Maternal obesity reverses the resistance to LPS-induced adverse pregnancy outcome and increases female offspring metabolic alterations in cannabinoid receptor 1 knockout mice

Maternal overnutrition negatively impacts the offspring's health leading to an increased risk of developing chronic diseases or metabolic syndrome in adulthood. What we eat affects the endocannabinoid system (eCS) activity, which in turn modulates lipogenesis and fatty acids utilization in hepatic, muscle, and adipose tissues. This study aimed to evaluate the transgenerational effect of maternal obesity on cannabinoid receptor 1 knock-out (CB1 KO) animals in combination with a postnatal obesogenic diet on the development of metabolic disturbances on their offspring. CB1 KO mice were fed a control diet (CD) or a high-fat diet (HFD; 33% more energy from fat) for 3 months. Offspring born to control and obese mothers were also fed with CD or HFD. We observed that pups born to an HFD-fed mother presented higher postnatal weight, lower hepatic fatty acid amide hydrolase activity, and increased blood cholesterol levels when compared to the offspring born to CD-fed mothers. When female mice born to HFD-fed CB1 KO mothers were exposed to an HFD, they gained more weight, presented elevated blood cholesterol levels, and more abdominal adipose tissue accumulation than control-fed adult offspring. The eCS is involved in several reproductive physiological processes. Interestingly, we showed that CB1 KO mice in gestational day 15 presented resistance to LPS-induced deleterious effects on pregnancy outcome, which was overcome when these mice were obese. Our results suggest that an HFD in CB1 receptor-deficient mice contributes to a “nutritional programming” of the offspring resulting in increased susceptibility to metabolic challenges both perinatally and during adulthood.     

Using proteomics to discover novel biomarkers for fatty liver development and response to CB1R antagonist treatment in an obese mouse model

Over activity of cannabinoid receptor type 1 (CB1R) plays a key role in increasing the incidence of obesity‐induced non‐alcoholic fatty liver disease. Tissue proteome analysis has been applied to investigate the bioinformatics regarding the mode of action and therapeutic mechanism. The aim of this study was to explore the potential pathways altered with CB1R in obesity‐induced fatty liver. Male C57BL/6 mice were fed either a standard chow diet (STD) or a high‐fat diet (HFD) with or without 1‐week treatment of CB1R inverse agonist AM251 at 5 mg/kg. Then, liver tissues were harvested for 2DE analysis and protein profiles were identified by using MALDI‐MS. Results showed that eight of significantly altered protein spots at the level of changes > twofold were overlapped among the three groups, naming major urinary protein 1, ATP synthase subunit β, glucosamine‐fructose‐6‐phosphate aminotransferase 1, zine finger protein 2, s‐adenosylmethionine synthase isoform type‐1, isocitrate dehydrogenase subunit α, epoxide hydrolase 2 and 60S acidic ribosomal protein P0. These identified proteins were involved in glucose/lipid metabolic process, xenobiotic metabolic system, and ATP synthesized process in mitochondria. Based on the findings, we speculated that CB1R blockade might exert its anti‐metabolic disorder effect via improvement of mitochondrial function in hepatic steatosis in HFD condition.     

Cannabinoid receptor antagonists and fatty acids alter endocannabinoid system gene expression and COX activity

Cyclooxygenase (COX) possesses substrate affinity for the endocannabinoids (EC) anandamide (AEA) and 2-arachidonylglycerol (2-AG). We hypothesized that selective antagonism/activation of the cannabinoid receptors will increase COX activity and the availability of EC as substrates will lead to higher COX activity. Since the relationship between EC signaling of the endocannabinoid system (ECS) and the COX pathway in muscle has not been investigated, we examined agonist, antagonists and polyunsaturated fatty acid effects on ECS genes in myoblasts. At 50% confluency, C2C12 myoblasts were pretreated with 5 μM of the cannabinoid receptor (CB)2 inverse agonist AM630 for 2 h and one with both AM630 and 1 μM of the CB1 antagonist NESS0327. Cell cultures pretreated with AM630 were then administered with 25 μM of either arachidonic acid (20:4n6), eicosapentaenoate (EPA) (20:5n3), docosahexaenoate (DHA) (22:6n3), AEA or bovine serum albumin (vehicle control) for 24 h. Quantitative polymerase chain reaction analyses were performed looking at ECS and prostaglandin genes. Total COX activity and COX-1 protein were greater in the AM630+AEA-treated cells compared to all other cell cultures. The mRNA for the AEA synthesis enzyme N-acyl phosphatidylethanolamine phospholipase D and the 2-AG synthesis enzymes diacylglycerol lipase (DAGL)α and DAGLβ were higher in AM630+EPA-treated cells compared to the other groups. The mRNA levels of CB1 and CB2 were both highest in the AM630+EPA group. The mRNA for interleukin-6 and tumor necrosis factor-α was higher with AEA but lower with DHA and docosahexaenoyl ethanolamide (DHEA), supporting previous findings that the EC AEA supports activation of the COX system. These findings suggest that COX activity and protein levels are influenced by the ECS, specifically by the ligand AEA for CB1 and by inverse agonism of CB2.     

Exposure to a Highly Caloric Palatable Diet during the Perinatal Period Affects the Expression of the Endogenous Cannabinoid System in the Brain,Liver and Adipose Tissue of Adult Rat Offspring

Recent studies have linked gestational exposure to highly caloric diets with a disrupted endogenous cannabinoid system (ECS). In the present study, we have extended these studies by analyzing the impact of the exposure to a palatable diet during gestation and lactation on a) the adult expression of endocannabinoid-related behaviors, b) the metabolic profile of adult offspring and c) the mRNA expression of the signaling machinery of the ECS in the hypothalamus, the liver and the adipose tissue of adult offspring of both sexes. Exposure to a palatable diet resulted in a) sex-dimorphic and perinatal diet specific feeding behaviors, including the differential response to the inhibitory effects of the cannabinoid receptor inverse agonist AM251, b) features of metabolic syndrome including increased adiposity, hyperleptinemia, hypertriglyceridemia and hypercholesterolemia and c) tissue and sex-specific changes in the expression of both CB1 and CB2 receptors and in that of the endocannabinoid-degrading enzymes FAAH and MAGL, being the adipose tissue the most affected organ analyzed. Since the effects were observed in adult animals that were weaned while consuming a normal diet, the present results indicate that the ECS is one of the targets of maternal programming of the offspring energy expenditure. These results clearly indicate that the maternal diet has long-term effects on the development of pups through multiple alterations of signaling homeostatic pathways that include the ECS. The potential relevance of these alterations for the current obesity epidemic is discussed.     

Cannabinoid modulation of electrically evoked pH and oxygen transients in the nucleus accumbens of awake rats

Cannabinoid receptors have been implicated in the regulation of blood flow in the cerebral vasculature. Because the nucleus accumbens (NAc) shows high levels of central cannabinoid receptor 1 (CB1) expression we examined the effects of cannabinoids on the local transient alkaline shifts and increases in extracellular oxygen induced by electrical stimulation of the medial forebrain bundle (MFB) in conscious animals. These changes result from increases in cerebral blood flow (CBF) and metabolism in the NAc that are evoked by the stimulation. Oxygen and pH changes were monitored using fast-scan cyclic voltammetry at carbon-fiber microelectrodes in the NAc of freely moving rats. Administration of the cannabinoid receptor agonist WIN55,212-2 potently inhibited extracellular oxygen and pH changes, an effect that was reversed and prevented by pre-treatment with the CB1 receptor antagonists SR141716A and AM251. The effects on pH following WIN55,212-2 were similar to those following nimodipine, a recognized vasodilator. When AM251 was injected alone, the amplitude of electrically evoked pH shifts was unaffected. Administration of AM404 and VDM11, endocannabinoid transport inhibitors, partially inhibited pH transients in a CB1 receptor-dependent manner. The present findings suggest that CB1 receptor activation modulates changes in two well-established indices of local blood flow and metabolism resulting from electrically evoked activation of ascending fibers. Although endogenous cannabinoid tone alone is not sufficient to modify these responses, uptake blockade demonstrates that the system has the potential to exert CB1-specific effects similar to those of full agonists.     

Adaptations of Striatal Endocannabinoid System During Stress

The endocannabinoid system (ECS) plays a fundamental role in the regulation of synaptic transmission. Exposure to stressful events triggers synaptic adaptations in many brain areas. The activity of the ECS in stress-responsive neural circuits suggests that it may be involved in the behavioral responses and synaptic effects typical of stress. In this review, we discuss evidence demonstrating that striatal ECS is modulated by stress. Chronic stress exposure alters endocannabinoid levels, cannabinoid CB1 receptor binding and cannabinoid CB1 receptor-mediated control of inhibitory synaptic transmission in the striatum. Recent studies have shown that impairment of endocannabinoid signalling is associated with inability to adapt to chronic stress and to the development of maladaptive behaviors. The ECS represents a novel potential pharmacological target to treat stress-associated neuropsychiatric conditions.     

Inhibition of salivary secretion by activation of cannabinoid receptors

It is known that marijuana use decreases saliva secretion. Therefore, we hypothesized that cannabinoid receptors (CBs) are located in salivary glands to mediate that effect. In these experiments, we used the submandibular gland (SMG) of male rats, which is one of the major salivary glands. Mammalian tissues contain at least two types of CBs, CB1 and CB2, mainly located in the nervous system and peripheral tissues, respectively. Both receptors are coupled to Gi protein and respond by inhibiting the activity of adenylyl cyclase. We demonstrated that both CB1 and CB2 are present in the SMG, each showing specific localizations. The best-known endocannabinoid is anandamide (AEA), which binds with high affinity to CB1 and CB2. We showed that AEA markedly reduced forskolin-induced increase of cAMP content in vitro. This effect was blocked by AM251 and AM630 (CB1 and CB2 antagonists, respectively), indicating that both receptors are implicated in SMG physiology. In addition, we showed that AEA injected intraglandularly to anesthetized rats inhibited norepinephrine (NE)- and methacholine (MC)-stimulated saliva secretion in vivo and that both AM251 or AM630 prevented the inhibitory action of AEA. Also, the intraglandular injection of AM251 increased saliva secretion induced by lower doses of NE or MC. This increase was synergized after coinjection with AM630. Therefore, we concluded that AEA decreases saliva secretion in the SMG acting through CB1 and CB2 receptors.     

Food Intake‐independent Effects of CB1 Antagonism on Glucose and Lipid Metabolism

Overactivity of the endocannabinoid system (ECS) has been linked to abdominal obesity and other risk factors for cardiovascular disease and type 2 diabetes. Conversely, administration of cannabinoid receptor type 1 (CB1) antagonists reduces adiposity in obese animals and humans. This effect is only in part secondary to the anorectic action of CB1 agonists. In order to assess the actions of CB1 antagonism on glucose homeostasis, diet‐induced obese (DIO) rats received the CB1 antagonist rimonabant (10 mg/kg, intraperitoneally (IP)) or its vehicle for 4 weeks, or were pair‐fed to the rimonabant‐treated group for the same length of time. Rimonabant treatment transiently reduced food intake, while inducing body weight loss throughout the study. Rats receiving rimonabant had significantly less body fat and circulating leptin compared to both vehicle and pair‐fed groups. Rimonabant, but not pair‐feeding, also significantly decreased circulating nonesterified fatty acid (NEFA) and triacylglycerol (TG) levels, and reduced TG content in oxidative skeletal muscle. Although no effects were observed during a glucose tolerance test (GTT), rimonabant restored insulin sensitivity to that of chow‐fed, lean controls during an insulin tolerance test (ITT). Conversely, a single dose of rimonabant to DIO rats had no acute effect on insulin sensitivity. These findings suggest that in diet‐induced obesity, chronic CB1 antagonism causes weight loss and improves insulin sensitivity by diverting lipids from storage toward utilization. These effects are independent of the anorectic action of the drug.     

Localization of cannabinoid receptors CB1, CB2, GPR55, and PPARα in the canine gastrointestinal tract

The endocannabinoid system (ECS) is composed of cannabinoid receptors, their endogenous ligands, and the enzymes involved in endocannabinoid turnover. Modulating the activity of the ECS may influence a variety of physiological and pathophysiological processes. A growing body of evidence indicates that activation of cannabinoid receptors by endogenous, plant-derived, or synthetic cannabinoids may exert beneficial effects on gastrointestinal inflammation and visceral pain. The present ex vivo study aimed to investigate immunohistochemically the distribution of cannabinoid receptors CB1, CB2, G protein-coupled receptor 55 (GPR55), and peroxisome proliferation activation receptor alpha (PPARα) in the canine gastrointestinal tract. CB1 receptor immunoreactivity was observed in the lamina propria and epithelial cells. CB2 receptor immunoreactivity was expressed by lamina propria mast cells and immunocytes, blood vessels, and smooth muscle cells. Faint CB2 receptor immunoreactivity was also observed in neurons and glial cells of the submucosal plexus. GPR55 receptor immunoreactivity was expressed by lamina propria macrophages and smooth muscle cells. PPARα receptor immunoreactivity was expressed by blood vessels, smooth muscle cells, and glial cells of the myenteric plexus. Cannabinoid receptors showed a wide distribution in the gastrointestinal tract of the dog. Since cannabinoid receptors have a protective role in inflammatory bowel disease, the present research provides an anatomical basis supporting the therapeutic use of cannabinoid receptor agonists in relieving motility disorders and visceral hypersensitivity in canine acute or chronic enteropathies.     

Inverse agonism and neutral antagonism at cannabinoid CB1 receptors

There are at least two types of cannabinoid receptor, CB1 and CB2, both G protein coupled. CB1 receptors are expressed predominantly at nerve terminals and mediate inhibition of transmitter release whereas CB2 receptors are found mainly on immune cells, one of their roles being to modulate cytokine release. Endogenous cannabinoid receptor agonists also exist and these "endocannabinoids" together with their receptors constitute the "endocannabinoid system". These discoveries were followed by the development of a number of CB1- and CB2-selective antagonists that in some CB1 or CB2 receptor-containing systems also produce "inverse cannabimimetic effects", effects opposite in direction from those produced by cannabinoid receptor agonists. This review focuses on the CB1-selective antagonists, SR141716A, AM251, AM281 and LY320135, and discusses possible mechanisms by which these ligands produce their inverse effects: (1) competitive surmountable antagonism at CB1 receptors of endogenously released endocannabinoids, (2) inverse agonism resulting from negative, possibly allosteric, modulation of the constitutive activity of CB1 receptors in which CB1 receptors are shifted from a constitutively active "on" state to one or more constitutively inactive "off" states and (3) CB1 receptor-independent mechanisms, for example antagonism of endogenously released adenosine at A1 receptors. Recently developed neutral competitive CB1 receptor antagonists, which are expected to produce inverse effects through antagonism of endogenously released endocannabinoids but not by modulating CB1 receptor constitutive activity, are also discussed. So too are possible clinical consequences of the production of inverse cannabimimetic effects, there being convincing evidence that released endocannabinoids can have "autoprotective" roles.     

Cannabinoid antagonist SR-141716 inhibits endotoxic hypotension by a cardiac mechanism not involving CB1 or CB2 receptors

Endocannabinoids and CB1 receptors have been implicated in endotoxin (LPS)-induced hypotension: LPS stimulates the synthesis of anandamide in macrophages, and the CB1 antagonist SR-141716 inhibits the hypotension induced by treatment of rats with LPS or LPS-treated macrophages. Recent evidence indicates the existence of cannabinoid receptors distinct from CB1 or CB2 that are inhibited by SR-141716 but not by other CB1 antagonists such as AM251. In pentobarbital-anesthetized rats, intravenous injection of 10 mg/kg LPS elicited hypotension associated with profound decreases in cardiac contractility, moderate tachycardia, and an increase in lower body vascular resistance. Pretreatment with 3 mg/kg SR-141716 prevented the hypotension and decrease in cardiac contractility, slightly attenuated the increase in peripheral resistance, and had no effect on the tachycardia caused by LPS, whereas pretreatment with 3 mg/kg AM251 did not affect any of these responses. SR-141716 also elicited an acute reversal of the hypotension and decreased contractility when administered after the response to LPS had fully developed. The LPS-induced hypotension and its inhibition by SR-141716 were similar in pentobarbital-anesthetized wild-type, CB1(-/-), and CB1(-/-)/CB2(-/-) mice. We conclude that SR-141716 inhibits the acute hemodynamic effects of LPS by interacting with a cardiac receptor distinct from CB1 or CB2 that mediates negative inotropy and may be activated by anandamide or a related endocannabinoid released during endotoxemia.     

Differences in spontaneously avoiding or approaching mice reflect differences in CB1-mediated signaling of dorsal striatal transmission

Approach or avoidance behaviors are accompanied by perceptual vigilance for, affective reactivity to and behavioral predisposition towards rewarding or punitive stimuli, respectively. We detected three subpopulations of C57BL/6J mice that responded with avoiding, balancing or approaching behaviors not induced by any experimental manipulation but spontaneously displayed in an approach/avoidance conflict task. Although the detailed neuronal mechanisms underlying the balancing between approach and avoidance are not fully clarified, there is growing evidence that endocannabinoid system (ECS) plays a critical role in the control of these balancing actions. The sensitivity of dorsal striatal synapses to the activation of cannabinoid CB1 receptors was investigated in the subpopulations of spontaneously avoiding, balancing or approaching mice. Avoiding animals displayed decreased control of CB1 receptors on GABAergic striatal transmission and in parallel increase of behavioral inhibition. Conversely, approaching animals exhibited increased control of CB1 receptors and in parallel increase of explorative behavior. Balancing animals reacted with balanced responses between approach and avoidance patterns. Treating avoiding animals with URB597 (fatty acid amide hydrolase inhibitor) or approaching animals with AM251 (CB1 receptor inverse agonist) reverted their respective behavioral and electrophysiological patterns. Therefore, enhanced or reduced CB1-mediated control on dorsal striatal transmission represents the synaptic hallmark of the approach or avoidance behavior, respectively. Thus, the opposite spontaneous responses to conflicting stimuli are modulated by a different involvement of endocannabinoid signaling of dorsal striatal neurons in the range of temperamental traits related to individual differences.     

BML-190 and AM251 act as inverse agonists at the human cannabinoid CB2 receptor: signalling via cAMP and inositol phosphates

The aminoalkylindole BML-190 and diarylpyrazole AM251 ligands have previously been shown to bind to cannabinoid CB(2) and CB(1) receptors, respectively. In HEK-293 cells stably expressing the human CB(2) receptor, BML-190 and AM251 potentiated the forskolin-stimulated accumulation of cAMP. Moreover, the CB(2) receptor can interact productively with 16z44, a promiscuous G alpha(16/z) chimera. BML-190 and AM251 reduce the basal levels of inositol phosphate production in cells expressing the CB(2) receptor and 16z44. These results demonstrate that BML-190 and AM251 act as inverse agonists at the human CB(2) receptor acting via G alpha(i/o) and G alpha(q) family-coupled pathways.     

The cannabinoid CB1 receptor is expressed in pancreatic delta-cells

Antagonists of cannabinoid CB1 receptor (CB1, CNR1) promote weight loss and decrease hyperglycemia in patients with type 2 diabetes. While the endocannabinoid system may modulate islet hormone secretion, the cell-type expressing CB1 receptor in islets has not been fully resolved. In this study, we verified receptor gene expression in rodent islets and cell lines and examined the distribution of CB1 receptor in mouse, rat, and human islets by confocal immunofluorescence (IF) microscopy. IF demonstrated CB1 receptor was present in β-cell lines, but co-localized solely with somatostatin in the islet δ-cells of Zucker rats, C57BL/6 mice, and humans; no CB1 receptor expression was observed in α-, β-, or pp-cells. Similarly, a rat somatostatinoma cell line, MSL-G2-Tu6, was found to express CB1 receptor. We also found monoacylglycerol lipase (MAGL) to be expressed in δ-cells and fatty acid amide hydrolase (FAAH) to be expressed in α-cells. The specific expression of CB1 in δ-cells suggests that the ECS may play a role in modulating islet hormone secretion. As there are some differences between our findings and previous reports, further studies, including detailed physiological studies of the effects of the ECS on islet function, are warranted.     

Effects of rTMS on Hippocampal Endocannabinoids and Depressive-like Behaviors in Adolescent Rats

Depression is a common mental disorder in adolescents, with a prevalence rate of 5.6%. Current anti-depressive options for adolescents are limited: psychological intervention and conventional antidepressants have low efficacy, a delayed onset of action and increased possibility of suicidal risk. Repetitive transcranial magnetic stimulation (rTMS) as an effective and noninvasive physical therapy for adult depression has been investigated in recent years. However, whether it also produces similar effects on juvenile depression and the underlying mechanism are not clearly understood. In this study, chronic unpredictable mild stress (CMS) was applied to 3-week-old male Sprague Dawley rats for 21 days. Then rTMS was performed for seven consecutive days, and the anti-depressive effects were evaluated by behavioral tests including the sucrose preference test (SPT), the forced swimming test (FST), and the novelty suppressed feeding test (NSF). Expression of hippocampal cannabinoid type I receptor (CB1R), 2-arachidonoylglycerol (2-AG) and relative synthetase and degradative enzymes-diacylglycerol lipase (DAGL) and monoacylglycerol lipase (MAGL) were also investigated. The behavioral parameters were also observed after the administration of the selective CB1 receptor antagonist AM251. The results showed that CMS induced a significant decrease in sucrose preference, a significant increase of immobility time in the FST, and an increased latency to feed in the NSF. In addition, reduced hippocampal CB1 receptor, 2-AG level and increased MAGL protein expression level were also observed in CMS rats. Meanwhile, rTMS treatment upregulated 2-AG level in the hippocampus and ameliorated depressive-like behaviors. The anti-depressive effect of rTMS was attenuated by AM251, a specific CB1R antagonist that was administered 30 min before the onset of rTMS by either intraperitoneal administration or hippocampal microinjection. These results indicate that rTMS can be used as an antidepressive therapy for juvenile depression at least partly mediated by increasing hippocampal 2-AG and CB1 receptor expression levels.     

Cannabinoids and Their Interactions with Diazepam on Modulation of Serum Corticosterone Concentration in Male Mice

Experimental results indicate a mutual interaction between cannabinoidergic and GABAergic systems; however, the interaction between these systems on corticosterone release has not been fully investigated. In this study, we treated male mice with either cannabinoid compounds alone or in combination with diazepam. Blood samples were collected at 60 min post-injection. The serum corticosterone (CORT) level was measured using ELISA technique. Acute treatment of mice by cannabinoid receptor agonist WIN55212-2 (2.5 mg/kg; i.p.) resulted in a significant reduction of CORT, while treatment with either endocannabinoid reuptake inhibitor AM404 or endocannabinoid degradation enzyme inhibitor URB597 increased CORT compared to control group. Co-administration of AM404 or URB597 with cannabinoid CB1 receptor antagonist AM251 blocked the effect of these compounds on CORT. Treatment of mice with different doses of diazepam alone did not alter CORT compared to control group. However, co-administration of diazepam and either AM404 or WIN55212-2 significantly reduced CORT compared to the respective group treated with cannabinoid compound alone. Co-administration of ineffective dose of URB597 and ineffective dose of diazepam increased CORT level compared to groups treated with each compound alone. In conclusion, our findings suggest that the endogenous cannabinoid system is active as a modulator of CORT in mice and diazepam can alter the effect of cannabinoid system in the modulation of neuroendocrine functions.     

The inhibitory action of exo- and endocannabinoids on [³H]GABA release are mediated by both CB₁and CB₂receptors in the mouse hippocampus

Exogenous and endogenous cannabinoids play an important role in modulating the release of neurotransmitters in hippocampal excitatory and inhibitory networks, thus having profound effect on higher cognitive and emotional functions such as learning and memory. In this study we have studied the effect of cannabinoid agonists on the potassium depolarization-evoked [(3)H]GABA release from hippocampal synaptosomes in the wild-type (WT) and cannabinoid 1 receptor (CB(1)R)-null mutant mice. All tested cannabinoid agonists (WIN55,212-2, CP55,940, HU-210, 2-arachidonoyl-glycerol, 2-AG; delta-9-tetra-hydrocannabinol, THC) inhibited [(3)H]GABA release in WT mice with the following rank order of agonist potency: HU-210>CP55,490>WIN55,212-2>2-AG>THC. By contrast, 2-AG and THC displayed the greatest efficacy eliciting almost complete inhibition of evoked [(3)H]GABA efflux, whereas the maximal inhibition obtained by HU-210, CP55,490, and WIN55,212-2 were less, eliciting not more than 40% inhibition. The inhibitory effect of WIN55,212-2, THC and 2-AG on evoked [(3)H]GABA efflux was antagonized by the CB(1) receptor inverse agonist AM251 (0.5 μM) in the WT mice. In the CB(1)R knockout mice the inhibitory effects of all three agonists were attenuated. In these mice, AM251 did not antagonize, but further reduced the [(3)H]GABA release in the presence of the synthetic agonist WIN55,212-2. By contrast, the concentration-dependent inhibitory effects of THC and 2-AG were partially antagonized by AM251 in the absence of CB(1) receptors. Finally, the inhibition of evoked [(3)H]GABA efflux by THC and 2-AG was also partially attenuated by AM630 (1 μM), the CB(2) receptor-selective antagonist, both in WT and CB(1) knockout mice. Our data prove the involvement of CB(1) receptors in the effect of exo- and endocannabinoids on GABA efflux from hippocampal nerve terminals. In addition, in the effect of the exocannabinoid THC and the endocannabinoid 2-AG, non-CB(1), probably CB(2)-like receptors are also involved.     

Maternal high-fat diet induces sex-specific endocannabinoid system changes in newborn rats and programs adiposity,energy expenditure and food preference in adulthood

Early life inadequate nutrition triggers developmental adaptations and adult chronic disease. Maternal high-fat (HF) diet promotes visceral obesity and hypothalamic leptin resistance in male rat offspring at weaning and adulthood. Obesity is related to over active endocannabinoid system (ECS). The ECS consists mainly of endogenous ligands, cannabinoid receptors (CB1 and CB2), and the enzymes fatty acid anandamide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). We hypothesized that perinatal maternal HF diet would regulate offspring ECS in hypothalamus and brown adipose tissue (BAT) at birth, prior to visceral obesity development, and program food preference and energy expenditure of adult offspring. Female rats received control diet (C, 9% fat) or isocaloric high-fat diet (HF, 28% fat) for 8 weeks before mating, and throughout gestation and lactation. We evaluated C and HF offspring at birth and adulthood. At birth, maternal HF diet decreased leptinemia and increased hypothalamic CB1, orexin-A, and proopiomelanocortin while it decreased thyrotropin-releasing hormone (Trh) in male pups. Differentially, maternal HF diet increased hypothalamic CB2 in female pups. In BAT, maternal HF diet decreased CB1 and increased CB2 in male and female pups, respectively. Besides presenting different molecular ECS profile at birth, HF adult offspring developed overweight, higher adiposity and high-fat diet preference, independently of the sex, but only males presented hyperleptinemia and higher energy expenditure. In conclusion, maternal HF diet alters ECS components and energy metabolism targets in hypothalamus and BAT of offspring at birth, in a sex-specific manner, which may contribute for hyperphagia, food preference and higher adiposity later in life.