The endocannabinoid system (ECS) is a widespread intercellular signaling system that plays a critical role in energy homeostasis, meant as the precise matching of caloric intake with energy expenditure which normally keeps body weight stable over time. Complex interactions between environmental and neurohormonal systems directly contribute to the balance of energy homeostasis. This review highlights established and more recent data on the brain circuits in which the ECS plays an important regulatory role, with focus on the hypothalamus, a region where numerous interacting systems regulating feeding, satiety, stress, and other motivational states coexist. Although not meant as an exhaustive review of the field, this...

Endocannabinoids are blood borne and may also be secreted by the endothelium. Accordingly, there has been interest in the interactions between (endo)cannabinoids and blood cells. There is certainly evidence that (endo)cannabinoids may promote platelet activation, indicating that they may be thrombogenic. Platelets are involved both in the metabolism and release of endocannabinoids, and so it is possible that their circulating levels may be regulated by platelets. This process is altered in disease states such that platelet-derived endocannabinoids contribute towards hypotension in cardiovascular shock. Not only may endocannabinoids regulate platelet function and possibly lead to thrombogenesis, but they may also influence haematopoiesis. Given these emerging...

Background and purpose: The endocannabinoids, N-arachidonoylethanolamide (anandamide) and 2-arachidonoylglycerol (2-AG) are rapidly degraded by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGL). Whilst these lipid mediators are known to modulate vascular tone, the extent to which they are inactivated via local metabolism in the vasculature remains unclear. Experimental approach: In rat isolated small mesenteric arteries, the regulatory role of FAAH, MGL and cyclooxygenase (COX) in relaxant responses to anandamide and 2-AG was evaluated by using inhibitors of these enzymes. Relaxations to nonhydrolysable analogues of endocannabinoids and arachidonic acid were also examined. Key results: Relaxation to anandamide but not 2-AG was potentiated by the...

We examined whether acetylcholine release in the hippocampus and striatum and noradrenaline release in the hippocampus is altered in CB1 receptor-de®cient mice. The electrically evoked tritium over¯ow from hippocampal slices preincubated with [3 H]-choline was increased by about 100% in CB1 7/7 compared to CB1 +/+ mice whereas the electrically evoked tritium over¯ow from striatal slices preincubated with [3 H]-choline and from hippocampal slices preincubated with [3 H]- noradrenaline did not di€er. The cannabinoid receptor agonist, WIN 55,212-2, inhibited, and the CB1 receptor antagonist, SR 141716, facilitated, the evoked tritium over¯ow from hippocampal slices (preincubated with [3 H]-choline) from CB1 +/+ as opposed to...

Background: Cannabidiol, a therapeutic with potential serotonin (5-hydroxytryptamine; 5-HT) 5- HT1A receptor agonist activity, is the second most prevalent cannabinoid in Cannabis after  9 - THC. The extent to which cannabidiol modifies the effects of  9 -THC has not been firmly established, especially with respect to abuse-related effects in rhesus monkeys where previously antagonistic interactions have been reported for some behavioral outcomes. Methods: Cannabidiol and the 5-HT1A receptor agonist (±)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OHDPAT) were tested in two separate discrimination assays in rhesus monkeys. One group (n=6) discriminated  9 -tetrahydrocannabinol ( 9 -THC; 0.1 mg/kg i.v.); a second group (n=6) discriminated the cannabinoid...

Abstract Gonadotropin-releasing hormone (GnRH) neurons are controlled by 17β-estradiol (E2) contributing to the steroid feedback regulation of the reproductive axis. In rodents, E2 exerts a negative feedback effect upon GnRH neurons throughout the estrus-diestrus phase of the ovarian cycle. The present study was undertaken to reveal the role of estrogen receptor subtypes in the mediation of the E2 signal and elucidate the downstream molecular machinery of suppression. The effect of E2 administration at low physiological concentration (10 pM) on GnRH neurons in acute brain slices obtained from metestrous GnRH-green fluorescent protein (GFP) mice was studied under paradigms of blocking or activating estrogen receptor subtypes...

Objective: Previous reports have shown that the D9 -tetrahydrocannabinol (D9 TCH), the major psychoactive cannabinoid components of marijuana, is unable to inhibit thyroid hormonal activity. The aim of this study was to characterize the CB1 functional expression in the rat thyroid by a multi-methods approach. Methods and Results: RT-PCR was used to detect the mRNA expression of the CB1 cannabinoid receptor (17:8^4:0% of the normalizing reference gene b2 microglobulin), as well as the expression of the endocannabinoid hydrolyzing enzyme, fatty acid amide hydrolase (46:9^4:3% of b2 microglobulin), in the rat thyroid gland. The CB1-encoded protein was detected in its glycosylated form (63 kDa) by...

Background and purpose: Cannabis is the source of at least seventy phytocannabinoids. The pharmacology of most of these has been little investigated, three notable exceptions being D9 -tetrahydrocannabinol, cannabidiol and D9 -tetrahydrocannabivarin. This investigation addressed the question of whether the little-studied phytocannabinoid, cannabigerol, can activate or block any G protein-coupled receptor. Experimental approach: The [35S]GTPgS binding assay, performed with mouse brain membranes, was used to test the ability of cannabigerol to produce G protein-coupled receptor activation or blockade. Its ability to displace [3 H]CP55940 from mouse CB1 and human CB2 cannabinoid receptors and to inhibit electrically evoked contractions of the mouse isolated vas deferens...

Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) occur naturally in marijuana (Cannabis) and may be formulated, individually or in combination in pharmaceuticals such as Marinol or Sativex. While it is known that these hydrophobic compounds can be transported in blood by albumin or lipoproteins, intracellular carrier have not been identified. Recent reports suggest that CBD and THC elevates the levels of the endocannabinoid anandamide (AEA) when administered to humans, suggesting that phytocannabinoids target cellular proteins involved in endocannabinoid clearance. Fatty acid binding proteins (FABPs) are intracellular proteins that mediate AEA transport to its catabolic enzyme fatty acid amide hydrolase (FAAH). By computational analysis and ligand displacement...

The roles of endocannabinoid signaling during central nervous system development are unknown. We report that CB1 cannabinoid receptors (CB1Rs) are enriched in the axonal growth cones of g-aminobutyric acid–containing (GABAergic) interneurons in the rodent cortex during late gestation. Endocannabinoids trigger CB1R internalization and elimination from filopodia and induce chemorepulsion and collapse of axonal growth cones of these GABAergic interneurons by activating RhoA. Similarly, endocannabinoids diminish the galvanotropism of Xenopus laevis spinal neurons. These findings, together with the impaired target selection of cortical GABAergic interneurons lacking CB1Rs, identify endocannabinoids as axon guidance cues and demonstrate that endocannabinoid signaling regulates synaptogenesis and target selection in vivo.