Capsaicin affects brain function in a model of hepatic encephalopathy associated with fulminant hepatic failure in mice

BACKGROUND AND PURPOSE

Hepatic encephalopathy is a neuropsychiatric syndrome caused by liver failure. In view of the effects of cannabinoids in a thioacetamide-induced model of hepatic encephalopathy and liver disease and the beneficial effect of capsaicin (a TRPV1 agonist) in liver disease, we assumed that capsaicin may also affect hepatic encephalopathy.

EXPERIMENTAL APPROACH

Fulminant hepatic failure was induced in mice by thioacetamide and 24 h later, the animals were injected with one of the following compound(s): 2-arachidonoylglycerol (CB(1), CB(2) and TRPV1 receptor agonist); HU308 (CB(2) receptor agonist), SR141716A (CB(1) receptor antagonist); SR141716A+2-arachidonoylglycerol; SR144528 (CB(2) receptor antagonist); capsaicin; and capsazepine (TRPV1 receptor agonist and antagonist respectively). Their neurological effects were evaluated on the basis of activity in the open field, cognitive function in an eight-arm maze and a neurological severity score. The mice were killed 3 or 14 days after thioacetamide administration. 2-arachidonoylglycerol and 5-hydroxytryptamine (5-HT) levels were determined by gas chromatography-mass spectrometry and high-performance liquid chromatography with electrochemical detection, respectively.

RESULTS

Capsaicin had a neuroprotective effect in this animal model as shown by the neurological score, activity and cognitive function. The effect of capsaicin was blocked by capsazepine. Thioacetamide induced astrogliosis in the hippocampus and the cerebellum and raised brain 5-hydroxytryptamine levels, which were decreased by capsaicin, SR141716A and HU-308. Thioacetamide lowered brain 2-arachidonoylglycerol levels, an effect reversed by capsaicin.

CONCLUSIONS

Capsaicin improved both liver and brain dysfunction caused by thioacetamide, suggesting that both the endocannabinoid and the vanilloid systems play important roles in hepatic encephalopathy. Modulation of these systems may have therapeutic value.

Cannabidiol ameliorates cognitive and motor impairments in mice with bile duct ligation

BACKGROUND/AIMS

The endocannabinoid system in mice plays a role in models of human cirrhosis and hepatic encephalopathy (HE), induced by a hepatotoxin. We report now the therapeutic effects of cannabidiol (CBD), a non-psychoactive constituent of Cannabis sativa, on HE caused by bile duct ligation (BDL), a model of chronic liver disease.

METHODS

CBD (5mg/kg; i.p.) was administered over 4weeks to mice that had undergone BDL.

RESULTS

Cognitive function in the eight arm maze and the T-maze tests, as well as locomotor function in the open field test were impaired by the ligation and were improved by CBD. BDL raised hippocampal expression of the TNF-alpha-receptor 1 gene, which was reduced by CBD. However, BDL reduced expression of the brain-derived neurotrophic factor (BDNF) gene, which was increased by CBD. The effects of CBD on cognition, locomotion and on TNF-alpha receptor 1 expression were blocked by ZM241385, an A(2)A adenosine receptor antagonist. BDL lowers the expression of this receptor.

CONCLUSIONS

The effects of BDL apparently result in part from down-regulation of A(2)A adenosine receptor. CBD reverses these effects through activation of this receptor, leading to compensation of the ligation effect.

Genomic survey of prepulse inhibition in mouse chromosome substitution strains

Prepulse inhibition (PPI) is a measure of sensorimotor gating, a pre-attentional inhibitory brain mechanism that filters extraneous stimuli. Prepulse inhibition is correlated with measures of cognition and executive functioning, and is considered an endophenotype of schizophrenia and other psychiatric illnesses in which patients show PPI impairments. As a first step toward identifying genes that regulate PPI, we performed a quantitative trait locus (QTL) screen of PPI phenotypes in a panel of mouse chromosome substitution strains (CSSs). We identified five CSSs with altered PPI compared with the host C57BL/6J strain: CSS-4 exhibited decreased PPI, whereas CSS-10, -11, -16 and -Y exhibited higher PPI compared with C57BL/6J. These data indicate that A/J chromosomes 4, 10, 11, 16 and Y harbor at least one QTL region that modulates PPI in these CSSs. Quantitative trait loci for the acoustic startle response were identified on seven chromosomes. Like PPI, habituation of the startle response is also disrupted in schizophrenia, and in the present study CSS-7 and -8 exhibited deficits in startle habituation. Linkage analysis of an F(2) intercross identified a highly significant QTL for PPI on chromosome 11 between positions 101.5 and 114.4 Mb (peak LOD = 4.54). Future studies will map the specific genes contributing to these QTLs using congenic strains and other genomic approaches. Identification of genes that modulate PPI will provide insight into the neural mechanisms underlying sensorimotor gating, as well as the psychopathology of disorders characterized by gating deficits.

Diet and lifestyle in managing postmenopausal obesity

The majority of adults are becoming increasingly overweight and one of the sub-populations in which this prevalence is growing most rapidly is postmenopausal women. It is as yet unclear whether the menopausal transition itself leads to weight gain, but it is known that the physiological withdrawal of estrogen brings about changes in fat distribution that increase the risk for the metabolic syndrome, diabetes and cardiovascular disease. The treatment of postmenopausal obesity is very simple logically, but incredibly difficult - eat less and exercise more. Recent studies suggest that being active and fit is more important than losing weight; hence, a major recommendation is to exercise regularly, for at least 30 min on at least 5 days of the week, while maintaining a healthy balanced diet. Unfortunately, there are no 'magic bullets' (drugs) that may provide long-term treatment, and all diets work irrespective of their composition as long as people comply to them. There is no substitute for a sensible lifestyle.

A global nutritional index

BACKGROUND

A standardized global nutritional index (GNI) would provide a single statistic for each country according to its overall level of nutrition, which could then guide national policies.

OBJECTIVES AND METHODS

We have developed a GNI modeled on the human development index (HDI), based on three indicators of nutritional status: deficits, excess, and food security. Calculations were made within four groups of countries (GNI) (32 developed countries, 26 countries in transition, 64 low-mortality developing countries, and 70 high-mortality developing countries) as well as between them-the Global Nutrition Index World wide (GNIg).

RESULTS

Complete data were available for 192 countries. The ranking of the highest and lowest countries in the four groups (with their GNIg values) is as follows: developed countries--Japan 1 (0.989), United States 99 (0.806); countries in transition--Estonia 10 (0.943), Tajikistan 173 (0.629); low-mortality developing countries--Republic of Korea 12 (0.939), Nauru 185 (0.565); high-mortality developing countries--Algeria 47 (0.876), Sierra Leone 192 (0.420). A "double burden," in which nutrient deficits and excesses coexist in the same country, was seen in Mauritania (rank 139), South Africa (rank 146), Samoa (rank 157), Lesotho (rank 160), and Fiji (rank 169). The correlation between GNIg and HDI was intermediate (0.74, 55% of variance explained), demonstrating that good nutrition and development are not necessarily synonymous. Countries may be developed yet have a low GNIg (e.g., Australia, Canada, and the United States) and vice versa (e.g., Indonesia and China).

CONCLUSIONS

Since nutrition is fundamental to a nation's health and productivity, the GNI and GNIg should be used alongside the HDI to obtain an optimal index of a country's overall well-being.

Psychosocial predictors of weight loss and psychological adjustment following bariatric surgery and a weight-loss program: the mediating role of emotional eating

OBJECTIVE

To examine a structural equation model of the effects of personal and interpersonal factors on treatment outcome of bariatric surgery and weight-loss program.

METHOD

Forty-four participants of the surgery group and 47 participants of the diet group completed questionnaires before treatment and 1 year afterward. Predictor measures are as follows: social support, motivation for control, sense of control, self-esteem, neuroticism, fear of intimacy, and emotional eating (EE).

OUTCOME MEASURES

Weight loss, quality of life, and mental health.

RESULTS

Neurotic predisposition (NP), a latent variable indicated by neuroticism, low self-esteem, and fear of intimacy, had an effect on weight loss that was fully mediated by EE. NP also had an effect on quality of life improvement that was fully mediated by EE and weight loss in both treatment groups.

DISCUSSION

Both NP and EE predict outcome of obesity treatments, but EE is the more proximal variable that mediates the effect of NP.

Cannabinoids and capsaicin improve liver function following thioacetamide-induced acute injury in mice

OBJECTIVES

We have shown the beneficial effects of cannabinoids in a murine model of hepatic encephalopathy following thioacetamide and now report their effects on the liver injury.

METHODS

Fulminant hepatic failure (FHF) was induced by administration of 200 mg/kg thioacetamide to wild-type (WT) and CB2 Knockout (KO) mice. Twenty-four hours later, mice were injected with 2-arachidonoylglycerol (CB1, CB2, and TRPV1 agonist), HU308 (CB2 agonist), SR141716 A (CB1 receptor blocker), SR141716 A+2-AG, and SR144528 (CB2 receptor blocker), capsaicin and capsazepine (TRPV1 agonist and antagonist receptors). Mice were sacrificed 2 days after thioacetamide administration (day 3) and liver biochemistry and histopathology as well as evaluation of 2-arachidonoylglycerol levels were performed on liver tissue.

RESULTS

Liver histopathology undertaken 48 h after thioacetamide showed evidence of necrosis and inflammation. SR141716 A, HU308, and 2-arachidonoylglycerol reduced inflammation and promoted regeneration 1 day after their administration. Liver enzymes increased after thioacetamide administration and were reversed after SR141716 A and 2-arachidonoylglycerol administered alone or combined, HU-308, but not SR144528. Thus, the beneficial effects mediated through CB2 receptors. However, CB2 KO mice still modulated liver function via the TRPV1 receptors. Capsaicin improved both liver pathology and function in WT thioacetamide-treated mice, while capsazepine impaired it.

CONCLUSIONS

The similar pattern found between the effect of cannabinoids and their antagonists on brain and liver indicated that the therapeutic effect might be directed by the improvement in both organs through CB2 receptors and/or TRPV1 receptors. Modulation of these systems may have therapeutic potential.

The dietary treatment of obesity

Dietary modulation is an essential part of weight loss and maintaining its reduction. Although simple in behavioral terms (eat less, exercise more), the tremendous difficulty of weight loss and maintenance has inspired many different diet regimens, in search of an easier, more efficient way to lose weight. Contemporary issues in this matter are the composition of diets (low fat versus low carbohydrate), the choice of carbohydrate (the glycemic index), and the role of calcium and dairy products. This article discusses the scientific evidence of the various dietary manipulations for weight loss and the challenges of maintaining a reduced obese state.

2-Arachidonoylglycerol, an endogenous cannabinoid receptor agonist, in various rat tissues during the evolution of experimental cholestatic liver disease

BACKGROUND/AIM

Changes in tissue levels of 2-arachidonoylglycerol (2-AG), an endocannabinoid, during the evolution of bile duct ligation (BDL) may indicate that endocannabinoids have a role in the hemodynamic changes that occur in this condition.

METHODS

2-AG levels, in various organs and vascular beds of BDL rats, 2 and 4 weeks post surgery, were determined. Untouched and sham-operated (SO) rats were used as controls.

RESULTS

2-AG content of a specific organ was not a static finding and depended on the rat's age, the time from the surgical procedure and the type of procedure. The most pronounced changes were observed in BDL rats 4 weeks post surgery. In these rats, hepatic, pulmonary, cardiac and renal medullary and papillary 2-AG levels were highest observed. No changes in splenic, aortic and renal cortical 2-AG levels were observed. In addition a stepwise increase in 2-AG levels from the cortex to the papilla was detected and was followed by a decrease in creatinine clearance.

CONCLUSIONS

2-AG probably has a role in the pathophysiologic changes in the liver, heart, lung and kidney that follows BDL.

Familial aggregation of red blood cell membrane fatty acid composition: the Kibbutzim Family Study

The fatty acid composition of membranes plays an important role in health and diseases. Whether genetic factors play a role in interindividual variability in membrane fatty acid levels has received limited attention. Using variance decomposition methods, we estimated the heritability of red blood cell (RBC) membrane fatty acids in an unselected population sample of 80 families (205 male and 212 female subjects) living in kibbutz settlements in Israel. Fatty acid levels were measured by gas chromatography. We estimated that polygenes explained 40% to 70% of the sex- and age-adjusted interindividual variability in all RBC fatty acids: saturated, monounsaturated, and polyunsaturated. The heritability estimates remained very similar after further adjustment for smoking, alcohol consumption, physical activity, lipoproteins, body mass index, waist to hip ratio, education, and religiosity. In bivariate genetic analyses, we observed positive genetic correlations for the fatty acid pairs 20:4n6-22:6n3 and 20:5n3-22:6n3, and negative genetic correlations for the pairs 16:0-20:4n6, 16:0-22:6n3, 18:1n9-20:3n6, 18:2n6-20:4n6, 18:2n6-24:0, and 20:3n6-20:4n6, suggesting that shared effects of the same sets of loci account for 12% to 30% of the additive genetic variance in these pairs of fatty acids. This study suggests a considerable polygenic component for all RBC membrane fatty acids and provides evidence that shared genetic effects account for the additive genetic variance in various fatty acid pairs. Future studies are needed to map the genes underlying the interindividual variation in these inherited phenotypes.

Determinants of disordered eating behaviors among Israeli adolescent girls

Eating behaviors were assessed by a modified SCOFF questionnaire in a National representative cross-sectional study among 2978 Israeli schoolgirls. The mean age was 14.7. Thirty percent met the criteria for disordered eating. Being Jewish or underweight reduced the odds for disordered eating. The following increased the risk: dieting, early onset of menarche, being overweight or obese, and suffering from constipation. School socio-economic status, physical activity, and smoking status were not contributory. These results help identify possible interventions to prevent the development of disordered eating behaviors.

Exercise in the menopause - an update

One of the most important components of lifestyle relates to physical activity. Sedentary people fare less well than those who exercise regularly. The benefits of exercise can be demonstrated in many organs of the body. The most frequently studied effect of exercise is reduction in cardiovascular morbidity and mortality, but positive effects on the musculoskeletal system, breast cancer, mood and cognition, and quality of life have been recorded as well. In many cases, a dose-response was evident, and even a mild to moderate degree of activity, performed only a few times weekly, may carry significant merits. The following article reviews this topic and brings updated information on the benefits of exercise on postmenopausal health.

BMI may overestimate the prevalence of obesity among women of lower socioeconomic status

OBJECTIVE

Our objective was to examine gender differences in height and weight associated with socioeconomic status (SES) and the consequent effect on body mass index in a multiethnic society.

RESEARCH METHODS AND PROCEDURES

A cross-sectional study, the First Israeli National Health and Nutrition Survey, was performed on a representative population sample of 3246 adults 25 to 64 years of age, between the years 1999 to 2001. Height and weight were measured, and BMI and other weight-height indices were calculated. SES was assessed by income and education.

RESULTS

Age-adjusted height was significantly lower at lower levels of SES among both women and men (p<0.001). As opposed to men, women of lower SES were heavier than those of higher SES, and the mean age-adjusted weight was 4.6 kg higher among those of lower SES (p<0.001). Thus, using the standard index of BMI, the prevalence of obesity was significantly higher among shorter women.

DISCUSSION

In this group of Israeli adults, the unfavorable effect of low SES on BMI was evident among women, partly due to their decreased height combined with increased weight common in this socioeconomic sector. Since BMI is only partly independent of height, it may overestimate the prevalence of obesity among women of lower SES. Alternative measures for classifying obesity in the lower SES groups that put less emphasis on height may be considered and studied.

The synthetic cannabinoid HU-210 attenuates neural damage in diabetic mice and hyperglycemic pheochromocytoma PC12 cells

Diabetic neuropathy (DN) is a common complication of diabetes mellitus resulting in cognitive dysfunction and synaptic plasticity impairment. Hyperglycemia plays a critical role in the development and progression of DN, through a number of mechanisms including increased oxidative stress. Cannabinoids are a diverse family of compounds which can act as antioxidative agents and exhibit neuroprotective properties. We investigated the effect of the synthetic cannabinoid HU-210 on brain function of streptozotocin (STZ)-induced diabetic mice. These animals exhibit hyperglycemia, increased cerebral oxidative stress and impaired brain function. HU-210, through a receptor independent pathway, alleviates the oxidative damage and cognitive impairment without affecting glycemic control. To study the neuroprotective mechanism(s) involved, we cultured PC12 cells under hyperglycemic conditions. Hyperglycemia enhanced oxidative stress and cellular injuries were all counteracted by HU-210-in a dose dependent manner. These results suggest cannabinoids might have a therapeutic role in the management of the neurological complications of diabetes.

Cannabinoids ameliorate cerebral dysfunction following liver failure via AMP‐activated protein kinase

Hepatic encephalopathy (HE) is a neuropsychiatric disorder of complex pathogenesis caused by acute or chronic liver failure. We studied the etiology of cerebral dysfunction in a murine model of HE induced by either bile duct ligation or thioacetamide administration. We report that stimulation of cerebral AMP-activated protein kinase (AMPK), a major intracellular energy sensor, is a compensatory response to liver failure. This function of AMPK is regulated by endocannabinoids. The cannabinoid system controls systemic energy balance via the cannabinoid receptors CB-1 and CB-2. Under normal circumstances, AMPK activity is mediated by CB-1 while CB-2 is barely detected. However, CB-2 is strongly stimulated in response to liver failure. Administration of delta9-tetrahydrocannabinol (THC) augmented AMPK activity and restored brain function in WT mice but not in their CB-2 KO littermates. These results suggest that HE is a disease of energy flux. CB-2 signaling is a cerebral stress response mechanism and makes AMPK a promising target for its treatment by modulating the cannabinoid system.

Endocannabinoids, feeding and suckling--from our perspective

In this overview we have summarized some aspects of our published work related to the effects of the endocannabinoid system on appetite and suckling. As noted also by several other groups we have found that anandamide, a major endocannabinoid, enhances appetite in mice. On partial or full food deprivation over 24 h the levels of 2-arachidonoyl glycerol (2-AG), a second major cannabinoid, are initially elevated in mouse brain; however, partial food deprivation over a longer period causes reduction of 2-AG levels. Blocking the endocannabinoid system with a CB1 antagonist on the 1st day after birth leads to inhibition of suckling; later administration also affects suckling, but does not fully block it.

AMPK activation regulates apoptosis, adipogenesis, and lipolysis by eIF2alpha in adipocytes

AMP-activated protein kinase (AMPK) is a metabolic master switch regulating glucose and lipid metabolism. Recently, AMPK has been implicated in the control of adipose tissue content. Yet, the nature of this action is controversial. We examined the effect on F442a adipocytes of the AMPK activator-AICAR. Activation of AMPK induced dose-dependent apoptotic cell death, inhibition of lipolysis, and downregulatation key adipogenic genes, such as peroxisome proliferator-activated receptor (PPARgamma) and CCAAT/enhancer-binding protein alpha (C/EBPalpha). We have identified the alpha-subunit of the eukaryotic initiation factor-2 (eIF2alpha) as a target gene which is phosphorylated following AICAR treatment. Such phosphorylation is one of the best-characterized mechanisms for downregulating protein synthesis. 2-Aminopurine (2-AP), an inhibitor of eIF2alpha kinases, could overcome the apoptotic effect of AICAR, abolishing the reduction of PPARgamma and C/EBPalpha and the lipolytic properties of AMPK. Thus, AMPK may diminish adiposity via reduction of fat cell number through eIF2alpha-dependent translation shutdown.

Nutritional status, cognition, and survival: a new role for leptin and AMP kinase

Although adequate nutrition is essential for optimal neural activity and survival, mild energy restriction may improve cognition and prolong longevity. Energy status is monitored by the cellular AMP-activated protein kinase (AMPK) system, whereas leptin regulates total energy balance. We investigated the roles of AMPK and leptin in cognition and survival under diet restriction (DR). Hippocampal AMPK activity increases with energy restriction. Modest activation (DR to 60%) induces neurogenesis and improves cognition. However, DR to 40% augmented AMPK activity, reduced cognition and catecholamines, and increased neural apoptosis and mortality. Leptin signaling is preserved only in DR to 60%, countering the effects of AMPK "overactivation" by preventing neuroapoptosis, restoring noradrenergic activity and behavioral performance, and increasing longevity. The balance between leptin and AMPK is crucial in determining neuronal fate, cognitive ability, and survival. Should these findings extend to Man, then controlled activation of AMPK may improve neurodegenerative diseases, and leptin may have a new role in treating stress-associated malnutrition.

Endocannabinoids and liver disease--review

AIMS

Endocannabinoids are endogenous compounds that bind to the same receptors as tetrahydrocannabinol, the active component in marijuana and hashish. They have been found to have many physiological and patho-physiological functions, including mood alteration, control of feeding and appetite, motor and co-ordination activities, analgesia, immune modulation and gut motility. In this review we aim to elucidate current knowledge as to their role in liver physiology and disease.

METHODS

The major findings published to date concerning endocannabinoids and liver disease are described, and their implications with regard to understanding disease mechanisms, and the development of new treatments is considered.

RESULTS

Recently, endocannabinoids have been implicated in the hemodynamic alterations occurring in cirrhosis. These changes appear to be mediated via specific cannabinoid receptors (CB1) on splanchnic and hepatic vascular endothelium. Plasma levels of endocannabinoids also seem to be elevated in hepatitis, and are involved in apoptosis of hepatocytes by a membrane mechanism not related to a specific receptor. Other studies suggest a beneficial role for cannabinoids in reducing the inflammation of experimental hepatitis. In an animal model of acute hepatic failure, both endocannabinoids and the antagonist to the CB1 receptor have been found to have a beneficial effect on neurological and cognitive function.

CONCLUSIONS

Endocannabinoids appear to be involved in several aspects of acute and chronic liver disease, including vascular changes, modulation of inflammatory process and neurological function, Further research may provide new insights into the pathophysiology of liver disease, as well as a basis for novel treatment modalities.

Endocannabinoids affect neurological and cognitive function in thioacetamide-induced hepatic encephalopathy in mice

Endocannabinoids function as neurotransmitters and neuromodulators in the central nervous system via specific receptors and apparently have a neuroprotective role. We assumed that the endocannabinoid system could be involved in the pathogenesis of hepatic encephalopathy (HE), a neuropsychiatric syndrome due to liver disease. We used a mouse model of a thioacetamide induced fulminant hepatic failure. We found that the levels of the endocannabinoid 2-arachidonoyl-glycerol (2-AG) were elevated in the brain. Treatment with either 2-AG or with the CB1 receptor antagonist, SR141716A, improved a neurological score, activity and cognitive function. Activation of the CB2 receptor by a selective agonist, HU308, also improved the neurological score. 2-AG activity could be blocked with the specific CB2 receptor antagonist SR144528A. The CB1 receptor agonist noladin ether was inactive. We conclude that the endocannabinoid system may play an important role in the pathogenesis of HE. Modulation of this system either by exogenous agonists specific for the CB2 receptors or possibly also by antagonists to the CB1 receptors may have therapeutic potential.

Prevalence of obesity in Israel

Israel is a multiethnic society and offers an ongoing 'experiment' concerning the cultural determinants of obesity. The First Israeli National Health and Nutrition Survey 1999-2001 (MABAT) measured a representative population of 2782 adults (49% men) aged 25-64 years (mean 43 years); it showed a prevalence of overweight in 39.3% and obesity in 22.9%. Overweight is more common in men and obesity is more prevalent in women; the Israeli Arab population is more obese than the Jewish one.

Lack of long-lasting consequences of starvation on eating pathology in Jewish Holocaust survivors of Nazi concentration camps

The purpose of the present study was to investigate whether Holocaust survivors will show the same eating pathologies that were found in other participants who had also undergone starvation. Fifty-five Holocaust survivors and 43 matched control participants answered a questionnaire designed to explore eating problems and pathologies described in the literature as lasting for decades after a period of severe food restriction. Confirmation of the survivors' reports was obtained from their children. No significant differences in current eating habits were found between the Holocaust survivors and their matched controls. Prolonged starvation in Holocaust survivors did not lead to disordered eating habits in the sample. These results conflict with the notion that severe starvation consistently leads to food preoccupation and disordered eating.