Cannabidiol regulates behavioural alterations and gene expression changes induced by spontaneous cannabinoid withdrawal

[Background and purpose]: Cannabidiol (CBD) represents a promising therapeutic tool for treating cannabis use disorder (CUD). This study aimed to evaluate the effects of CBD on the behavioural and gene expression alterations induced by spontaneous cannabinoid withdrawal.[Experimental approach]: Spontaneous cannabinoid withdrawal was evaluated 12 h after cessation of CP-55,940 treatment (0.5 mg·kg-1 every 12 h, i.p.; 7 days) in C57BL/6J mice. The effects of CBD (5, 10 and 20 mg·kg-1 , i.p.) on withdrawal-related behavioural signs were evaluated by measuring motor activity, somatic signs and anxiety-like behaviour. Furthermore, gene expression changes in TH in the ventral tegmental area, and in the opioid μ receptor (Oprm1), cannabinoid CB1 receptor (Cnr1) and CB2 receptor (Cnr2) in the nucleus accumbens, were also evaluated using the real-time PCR technique.[Key results]: The administration of CBD significantly blocked the increase in motor activity and the increased number of rearings, rubbings and jumpings associated with cannabinoid withdrawal, and it normalized the decrease in the number of groomings. However, CBD did not change somatic signs in vehicle-treated animals. In addition, the anxiogenic-like effect observed in abstinent mice disappeared with CBD administration, whereas CBD induced an anxiolytic-like effect in non-abstinent animals. Moreover, CBD normalized gene expression changes induced by CP-55,940-mediated spontaneous withdrawal.[Conclusions and implications]: The results suggest that CBD alleviates spontaneous cannabinoid withdrawal and normalizes associated gene expression changes. Future studies are needed to determine the relevance of CBD as a potential therapeutic tool for treating CUD.This research was supported by the ‘Instituto de Salud Carlos III’ (RTA, RD12/0028/0019 and RD16/0017/0014, Fondos FEDER), ‘Plan Nacional Sobre Drogas’ (PNSD 2016/016) and ‘Ministerio de Economía y Competitividad’ (FIS, PI14/00438).Peer reviewe

Role of CB1 and CB2 cannabinoid receptors in the development of joint pain induced by monosodium iodoacetate

Joint pain is a common clinical problem for which both inflammatory and degenerative joint diseases are major causes. The purpose of this study was to investigate the role of CB1 and CB2 cannabinoid receptors in the behavioral, histological, and neurochemical alterations associated with joint pain. The murine model of monosodium iodoacetate (MIA) was used to induce joint pain in knockout mice for CB1 (CB1KO) and CB2 cannabinoid receptors (CB2KO) and transgenic mice overexpressing CB2 receptors (CB2xP). In addition, we evaluated the changes induced by MIA in gene expression of CB1 and CB2 cannabinoid receptors and μ-, δ- and κ-opioid receptors in the lumbar spinal cord of these mice. Wild-type mice, as well as CB1KO, CB2KO, and CB2xP mice, developed mechanical allodynia in the ipsilateral paw after MIA intra-articular injection. CB1KO and CB2KO demonstrated similar levels of mechanical allodynia of that observed in wild-type mice in the ipsilateral paw, whereas allodynia was significantly attenuated in CB2xP. Interestingly, CB2KO displayed a contralateral mirror image of pain developing mechanical allodynia also in the contralateral paw. All mouse lines developed similar histological changes after MIA intra-articular injection. Nevertheless, MIA intra-articular injection produced specific changes in the expression of cannabinoid and opioid receptor genes in lumbar spinal cord sections that were further modulated by the genetic alteration of the cannabinoid receptor system. These results revealed that CB2 receptor plays a predominant role in the control of joint pain manifestations and is involved in the adaptive changes induced in the opioid system under this pain state.This work was supported by the Spanish “Ministerio de Ciencia e Innovación” (SAF2007-64062), “Instituto de Salud Carlos III” (RETICS-Red de Trastornos Adictivos-Redes Temáticas de Investigación Cooperativa en Salud: RD06/0001/0001, RD06/0001/1004), Plan Nacional sobre Drogas (PNSD 2009/026), the Catalan Government (SGR2009-00131), the ICREA Foundation (ICREA Academia-2008), the DG Research of the European Commission (GENADDICT, LSHM-CT-2004-05166, and PHECOMP, LSHM-CT-2007-037669), and the CENIT program (CEN-20061005) from the “Centro para el Desarollo Technológico Industrial” from the Spanish Ministry of Science and Innovation. CLP is a recipient of a predoctoral fellowship from the Spanish Ministry of Education. AAF (predoctoral fellow) and AR (technician) are supported by RETICS. The partial support of FEDER funds (EU) is also acknowledged.Peer reviewe

Differential pharmacological regulation of sensorimotor gating deficit in CB1 knockout mice and associated neurochemical and histological alterations

The endocannabinoid system has been widely involved in the pathophysiology of sensorimotor gating deficits. This study aimed to evaluate the pharmacological modulation of the sensorimotor gating impairment induced by cannabinoid CB1 receptor (CB1r) deletion. For this purpose, the prepulse inhibition (PPI) paradigm was used to evaluate the effect of two antipsychotics drugs (risperidone and haloperidol) and a psychostimulant (methylphenidate) on the preattentional deficit presented by CB1KO mice. Furthermore, the effects of the CB1r antagonist AM251 on PPI were evaluated in WT mice. Real-time PCR and immunohistochemical studies were carried out to analyze dopamine transporter (DAT) and α-2C adrenergic receptor (ADRA2C) gene expressions and the distribution of parvalbumin (PV) and cholecystokinin-8 (CCK) immunoreactive (ir) cortical neurons, respectively. Neither risperidone nor haloperidol significantly modified the PPI of WT and CB1KO mice, whereas methylphenidate improved the preattentional deficit of CB1KO mice. In addition, treatment with AM251 (3 mg/kg; i.p.) significantly decreased the PPI of WT animals. The administration of methylphenidate increased DAT and ADRA2C gene expressions in CB1KO mice without producing any effect in WT animals. Immunohistochemical studies revealed that there were no significant changes in CCK immunolabeling between WT and CB1KO mice, whereas the radial distribution of PV-ir neurons was abnormal in CB1KO mice. These data further support the important role of CB1r in sensorimotor gating regulation and the therapeutic usefulness of methylphenidate for the treatment of psychiatric disorders with associated preattentional deficits.This study was supported by the following research grants: Ministerio de Ciencia e Innovación SAF2011–23420 to Jorge Manzanares and SAF2009–10689 to Pere Berbel; Foundation Alicia Koplowitz to Pere Berbel; and Instituto de Salud ‘Carlos III’ (FIS), RETICS, Red de Trastornos Adictivos (RD06/0001/1004, RD12/0028/0019) to Jorge Manzanares.Peer reviewe

Cannabinoid CB1 and CB2 receptors, and monoacylglycerol lipase gene expression alterations in the basal ganglia of patients with Parkinson's disease

Previous studies suggest that the endocannabinoid system plays an important role in the neuropathological basis of Parkinson’s disease (PD). This study was designed to detect potential alterations in the cannabinoid receptors CB1 (CB1r) and CB2 (A isoform, CB2Ar), and in monoacylglycerol lipase (MAGL) gene expression in the substantia nigra (SN) and putamen (PUT) of patients with PD. Immunohistochemical studies were performed to identify precise CB2r cellular localization in the SN of control and PD patients. To ensure the validity and reliability of gene expression data, the RNA integrity number (RIN) was calculated. CB1r, CB2Ar, and MAGL gene expressions were evaluated by real-time polymerase chain reaction (real-time PCR) using Taqman assays. Immunohistochemical experiments with in situ proximity ligation assay (PLA) were used to detect the precise cellular localization of CB2r in neurons, astrocytes, and/or microglia. All RIN values from control and PD postmortem brain samples were > 6. CB1r gene expression was unchanged in the SN but significantly higher in the PUT of patients with PD. CB2Ar gene expression was significantly increased (4-fold) in the SN but decreased in the PUT, whereas MAGL gene expression was decreased in the SN and increased in the PUT. Immunohistochemical analyses revealed that CB2r co-localize with astrocytes but not with neurons or microglial cells in the SN. The results of the present study suggest that CB1r, CB2r, and MAGL are closely related to the neuropathological processes of PD. Therefore, the pharmacological modulation of these targets could represent a new potential therapeutic tool for the management of PD.We thank Fundación CIEN Brain Bank (Madrid, Spain), Fundación Alcorcón University Hospital Brain Bank (Madrid, Spain), London Neurodegenerative Diseases Brain Bank (London, UK), Parkinson’s UK Brain Bank (London, UK), and Navarrabiomed Brain Bank (Pamplona, Spain) for the supply of postmortem brain tissue. This work was supported by “DISTEC professorship for the study of Parkinson’s disease” to J. Manzanares, and by a grant from the Spanish Ministry of Economy (BFU2012-37907) to J.L. Lanciego.Peer reviewe

Opioid and cannabinoid systems as therapeutic targets for the treatment of alcohol dependence: From animal models to clinical practice

The development of alcohol dependence is the result of a combination of various factors. Psychosocial and psychiatric conditions, together with functional alterations of the brain or genetic traits, contribute to the development of problems related to alcohol use or alcohol dependence. Clinical studies using neuroimaging techniques (PET, fMRI) and preclinical studies using different animal models of problems related to ethanol consumption have improved our knowledge of the neurochemical mechanisms involved in alcohol dependence. These studies have served to identify peptides or receptors modified by ethanol consumption, which are functionally altered in strains of rats or mice highly vulnerable to ethanol consumption. Such peptides or receptors may be interesting targets for the treatment of alcoholism. Among the different targets studied in recent years, the opioid and cannabinoid systems meet a number of conditions for eligibility as candidates for the treatment of alcohol dependence. The μ-opioid receptor and cannabinoid CB1 receptor, in particular, are affected by ethanol consumption. In clinical studies, genetic polymorphisms of the μ-opioid and CB1 receptors have been associated with increased vulnerability to alcohol consumption. Similarly, functional alterations in μ-opioid and cannabinoid receptors have been identified in specific strains of rats or mice with high preference to ethanol consumption. Furthermore, several studies have shown that the manipulation of these receptors using agonists or antagonists may increase or decrease ethanol consumption, which confirms the validity of these receptors as targets for the treatment of alcohol dependence. In this review, we analyzed the genetic traits and psychiatric and/or psychosocial conditions that affect vulnerability to and the pharmacologic treatment of alcohol dependence, with special emphasis on the role of opioid and cannabinoid receptors. The use of animal models as important tools for identifying neurochemical mechanisms relevant to understanding and treating alcohol use problems was evaluated.Peer Reviewe

Role of CB1 and CB2 cannabinoid receptors in the development of joint pain induced by monosodium iodoacetate

Joint pain is a common clinical problem for which both inflammatory and degenerative joint diseases are major causes. The purpose of this study was to investigate the role of CB1 and CB2 cannabinoid receptors in the behavioral, histological, and neurochemical alterations associated with joint pain. The murine model of monosodium iodoacetate (MIA) was used to induce joint pain in knockout mice for CB1 (CB1KO) and CB2 cannabinoid receptors (CB2KO) and transgenic mice overexpressing CB2 receptors (CB2xP). In addition, we evaluated the changes induced by MIA in gene expression of CB1 and CB2 cannabinoid receptors and μ-, δ- and κ-opioid receptors in the lumbar spinal cord of these mice. Wild-type mice, as well as CB1KO, CB2KO, and CB2xP mice, developed mechanical allodynia in the ipsilateral paw after MIA intra-articular injection. CB1KO and CB2KO demonstrated similar levels of mechanical allodynia of that observed in wild-type mice in the ipsilateral paw, whereas allodynia was significantly attenuated in CB2xP. Interestingly, CB2KO displayed a contralateral mirror image of pain developing mechanical allodynia also in the contralateral paw. All mouse lines developed similar histological changes after MIA intra-articular injection. Nevertheless, MIA intra-articular injection produced specific changes in the expression of cannabinoid and opioid receptor genes in lumbar spinal cord sections that were further modulated by the genetic alteration of the cannabinoid receptor system. These results revealed that CB2 receptor plays a predominant role in the control of joint pain manifestations and is involved in the adaptive changes induced in the opioid system under this pain state.This work was supported by the Spanish “Ministerio de Ciencia e Innovación” (#SAF2007-64062), “Instituto de Salud Carlos III” (RETICS- Red de Trastornos Adictivos-Redes Temáticas de Investigación Cooperativa en Salud: #RD06/0001/0001, #RD06/0001/1004), Plan Nacional sobre Drogas (PNSD #2009/026), the Catalan Government (SGR2009-00131), the ICREA Foundation (ICREA Academia-2008), the DG Research of the European Commission (GENADDICT, # LSHM-CT-2004-05166, and PHECOMP, # LSHM-CT-2007-037669), CENIT program (CEN-20061005) from/nthe “Centro para el Desarollo Technológico Industrial” from the Spanish Ministry of Science and Innovation. Carmen La Porta (C.L.P) is a recipient of a predoctoral fellowship from the Spanish Ministry of Education. Auxiliadora Aracil-Fernández (A.A.F., predoctoral fellow) and Analía Rico (A.R., technician) are supported by RETICS. The partial support of FEDER funds (EU) is also acknowledge

Role of cannabinoid CB2 receptor in the reinforcing actions of ethanol

This study examines the role of the cannabinoid CB2 receptor (CB2 r) on the vulnerability to ethanol consumption. The time-related and dose-response effects of ethanol on rectal temperature, handling-induced convulsions (HIC) and blood ethanol concentrations were evaluated in CB2 KO and wild-type (WT) mice. The reinforcing properties of ethanol were evaluated in conditioned place preference (CPP), preference and voluntary ethanol consumption and oral ethanol self-administration. Water-maintained behavior schedule was performed to evaluate the degree of motivation induced by a natural stimulus. Preference for non-alcohol tastants assay was performed to evaluate the differences in taste sensitivity. Tyrosine hydroxylase (TH) and μ-opioid receptor gene expressions were also measured in the ventral tegmental area and nucleus accumbens (NAcc), respectively. CB2 KO mice presented increased HIC score, ethanol-CPP, voluntary ethanol consumption and preference, acquisition of ethanol self-administration, and increased motivation to drink ethanol compared with WT mice. No differences were found between genotypes in the water-maintained behavior schedule or preference for non-alcohol tastants. Naïve CB2 KO mice presented increased μ-opioid receptor gene expression in NAcc. Acute ethanol administration (1-2 g/kg) increased TH and μ-opioid receptor gene expressions in CB2 KO mice, whereas the lower dose of ethanol decreased TH gene expression in WT mice. These results suggest that deletion of the CB2 r gene increased preference for and vulnerability to ethanol consumption, at least in part, by increased ethanol-induced sensitivity of the TH and μ-opioid receptor gene expressions in mesolimbic neurons. Future studies will determine the role of CB2 r as a target for the treatment of problems related with alcohol consumption.This research was supported by ‘Instituto de Salud Carlos III’ (RETICS, RD06/0001/1004, RD12/0028/0019), ‘Plan Nacional Sobre Drogas’ (PNSD 2007/061; 2011/043), Fundación Sociosanitaria de Castilla—La Mancha, (FISCAM) and ‘Ministerio de Economía y Competitividad’ (#SAF 2008-01106, SAF 2011-23420) grants to J.M. Postdoctoral fellows A.O.A and A.T, and Raquel Poveda (R.P., technician) and Mar Ruiz (M.R., technician) are supported by FISCAM. F.N. (postdoctoral fellow), A.A.F. (postdoctoral fellow) and Analía Rico (A.R., technician) are supported by RETICS. MSGG (postdoctoral fellow) and Patricia Rodríguez (P.R., technician) are supported by Miguel Hernández University. We thank R.P., M.R., A.R and P.R. for excellent technical assistance. The partial support of FEDER funds (EU) is also acknowledged.Peer reviewe

Role of CB1 and CB2 cannabinoid receptors in the development of joint pain induced by monosodium iodoacetate

Joint pain is a common clinical problem for which both inflammatory and degenerative joint diseases are major causes. The purpose of this study was to investigate the role of CB1 and CB2 cannabinoid receptors in the behavioral, histological, and neurochemical alterations associated with joint pain. The murine model of monosodium iodoacetate (MIA) was used to induce joint pain in knockout mice for CB1 (CB1KO) and CB2 cannabinoid receptors (CB2KO) and transgenic mice overexpressing CB2 receptors (CB2xP). In addition, we evaluated the changes induced by MIA in gene expression of CB1 and CB2 cannabinoid receptors and μ-, δ- and κ-opioid receptors in the lumbar spinal cord of these mice. Wild-type mice, as well as CB1KO, CB2KO, and CB2xP mice, developed mechanical allodynia in the ipsilateral paw after MIA intra-articular injection. CB1KO and CB2KO demonstrated similar levels of mechanical allodynia of that observed in wild-type mice in the ipsilateral paw, whereas allodynia was significantly attenuated in CB2xP. Interestingly, CB2KO displayed a contralateral mirror image of pain developing mechanical allodynia also in the contralateral paw. All mouse lines developed similar histological changes after MIA intra-articular injection. Nevertheless, MIA intra-articular injection produced specific changes in the expression of cannabinoid and opioid receptor genes in lumbar spinal cord sections that were further modulated by the genetic alteration of the cannabinoid receptor system. These results revealed that CB2 receptor plays a predominant role in the control of joint pain manifestations and is involved in the adaptive changes induced in the opioid system under this pain state.This work was supported by the Spanish “Ministerio de Ciencia e Innovación” (#SAF2007-64062), “Instituto de Salud Carlos III” (RETICS- Red de Trastornos Adictivos-Redes Temáticas de Investigación Cooperativa en Salud: #RD06/0001/0001, #RD06/0001/1004), Plan Nacional sobre Drogas (PNSD #2009/026), the Catalan Government (SGR2009-00131), the ICREA Foundation (ICREA Academia-2008), the DG Research of the European Commission (GENADDICT, # LSHM-CT-2004-05166, and PHECOMP, # LSHM-CT-2007-037669), CENIT program (CEN-20061005) from/nthe “Centro para el Desarollo Technológico Industrial” from the Spanish Ministry of Science and Innovation. Carmen La Porta (C.L.P) is a recipient of a predoctoral fellowship from the Spanish Ministry of Education. Auxiliadora Aracil-Fernández (A.A.F., predoctoral fellow) and Analía Rico (A.R., technician) are supported by RETICS. The partial support of FEDER funds (EU) is also acknowledge

Changes in gene expression and sensitivity of cocaine reward produced by a continuous fat diet

[Rationale] Preclinical studies report that free access to a high-fat diet (HFD) alters the response to psychostimulants.[Objectives] The aim of the present study was to examine how HFD exposure during adolescence modifies cocaine effects. Gene expression of CB1 and mu-opioid receptors (MOr) in the nucleus accumbens (N Acc) and prefrontal cortex (PFC) and ghrelin receptor (GHSR) in the ventral tegmental area (VTA) were assessed.[Methods] Mice were allowed continuous access to fat from PND 29, and the locomotor (10 mg/kg) and reinforcing effects of cocaine (1 and 6 mg/kg) on conditioned place preference (CPP) were evaluated on PND 69. Another group of mice was exposed to a standard diet until the day of post-conditioning, on which free access to the HFD began.[Results] HFD induced an increase of MOr gene expression in the N Acc, but decreased CB1 receptor in the N Acc and PFC. After fat withdrawal, the reduction of CB1 receptor in the N Acc was maintained. Gene expression of GHSR in the VTA decreased during the HFD and increased after withdrawal. Following fat discontinuation, mice exhibited increased anxiety, augmented locomotor response to cocaine, and developed CPP for 1 mg/kg cocaine. HFD reduced the number of sessions required to extinguish the preference and decreased sensitivity to drug priming-induced reinstatement.[Conclusion] Our results suggest that consumption of a HFD during adolescence induces neurobiochemical changes that increased sensitivity to cocaine when fat is withdrawn, acting as an alternative reward.This study was supported by the Spanish Ministry of Economy and Innovation and FEDER (PSI2014-51847-R and PSI2011-24762), Spanish Ministry of Health, Social Affairs and Equality (PNSD 2014-007); Instituto de Salud Carlos III, Red de Trastornos Adictivos (RTA) (RD12/0028/0005, RD12/0028/0019, RD16/0017/0007) and Unión Europea, Fondos FEDER “una manera de hacer Europa.” Generalitat Valenciana, PROMETEOII/2014/063.Peer reviewe

Effects of bingeing on fat during adolescence on the reinforcing effects of cocaine in adult male mice

Binge eating is a specific form of overeating characterized by intermittent excessive eating. In addition to altering the neurobiological reward system, several studies have highlighted that consumption of palatable food increases vulnerability to drug use. The aim of the present study was to evaluate the effects of a high-fat diet consumed in a binge pattern during adolescence on the reinforcing effects of cocaine. After 40 days of binge-eating for 2 h, three days a week (PND 29–69), the reinforcing effects of cocaine on conditioning place preference and intravenous self-administration paradigm were evaluated in adolescent male mice. Circulating leptin and ghrelin levels and the effects of bingeing on fat on CB1 mu opioid receptor (MOr) and ghrelin receptor (GHSR) gene expression in the Nucleus Accumbens (NAcc) and Ventral Tegmental Area (VTA) were also assessed. Our results showed a significant escalation in the consumption of a high-fat diet between the first and last week. High-fat binge (HFB) animals were more sensitive to the reinforcing effects of a subthreshold dose of cocaine in the paradigms assayed, and animals under fat withdrawal were more vulnerable to the reinstatement of conditioned place preference. HFB mice also showed enhanced cocaine self-administration. After fat withdrawal, exposure to a new fat binge reinstated cocaine seeking. Although HFB did not modify leptin levels, a decrease in plasmatic ghrelin was observed. Moreover, this pattern of fatty diet resulted in a reduction of MOr and CB1 gene expression in the NAcc and an increase in GHSR expression in the VTA. We propose that bingeing on fat during adolescence induces long-lasting changes in the brain through the sensitization of brain reward circuits, which predisposes individuals to seek cocaine during adulthood.This study was supported by the Spanish Ministry of Economy and Innovation and FEDER (SAF2013-41761-R; PSI2014-51847-R; and PSI2011-24762), Spanish Ministry of Health, Social Affairs and Equality (PNSD 2014-020 and 2014-I007); Instituto de Salud Carlos III, Red de Trastornos Adictivos (RTA) (RD12/0028/0005, RD12/0028/0019 and RD12/0028/0024) and Unión Europea, Fondos FEDER “una manera de hacer Europa”. Generalitat Valenciana, PROMETEOII/2014/063 and Generalitat de Catalunya (2014SGR34).Peer reviewe