Speeding is a major contributor to motor vehicle deaths, especially among younger drivers. While impulsivity has been linked to the neurobiology of gambling, how fast gamblers drive over the posted speed limits (“speeding”) has not been specifically evaluated. In our clinical experience, pathological gambling patients often describe speeding as embodying a sense of winning (i.e. beating time, boredom, police, and other cars as if on a raceway). We have completed the first statewide survey of gambling and problem gambling in Florida adolescents ages 13 to 17 (n=1,051). This phone survey asked respondents about gambling activities, demographic questions, and speeding. Self-reported speeding and intent to speed have been shown to correlate with actual driving speed. A simple correlation analysis (ages 15 to 17) revealed that speeding as measured by miles per hour (mph) self-reported over the speed limit, is significantly related with gambling behavior as well as with alcohol, tranquilizers, marijuana, cocaine...

Cannabinoids derive from D-9 tetrahydrocannabinol, the active principle of marihuana. Although it is known that cannabinoids reduce motor activity at the central level in humans as well as in animals, little information exists about their direct effects on skeletal muscle. By means of isometric-tension recording, in fast skeletal muscle fibers obtained from the EDL digiti IV of Rana pipiens, we have analyzed the effect of the cannabinoid agonist WIN 55,212-2 (WIN) on the contractile responses that follow depolarization evoked by chloride-free high-potassium solution. The normal saline was (in mM): NaCl, 117.5; KCl, 2.5; CaCl2, 1.8; with imidazol-chloride 2.0 mM being added to adjust the pH to 7.4. Chloride-free high-potassium solution (40 mM) was prepared similar the above solution by an equimolar replacement of sodium by potassium and by substituting the chloride ions with an osmotically equivalent amount of gluconate. The experiments were performed at room temperature (22-24 °C). The effects of WIN(10-50...

Endogenous opioids are thought to mediate reinforcing effects of drugs of abuse like cocaine and ethanol. Opioid antagonists reduce cocaine and ethanol self-administration (SA), whereas chronic treatment with naltrexone (NTX) enhances initiation of cocaine SA. μ-Opioid receptor knockout mice are less sensitive to morphine, ethanol and Δ-THC in SA or CPP. In the present study we investigated interactions between μ-opioid receptors and the mesolimbic dopamine system and the role of μ-opioid receptors in behavioral effects of cocaine. We used MOR knockout mice and chronic NTX mice, a model for opioid receptor upregulation. Dopamine D1-like, D2-like and D3 receptor number and TH mRNA levels were determined in mesolimbic areas. D1-like receptors were upregulated in striatum of MOR knockout mice. There were no further changes in dopamine parameters in MOR deficient or chronic NTX treated mice. Basal activity and acute effects of cocaine were assessed in MOR knockout mice in an open field. Basal activity of MOR d...

Many studies have shown that the active components of marijuana (cannabinoids) demonstrate neuroprotective properties in animal models of ischemia, PD and HD. Both exogenous and endogenous cannabinoids bind to CB1 receptors found in several areas of the brain, including the cerebellum and hippocampus. Our lab studies the spasticHan-Wistar rat (sHW), a genetic model of glutamate excitotoxicity, that exhibits neurodegeneration in the cerebellum and hippocampus, beginning at 30 days of age. This progressive disorder generates hyperactivity, fore limb tremor, and hind limb ataxia, leading to death due to respiratory difficulties. This current study was conducted to investigate the potential neuroprotective properties of cannabinoids on the sHW rat. An equal mix of mutant and normal siblings was used in this study. At 24-28 days of age, the animals were treated with either one of two agonists, 0.1 mg/kg anandamide (n=15) and 0.1 mg/kg R-(+)-Win 55,212-2 (n=10), the cannabinoid antagonist SR141716A (n=11) or veh...

Patch clamping (excised patches) and radioligand binding techniques (membranes) were used to study effects of cannabinoid1receptor (CB1R) agonists on human 5-HT3A receptors (h5-HT3AR), stably transfected in HEK-293 cells. At negative membrane potentials, 5-HT induced concentration-dependent currents (EC50 value 9 μM) sensitive to blockade by 0.3 nM ondansetron. The CB1R agonists delta-9-tetrahydrocannabinol (IC50: 0.04 μM), WIN 55212-2 (IC50: 0.1 μM), anandamide (IC50: 0.2 μM) and CP55940 (IC50: 0.7 μM) concentration-dependently inhibited 5-HT (30 µM)-induced currents, whereas WIN 55212-3 (an enantiomer of WIN 55212-2) at up to 1 μM did not. The CB1R antagonist SR141716 (1 μM) failed to counteract the almost complete blockade by 1 μM WIN 55212-2. In non-transfected HEK-293 cells, virtually no mRNA for CB1R was present and in membranes prepared from such cells no specific [3H]SR141716 binding was detectable. In membranes from cells expressing the h5-HT3AR, the CB1R ligands WIN 55212-2, CP55940 and SR141716 ...

Cannabinoids are known to protect neurons from toxicity as induced by different insults. However, the possibility that cannabinoids protect astrocytes from death has not been studied to date. Here, we tested whether cannabinoids are cytoprotective in a model in which primary astrocytes are exposed to C2-ceramide, a cell-permeable analogue of the pro-apoptotic lipid ceramide, to trigger apoptosis. Data show that (i) Δ9-tetrahydrocannabinol and other cannabinoids rescued astrocytes from ceramide-induced apoptosis, and (ii) this effect was CB1 receptor-mediated since SR141716 abolished the cannabinoid effect. Next we wondered on the mechanism involved in this anti-apoptotic effect of cannabinoids. We have recently shown that in transfected cells the CB1 receptor is coupled to the activation of PI3K/PKB, a pathway which is widely involved in cell survival. Data show that (i) the anti-apoptotic action of cannabinoids in primary astrocytes relied on PI3K activation, but (ii) this effect seemed to be independent ...

Ca2+-dependent inactivation and facilitation of presynaptic Cav2.1 Ca2+ channels can produce corresponding changes in synaptic efficacy. We have shown that this dual-feedback regulation of Cav2.1 by Ca2+ is mediated by calmodulin (CaM) through a direct interaction with a CaM-binding domain (CBD) in the α1 subunit of Cav2.1 (α12.1). Ca2+-binding protein 1 (CaBP1) is a neuron-specific isoform of CaM-like proteins that could substitute for CaM in binding to Cav2.1. However, structural distinctions between CaBP1 and CaM could underly distinct forms of Cav2.1 regulation. We tested this in whole-cell patch clamp recordings from tsA-201 cells cotransfected with cDNAs encoding CaBP1 and Cav2.1 channel subunits. CaBP1 significantly enhanced inactivation of Cav2.1 Ca2+ currents, caused a depolarizing shift in the voltage-dependence of activation, and prevented overt Ca2+-dependent facilitation of Cav2.1. Unlike the Ca2+-dependent modulation of Cav2.1 by CaM, these inhibitory effects of CaBP1 were observed with intra...

5-HT2-type serotonin receptors (5-HT2Rs) are widely expressed throughout the brain and mediate many of the modulatory effects of serotonin. It has been thought that postsynaptic 5-HT2Rs act primarily by depolarizing neurons and thereby increasing their excitability. However, it is also known that 5-HT2Rs are coupled to Gq/11-type G-proteins and that some other types of Gq/11-coupled receptors can regulate synapses by evoking endocannabinoid release and activating presynaptic cannabinoid-type 1 receptors (CB1Rs). Here, we examine whether activation of 5-HT2Rs can regulate synapses through such a mechanism by studying excitatory synapses onto cells in the inferior olive (IO). These cells express 5-HT2Rs on their soma and dendrites, and the IO receives extensive serotonergic input. We find that the excitatory synaptic inputs onto IO cells are strongly suppressed by serotonin receptor agonists as well as release of endogenous serotonin. Both 5-HT2Rs and 5-HT1BRs contribute to this modulation by decreasing the ...

The endocannabinoid, anandamide (known to mimic the actions of Δ 9 THC in vivo), has been shown to modulate CNS receptors, including AMPA glutamate receptors in vivo, in a presynaptic fashion. Anandamide has also been shown to inhibit CNS receptors, including the recombinant AMPA glutamate receptors in vitro, independently of the cannabinoid receptor system. In order to probe the molecular mechanisms of anandamide inhibition of AMPA receptor function, we used the two-electrode voltage-clamp technique, to study Xenopus laevis oocyte expression of wild-type and c-terminal mutant AMPA receptors and their sensitivities to anandamide in vitro. The mutations targeted phosphorylation sites at the intracellular c-terminal domain of the AMPA receptor. The mutant receptors studied are S831A, T840A, S845A and S831A/S845A. Our results show that mutant receptors were significantly, less sensitive to anandamide inhibition than the wild-type GluR1 receptor subunit. The sensitivity differences between the mutants and the ...

Cannabinoids, the active components of marijuana and their endogenous counterparts, exert their effects on the central nervous system through the CB1 receptor. This G-protein-coupled receptor has been shown to be functionally coupled to inhibition of adenylyl cyclase, activation of extracellular signal-regulated kinase and modulation of ion channels. This study was undertaken to test whether the CB1 receptor is coupled to ceramide generation, which may be involved in the control of cell fate. (a) Short-term incubation with cannabinoids induced sphingomyelin breakdown and ceramide accumulation in primary astrocytes and C6 glioma cells, but not in primary neurons. Cannabinoid-induced sphingomyelin hydrolysis was dependent on CB1 receptor activation but independent of Gi/o proteins. A role for the adaptor protein FAN is supported by coimmunoprecipitation experiments and by the use of cells overexpressing wild-type or dominant-negative forms of FAN. (b) Long-term incubation of C6 glioma cells with cannabinoids...