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During marijuana and alcohol consumption as well as during inflammation the reproductive axis is inhibited, mainly through the inhibition of luteinizing hormone-releasing hormone release. In male rats, this inhibitory effect is mediated, at least in part, by the activation of hypothalamic cannabinoid type 1 receptors (CB1). During inflammation, this activation of the endocannabinoid system seems to be mediated by an increase in TNF-α production followed by anandamide augmentations, similarly the effect of intragastric administration of ethanol (3 g/kg) seems to be due to an increase in anandamide. On the other hand, a number of different actions mediated by the endocannabinoid system in various organs and tissues have been described. Both cannabinoid receptors, CB1 and CB2, are localized in the submandibular gland where they mediate the inhibitory effect of intrasubmandibular injections of the endocannabinoid anandamide (6 × 10–5M) on salivary secretion. Lipopolysaccharide (5 mg/kg/3 h) injected intraperitoneally and ethanol (3 g/kg/1 h) injected intragastrically inhibited the salivary secretion induced by the sialogogue metacholine; this inhibitory effect was blocked by CB1 and/or CB2 receptor antagonists. Similar to the hypothalamus, these effects seem to be mediated by increased anandamide. In summary, similar mechanisms mediate the inhibitory actions of endocannabinoids and cannabinoids in both hypothalamus and submandibular gland during drug consumption and inflammation. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

During marijuana and alcohol consumption as well as during inflammation the reproductive axis is inhibited, mainly through the inhibition of luteinizing hormone-releasing hormone release. In male rats, this inhibitory effect is mediated, at least in part, by the activation of hypothalamic cannabinoid type 1 receptors (CB1). During inflammation, this activation of the endocannabinoid system seems to be mediated by an increase in TNF-α production followed by anandamide augmentations, similarly the effect of intragastric administration of ethanol (3 g/kg) seems to be due to an increase in anandamide. On the other hand, a number of different actions mediated by the endocannabinoid system in various organs and tissues have been described. Both cannabinoid receptors, CB1 and CB2, are localized in the submandibular gland where they mediate the inhibitory effect of intrasubmandibular injections of the endocannabinoid anandamide (6 × 10–5M) on salivary secretion. Lipopolysaccharide (5 mg/kg/3 h) injected intraperitoneally and ethanol (3 g/kg/1 h) injected intragastrically inhibited the salivary secretion induced by the sialogogue metacholine; this inhibitory effect was blocked by CB1 and/or CB2 receptor antagonists. Similar to the hypothalamus, these effects seem to be mediated by increased anandamide. In summary, similar mechanisms mediate the inhibitory actions of endocannabinoids and cannabinoids in both hypothalamus and submandibular gland during drug consumption and inflammation. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Submitted in fulfillment of the requirement for the degree of Doctor of Philosophy in the Faculty of Health Sciences at the University of the Witwatersrand, Johannesburg / Renewed interest in cannabinoid compounds arose since the discovery of the endocannabinoid system in the early 1990’s and its role in mediating the body’s energy balance. The aim of this study was to investigate the effect of an organic Cannabis sativa (hereafter referred to as C. sativa) extract on β-cell secretory function using an in vivo diet-induced obese rat model and an in vitro isolated rat pancreatic islet model and to determine the associated molecular changes within the pancreatic tissue. Materials and methods: Diet-induced obese Wistar rats and rats fed on standard pellets were subcutaneously injected, over a 28 day period, with an organic C. sativa extract or the vehicle (1% Tween 80® in saline). The effect of diet and treatment was evaluated using the intraperitoneal glucose tolerance tests (IPGTTs) and quantitative polymerase chain reaction (qPCR) analysis on rat pancreata. In vitro studies were conducted using isolated rat islets exposed to 11.1 (representative of normoglycemic conditions) and 33.3 mM glucose levels (representative of hyperglycemic conditions) over a 24-(D1; acute) and 96-hour (D4; chronic) period, and treated with C. sativa extract containing an equivalent of 2.5 (T1) and 5 ng/mL (T2) tetrahydrocannabinol (THC). Glucose-stimulated insulin secretion (GSIS), immunohistocytochemistry for apoptosis and proliferation detection and western blotting for detection of cannabinoid receptor type 1 (CB1), CB2 receptors and specific transduction factors were undertaken. Antagonist studies were conducted using AM251 (A1) and AM630 (A2) to block CB1 and CB2, respectively, to determine the role of cannabinoid receptors in insulin secretion. Results: The overall increase in body weight in the experimental groups occurred at a significantly slower rate than the control groups (P < 0.01), irrespective of diet. In the lean group, the area under the curve for glucose (AUCg) was significantly higher compared to the diet-induced obese group (P < 0.001), while C. sativa treatment significantly improved the AUCg in the lean rats (P < 0.05). The cafeteria diet did not induce hyperglycemia and insulin resistance in the obese rats and C. sativa treatment maintained a plasma glycemic profile similar to the obese control rats. The lower AUCg values in the obese group may, in part, be due to the inclusion of milk products (shown to be beneficial in reducing diabetes) in the cafeteria diet. qPCR analysis showed that the cafeteria diet induced down-regulation of the following genes in the obese control group, relative to lean controls: UCP2 (P < 0.01), c-MYC (P < 0.05) and FLIP (P < 0.05), and upregulation of CB1 (P < 0.01), GLUT2 (P < 0.001), UCP2 (P < 0.001) and PKB (P < 0.05), relative to the obese control group, while c-MYC levels were down-regulated (P < 0.05), relative to the lean control group. In the in vitro study, results showed C. sativa treatment decreased chronic insulin secretion in islets cultured under normoglycemic condition for D1 (P < 0.05), but not for D4. In islets cultured under hyperglycemic conditions, C. sativa treatment for the D4 period showed a significant increase in their chronic insulin secretion (HD4T1, P = 0.07; HD4T2, P < 0.001), increase in basal insulin secretion (HD4T1, P < 0.001; HD4T2, P < 0.001), increase in GSIS (HD4T1, P < 0.05; HD4T2, P < 0.001), reduction in glucose-stimulated:basal insulin production (HD4T1, P < 0.05; HD4T2, P < 0.05), reduction in insulin content (HD4T1, P < 0.001), increase in the percentage basal : content ratio (HD4T1, P < 0.001; HD4T2, P < 0.01) and increase in the percentage GSIS : content ratio (HD4T1, P < 0.001; HD4T2, P < 0.05), relative to ND4C islets. In antagonist studies, A2 preconditioning did not affect suppress the stimulatory effect of C. sativa treatment on chronic insulin secretion under normo- and hyperglycemic conditions, relative to the NC and HC islets, respectively. qPCR studies showed that C. sativa exposure induced a 2.2-fold increase in CB1 gene expression, relative to normoglycemic control islets (P < 0.05), while c-MYC and FLIP expression was significantly reduced by 12% (ND4T1, P < 0.05) and 37% (HD4T1, P < 0.05), respectively. C. sativa treatment also induced increased secretion of anti-inflammatory cytokines/chemokines under hyperglycemic conditions. Conclusion: These results suggest that C. sativa protects pancreatic islets against the negative effects of obesity (in vivo studies) and hyperglycemia (in vitro studies). In light of these findings, further investigation into the potential of C. sativa as a complementary therapeutic agent in the treatment of the deleterious effects of hyperglycemia in diabetic patients is warranted. In addition, the significant effect of C. sativa treatment on adipose tissue in experimental rats needs further investigation to determine how the cannabinoids affect the mechanisms of adipogenesis and lipolysis in diet-induced obesity. Keywords: Diet-Induced Obesity, Cannabinoids, C. sativa, THC, β-cell, AM251, AM630.

Implications for the endocannabinoid system in global cerebral ischemia has not been clearly defined. Ischemia produces an excitotoxic environment that is severely damaging to neurons, causing degradation of cell membrane and ultimately cell death. Contradicting research suggests both the benefits and adverse effects of endocannabinoids on neurological injury. Due to the excitotoxic nature of ischemic injury, and the mechanisms at play with endocannabinoid agonists, such as increased transmission of dopamine and glutamate, it is suspected that endocannabinoid antagonists, such as AM251, may a provide cell protection.40 male Wistar rats were separated into 4 groups (n=10/group). The first group of rats were administered AM251 (2 mg/kg, i.p) 30 minutes prior to global cerebral ischemia (four vessel occlusion), while the second group were given AM251, 30 minutes prior to sham surgery. Finally the last two groups were given a vehicle control instead of AM251 and given either ischemia or the sham surgery. Behavioural testing, open field test and elevated plus maze, took place after a five day recovery period following ischemia. Immunohistochemical analyses were performed using to mark tyrosine hydroxylase (TH) and dopamine receptor 1(DRD1) to compare dopamine function amongst groups. Cell survival was also evaluated using thionin staining. Ischemia induced significant reduction in dopamine within the mesolimbic circuit, including: ventral tegmental area, nucleus accumbens, CA3 & CA1 of the hippocampus, and basolateral amygdala. These reductions in dopamine transmission by global ischemia were partially or fully reversed when AM251 was given beforehand. Furthermore, cell survival was increased in the CA1 from treatment of AM251. Behavioural results show similar results that AM251 reversed emotional irregularities associated with ischemia insult. The endocannabinoid antagonist AM251 improves deficits in dopamine function, prevents cell death and regulates emotionality when given prior global cerebral ischemia.

Implications for the endocannabinoid system in global cerebral ischemia has not been clearly defined. Ischemia produces an excitotoxic environment that is severely damaging to neurons, causing degradation of cell membrane and ultimately cell death. Contradicting research suggests both the benefits and adverse effects of endocannabinoids on neurological injury. Due to the excitotoxic nature of ischemic injury, and the mechanisms at play with endocannabinoid agonists, such as increased transmission of dopamine and glutamate, it is suspected that endocannabinoid antagonists, such as AM251, may a provide cell protection.40 male Wistar rats were separated into 4 groups (n=10/group). The first group of rats were administered AM251 (2 mg/kg, i.p) 30 minutes prior to global cerebral ischemia (four vessel occlusion), while the second group were given AM251, 30 minutes prior to sham surgery. Finally the last two groups were given a vehicle control instead of AM251 and given either ischemia or the sham surgery. Behavioural testing, open field test and elevated plus maze, took place after a five day recovery period following ischemia. Immunohistochemical analyses were performed using to mark tyrosine hydroxylase (TH) and dopamine receptor 1(DRD1) to compare dopamine function amongst groups. Cell survival was also evaluated using thionin staining. Ischemia induced significant reduction in dopamine within the mesolimbic circuit, including: ventral tegmental area, nucleus accumbens, CA3 & CA1 of the hippocampus, and basolateral amygdala. These reductions in dopamine transmission by global ischemia were partially or fully reversed when AM251 was given beforehand. Furthermore, cell survival was increased in the CA1 from treatment of AM251. Behavioural results show similar results that AM251 reversed emotional irregularities associated with ischemia insult. The endocannabinoid antagonist AM251 improves deficits in dopamine function, prevents cell death and regulates emotionality when given prior global cerebral ischemia.

Hepatitis C virus (HCV) is a hepatotropic positive-sense RNA virus of the Flaviviridae virus family and is a major cause of chronic liver disease worldwide. Like all obligate parasites, HCV relies on host pathways to enable its pathogenesis. HCV, in particular, has a clear link with hepatic lipid metabolism, promoting a lipid-rich environment for its proliferation. This manifests as liver steatosis in many patients harboring chronic HCV infection. Based on our recent findings regarding an immunometabolic and HCV antiviral microRNA (miRNA), miRNA-185 targeting and down regulating serine hydrolases (SH) involved in lipid and endocannabinoid metabolism, here we investigate HCV and its dependency on certain metabolic serine hydrolases involved in lipid and endocannabinoid metabolism. Serine hydrolases are one of the largest and most diverse enzyme families. This enzyme family has emerged as a center of therapeutic potential due to its implications in many metabolic roles. Here, we demonstrate that pharmacological inhibition of metabolic serine hydrolases alpha-beta hydrolyzing domain 6 (ABHD6), carboxylesterase 1 (CES1), and monoacylglycerol lipase (MGLL), enzymes involved in the hydrolysis of the endogenous cannabinoid receptor 1 (CB1) agonist 2-arachidonoyl glycerol (2-AG) are potently antiviral against HCV. Serine hydrolase inhibition with the MGLL inhibitor MJN110 paired with endocannabinoid signaling antagonization led to additive antiviral effects against HCV and has revealed modulation of the viral pathogenic phenotype to be its key course of action. MGLL inhibitor MJN110 transcriptomic characterization revealed modulations in humoral immunity and phagocytosis and acts antiviraly against HCV independent of CB1 antagonization. This provides an avenue for future investigation, assessing the viability of CB1 antagonization, and MGLL as a key host targeted antiviral factor in affecting HCV viral life cycle.

Résumé confidentiel / Résumé confidentiel

Depuis quelques décennies, la consommation de cannabis et son usage thérapeutique sont le sujet de nombreux débats. Le cannabis est la drogue illicite la plus consommée au monde et cette consommation se trouve dix fois plus élevée chez les patients atteints de schizophrénie que dans la population générale. L’hypothèse d’une automédication initialement proposée afin d’expliquer la consommation élevée de cannabis chez les patients atteints de schizophrénie est maintenant remise en question. En effet, les rapports indiquant une aggravation des symptômes plutôt qu’une amélioration suite à une consommation à long terme sont de plus en plus nombreux. Sachant que le cannabis peut induire des effets soit plaisants soit aversifs, la question se pose à savoir si une prédominance de la valence motivationnelle positive ou une diminution de la valence négative du cannabis peut expliquer la consommation élevée parmi les individus ayant un diagnostic de schizophrénie? Bien qu’un grand nombre de recherches pré-cliniques aient été menées chez l’animal normal pour évaluer l’effet motivationnel du Δ9-tétrahydrocannabinol (THC) et autres cannabinoïdes synthétiques, aucune n’a abordé cette problématique dans un modèle animal de la schizophrénie. Cette lacune nous a donc amené à étudier la valence motivationnelle du THC et de l’agoniste cannabinoïde WIN55,212-2 (WIN) dans un modèle animal de la schizophrénie: la lésion néonatale de l’hippocampe ventral (NVHL). Dans le premier article, nous présentons les résultats de quatre expériences. Une première avait pour objectif de déterminer si la procédure expérimentale que nous avons utilisée permettait de reproduire des signes distinctifs du modèle animal de la schizophrénie. Par la suite, nous avons évalué i) l’effet d’une dose de WIN sur l’activité locomotrice spontanée et ii) la valence motivationnelle du THC (0.5 mg/kg, i.p) et du WIN (1 mg/kg, i.p) chez les rats adolescents (jour post-natal 28-40, PD28-40) et adultes (PD56) au moyen du paradigme de préférence de place conditionnée (PPC). Tel qu’attendu, la réponse locomotrice à l’amphétamine (0.75 et 1.5 mg/kg) chez les rats NVHL adultes était supérieure à celle des rats contrôles (test distinctif du modèle). Le THC a induit une tendance aversive chez les rats contrôles adultes. Enfin, le WIN a stimulé l’activité locomotrice et induit une aversion significative chez les rats adultes NVHL. Dans un deuxième article, nous avons évalué la valence motivationnelle du THC (0.5 mg/kg), du WIN (1 et 3 mg/kg) et l’effet de l’amphétamine au moyen du paradigme d’autostimulation électrique intracérébrale (ASI). Les résultats montrent que : i) l’effet amplificateur de l’amphétamine sur l’ASI était de plus courte durée chez les rats NVHL; ii) le THC produit une légère atténuation de la récompense chez les rats contrôles tandis que le WIN a produit une atténuation plus prononcée de la récompense chez les rats NVHL, un effet qui a été bloqué par l’antagoniste aux récepteurs CB1, le AM251 (3 mg/kg). Pour la première fois les résultats suggèrent une altération du système endocannabinoïde dans un modèle animal de la schizophrénie. Ils indiquent qu’une exposition aigüe conduit à une prédominance de la valence négative. Bien qu’en apparente contradiction avec les études cliniques, ces résultats soulignent l’importance du contexte socio-environnemental pour expliquer les effets du cannabis chez les patients. De plus ils encouragent les futures études à évaluer cette valence sur un modèle d’exposition chronique. / Over the past few decades, the cannabis consumption and its therapeutic use have been the subject of many debates. Cannabis is the most widely used illicit drug and among patients with a diagnosis of schizophrenia, its consumption is ten times higher than in the general population. The self-medication hypothesis that has been initially proposed to account for the co-morbidity schizophrenia – cannabis is now questioned on the basis of several reports showing that long term cannabis consumption worsen schizophrenia symptoms in patients. Knowing that cannabis can provoke both rewarding and aversive effects in human and in animal, the following question can be raised: can co-morbidity schizophrenia – cannabis be explained by a salient positive or a blunted negative motivational valence of cannabis? Even though many pre-clinical studies have been carried out in normal animals on the motivational effects of Δ9-Tetrahydrocannabinol (THC) or other synthetic cannabinoids, none has measured these effects in an animal model of schizophrenia. On the basis of this, we undertook a series of studies on the motivational valence of THC and the cannabinoid agonist WIN55,212-2 (WIN) in an animal model of schizophrenia : the neonatal ventral hippocampus lesion (NVHL). In the first report, we present the results of four studies. The first was aimed at showing that the experimental procedures that we used reproduced some abnormal features of the animal model. Then we evaluated i) the effect of WIN (1 mg/kg) on spontaneous locomotor activity and ii) the motivational valence of THC (0.5 mg/kg) and WIN (1 mg/kg) in the young (post-natal day 28-40, PD28-40) and adult (PD56) rats with the conditioned place-preference paradigm (CPP). As expected, amphetamine produced a higher locomotor activity in NVHL rats, an effect observed at PD56 and not at PD35 (NVHL usual test). THC tended to induce an aversion in control rats at PD56 while WIN produced a significant aversion at PD56 in NVHL rats only. We also assessed, in a second report, the valence of THC (0.5 mg/kg) and WIN (1 and 3 mg/kg), and amphetamine (0.75 mg/kg) using the brain stimulation reward paradigm. Results show that i) the enhancement effect of amphetamine on reward was shorter in adult NVHL rats; ii) THC induced a weak reward attenuation in control rats while WIN produced a marked dose-dependent attenuation in NVHL rats; this effect of WIN was blocked by AM251 (3 mg/kg), an antagonist at CB1 receptors. For the first time, these results suggest that the endogenous cannabinoid system is altered in this animal model of schizophrenia. They indicate that an acute exposure leads to a predominance of negative valence. Even if this seems contradictory with clinical studies, these results highlight the interconnection between the drug and the socio-environment aspects. In addition, they encourage future studies to evaluate this valence on a chronic exposure paradigm with this animal model of schizophrenia.