 30 kg/m2), or overweight patients (BMI > 27 kg/m2) with associated risk factors, such as type 2 diabetes or dyslipidaemia. In the present study, a reversed phase liquid chromatographic method was developed and validated for quantitative analysis of rimonabant in pharmaceutical products, and also a dissolution testing has been developed for coated tablets and capsules. The chromatographic method for determination of rimonabant in pharmaceutical formulations was performed on a Gemini C18 (150 × 4.6 mm i.d., 5 μm) column, with a mobile phase composed of acetonitrile: water (75:25, v/v), which was pumped at a flow-rate of 1 mL min-1 and ultraviolet detection at 215 nm. The analytical assay was validated by evaluating the parameters specificity, linearity, precision, accuracy, robustness, limit of detection and quantification, giving results within the acceptable range as defined by international validation guidelines. The selected conditions for the dissolution testing were 900 mL of 0.15% sodium lauryl sulfate in water as dissolution medium, USP apparatus 2 (paddle), stirring speed of 50 rpm and drug analysis by liquid chromatography. A study was assessed to compare some commercially available drug products, such as film-coated tablets (brand name Acomplia®) and compounded capsules from different suppliers. The physicalchemical tests applied to samples were average weight, content uniformity, active substance assay and dissolution profile, which have showed distinct results. In addition, rimonabant capsules containing different excipients were prepared for evaluation of formulation parameters on in vitro release profile of the drug. / O rimonabanto é um fármaco pertencente à classe dos antagonistas dos receptores canabinóides tipo 1 (CB1) utilizado para o tratamento adjuvante à dieta e aos exercícios físicos de pacientes obesos ou com sobrepeso com fatores de risco associados, tais como diabetes tipo 2 ou dislipidemia. No presente trabalho desenvolveu-se e validou-se método por cromatografia líquida em fase reversa para análise quantitativa de rimonabanto em produtos farmacêuticos, bem como foi desenvolvido ensaio de dissolução para comprimidos revestidos e cápsulas do fármaco. O método cromatográfico para determinação de rimonabanto em formulações farmacêuticas empregou coluna Gemini C18 (150 × 4.6 mm d.i., 5 μm), fase móvel composta de acetonitrila: água (75:25, v/v), eluída na vazão de 1 mL min-1 e detecção no ultravioleta em 215 nm. Foi realizada a validação do procedimento através da avaliação dos parâmetros especificidade, linearidade, precisão, exatidão, robustez, limite de detecção e quantificação, cujos resultados cumpriram os requisitos preconizados internacionalmente. As condições selecionados para o ensaio de dissolução foram 900 mL de lauril sulfato de sódio 0,15% em água como meio, aparato 2 (pá), velocidade de agitação de 50 rpm e quantificação do fármaco por cromatografia líquida. Foi realizado estudo comparativo entre alguns produtos disponíveis comercialmente, entre eles o medicamento de referência (Acomplia®) e cápsulas manipuladas por três farmácias diferentes. Os testes físico-químicos realizados nas amostras foram peso médio, uniformidade de doses unitárias, teor e perfil de dissolução, os quais demonstraram resultados bastante distintos entre os produtos. Paralelamente, cinco formulações contendo diferentes tipos de excipientes foram preparadas para avaliar o efeito desse parâmetro na velocidade de liberação do fármaco in vitro.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A method to obtain fourteen enones [EtO2CC(O)C(R2)=C(R1)OR, where R = H, Me; R1 = Pr, Ph, 4-MeOC6H4, 4-MeC6H4, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-NO2C6H4, Fur- 2-yl; R2 = H; R1,R2 = -(CH2)3-, -(CH2)4-, -(CH2)5-, -(CH2)6-, 3,4-dihydronaphthalen-2-yl] from acylation of acetals with ethyl oxalyl chloride is reported. The cyclocondensation reaction of these substrates with 2,4-dichlorophenyl hydrazine hydrochloride under ultrasound irradiation furnished a series of 1-(2,4-dichlorophenyl)-3-ethylcarboxylate-1Hpyrazoles in 71-92% yields. The pyrazole ester derivatives with R1,R2 = -(CH2)3-, - (CH2)4-, -(CH2)5-, and (CH2)6- suffered hidrolysis reaction in basic media supplied the carboxylic acids (94-97%) which were converted to the corresponding acid chlorides after reaction with thionyl chloride. The reaction of acid chlorides with primary amines (piperidin-1-ylamine, propylamine, 2-morpholino-4-yl-ethylamine, aniline, 4-metoxiphenylamina, 4-nitrophenylamina) led to respective 3-carboxyamide-1-(2,4-dichlorophenyl)-1H-pyrazoles in 85-97% yields. In addition to spectroscopic data the structure of the compounds was studied by X-ray diffraction experiments. Since, the 3-carboxyamide-1-(2,4-dichlorophenyl)-1H-pyrazoles are structurally similar to Rimonabant, a known antagonist of CB1 receptors, binding assays were performed to the cannabinoid receptor CB1. The most promising ligand and candidate to become prototype was the 1-(2,4-dichlorophenyl)-4,5,6,7,8,9-hexahydro-1Hcycloocta[c]pyrazole-3-carboxylicacid-piperidin-1-ylamide which shifted approximately 100% of [3H]Rimonabant in the tests. / Este trabalho descreve um método para obter catorze enonas [EtO2CC(O)C(R2)=C(R1)OR, onde R = H, Me; R1 = Pr, Ph, 4-MeOC6H4, 4-MeC6H4, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-NO2C6H4, Fur-2-il; R2 = H; R1,R2 = -(CH2)3-, -(CH2)4-, - (CH2)5-, -(CH2)6-, 3,4-diidronaftalen-2-il] a partir da acilação de acetais com cloreto de etil oxalila. A reação de ciclocondensação desses substratos com cloridrato de 2,4- diclorofenil hidrazina utilizando irradiação de ultrassom forneceu uma série de 1-(2,4-diclorofenil)-3-etilcarboxilato-1H-pirazóis em 71-92% de rendimento. Os pirazóis sintetizados (R1,R2 = -(CH2)3-, -(CH2)4-, -(CH2)5-, -(CH2)6-) sofreram hidrólise em meio básico conduzindo aos respectivos ácidos carboxílicos (94-97%) os quais foram convertidos aos cloretos de ácido correspondentes após reação com cloreto de tionila. A reação desses cloretos de ácido com aminas primárias (piperidin-1-ilamina, propilamina, 2-morfolin-4-il-etilamina, anilina, 4-metoxifenilamina, 4-nitrofenilamina) conduziram aos respectivos 3-carboxiamida-1-(2,4-diclorofenil)-1H-pirazóis em 85-97% de rendimento. Adicionalmente aos dados espectroscópicos, a estrutura dos compostos foi estudada por experimentos de difração raios-X. Uma vez que os 3-carboxiamida-1- (2,4-diclorofenil)-1H-pirazóis são estruturalmente análogos ao Rimonabanto, um conhecido antagonista dos receptores CB1, foram realizados ensaios de ligação específica desses compostos para o receptor canabinóide CB1. O ligante mais promissor, candidato a protótipo, foi o 3-carboxiamida-1-(2,4-diclorofenil)-N-(piperidin-1-il)-4,5,6,7,8,9-hexaidro-1H-ciclocta[c]pirazol o qual deslocou, aproximadamente, 100% do [3H]Rimonabanto nos ensaio realizados.

Acyl coenzyme A:cholesterol acyltransferase (ACAT) catalyzes the intracellular synthesis of cholesteryl esters (CE). Both ACAT isoforms, ACAT1 and ACAT2, play key roles in the pathophysiology of atherosclerosis and ACAT inhibition retards atherosclerosis in animal models. Rimonabant, a type 1 cannabinoid receptor (CB1) antagonist, produces anti-atherosclerotic effects in humans and animals by mechanisms which are not completely understood. Rimonabant is structurally similar to two other cannabinoid receptor antagonists, AM251 and SR144528, recently identified as potent inhibitors of ACAT. Therefore, we examined the effects of Rimonabant on ACAT using both in vivo cell-based assays and in vitro cell-free assays. Rimonabant dose-dependently reduced ACAT activity in Raw 264.7 macrophages (IC50=2.9±0.38μM) and isolated peritoneal macrophages. Rimonabant inhibited ACAT activity in intact CHO-ACAT1 and CHO-ACAT2 cells and in cell-free assays with approximately equal efficiency (IC50=1.5±1.2μM and 2.2±1.1μM for CHO-ACAT1 and CHO-ACAT2, respectively). Consistent with ACAT inhibition, Rimonabant treatment blocked ACAT-dependent processes in macrophages, oxysterol-induced apoptosis and acetylated-LDL induced foam cell formation. From these results we conclude that Rimonabant is an ACAT1/2 dual inhibitor and suggest that some of the atherosclerotic beneficial effects of Rimonabant are, at least partly, due to inhibition of ACAT.

This dissertation is divided into three parts. The first part aimed to investigate the cannabidiol anxiolytic effect in treatment-naïve individuals with social anxiety disorder through simulation of public speaking. Twenty-four never-treated social anxiety disorder subjects were allocated to receive 0 or 600 mg cannabidiol (CBD; n=12) in a double-blind randomized design. The same number of controls performed the simulation of a public speaking test without receiving any medication. Pretreatment with CBD significantly reduced anxiety, cognitive impairment, and discomfort in speech performance and significantly decreased alertness in their anticipatory speech. The placebo group displayed higher anxiety, cognitive impairment, discomfort, and alertness when compared with controls as assessed with the Visual Analogue Mood Scale (VAMS). The SSPS-N scores showed significant increases during testing of the placebo group that was almost abolished in the cannabidiol group. No significant differences were observed between the cannabidiol and control groups in SSPS-N scores or in cognitive impairment, discomfort, and alertness factors of the VAMS. The second part evaluated healthy subjects\' x y during a public speaking test following a high rimonabant oral dose, to understand better the possible pharmacological approaches for anxiety disorder treatment. Twenty four participants were randomly allocated to receive 0 or 90 mg rimonabant (n=12) in a double-blind design. No significant adverse effects were reported in either group. Participants who received rimonabant showed increased anxiety levels compared to placebo during anticipatory speech and performance measurements. Rimonabant treatment did not affect sedation, cognitive impairment, discomfort, blood pressure, heart rate, self-statements during public speaking, or bodily symptoms scales. Increased anxiety may reflect lower endocannabinoid activity in CB1 receptors and CB1 p \' possible role in modulation of anxiety and anxiety disorders. The third part aimed to monitor cannabinoid blood concentrations during sustained abstinence from chronic daily cannabis smoking. Thirty male chronic daily cannabis smokers resided on a secure clinical research unit for up to 33 days, with blood collected once daily. ?9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH) whole blood concentrations were quantified by two-dimensional gas chromatography-mass spectrometry. Twenty-seven of 30 participants were THC-positive on admission, with a median (range) concentration 1.4 ng/mL (0.3-6.3). THC decreased gradually with only 1 of 11 participants negative at 26 days; 2 of 5 participants remained THC-positive (0.3 ng/mL) for 30 days. 5.0% f p p h TH >=1 0 g/ L f 12 y M 11-OH-THC w 1 1 g/ L w h >=1 0 g/ L 24h THCCOOH detection rates were 96.7 on admission, decreasing slowly to 95.7 and 85.7% on days 8 and 22, respectively; four of 5 participants remained THCCOOH positive (0.6-2.7 ng/mL) after 30 days and one remained positive on discharge at 33 days. THC was quantified in some participants for 30 days, albeit in low concentrations, due to the large cannabinoid body burden from extended exposure / Esta tese é dividida em três partes. A primeira parte consiste em investigar o efeito ansiolítico do canabidiol na ansiedade social através do teste de simulação de falar em público. Vinte e quatro sujeitos com ansiedade social, nunca tratados, receberam placebo ou canabidiol (CBD) 600 mg (n=12) em um estudo randomizado e duplo-cego. O mesmo número de indivíduos saudáveis realizaram o teste de simulação de falar em público sem receber medicação. A administração do CBD reduziu significativamente a ansiedade, sedação física e outros sentimentos e atitudes durante a fase de estresse, e diminui o nível de alerta na fase pré-estresse. O grupo placebo apresentou níveis elevado de ansiedade, sedação física, outros sentimentos e atitudes, e alerta comparado com o grupo controle. A pontuação do SSPS-N evidenciou aumento significativo durante o teste no grupo placebo, enquanto que o CBD reduziu estes níveis. Não houve diferenças significativas entre os grupos CBD e controle na SSPS-N e nos fatores sedação física, outros sentimentos e atitudes e alerta, da Visual Analogue Mood Scale (VAMS). A segunda parte do estudo avaliou a ansiedade em indivíduos saudáveis que receberam alta dose oral de rimonabanto e submetidos ao teste de simulação de falar em público, para melhor entendimento do possível mecanismo farmacológico para tratamento de transtornos de ansiedade. Vinte e quatro sujeitos saudáveis receberam placebo ou rimonabanto 90 mg (n=12) em um randomizado e duplo-cego. Não foi observado efeitos adversos significativo em ambos grupos. O grupo rimonabanto apresentou maiores níveis de ansiedade na fase pré-estresse e durante o estresse. Não houve diferença significativa quanto aos demais fatores avaliados entre os grupos. O aumento na ansiedade após administração do rimonabanto pode-se ao fato de haver diminuição no sistema endocanabinóide nos receptores CB1 e a possível modulação na ansiedade clínica e patológica. A terceira parte objetivou quantificar canabinóides no sangue total em usuários crônicos de cannabis durante abstinência supervisionada. Trinta usuários crônicos de cannabis, do sexo masculino, permaneceram no centro de pesquisa por até 33 dias, com coleta de sangue uma vez ao dia. ?9-tetrahidrocanabinol (THC), 11-hidróxi-THC (11-OH-THC) e 11-nor-9-carbóxi-THC (THCCOOH) foram quantificados no sangue por meio da cromatografia gasosa-espectrometria de massa bidimensional. Vinte e sete de 30 usuários foram positivos para THC no ingresso do estudo, com concentração mediana (variação) de 1.4 ng/mL (0.3-6.3). Níveis de THC diminuíram gradativamente com somente 1 de 11 participantes negativo no dia 26; 2 de 5 indivíduos permaneceram positivos para THC (0.3 g/ L p 30 5 0% j TH >=1 0 g/ L p 12 ç mediana de 11-OH-TH f 1 1 g/ L g >=1 0 g/ L pó 24h. A taxa de detecção de THCCOOH foi 96.7% no ingresso, diminuindo gradativamente para 95.7 e 85.7% nos dias 8 e 22, respectivamente; 4 de 5 sujeitos permaneceram positivo para THCCOOH (0.6-2.7 ng/mL) após 30 dias e um permaneceu positivo no 33º dia. Foi detectado THC em alguns indivíduos por 30 dias, porém em baixas concentrações, devido a extensa eliminação do canabinóide em decorrência da exposição crônica

This dissertation is divided into three parts. The first part aimed to investigate the cannabidiol anxiolytic effect in treatment-naïve individuals with social anxiety disorder through simulation of public speaking. Twenty-four never-treated social anxiety disorder subjects were allocated to receive 0 or 600 mg cannabidiol (CBD; n=12) in a double-blind randomized design. The same number of controls performed the simulation of a public speaking test without receiving any medication. Pretreatment with CBD significantly reduced anxiety, cognitive impairment, and discomfort in speech performance and significantly decreased alertness in their anticipatory speech. The placebo group displayed higher anxiety, cognitive impairment, discomfort, and alertness when compared with controls as assessed with the Visual Analogue Mood Scale (VAMS). The SSPS-N scores showed significant increases during testing of the placebo group that was almost abolished in the cannabidiol group. No significant differences were observed between the cannabidiol and control groups in SSPS-N scores or in cognitive impairment, discomfort, and alertness factors of the VAMS. The second part evaluated healthy subjects\' x y during a public speaking test following a high rimonabant oral dose, to understand better the possible pharmacological approaches for anxiety disorder treatment. Twenty four participants were randomly allocated to receive 0 or 90 mg rimonabant (n=12) in a double-blind design. No significant adverse effects were reported in either group. Participants who received rimonabant showed increased anxiety levels compared to placebo during anticipatory speech and performance measurements. Rimonabant treatment did not affect sedation, cognitive impairment, discomfort, blood pressure, heart rate, self-statements during public speaking, or bodily symptoms scales. Increased anxiety may reflect lower endocannabinoid activity in CB1 receptors and CB1 p \' possible role in modulation of anxiety and anxiety disorders. The third part aimed to monitor cannabinoid blood concentrations during sustained abstinence from chronic daily cannabis smoking. Thirty male chronic daily cannabis smokers resided on a secure clinical research unit for up to 33 days, with blood collected once daily. ?9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH) whole blood concentrations were quantified by two-dimensional gas chromatography-mass spectrometry. Twenty-seven of 30 participants were THC-positive on admission, with a median (range) concentration 1.4 ng/mL (0.3-6.3). THC decreased gradually with only 1 of 11 participants negative at 26 days; 2 of 5 participants remained THC-positive (0.3 ng/mL) for 30 days. 5.0% f p p h TH >=1 0 g/ L f 12 y M 11-OH-THC w 1 1 g/ L w h >=1 0 g/ L 24h THCCOOH detection rates were 96.7 on admission, decreasing slowly to 95.7 and 85.7% on days 8 and 22, respectively; four of 5 participants remained THCCOOH positive (0.6-2.7 ng/mL) after 30 days and one remained positive on discharge at 33 days. THC was quantified in some participants for 30 days, albeit in low concentrations, due to the large cannabinoid body burden from extended exposure / Esta tese é dividida em três partes. A primeira parte consiste em investigar o efeito ansiolítico do canabidiol na ansiedade social através do teste de simulação de falar em público. Vinte e quatro sujeitos com ansiedade social, nunca tratados, receberam placebo ou canabidiol (CBD) 600 mg (n=12) em um estudo randomizado e duplo-cego. O mesmo número de indivíduos saudáveis realizaram o teste de simulação de falar em público sem receber medicação. A administração do CBD reduziu significativamente a ansiedade, sedação física e outros sentimentos e atitudes durante a fase de estresse, e diminui o nível de alerta na fase pré-estresse. O grupo placebo apresentou níveis elevado de ansiedade, sedação física, outros sentimentos e atitudes, e alerta comparado com o grupo controle. A pontuação do SSPS-N evidenciou aumento significativo durante o teste no grupo placebo, enquanto que o CBD reduziu estes níveis. Não houve diferenças significativas entre os grupos CBD e controle na SSPS-N e nos fatores sedação física, outros sentimentos e atitudes e alerta, da Visual Analogue Mood Scale (VAMS). A segunda parte do estudo avaliou a ansiedade em indivíduos saudáveis que receberam alta dose oral de rimonabanto e submetidos ao teste de simulação de falar em público, para melhor entendimento do possível mecanismo farmacológico para tratamento de transtornos de ansiedade. Vinte e quatro sujeitos saudáveis receberam placebo ou rimonabanto 90 mg (n=12) em um randomizado e duplo-cego. Não foi observado efeitos adversos significativo em ambos grupos. O grupo rimonabanto apresentou maiores níveis de ansiedade na fase pré-estresse e durante o estresse. Não houve diferença significativa quanto aos demais fatores avaliados entre os grupos. O aumento na ansiedade após administração do rimonabanto pode-se ao fato de haver diminuição no sistema endocanabinóide nos receptores CB1 e a possível modulação na ansiedade clínica e patológica. A terceira parte objetivou quantificar canabinóides no sangue total em usuários crônicos de cannabis durante abstinência supervisionada. Trinta usuários crônicos de cannabis, do sexo masculino, permaneceram no centro de pesquisa por até 33 dias, com coleta de sangue uma vez ao dia. ?9-tetrahidrocanabinol (THC), 11-hidróxi-THC (11-OH-THC) e 11-nor-9-carbóxi-THC (THCCOOH) foram quantificados no sangue por meio da cromatografia gasosa-espectrometria de massa bidimensional. Vinte e sete de 30 usuários foram positivos para THC no ingresso do estudo, com concentração mediana (variação) de 1.4 ng/mL (0.3-6.3). Níveis de THC diminuíram gradativamente com somente 1 de 11 participantes negativo no dia 26; 2 de 5 indivíduos permaneceram positivos para THC (0.3 g/ L p 30 5 0% j TH >=1 0 g/ L p 12 ç mediana de 11-OH-TH f 1 1 g/ L g >=1 0 g/ L pó 24h. A taxa de detecção de THCCOOH foi 96.7% no ingresso, diminuindo gradativamente para 95.7 e 85.7% nos dias 8 e 22, respectivamente; 4 de 5 sujeitos permaneceram positivo para THCCOOH (0.6-2.7 ng/mL) após 30 dias e um permaneceu positivo no 33º dia. Foi detectado THC em alguns indivíduos por 30 dias, porém em baixas concentrações, devido a extensa eliminação do canabinóide em decorrência da exposição crônica

La 3,4-metilendioximetamfetamina (MDMA, èxtasi) i el cannabis són dues drogues les quals es consumeixen conjuntament de manera habitual. Malgrat que tots dos compostos presenten propietats reforçant i potencial addictiu, també tenen propietats farmacològiques oposades. La MDMA es una droga psicoestimulant, la qual causa hiperlocomoció, hipertèrmia, resposted de tipus asiogènic i neurotoxicitat. Per altra banda el Δ9-tetrahydrocannabinol (THC), principal compost psicoactiu del cannabis, posseeix efectes relaxants, hipolocomotors, hipotèrmics i neuroprotectors. Els efectes de la MDMA i el THC al sistema nerviós central es troben mediats per dos mecanismes notablement diferents. La MDMA augmenta els nivells extracel·lulars de dopamina i serotonina, mentre que el THC produeix l'activació del receptor cannabinoide CB1. Cal destacar a més que les interaccions entre els sistemes monoaminèrgic i endocannabinoide s'observa de manera freqüent en l'organisme.En el present estudi hem explorat la implicació del sistema endocannabinoide i la MDMA en diversos aspectes. Per una banda el receptor cannabinoide CB1 juga un important paper en els efectes hiperlocomotors i hipertèrmics, i en les respostes de tipus ansiogènic produïdes per la MDMA. Curiosament, encara que el receptor CB1 no participa en els efectes recompensants primaris de la MDMA, és imprescindible per que tinguin lloc els seus efectes reforçants. Així mateix, l'alliberació de serotonina per part de la MDMA redueix de manera dosi-depenent la simptomatologia física causada pel síndrome d'abstinència a cannabinoides precipitada per un antagonista del receptor CB1. Finalment, el tractament amb THC era capaç de prevenir la hipertèrmia, activació glial, estrès oxidatiu i pèrdua de terminals causada per la MDMA. Com a conseqüència el THC exerceix un efecte neuroprotector contra la neurotoxicitat induïda per la MDMA. / 3,4-methylenedioximethamphetamine (MDMA, ecstasy) and cannabis are two drugs frequently consumed in combination. Despite both compounds have rewarding properties and abuse liability, they show opposite pharmacological properties. On the one hand, MDMA is a psychostimulant drug with hyperlocomotor, hyperthermic, anxiogenic-like and neurotoxic effects. On the other hand, Δ9-tetrahydrocannabinol (THC), the main psychoactive compound of cannabis, has relaxant, hypolocomotor, hypothermic and neuroprotective properties. The effects of MDMA and THC in the central nervous system are mediated by two different mechanisms. MDMA enhances the extracellular levels of dopamine and serotonin, whereas THC activates the CB1 cannabinoid receptor. Likewise, interactions between the monoaminergic and the endogenous cannabinoid system have been frequently observed.In the current study, we explored the involvement of CB1 cannabinoid receptor on the hyperlocomotor, hyperthermic, anxiogenic-like, rewarding and reinforcing effects of MDMA. We also studied the effect of acute and chronic administration of MDMA on rimonabant-precipitated THC withdrawal syndrome. Furthermore, we explored the neuroprotective effects of THC on MDMA-induced neurotoxicity.As a result of this study we may conclude that endocannabinoid system and MDMA interact in a wide variety of aspects. CB1 receptor plays an important role on the hyperlocomotor, hyperthermic, and anxiogenic-like effects of MDMA. Interestingly, CB1 receptor is essential for the reinforcing but not the primary rewarding properties of MDMA. In addition, the release of serotonin by MDMA dose-dependently reduced the severity of THC withdrawal syndrome triggered by a CB1 antagonist. Finally, pretreatment with THC prevented the hyperthermia, glial activation, oxidative stress and terminal loss caused by MDMA. Consequently, THC exerts a neuroprotective effect against MDMA-induced neurotoxicity.