piperidines and noladin-ether

To investigate the role of GPR55 receptors, which are expressed in human and rat striatum (a structure that regulates procedural memory), Wistar rats received five training sessions (10 trials/session, 1 session/day) to solve a T-maze paradigm. From these data, we constructed learning curves following pharmacological manipulation of GPR55. Five minutes before each session, animals received bilateral intradorsolateral striatum injections of noladin-ether (3.1 nmol/l; endogenous agonist of GPR55 and CB1 receptors), CID16020036 (5.6 nmol/l; GPR55 antagonist), AM251 (5.6 nmol/l; CB1 antagonist), or a combination of noladin-ether with each antagonist. Noladin-ether by itself induced no significant changes in the learning curve. Nevertheless, while simultaneously blocking CB1 receptors (with AM251), noladin-ether improved acquisition. In contrast, while simultaneously blocking GPR55 (with CID16020036), noladin-ether weakened acquisition. CID16020036 by itself impaired learning, whereas AM251 by itself reduced the efficiency in the task. There were no differences between groups in the latency to reach the arms from the starting point; thus, no motor coordination impairments interfered with this task. These results strongly suggest a role of GPR55 in procedural memory and constitute the first evidence indicating that this receptor regulates cognitive processes.

Topics: Animals; Azabicyclo Compounds; Benzoates; Cognition; Corpus Striatum; Glycerides; Male; Maze Learning; Memory; Piperidines; Pyrazoles; Rats; Rats, Wistar; Receptors, Cannabinoid; Receptors, G-Protein-Coupled

2-Arachidonoylglycerol (2-AG) is recognized as a potent endocannabinoid, which reduces synaptic transmission through cannabinoid CB(1) receptors, and is hydrolyzed by monoacylglycerol lipase (MGL) to arachidonic acid (AA), a cyclooxygenase substrate. We already reported that centrally administered MGL and cyclooxygenase inhibitors each reduced the intracerebroventricularly (i.c.v.) administered bombesin-induced secretion of adrenal catecholamines, while a centrally administered CB(1)-antagonist potentiated the response, indirectly suggesting bidirectional roles of brain 2-AG (stimulatory and inhibitory roles) in the bombesin-induced response. In the present study, we separately examined these bidirectional roles using 2-AG and 2-AG ether (2-AG-E) (stable 2-AG analog for MGL) in rats. 2-AG (0.5 μmol/animal, i.c.v.), but not 2-AG-E (0.5 μmol/animal, i.c.v.), elevated basal plasma catecholamines with JZL184 (MGL inhibitor)- and indomethacin (cyclooxygenase inhibitor)-sensitive brain mechanisms. 2-AG-E (0.1 μmol/animal, i.c.v.) effectively reduced the bombesin (1 nmol/animal, i.c.v.)-induced elevation of plasma catecholamines with rimonabant (CB(1) antagonist)-sensitive brain mechanisms. Immunohistochemical studies demonstrated the bombesin-induced activation of diacylglycerol lipase α (2-AG-producing enzyme)-positive spinally projecting neurons in the hypothalamic paraventricular nucleus, a control center of central adrenomedullary outflow. These results directly indicate bidirectional roles of brain 2-AG, a stimulatory role as an AA precursor and an inhibitory role as an endocannabinoid, in the bombesin-induced central adrenomedullary outflow in rats.

Topics: Adrenal Medulla; Animals; Arachidonic Acids; Benzodioxoles; Bombesin; Cannabinoid Receptor Agonists; Cannabinoid Receptor Antagonists; Catecholamines; Cyclooxygenase Inhibitors; Drug Interactions; Endocannabinoids; Glycerides; Indomethacin; Injections, Intraventricular; Lipoprotein Lipase; Male; Monoacylglycerol Lipases; Neurotransmitter Agents; Paraventricular Hypothalamic Nucleus; Piperidines; Pyrazoles; Rats; Rimonabant

BACKGROUND AND PURPOSE Endocannabinoid systems are strongly implicated in the physiological control of appetite and eating behaviour, with cannabinoid CB(1) receptor agonists and antagonists, respectively, increasing or decreasing food intake. This study examined the acute actions of the putative endocannabinoid noladin ether on food intake and eating motivation, assessing how it affects the amount of work expended by animals to obtain food. EXPERIMENTAL APPROACH Non-deprived male rats were injected systemically with noladin ether to assess its acute effects on ad libitum feeding of a standard laboratory diet. Additionally, the effects of noladin on lever pressing for palatable food were determined using a progressive ratio (PR) operant paradigm. KEY RESULTS Noladin dose dependently increased 2 h food intake, with a significant effect over 1 h after a dose of 0.5 mg·kg(-1). In the PR test, this hyperphagic dose of noladin ether promoted sustained high rates of responding and significantly increased the total number of lever presses and break-point. These latter effects were prevented by pretreatment with 1.0 mg·kg(-1) of the selective CB(1) antagonist surinabant (SR147778), that alone had no effect on responding. CONCLUSIONS AND IMPLICATIONS This is the first report of hyperphagia induced by acute noladin administration, and the first description of behavioural actions in rats. Consistent with prevailing notions about the role of endocannabinoids in appetite, a hyperphagic dose of noladin markedly increased efforts expended by animals to obtain food. Thus, noladin exerts a specific action on eating motivation; possibly promoting eating by increasing the incentive value of food.

Topics: Animals; Behavior, Animal; Cannabinoid Receptor Modulators; Eating; Endocannabinoids; Glycerides; Hyperphagia; Male; Motivation; Piperidines; Pyrazoles; Rats; Receptor, Cannabinoid, CB1

Stimulation of cannabinoid CB(1) receptors in nucleus accumbens shell has been shown to stimulate feeding and enhance positive 'liking' reactions to intraoral sucrose. This study examined the behavioural effects of noladin ether and 2-arachidonoylglycerol following infusion into accumbens shell, on chow intake and food preference in high-carbohydrate and high-fat preferring rats. Noladin ether, potently and dose-dependently stimulated chow intake as compared with 2-arachidonoylglycerol in free-feeding rats. In the diet preference paradigm, in which rats were given free access to both, high-carbohydrate (HC) and high-fat (HF) diets simultaneously, an intra-accumbens administration of noladin ether as well as 2-arachidonoylglycerol, preferentially enhanced fat consumption over carbohydrate in both HF- and HC-preferring rats. These effects were significantly attenuated by the CB(1) receptor antagonist, AM 251. These results suggesting that, the endocannabinoids through CB(1) receptors, affects appetite for specific dietary components. Both these agents exert a specific action on eating motivation and possibly promoting eating by enhancing the incentive value of food. Altogether these findings reinforce the idea that the endogenous cannabinoid system in the accumbens shell may be important to augment reward-driven feeding via modulation of CB(1) receptor signalling pathways.

Topics: Animals; Appetite; Arachidonic Acids; Cannabinoid Receptor Modulators; Diet; Diet, High-Fat; Dietary Carbohydrates; Eating; Endocannabinoids; Food Preferences; Glycerides; Hyperphagia; Male; Nucleus Accumbens; Piperidines; Pyrazoles; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1; Sucrose

The receptor(s) used by cannabinoids to relax vascular smooth muscle is unknown. Here, we investigated the effects of 2-arachidonylglyceryl ether (2-AG ether), a metabolically stable endocannabinoid, and abnormal cannabidiol (abn-CBD) on relaxation of permeabilized pulmonary arterial strips monitored with force, and on extracellular signal-regulated mitogen-activated protein kinases (ERK1/2) phosphorylation in permeabilized vascular smooth muscle cells using immunoblotting. We found that 2-AG ether and abn-CBD caused relaxation and increased phosphorylation of ERK1/2. 2-AG ether effects were completely abolished by N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251), and N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716A), and partially blocked by (-)-1.3-dimethoxy-2-(3-3,4-trans-p-menthadien-(1,8)-yl)-orcinol (O-1918). In contrast, abn-CBD effects were completely abolished by O-1918, and only partially blocked by AM251, and SR141716A. Both 2-AG ether and abn-CBD effects were partially blocked by pertussis toxin, an inhibitor of Gi/o proteins. PD98059, an inhibitor of mitogen activated protein kinase kinase (MEK), completely abolished the relaxation, but only partially blocked the increased phosphorylation of ERK1/2 by 2-AG ether. In contrast, abn-CBD-induced relaxation was partially blocked and the increased phosphorylation of ERK1/2 was abolished by PD98059. These findings suggest that 2-AG ether and abn-CBD-induced vascular smooth muscle relaxation are mediated by the cannabinoid CB1 receptor, and the abn-CBD receptor, respectively, and are modulated by cross-talk between the receptors. These responses occur mainly by coupling to pertussis toxin sensitive G proteins, but also, in part independent of these G proteins, which have been classically thought to initiate MEK/ERK1/2 signaling to relax vascular smooth muscle.

Topics: Animals; Animals, Newborn; Cells, Cultured; Dose-Response Relationship, Drug; Flavonoids; Glycerides; In Vitro Techniques; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Pertussis Toxin; Phosphorylation; Piperidines; Protein Kinase Inhibitors; Pulmonary Artery; Pyrazoles; Rabbits; Receptor Cross-Talk; Receptor, Cannabinoid, CB1; Receptors, G-Protein-Coupled; Resorcinols; Rimonabant; Vasodilation; Vasodilator Agents

To study the effects of 2-arachidonyl glyceryl ether (noladin ether), an endocannabinoid ligand selective for cannabinoid (CB)1 receptor, on aqueous humor outflow facility, to investigate the involvement of trabecular meshwork CB1 receptors and the p42/44 MAP kinase signaling pathway and to explore the cellular mechanisms of noladin ether-induced changes of outflow facility.. The effects of noladin ether on aqueous humor outflow facility were measured in a porcine anterior-segment-perfused organ culture model. The expression of CB1 receptors on cultured porcine trabecular meshwork cells and the coupling of these receptors to p42/44 MAP kinase was determined by immunofluorescence microscopy and Western blot analysis. Both Western blot and zymography were used to monitor the effects of noladin ether on matrix metalloproteinase (MMP)-2. In morphologic studies, AlexaFluor 488-labeled phalloidin staining was used to examine actin filament, and immunohistochemistry with anti-paxillin antibodies was used to detect focal adhesions.. Within 1 hour after adding 3, 30, or 300 nM of noladin ether, the aqueous humor outflow facility increased concentration dependently. The effect of 30 nM of noladin ether was completely blocked by SR141716A, a selective CB1 antagonist. Positive signals were detected on cultured porcine trabecular meshwork cells with an anti-CB1 antibody in immunofluorescence microscopy and Western blot studies. Treatment of trabecular meshwork cells with 30 nM of noladin ether activated p42/44 MAP kinase, whereas pretreatment with SR141716A blocked the p42/44 MAP kinase-activating effects of noladin ether. In addition, the enhancement of outflow facility induced by noladin ether was blocked by pretreatment of porcine anterior segments with PD98059, an inhibitor of p42/44 MAP kinase pathway. Furthermore, noladin ether treatment caused rounding of trabecular meshwork cells, and there was a decrease of actin stress fibers, as well as a decrease in focal adhesions. These noladin ether-induced morphologic changes were also blocked by SR141716A and PD98059.. The results demonstrate for the first time that administration of noladin ether, an endocannabinoid agonist selective for the CB1 receptor, increases aqueous humor outflow facility. The data also show that noladin ether-induced enhancement of outflow facility is mediated through the trabecular meshwork CB1 receptor, with an involvement of p42/44 MAP kinase signaling pathway and changes in actin cytoskeletons.

Topics: Actins; Animals; Aqueous Humor; Blotting, Western; Cells, Cultured; Enzyme Inhibitors; Flavonoids; Glycerides; Matrix Metalloproteinase 2; Microscopy, Fluorescence; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Organ Culture Techniques; Perfusion; Phosphorylation; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Rimonabant; Signal Transduction; Swine; Trabecular Meshwork

We have investigated the effect of 2-arachidonylglyceryl-ether (Noladin) on food consumption, weight, activity, and cognitive function in mice during diet restriction for 17 days and subsequent ad libitum feeding for 32 days. Female Sabra mice were given food for 2.5 h/day (equal to 60% diet restriction), received Noladin (0.001, 0.01, 0.1 mg/(kg day) intraperitonially (i.p.)) with or without the CB1 antagonist SR141716A (1 mg/kg i.p.) during days 3-17. Noladin (0.001 mg/kg) significantly increased food consumption without a change in body weight, probably due to increased activity and there was no change in cognitive function. A higher dose (0.1 mg/kg) did not affect food consumption, but increased activity and slightly decreased weight 32 days after termination of Noladin administration; however, cognitive deterioration was observed. At all doses tested, Noladin did not affect weight during the diet-restriction period, whereas the CB1 antagonist (with or without Noladin) caused a very significant decline in weight in this phase. Weight catch-up was observed 1 month after administration of Noladin was discontinued. Weight at day 32 after the termination of Noladin (0.1 mg/(kg day)) treatment was 5% less than control. Female C57BL/6 mice (same protocol, with 0.001 mg/(kg day) Noladin) gave similar results to 0.1 mg/kg in Sabra mice as regards weight. CB1 antagonist treatment caused very significant decline in both weight and food consumption; cognition and activity were unchanged. These results indicate that Noladin has a significant dose-dependent effect on food consumption, cognition and weight maintenance after weight loss. Low doses of Noladin may possibly allow an increase in food intake without a gain in weight after dieting. Thus, Noladin could be of potential clinical benefit in treating disorders of body weight. Noladin seems to signal food consumption and weight through CB1 receptors based on effects observed with the CB1 antagonist, while the cognition and activity are probably mediated by non-cannabinoid receptors.

Topics: Animals; Body Weight; Cannabinoid Receptor Modulators; Cognition; Cognition Disorders; Dose-Response Relationship, Drug; Eating; Endocannabinoids; Feeding and Eating Disorders; Female; Food Deprivation; Glycerides; Mice; Mice, Inbred C57BL; Motor Activity; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Rimonabant; Species Specificity; Weight Gain

In the globus pallidus, cannabinoid CB(1) receptors are localized pre-synaptically on GABAergic neurons. We assessed the influence of the endocannabinoids, anandamide, 2-arachidonoyl-glycerol (2-AG) and noladin ether, on the uptake of [(3)H]-GABA in pallidal slices from rat. Both 2-AG and noladin ether increased [(3)H]-GABA uptake (by 40.8 +/- 8.0% and 38.4 +/- 12.5%). The effect of 2-AG was blocked by the cannabinoid CB(1) receptor antagonist AM 251. In contrast, neither anandamide nor the agonist WIN 55,212-2 had an effect on [(3)H]-GABA uptake. Different roles might be played by different endocannabinoids, both physiologically and in basal ganglia disorders, such as Parkinson's disease.

Topics: Animals; Arachidonic Acids; Binding, Competitive; Cannabinoid Receptor Modulators; Endocannabinoids; gamma-Aminobutyric Acid; Globus Pallidus; Glycerides; In Vitro Techniques; Male; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Rats; Rats, Sprague-Dawley; Receptor, Cannabinoid, CB1; Tritium

The endogenous cannabinoids N-arachidonylethanolamide (AEA) and 2-arachidonylglycerol (2-AG) are known to decrease intraocular pressure (IOP). Recently, a novel putative endogenous cannabinoid, noladin ether, was isolated in porcine and rat brains. In the present study, both the degradation of endogenous cannabinoids in ocular tissues and the effect on IOP of 2-AG and noladin ether were compared.. The rates of enzymatic degradation for AEA, 2-AG, and noladin ether were determined in bovine cornea and iris-ciliary body homogenates. 2-AG and noladin ether were dissolved in either hydroxypropyl-beta-cyclodextrin (HP-beta-CD) or propylene glycol and administered unilaterally to the rabbit eye. IOPs were measured in the treated and untreated eyes. The CB1 receptor antagonist AM251 was administered topically 15 minutes before the cannabinoids to investigate whether CB1 receptors mediate the effect on IOP produced by 2-AG and noladin ether.. Noladin ether degraded more slowly than either 2-AG or AEA in the iris-ciliary body and cornea homogenates. The effect on IOP of 2-AG was biphasic (i.e., an initial increase in IOP followed by a reduction in the treated eye). Noladin ether decreased IOP immediately after topical administration, and no initial IOP increase was observed in the treated eye. The CB1 receptor antagonist AM251 (25 micro g) blocked the effect on IOP of noladin ether but did not affect the action of 2-AG.. Topical administration of the novel putative endogenous cannabinoid noladin ether decreased IOP in rabbits. This IOP reduction was most probably mediated through the CB1 receptor. The effect on IOP of noladin ether differed from those of the known endogenous cannabinoids AEA and 2-AG, probably because of its more stable chemical structure.

Topics: Animals; Arachidonic Acids; Cannabinoid Receptor Modulators; Cattle; Ciliary Body; Cornea; Endocannabinoids; Enzyme Stability; Female; Glycerides; Intraocular Pressure; Iris; Male; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Rabbits; Receptors, Cannabinoid; Receptors, Drug