Faculty Bibliography

The aim of this study was to examine the role of fatty acid amide hydrolase (FAAH) on ethanol sensitivity, preference, and dependence. The deletion of FAAH gene or the inhibition of FAAH by carbamoyl-biphenyl-3-yl-cyclohexylcarbamate (URB597) (0.1 mg/kg) markedly increased the preference for ethanol. The study further reveals that URB597 specifically acts through FAAH and that cannabinoid-1 (CB(1)) receptor is critical for N-arachidonoyl ethanolamide (AEA) mediated ethanol-reinforced behavior as revealed by lack of URB597 effect in both FAAH and CB(1)-/- mice compared with vehicle-treated -/- mice. The FAAH -/- mice displayed a lower sensitivity to hypothermic and sedative effects to acute ethanol challenge. The FAAH -/- mice also exhibited a reduction in the severity of handling-induced convulsions following withdrawal from chronic ethanol exposure. The CB(1) receptor and proenkephalin gene expressions, and CB(1) receptor and mu-opioid (MO) receptor-mediated G-protein activation were found to be significantly lower in the caudate-putamen, nucleus accumbens core and shell of FAAH -/- than +/+ mice. Interestingly, the MO receptor-stimulated G-protein signaling was greater in the striatum of FAAH -/- than +/+ mice following voluntary ethanol consumption. These findings suggest that an elevation in the AEA content and its action on the limbic CB(1) receptor and MO receptor might contribute to ethanol-reinforced behavior. Treatment with drugs that decrease AEA tone might prove useful in reducing excessive ethanol consumption

The endocannabinoid system is an important regulator of hepatic fibrogenesis. In this study, we determined the effects of 2-arachidonoyl glycerol (2-AG) on hepatic stellate cells (HSCs), the main fibrogenic cell type in the liver. Culture-activated HSCs were highly susceptible to 2-AG-induced cell death with >50% cell death at 10 microM after 18 h of treatment. 2-AG-induced HSC death showed typical features of apoptosis such as PARP- and caspase 3-cleavage and depended on reactive oxygen species (ROS) formation. Confocal microscopy revealed mitochondria as primary site of ROS production and demonstrated mitochondrial depolarization and increased mitochondrial permeability after 2-AG treatment. 2-AG-induced cell death was independent of cannabinoid receptors but required the presence of membrane cholesterol. Primary hepatocytes were resistant to 2-AG-induced ROS induction and cell death but became susceptible after GSH depletion suggesting antioxidant defenses as a critical determinant of 2-AG sensitivity. Hepatic levels of 2-AG were significantly elevated in two models of experimental fibrogenesis and reached concentrations that are sufficient to induce death in HSCs. These findings suggest that 2-AG may act as an antifibrogenic mediator in the liver by inducing cell death in activated HSCs but not hepatocytes

The present study investigated the effect of ethanol (EtOH) exposure and its withdrawal on the central endocannabinoid system utilizing an EtOH vapor inhalation model, which is known to produce functional tolerance and dependence to EtOH. Swiss Webster mice (n=24) were exposed to EtOH vapors for 72h. Mice were sacrificed after 72h following EtOH exposure (n=12) and 24h after its withdrawal (n=12). Radioligand binding assays were performed to measure the density of CB(1) receptor and CB(1) receptor agonist-stimulated [(35)S]GTPgammaS binding in crude synaptic membranes isolated from the cortex, hippocampus, striatum and cerebellum. The density of CB(1) receptor was significantly decreased (31-39%) in all the brain regions when compared to the control group. The CB(1) receptor-stimulated G(i/o) protein activation was also found to be decreased (29-40%) in these brain regions of EtOH exposed mice. Recovery of the CB(1) receptor density, in addition to, the CB(1) receptor-mediated G-protein activation was observed after 24h withdrawal from EtOH. The levels of cortical anandamide, which was significantly increased (147%) by EtOH exposure, returned to basal levels after 24h of withdrawal from EtOH exposure. A significant reduction (21%) in the activity of fatty acid amide hydrolase was found in the cortex of EtOH administered mice. Taken together, the neuroadaptation in the EC system may have a potential role in development of tolerance and dependence to EtOH

Depression is one of the most prevalent forms of neuropsychiatric disorder and is a major cause of suicide worldwide. The prefrontal cortex is a crucial brain region that is thought to be involved in the regulation of mood, aggression and/or impulsivity and decision making, which are altered in suicidality. Evidence of the role of the endocannabinoid (EC) system in the neurobiology of neuropsychiatric disorders is beginning to emerge. The behavioral effects of ECs are believed to be mediated through the central cannabinoid CB1 receptor. Alterations in the levels of ECs, and in the density and coupling efficacy of CB1 receptors, have been reported in the prefrontal cortex of depressed and alcoholic suicide victims. These findings support our hypothesis that altered EC function contributes to the pathophysiological aspects of suicidal behavior. Here, we provide a brief overview of the role of the EC system in alcoholism, depression and suicide, and discuss possible therapeutic interventions and directions for future research

G-protein-coupled receptor (GPCR)-mediated signalling is the most widely used signalling mechanism in cells, and its regulation is important for various physiological functions. The cannabinoid-1 (CB(1)) receptor, a GPCR, has been shown to play a critical role in neural circuitries mediating motivation, mood and emotional behaviours. Several recent studies have indicated that impairment of CB(1) receptor-mediated signalling may play a critical role in the pathophysiology of various neuropsychiatric disorders. In this article, the authors briefly review literature relating to the role played by the endocannabinoid system in various neuropsychiatric disorders, and the CB(1) receptor as a potential therapeutic target for the treatment of alcoholism, depression, anxiety and schizophrenia

AIMS: The current study investigated the efficacy of CB1 receptor-targeted drugs on the development and expression of tolerance to alcohol (EtOH). METHODS: An EtOH-inhalation model was used to induce tolerance, as measured by EtOH-induced sedation and hypothermia after a 24 h withdrawal period. Two drug treatment procedures, (i) co-treatment with EtOH and (ii) acute drug administration following chronic EtOH treatment, were used to test the efficacy of CB1 receptor manipulations on EtOH tolerance. RESULTS: The effects of the CB1 receptor agonist CP-55,940 varied depending on paradigm and behavioural measure. Chronic CP-55,940 co-treatment blocked tolerance to EtOH-induced hypothermia but not to the sedative effect (sleep time) in EtOH-exposed mice. However, chronic CP-55,940 administration alone resulted in tolerance to the sedative effect of a challenge dose of EtOH in control mice. Acute CP-55,940 administration after chronic alcoholization blocked the development of tolerance to EtOH-induced sedation compared to the EtOH alone exposed group, but induced tolerance to the hypothermic effects of EtOH in control mice. Chronic blockade of CB1 receptor function by SR141716A resulted in tolerance to both the sedative and hypothermic effects of EtOH in control mice, but had no effect on EtOH-exposed mice. CONCLUSIONS: The data support a role for the endocannabinoid (EC) system in EtOH tolerance/dependence and suggest that drugs targeted against EC system could be therapeutically useful in treating alcohol-related disorders

Several natural lipids have emerged as candidate modulators of central nervous system (CNS) functions. Fatty acid amides and their coupled signaling pathways are known to regulate several physiological and behavioral processes. Recent studies from our laboratory and others also have implicated endogenous marijuana-like brain constituents, endocannabinoids (ECs), and cannabinoid-1 (CB1) receptors in the neural circuitry that mediate drug addiction and neuropsychiatric disorders. Neuroadaptation to chronic ethanol (EtOH) has been shown to involve changes in the EC system. These changes include alterations in the synthesis of EC, their precursors, as well as density and coupling efficacy of CB1 receptors. The evidence for the participation of the EC system in the pathophysiology of various neuropsychiatric disorders is just beginning to evolve. It is of great interest to explore the components of EC system in different areas of the CNS for further understanding of its role in health and disease. This article presents a comprehensive overview of the currently available literature pertaining to the role of the EC system in alcoholism, schizophrenia, depression and/or suicide

BACKGROUND: Although a large body of evidence suggests a role for the opioid system in alcoholism, the precise role of mu-, delta-, kappa-, and ORL1-opioid receptors and the physiological significance of their natural genetic variation have not been identified. The method of targeted gene disruption by homologous recombination has been used to knock out (KO) genes coding for opioid receptors, and study their effects on alcohol self-administration. Here we examined the effects of targeted disruption of kappa-opioid receptor (KOR) on oral alcohol self-administration and other behaviors. METHODS: Oral alcohol, saccharin and quinine self-administration was assessed in a two-bottle choice paradigm using escalating concentrations of alcohol, or tastant solutions. In preference tests 12% alcohol, 0.033% and 0.066% saccharin, and 0.03 mM and 0.1 mM quinine solutions were used. Open-field activity was determined in an arena equipped with a computer-controlled activity-detection system. Subjects were tested for three consecutive days. Locomotor activity was assessed on days 1 and 2 (after saline injection, i.p.) and on day 3 (after alcohol injection, i.p.). Alcohol-induced locomotor activity was determined as the difference in activity between day 3 and day 2. RESULTS: Male KOR KO mice in preference tests with 12% alcohol consumed about half as much alcohol as wild-type (WT) or heterozygous (HET) mice, showed lower preference for saccharin (0.033% and 0.066%) and higher preference to quinine (0.1 mM) than WT mice. Female KOR KO mice showed similar reduction in alcohol consumption in comparison to WT and HET mice. Partial deletion of KOR in HET mice did not change alcohol consumption in comparison to WT mice. In all genotype-groups females drank significantly more alcohol than males. MANOVA of locomotor activity among KO, WT, and HET mice indicated that strain and sex effects were not significant for alcohol-induced activation (p > 0.05), while strain x sex interaction effects on alcohol-induced activation could be detected (F(1,55) = 6.07, p < 0.05). CONCLUSION: Our results indicating decreased alcohol consumption, lower saccharin preference, and higher quinine preference in KOR KO mice are in line with previous observations of opioid involvement in maintenance of food intake and raise the possibility that the deficient dynorphin/KOR system affects orosensory reward through central mechanisms which reduce alcohol intake and disrupt tastant responses, either as direct effects of absence of kappa-opioid receptors, or as effects of indirect developmental compensatory changes

BACKGROUND: Alcoholism is often comorbid with mood disorders and suicide. We recently reported an upregulation of CB(1) receptor-mediated signaling in the dorsolateral prefrontal cortex (DLPFC) of subjects with major depression who died by suicide. In the present study, we sought to determine whether the changes in depressed suicides would also be present in alcoholic suicides and whether the endocannabinoid (EC) system plays a role in suicide in alcoholism. METHODS: The density of CB(1) receptor and its mediated [(35)S]GTP gamma S signaling were measured in the DLPFC of alcoholic suicides (AS) (n = 11) and chronic alcoholics (CA) (n = 11). The levels of ECs were measured by a liquid chromatograph/mass spectrometry. RESULTS: The CB(1) receptor density was higher in AS compared with the CA group in the DLPFC. Western blot analysis confirmed a greater immunoreactivity of the CB(1) receptor in AS. The CB(1) receptor-mediated [(35)S]GTP gamma S binding indicated a greater signaling in AS. Higher levels of N-arachidonyl ethanolamide and 2-arachidonylglycerol were observed in the DLPFC of AS. CONCLUSIONS: The elevated levels of ECs, CB(1) receptors, and CB(1) receptor-mediated [(35)S]GTP gamma S binding strongly suggest a hyperactivity of endocannabinoidergic signaling in AS. EC system may be a novel therapeutic target for the treatment of suicidal behavior

Endogenous and exogenous cannabinoids (CBs) acting through the CB(1) receptors have been implicated in the regulation of several behavioral and neuroendocrine functions. Modulation of endocannabinoidergic system by ethanol in mouse brain, and the association of suicide and mood disorders with alcoholism suggest possible involvement of the cannabinoidergic system in the pathophysiology of depression and suicide. Therefore, the present study was undertaken to examine the levels of CB(1) receptors and mediated signaling in the dorsolateral prefrontal cortex (DLPFC) of subjects with major depression who had died by suicides (depressed suicides, DS). [(3)H]CP-55,940 and CB(1) receptor-stimulated [(35)S]GTPgammaS binding sites were analyzed in membranes obtained from DLPFC of DS (10) and matched normal controls (10). Upregulation (24%, P<0.0001) of CB(1) receptor density (B(max)) was observed in DS (644.6+/-48.8 fmol/mg protein) compared with matched controls (493.3+/-52.7 fmol/mg protein). However, there was no significant alteration in the affinity of receptor (DS; 1.14+/-0.08 vs control; 1.12+/-0.10 nM). Higher density of CB(1) receptors in DS (38%, P<0.001) was also demonstrated by Western blot analysis. The CB(1) receptor-stimulated [(35)S]GTPgammaS binding was significantly greater (45%, P<0.001) in the DLPFC of DS compared with matched controls. The observed upregulation of CB(1) receptors with concomitant increase in the CB(1) receptor-mediated [(35)S]GTPgammaS binding suggests a role for enhanced cannabinoidergic signaling in the prefrontal cortex of DS. The cannabinoidergic system may be a novel therapeutic target in the treatment of depression and/or suicidal behavior