Marijuana is a widely used drug of abuse and its psychoactive compounds are called cannabinoids. In the brain cannabinoids are known to activate CB1-receptors, and possibly other non-CB1 receptors, which are widely expressed in the neocortex, cerebellum and hippocampus. At the single-cell level, cannabinoids regulate neuronal excitability and decrease release of various neurotransmitters. Moreover, they alter long-term synaptic plasticity, a candidate model of memory storage. At the behavioral level cannabinoids alter memory formation in both laboratory animals and human. Yet, little is known about the link between the effects of cannabinoids at the single-cell level, as studied in slice preparations and their behavioral effects. As a result, the impact of cannabinoids on network activity is poorly understood. We combined silicon and tetrode recordings in the hippocampal CA1 region of freely moving and head-restrained awake rats before and after systemic injection of CP55940, a synthetic cannabinoid. CP559...

The orbitofrontal cortex (OFC) is involved in intoxication, craving, bingeing and withdrawal in drug addiction (Am J Psychiatry 2002, 159:1642-1652). In the present study we examined transcriptional patterns in postmortem OFC from 34 drug abuse cases (primarily cocaine and THC) and 34 controls. For each case, duplicate NIA MGC microarrays were hybridized with 33P-labeled cDNA reverse transcribed from 8 ug total RNA. Each drug abuse case was compared to the four best-matching controls and to a pool of all controls. Hierarchical clustering of transcriptional profiles showed that there were three main clusters, or subgroups, of drug abuse cases. For each pairing of subgroups, a subset of transcripts could be identified for which expression was increased in one subgroup and decreased in the second subgroup. The subgroups were not clearly related to drug abuse history. We are evaluating toxicological profiles by gas chromatography-mass spectrometry, and further evaluating patterns of past drug use via medical r...

MDMA addicts are frequently polydrug abusers, combining MDMA with alcohol and marijuana as well as other psychostimulants including cocaine. Although psychostimulants are similar pharmacologically, they differ substantially in terms of neurotoxic effects. Thus, whereas methylated amphetamines, such as MDMA, deplete neostriatal serotonin (5-HT), repeated administration of high doses of cocaine produces no toxic effects on central monoamine systems. In the present experiments, we administered a 5-HT toxic regimen of four repeated MDMA injections (10 mg/kg, i.p.) followed by seven daily injections of cocaine (15 mg/kg, i.p.) or the selective dopamine re-uptake blocker GBR-12909 (10 mg/kg, i.p.). Treatment with MDMA alone depleted neostriatal 5-HT while having no effect on neostriatal dopamine. The groups of rats pretreated MDMA and then administered cocaine or GBR-12909 had profound depletions of neostriatal 5-HT and dopamine. Taken together, these results indicate that blockade of dopamine reuptake is the ma...

The G-protein coupled CB1 receptor is the major brain site at which cannabinoid marijuana constituents are psychoactive and the principal brain receptor for endogenous anandamide ligands. CB1 receptor knockout mice display differences in reward exerted by a number of drugs and in ethanol withdrawal syndromes. Initial association studies within CB1 coding exon and 3’flanking region variants suggested possible roles for human CB1 variants in vulnerabilities to psychoses or addictions. These sorts of data make elucidation of the complete CB1 receptor gene, its variants, and their haplotypes of importance. Accordingly, we have worked to improve definition of the human CB1 receptor gene and mRNAs. Using Northern and RACE analyses, we identified three novel exons that encode CB1 mRNA 5’ UTR sequences. We identified 5 novel splice variant sequences that incorporate these exons in varying patterns, and quantitated them by RT-PCR. Northern analyses using exon-specific probes reveal one major and three minor mRNA sp...

Abundant filamentous tau inclusions in oligodendrocytes (OLGs) are hallmarks of neurodegenerative tauopathies, including sporadic corticobasal degeneration and hereditary frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). However, mechanisms of neurodegeneration in these tauopathies are unclear in part because of the lack of animal models for experimental analysis. We address this by generating transgenic (Tg) mice expressing human tau exclusively in OLGs using the 2′,3′-cyclic nucleotide 3′-phosphodiesterase promoter. Filamentous OLG tau inclusions developed in these Tg mice as a result of human tau expression in OLGs, especially those expressing the FTDP-17 human P301L mutant tau. Notably, structural disruption of myelin and axons preceded the emergence of thioflavin-S positive tau inclusions in OLGs, but impairments in axonal transport occurred even earlier, whereas motor deficits developed subsequently, especially in Tg mice with the highest tau expression levels. These data s...

Significant progress has been achieved in cannabinoid research. However little information is available at the molecular level about cannabinoid receptor (Cnr)gene structure and regulation. We have continued studies on Cnr genetics and signaling in order to understand the role of the endocannabinoid physiological control system (EPCS). Using in-vivo and in-vitro techniques we present data on Cnr CB1 transcript size, SNPs, trinucleotide repeat and variants. The presence of Cnr CB1 protein and gene expression in the shrew brain and gut, mouse and rat brains and human blood is presented as further evidence for the existence of the EPCS. We constructed a graphical representation of Cnr phylogenetic tree and using gene bank entries deduced amino acid sequence alignments of CB1 and CB2 Cnrs in a number of species. In-vivo, there was decreased effects of THC in the Rotorod and plus-maze tests suggesting the interaction of EPCS with mu opiate receptor. Together our data reveals an elaborate network of this EPCS an...

Cannabinoids have been shown to influence food intake, and until recently, the neural pathways mediating these effects have remained obscure. It has been previously shown that i.c.v. injection of Δ9-THC causes increased consumption of palatable foods in rats (Koch an Matthews, 2001), and we postulated the involvement of the hindbrain in this cannabinoid-induced food intake. Cannulated rats (both female and male groups) trained to consume sweetened condensed milk received either lateral or 4th ventricle injections of CP 55,940 and were presented with sweetened condensed milk 15 minutes after injection. All rats were injected over a range of doses between 10 pg and 10 μg per rat. Milk intake was recorded every 10 minutes for 30 minutes and then every hour thereafter for a total of 3 hours. Lateral ventricle injection of CP 55,940 increased milk intake and induced c-fos immunoreactivity in the region of the rostral 4th ventricle at doses in the microgram range; however, CP 55,940 was effective in increasing f...

The Nucleus Accumbens (NAc) represents a critical site for the rewarding properties of drugs of abuse. Glutamatergic afferents to the NAc are involved in the actions of psychostimulants and opioids, while the potentiation of dopaminergic neurotransmission in the NAc is a common feature of abused drugs, including cannabinoids. Cannabinoid receptors (CB1) are densely expressed in regions that provide excitatory innervation to the NAc, such as the amygdala, the cortex and the hippocampus. In this study we recorded extracellularly from neurons in the shell of the NAc which responded to the stimulation of the baso-lateral amygdala (BLA) or the medial prefrontal cortex (PFC) in urethane anaesthetized rats. The generation of action potentials in NAc neurons induced by BLA or PFC stimulation was strongly inhibited by the synthetic cannabinoid agonists WIN 55212,2 (0.062-0.25 mg/kg, i.v.) and HU-210 (0.125-0.25 mg/kg, i.v.) or the psychoactive principle of Cannabis Δ9-tetrahydrocannabinol (1.0 mg/kg, i.v.). Neither...

Cannabinoids are novel neuromodulators derived from marijuana (Cannabis sativa) an old and widely used drug with important psychoactive effects. These substances have been described to act as retrograde messengers modulating the release of both glutamate and GABA at the level of the hippocampus and cerebellum. The cannabinoid receptor, CB1 is widely distributed in the CNS, with high density at the level of the inner layers of the olfactory bulb. In this structure GABA has been demonstrated to be highly concentrated by granule cells and we have previously shown that GABA is released in a Ca++ dependent manner when stimulated with KCl or glutamate. We were interested to test whether Cannabinoids could modulate basal or stimulated GABA release. Slices containing the inner layers of the olfactory bulb were incubated with 3H-GABA and release measured using continuous superfusion. Slices were then exposed for 4 min with different concentrations of WIN55,212-2 an agonist of CB1 receptors. 1- and 5 uM of the drug,...

Tau exon 10 splice site mutations in FTDP-17 result in the relative increase of tau isoforms containing four microtubule binding repeats (4R-tau) over three repeat isoforms (3R-tau). This is considered a fundamental process in disease pathogenesis. Although other tauopathies including PSP, CBD, PiD and FTDP-17 with tau missense mutations are not primarily caused by the same mechanism, insoluble, fibrillar tau in the pathological inclusions in these disorders are classified by differences in their tau isoform profiles. In order to study the relevance of these isoform differences in selective neuonal death, we have developed specific monoclonal antibodies, RD3 and RD4 that recognise the 3R- and 4R-tau, respectively. Using these, we have identified changes in the ratio and cellular distribution of these isoforms, and compare these changes in the different tauopathies. These findings could give us insight into the possible basis of the phenotypic range of the tauopathies and the selective vulnerability of diff...