Peripheral Aß acts as a negative modulator of insulin secretion.

Type 2 diabetes mellitus is known to be a risk factor for Alzheimer's disease (AD), but the underlying mechanisms remain unclear. In AD, the cerebral accumulation of amyloid ß (Aß) triggers a pathological cascade leading to neurodegeneration. Plasma Aß levels are thought to reflect the brain amyloid pathology and currently used as a diagnostic biomarker of AD. However, amyloid precursor protein and Aß-generating enzymes, ß- and γ-secretases, are widely expressed in various peripheral tissues. Previous reports have shown that glucose and insulin loading cause a transient increase of plasma Aß in mice and humans. These findings led us to speculate that plasma Aß is produced from glucose- and insulin-susceptible peripheral tissues to play a role in glucose and insulin metabolism. To test this hypothesis, we investigated the effects of glucose and insulin on Aß secretion and the effect of Aß on insulin secretion in vivo, ex vivo, and in vitro. Aß was found to be secreted from ß-cells of the pancreas along with insulin upon glucose stimulation. Upon insulin stimulation, Aß was secreted from cells of insulin-targeted organs, such as adipose tissues, skeletal muscles, and the liver, along with their organokines. Furthermore, Aß inhibited the glucose-triggered insulin secretion from ß-cells, slowing down glucose clearance from the blood. These results suggest that peripheral Aß acts as a negative modulator of insulin secretion. Our findings provide a possible mechanism linking diabetes to AD and call attention to how plasma Aß levels are used in AD diagnosis.

Traditional Japanese apricot (Prunus mume) induces osteocalcin in osteoblasts.

The fruit of Prunus mume (ume, also known as Japanese apricot) has been used as a functional food in Japan since ancient times. We previously reported that ume stimulates the differentiation of preosteoblastic cells. Osteocalcin (OCN) is secreted by osteoblasts, and there is known association with glucolipid metabolism and cognitive function. This study sought to clarify the relationship between ume extracts and OCN production both in vitro and in vivo. Alkaline phosphatase activity and OCN level in the ethyl acetate extracts of ume-treated extracts were significantly increased in preosteoblast MC3T3-E1 cells compared with the control group. In human study, serum OCN level was significantly higher in the high ume intake group than in the low intake group in community-dwelling participants over 60 years old. These results suggest that ume has the potential to upregulated OCN production both in vitro and in vivo.

Influence of continued ingestion of matcha on emotional behaviors after social stress in mice.

Matcha has high contents of theanine, caffeine, and epigallocatechin gallate (EGCG). Among these, theanine reduces psychological and physiological stress responses, although this effect is disturbed by caffeine and EGCG. It was reported that the continued ingestion of high-quality matcha, whose molar ratio of caffeine and EGCG to theanine and arginine was kept at less than two, reduces stress responses. However, most matcha on the market has an inadequate ratio. Therefore, we investigated the influence of continued ingestion of matcha with a ratio of over two, on emotional behaviors after stress. Continued ingestion of matcha was suggested to reduce the anxiety-like behaviors induced by psychological and physiological stresses.

Effects of flavonol-rich green tea cultivar (Camellia sinensis L.) on plasma oxidized LDL levels in hypercholesterolemic mice.

To examine the possible benefits of tea flavonols, we compared anti-atherogenic effects between common and flavonol-rich tea cultivars. The tea infusion made from a flavonol-rich cultivar, but not a common cultivar, significantly decreased the plasma oxidized low-density lipoprotein level in mice fed a high-cholesterol diet. The result suggests that tea flavonols have the potential to protect against cardiovascular diseases.

Locomotive syndrome is associated with body composition and cardiometabolic disorders in elderly Japanese women.

BACKGROUND: A concept referred to as locomotive syndrome (LS) was proposed by the Japanese Orthopaedic Association in order to help identify middle-aged and older adults who may be at high risk of requiring healthcare services because of problems associated with locomotion. Cardiometabolic disorders, including obesity, hypertension, diabetes, and dyslipidemia, have a high prevalence worldwide. The purpose of this study was to determine the associations between LS and both body composition and cardiometabolic disorders. METHODS: The study participants were 165 healthy adult Japanese women volunteers living in rural areas. LS was defined as a score ≥16 on the 25-question Geriatric Locomotive Function Scale (GLFS-25). Height, body weight, body fat percentage, body mass index (BMI), and bone status were measured. Bone status was evaluated by quantitative ultrasound (i.e., the speed of sound [SOS] of the calcaneus) and was expressed as the percent of Young Adult Mean of the SOS (%YAM). Comorbid conditions of hypertension, hyperlipidemia, and diabetes were assessed using self-report questionnaires. RESULTS: Twenty-nine participants (17.6 %) were classed as having LS. The LS group was older, shorter, and had a higher body fat percentage, a higher BMI, and lower bone status than the non-LS group. Multiple logistic regression analysis showed that participants with a BMI ≥23.5 kg/m2 had a significantly higher risk for LS than those with a BMI <23.5 kg/m2 (odds ratio [OR] = 3.78, p < 0.01). Furthermore, GLFS-25 scores were higher in participants with than those without hypertension, diabetes, or obesity, and significantly increased with the number of present disorders. CONCLUSIONS: These findings suggest that BMI may be a useful screening tool for LS. Furthermore, because hypertension and diabetes were associated with LS, the prevention of these disorders accompanied by weight management may help protect against LS.

The E693Δ (Osaka) mutation in amyloid precursor protein potentiates cholesterol-mediated intracellular amyloid ß toxicity via its impaired cholesterol efflux.

It has been shown that amyloid ß (Aß) secretion regulates cholesterol efflux from cells and that the E693Δ (Osaka) mutation in amyloid precursor protein (APP) promotes intracellular accumulation of Aß and thus reduces its secretion. These findings led us to speculate that APP with the Osaka mutation (APPOSK ) might have a defect in cholesterol efflux and thus cause cellular malfunction. We therefore examined the effects of this mutation on intracellular cholesterol transport and efflux in cultured cells. Upon cholesterol loading, APPOSK -expressing cells exhibited higher levels of cellular cholesterol than wild-type APP-expressing cells, suggesting impaired cholesterol efflux. It is known that, after its internalization, cholesterol is transported from the endosomes to the endoplasmic reticulum (ER) and Golgi apparatus and then to the plasma membrane. In APPOSK -expressing cells, cholesterol accumulated with Aß in the ER and Golgi apparatus and alone in endosomes/lysosomes. These results imply that the mutation-induced disturbance of Aß trafficking from the ER to the plasma membrane affects cholesterol transport to cause cholesterol accumulation in the ER and Golgi apparatus and, consequently, in endosomes. Furthermore, we detected an enhanced mitochondrial accumulation of Aß and cholesterol in APPOSK -expressing cells, and this was accompanied by an increase in the generation of reactive oxygen species (ROS). The present findings suggest that Aß trafficking is important for intracellular cholesterol transport and efflux and that the Osaka mutation potentiates cholesterol-dependent exacerbation of intracellular Aß toxicity, i.e. Aß-induced ROS generation, by disturbing Aß-mediated cholesterol efflux from the cell.

Comparing Effects of Caffeine and Theobromine on Adrenal Hypertrophy and Social Behavior in Psychosocial Stressed Mice.

Management of chronic psychological stress is important for the prevention of depression, mood disorders, and other related ailments. Recent studies have shown that dietary methylxanthines, such as caffeine and theobromine, exert preventive effects on these ailments. Although the psychological effects of caffeine are well-investigated, those of theobromine are not fully understood. In the present study, the effects of theobromine were evaluated and compared with those of caffeine using a mouse stress model based on confrontational housing. Male mice were kept separately in partition cages (two per cage) to allow the establishment of territories for confrontational housing. The mice were administered caffeine or theobromine daily via oral gavage (6 mg/kg). Thereafter, the partition was removed to induce confrontational stress. We found that theobromine, but not caffeine, suppressed adrenal hypertrophy caused by confrontational stress. Moreover, sociability tests revealed that caffeine and theobromine had different effects on the behavioral changes caused by confrontational stress. Our results suggest that orally administered theobromine suppresses adrenal hypertrophy caused by psychosocial stress and induces different behavioral changes than dose caffeine.

Effects of a Tea Cultivar "MK5601" on Behaviors and Hippocampal Neurotrophin-3 Levels in Middle-Aged Mice.

Dietary factors are thought to play an important role in the prevention of cognition diseases and depression in late life. In the present study, we compared the effects between the theogallin-rich tea cultivar, "MK5601" and a common Japanese tea cultivar, "Yabukita" on behaviors and hippocampal neurotrophin levels in experimental animals. Middle-aged mice (aged 8 mo) were given either of the tea infusions or water ad libitum for 4 mo. In the novel object location test, the middle-aged mice drinking water or "Yabukita" performed worse than young mice (aged 2-3 mo) although the middle-aged mice drinking "MK5601" retained spatial memory at the same level as the young mice. We also found that the middle-aged mice drinking "MK5601" showed high levels of neurotrophin-3 in the hippocampus. In conclusion, the "MK5601" tea infusion appears to be effective in preventing age-related changes in cognitive function, as compared with a common Japanese tea cultivar.

Hormone-sensitive lipase is critical mediators of acute exercise-induced regulation of lipolysis in rat adipocytes.

The purpose of the present study was to investigate the effect of acute exercise on lipolysis via coordination of hormone-sensitive lipase (HSL) and scaffold proteins, i.e., perilipin A and comparative gene identification-58 (CGI-58), in rat primary adipocytes. Glycerol release was significantly elevated immediately (0h) and three hours (3h) after exercise. Both activity and localization to the pellet of HSL were significantly greater in the pellet fraction, which is included in lipid droplet associated-proteins, than in the supernatant fraction. In the pellet fraction, although neither perilipin A nor CGI-58 protein level changed, level of perilipin A/CGI-58 complex was significantly reduced, accompanied by up-regulated association of perilipin A/HSL at 0h and 3h after exercise. On the other hand, there were no changes in these molecules at 24h after exercise, despite a significant decrease in lipolysis that was observed in response to isoproterenol. These findings suggest that acute exercise enhances lipolysis up to at least 3h after exercise in a manner dependent on modification of HSL and its association with and alteration in scaffold protein.

Two Japanese pepper (Zanthoxylum piperitum) fruit-derived compounds attenuate IgE-mediated allergic response in vitro and in vivo via inhibition of mast cell degranulation.

Zanthoxylum piperitum (ZP, 'Japanese pepper') is a traditional medicine and pepper used in Asian countries such as Japan. Hydroxy-α-sanshool, a pungent-tasting substance contained within ZP, has been reported to slightly suppress immunoglobulin E (IgE)-mediated mast cell degranulation. The current study aims to newly identify anti-allergic compounds derived from ZP. We examine the inhibitory mechanisms behind IgE-mediated mast cell degranulation. By inhibitory effect-guided isolation, we identified degranulation inhibitory compounds derived from ZP fruit: 1-acetoxy-7-hydroxy-3, 7-dimethylocta-2E, 5E-diene (ZP1) and 8-hydroxygeranyl acetate (ZP2). ZP1 and ZP2 inhibited IgE-mediated degranulation and A23187-mediated degranulation in RBL-2H3 mast cells. Our findings suggest the inhibition of degranulation by ZP1 and ZP2 was by inhibition of Lyn phosphorylation, followed by inhibition of intracellular Ca2+ mobilization, protein kinase C alpha phosphorylation, membrane ruffling, and granule-to-plasma membrane fusion. Oral administration of ZP1 or ZP2 attenuated an IgE-mediated passive cutaneous anaphylactic reaction in mice. Histological observation suggests that this effect occurred via inhibition of mast cell degranulation. These findings indicate that ZP1 and ZP2 attenuate allergic reaction via inhibition of IgE-mediated mast cell degranulation.

Autoantibody to glial fibrillary acidic protein in the sera of cattle with bovine spongiform encephalopathy.

It is desirable to make the diagnosis in live cattle with bovine spongiform encephalopathy (BSE), and thus surrogate markers for the disease have been eagerly sought. Serum proteins from BSE cattle were analyzed by 2-D Western blotting and TOF-MS. Autoantibodies against proteins in cytoskeletal fractions prepared from normal bovine brains were found in the sera of BSE cattle. The protein recognized was identified to be glial fibrillary acidic protein (GFAP), which is expressed mainly in astrocytes in the brain. The antigen protein, GFAP, was also found in the sera of BSE cattle. The percentages of both positive sera in the autoantibody and GFAP were 44.0% for the BSE cattle, 0% for the healthy cattle, and 5.0% for the clinically suspected BSE-negative cattle. A significant relationship between the presence of GFAP and the expression of its autoantibody in the serum was recognized in the BSE cattle. These findings suggest a leakage of GFAP into the peripheral blood during neurodegeneration associated with BSE, accompanied by the autoantibody production, and might be useful in understanding the pathogenesis and in developing a serological diagnosis of BSE in live cattle.

Teriparatide Improves Bone and Lipid Metabolism in a Male Rat Model of Type 2 Diabetes Mellitus.

Osteoporosis is a complication of diabetes mellitus (DM). The pathology of diabetic osteoporosis is distinct from postmenopausal osteoporosis, and there are no specific treatment guidelines for diabetic osteoporosis. In the current study, this issue was addressed by evaluating the effect of osteoporosis medications, such as the anabolic agent PTH [teriparatide (TPTD)] and the antiresorptive agents calcitonin [elcatonin (ECT)] and bisphosphonate [risedronate (RIS)], on bone metabolism as well as on glucose and lipid metabolism in spontaneously diabetic Torii (SDT) fatty rats, which are a model of type 2 DM (T2DM). The medicines were injected subcutaneously into 8-week-old male SDT fatty rats three times weekly for 8 weeks. TPTD treatment in SDT fatty rats increased the osteoblast number and function on trabecular bone in vertebrae, and increased the trabecular bone mass, bone mineral density (BMD), and mechanical strength of vertebrae. Additionally, TPTD improved cortical bone structure and increased BMD. RIS decreased the osteoclast number and function, which led to an increase in vertebral bone mineral content and BMD in the femoral diaphysis, and mechanical strength was increased in the vertebrae. ECT showed no clear effects on bone mass or metabolism. Similar to diabetic lesions, all of the drugs had no effects on hyperglycemia, pancreas morphology, or serum insulin and glucagon levels. However, triglyceride levels and lipid droplets in fatty liver were decreased in the TPTD group. These results suggest that TPTD may be useful for treating fatty liver in addition to osteoporosis in T2DM.

Tea catechins enhance the mRNA expression of uncoupling protein 1 in rat brown adipose tissue.

The aim of the present study was to determine whether the antiobesity effects of tea catechins (TCs) are associated with the expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT). Male Sprague-Dawley rats were fed a high-fat (HF; 35% fat) diet for 5 weeks, then divided into four groups and fed an HF, HF with 0.5% TC (HFTC), normal-fat (NF; 5% fat) or NF with 0.5% TC (NFTC) diet for 8 weeks. At the end of the experimental period, perirenal and epididymal white adipose tissues (WATs) and interscapular BAT were isolated. The NFTC group had significantly lower perirenal WAT weights than the NF group (NF: 12.7+/-0.53 g; NFTC: 10.2+/-0.43 g; P<.01), but the HF and HFTC groups did not differ significantly. TC intake had no effects on epididymal WAT weights. The NFTC and HFTC groups had significantly lower BAT weights than the NF and HF groups, respectively. The NFTC group had significantly higher UCP1 mRNA levels in BAT than the NF group (NF: 0.35+/-0.02; NFTC: 0.60+/-0.11; P<.05), but the HF and HFTC groups did not differ significantly. Thus, TC intake in the context of the NF diet reduced perirenal WAT weight and up-regulated UCP1 mRNA expression in BAT. These results suggest that the suppressive effect of TC on body fat accumulation is associated with UCP1 expression in BAT.

Differential metabolism of 4-n- and 4-tert-octylphenols in perfused rat liver.

Octylphenols, widely used in a variety of detergents and plastics, are known to exhibit estrogenicity in vivo. The details of their metabolism are needed to better understand the endocrine disruptions. We have previously shown that alkylphenols, having short alkyl chains, are glucuronidated and readily excreted into the bile from the liver, while 4-n-nonylphenol, having longer alkyl chains, remains as the alkylphenol's glucuronide in the tissue. This study elucidated the dependence of the metabolism on the shape of the alkyl chains by comparing 4-n-octylphenol and 4-tert-octylphenols in a perfused rat liver. Both octylphenols were highly glucuronidated by the liver microsomal fractions. The Vmax value of 4-tert-octylphenol glucuronidation was twice as high as that of 4-n-octylphenol in the liver microsomes. On the other hand, the Km values, being measures of enzymatic activity against these chemicals, were similar. 4-n-Octylphenol and 4-tert-octylphenol were both glucuronidated by a UDP-glucuronosyltransferase isoform, UGT2B1, expressed in the liver. In the liver perfusion, almost all of the 4-n-octylphenol perfused was metabolized directly to the glucuronide, whereas a portion of 4-tert-octylphenol was hydroxylated and then glucuronidated. The glucuronide of 4-n-octylphenol accumulated in the liver tissue in the same manner as 4-n-nonylphenol, but 4-tert-octylphenol and the hydroxylated metabolites were excreted readily into the bile. Only a small amount of 4-n-octylphenol-glucuronide and glucuronides of 4-tert-octylphenol and its hydroxylated metabolites could be excreted into the bile of Eisai hyperbilirubinemic rats (EHBR). These animals are deficient in xenobiotic conjugate transporter, multidrug resistance-associated protein (MRP-2), indicating that the glucuronides of both octylphenols are transported by MRP-2. These results indicate that the differences in metabolism of these octylphenols are due to the shape of their alkyl chains, suggesting that the estrogenic activities of not only the parent chemicals but also these metabolites must be taken into consideration.

A Randomized, Placebo-Controlled Study on the Safety and Efficacy of Daily Ingestion of Green Tea (Camellia sinensis L.) cv. "Yabukita" and "Sunrouge" on Eyestrain and Blood Pressure in Healthy Adults.

The green tea (Camellia sinensis L.) cultivar “Sunrouge” contains anthocyanins, catechins and flavonols. To determine whether ingesting green tea containing anthocyanins improves visual function and blood pressure (BP) in healthy adults, a randomized, double-blind, placebo-controlled study was performed. A total of 120 healthy subjects, aged between 20 and 60 years and with a systolic BP (SBP) value of ≤125 and <155 and a diastolic BP (DBP) value <95, or a DBP of ≤75 mmHg and <95 mmHg and a SBP <155 mmHg, were randomly assigned to one of three groups. For 12 weeks, the placebo group received barley extract without catechin; another group received “Sunrouge” extract containing 11.2 mg anthocyanin and 323.6 mg epigallocatechin-3-O-gallate (EGCG); and a third group received “Yabukita” extract containing 322.2 mg EGCG. Home BP, accommodation ability, visual analog scale questionnaires for eyestrain, and metabolic-associated markers were analyzed at weeks 0, 4, 8, and 12 of the intake period. The ingestion of “Sunrouge” tea significantly improved accommodation ability and eyestrain in subjects younger than 45 years and in subjects who operated visual display terminals every day. It also elevated BP. “Yabukita” tea ingestion significantly increased serum adiponectin levels. No adverse effects were observed. We conclude that long-term intake of “Sunrouge” tea containing anthocyanins and flavonols might improve visual function.

Biological and epidemiological evidence of anti-allergic effects of traditional Japanese food ume (Prunus mume).

Japanese apricot (Prunus mume; ume) is a traditional food in Japan that has been shown to have various beneficial health effects. There is some evidence to suggest that ume is also effective against allergic disease. Here, we conducted a cross-sectional epidemiological pilot study to examine the association between ume intake frequency and allergic symptoms including rhinitis in 563 adults (288 men and 275 women) who resided in Wakayama, Japan. After adjusting for age, present illness and medication, women with high ume intake had significantly lower odds ratio (OR) for the presence of symptoms of allergy [OR: 0.49 with 95% confidence interval (CI): 0.25-0.97]. Therefore, we investigated the anti-allergic effect of ume on passive cutaneous anaphylaxis (PCA) reaction in immunoglobulin E (IgE)-sensitized mice. The animal study demonstrated that oral administration of ume extract attenuated the PCA reaction and mast cell degranulation. Furthermore, RBL-2H3 mast cells were used to identify anti-allergic ume compounds. The following ume compounds inhibited IgE-mediated mast cell degranulation: vanillin, syringic acid, protocatechuic aldehyde, lyoniresinol and p-coumaric acid. These results suggested that ume has the potential to inhibit mast cell degranulation and may be associated with reduced risk of allergic symptoms in women.

Endogenous calcitonin regulates lipid and glucose metabolism in diet-induced obesity mice.

Calcitonin (CT) plays an important role in calcium homeostasis, and its precursor, proCT, is positively associated with the body mass index in the general human population. However, the physiological role of endogenous CT in the regulation of metabolism remains unclear. Knockout mice with gene-targeted deletion of exon 4 of Calca (CT KO) were generated by targeted modification in embryonic stem cells. Male mice were used in all experiments and were fed a slightly higher fat diet than the standard diet. The CT KO mice did not exhibit any abnormal findings in appearance, but exhibited weight loss from 15 months old, i.e., significantly decreased liver, adipose tissue, and kidney weights, compared with wild-type control mice. Furthermore, CT KO mice exhibited significantly decreased fat contents in the liver, lipid droplets in adipose tissues, serum glucose, and lipid levels, and significantly increased insulin sensitivity and serum adiponectin levels. CT significantly promoted 3T3-L1 adipocyte differentiation and suppressed adiponectin release. These results suggested that CT gene deletion prevents obesity, hyperglycemia, and hyperlipidemia in aged male mice. This is the first definitive evidence that CT may contribute to glucose and lipid metabolism in aged male mice, possibly via decreased adiponectin secretion from adipocytes.

The Relationship between Locomotive Syndrome and Depression in Community-Dwelling Elderly People.

Locomotive syndrome (LS) is a concept that refers to the condition of people requiring healthcare services because of problems associated with locomotion. Depression is a major psychiatric disease among the elderly, in addition to dementia. The purpose of this study was to determine the association between LS and depression. The study participants were 224 healthy elderly volunteers living in a rural area in Japan. LS was defined as scores ≥ 16 on the 25-question Geriatric Locomotive Function Scale (GLFS-25). Depression was defined as scores ≥ 5 on the 15-item Geriatric Depression Scale (GDS-15). Height and body weight were measured. The prevalence of LS and depression was 13.9% and 24.2%, respectively. Compared with the non-LS group, the LS group was older, was shorter, had a higher BMI, and had higher GDS-15 scores. Logistic regression analysis showed that participants with GDS-15 scores ≥ 6 had higher odds for LS than those with GDS-15 scores < 6 (odds ratio [OR] = 4.22). Conversely, the depression group had higher GLFS-25 scores than the nondepression group. Participants with GLFS-25 scores ≥ 5 had higher odds for depression than those with GLFS-25 scores < 5 (OR = 4.53). These findings suggest that there is a close relationship between LS and depression.

Comparison of the Effects of Three Tea Cultivars (Camellia sinensis L.) on Nitric Oxide Production and Aortic Soluble Guanylate Cyclase Expression in High-Salt Diet-Fed Spontaneously Hypertensive Rats.

Studies have suggested that the consumption of green tea reduces the risk of cardiovascular diseases. Although epigallocatechin gallate (EGCG) is the best studied active substance characteristic of green tea, previous results on EGCG do not appear sufficient to explain completely the mechanism of cardiovascular protection by green tea. Therefore, we investigated the effect of three different tea cultivars, "Yabukita," "Sofu," and "Sunrouge," which have characteristic flavonoid compositions, on the nitric oxide (NO) production and the related protein expression in the aorta of spontaneously hypertensive rats (SHRs) fed a high-salt diet. As a result, the reduction of urinary NO metabolite (NOx) levels, which reflect whole-body NO production, caused by the high-salt diet were significantly prevented by all three tea infusions. The improvement of NOx reduction in the tea-intake groups was unlikely to be caused by the changes in oxidative damage. On the other hand, as a partial effect, only "Yabukita" or "Sofu" increased the expression of the soluble guanylate cyclase, a receptor for NO, in the thoracic aorta. In the present study, the differences in the composition of these three cultivars led to partially different effects on NO signaling in SHRs, suggesting the physiological significance of subdominant ingredients besides EGCG.

A role of the histaminergic system for the control of feeding by orexigenic peptides.

A considerable number of neuropeptides are involved in the hypothalamic regulation of feeding behavior. We previously reported that leptin, the ob gene product, expressed its anorectic effect though the histaminergic system via histamine H(1) receptors. However, the interactions among the orexigenic neuropeptides, such as orexin-A, neuropeptide Y (NPY), and ghrelin, and the histaminergic system have not yet been clarified. In this study, we investigated the effect of the neuropeptides on the hypothalamic histamine release in rats, and on food intake and locomotor activity in H(1)-receptor knockout (H1R-KO) mice. Orexin-A increased the histamine release and locomotor activity, but not food intake, suggesting that the histaminergic system participates in arousal rather than feeding by orexin-A. NPY also increased histamine release, but its effect was not immediate. NPY-injected H1R-KO mice consumed more food than the wild-type mice; thus, the histaminergic system may act as a feedback factor downstream of NPY. Ghrelin did not affect histamine release, and it increased food intake, even in H1R-KO mice. Thus, ghrelin expresses its action in a histamine-independent manner.