Central CRTH2, a second prostaglandin D2 receptor, mediates emotional impairment in the lipopolysaccharide and tumor-induced sickness behavior model.

Chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2) is a second prostaglandin D2 receptor involved in mediating the allergic response; however, its central function is not yet known. Here, we demonstrate that central CRTH2 mediates emotional impairment. Lipopolysaccharide (LPS)-induced decreases in social interaction and novel exploratory behavior were observed in wild-type (CRTH2(+/+)) mice but not CRTH2-deficient (CRTH2(-/-)) mice, but both genotypes showed hypolocomotion and anorexia following LPS injection. Tumor (colon 26) inoculation, a more pathologically relevant model, induced decreases in social interaction and novel exploratory behavior in CRTH2(+/+), but not CRTH2(-/-) mice. In addition, the CRTH2 antagonists including clinically available ramatroban reversed impaired social interaction and novel exploratory behavior after either LPS or tumor inoculation in CRTH2(+/+) mice. Finally, LPS-induced c-Fos expression in the hypothalamic paraventricular nucleus (PVN) and central amygdala (CeA) was selectively abolished in CRTH2(-/-) mice. These results show that CRTH2 participates in LPS-induced emotional changes and activation in the PVN and CeA. Our study provides the first evidence that central CRTH2 regulates specific emotional behaviors, and that CRTH2 antagonism has potential as a therapeutic target for behavioral symptoms associated with tumors and infectious diseases.

15d-prostaglandin J2 enhancement of nerve growth factor-induced neurite outgrowth is blocked by the chemoattractant receptor- homologous molecule expressed on T-helper type 2 cells (CRTH2) antagonist CAY10471 in PC12 cells.

The chemoattractant receptor-homologous molecule expressed on T-helper type 2 cells (CRTH2) is the most recently identified prostaglandin (PG) receptor for both PGD(2) and 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)). We examined the mechanism by which 15d-PGJ(2) enhances nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells. CAY10471 (CRTH2 antagonist) inhibited both the neurite-promotion and p38 mitogen-activated protein (MAP) kinase phosphorylation induced by 15d-PGJ(2). In contrast, 13,14-dihydro-15-keto-PGD(2 )(DK-PGD(2)) (selective CRTH2 agonist) stimulated its phosphorylation but failed to produce neurite-promoting effects. These suggest, for the first time, the action of 15d-PGJ(2) is mediated by CRTH2, although the CRTH2 activation alone is insufficient for the underlying action.

Retardation of retinal vascular development in apelin-deficient mice.

OBJECTIVE: Apelin is an endogenous ligand for the G protein-coupled receptor, APJ, and participates in multiple physiological processes. To identify the roles of endogenous apelin, we investigated the phenotype of apelin-deficient (apelin-KO) mice. METHODS AND RESULTS: Apelin-KO mice showed impaired retinal vascularization and ocular development, which were analyzed by histology, immunohistochemistry, real-time polymerase chain reaction, and the mouse corneal micropocket assay. Apelin-KO mice showed significantly impaired retinal vascularization in the early postnatal period. Retinal apelin/APJ mRNAs were transiently upregulated during the first 2 postnatal weeks but were undetectable in adults. There were no differences in VEGF or FGF2 mRNA expression, or in the morphology and localization of GFAP-positive astrocytes, in the apelin-KO retinas at P5. The corneal pocket assay showed that angiogenic responses to VEGF and FGF2 were remarkably decreased in apelin-KO mice. The reduced responses to VEGF and FGF2 in apelin-KO mice were partially restored by apelin, but apelin alone did not induce angiogenesis. CONCLUSIONS: Our results suggest that spatiotemporally regulated apelin/APJ signaling participates in retinal vascularization in a cooperative manner with VEGF or FGF2, and contributes to normal ocular development.

Lack of light-induced elevation of renal sympathetic nerve activity and plasma corticosterone levels in PACAP-deficient mice.

PACAP is a neurotransmitter involved in the signal transduction of light stimulation in the suprachiasmatic nucleus (SCN). Light stimulation affects autonomic nerve activity via the SCN, and here we tested whether PACAP participates in light-induced regulation of sympatho-adrenal activity by using PACAP-deficient (Adcyap1(-/-)) mice. Light stimulation (100 lux, 30 min) significantly elevated both renal sympathetic nerve activity (RSNA), which was monitored on a digital oscilloscope, and plasma corticosterone levels in wild-type mice, but both responses were almost abolished in Adcyap1(-/-) mice. Although light-induced c-Fos expression in the SCN was observed in both genotypes, the numbers of c-Fos positive cells were significantly decreased in Adcyap1(-/-) mice. These data suggest that PACAP signaling pathway is involved in light-induced stimulation of RSNA and plasma corticosterone release through SCN of brain.

CRTH2, a prostaglandin D2 receptor, mediates depression-related behavior in mice.

Depression is a complex neuropsychiatric disorder with an unclear molecular etiology. Inflammatory cytokines and molecular intermediates (including prostaglandins) are suggested to be involved in depression; however, the roles of prostaglandins and their respective receptors are largely unknown in depression. Using genetic and pharmacological approaches, we show here that chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2), a second receptor for prostaglandin D2 (PGD2), mediates depression-related behavior in mice. CRTH2-deficient (CRTH2(-/-)) mice showed antidepressant-like activity in a chronic corticosterone treatment-induced depression. Consistent with this observation, the pharmacological inhibition of CRTH2 via the clinically available drug ramatroban also rescued abnormal social interaction and depression-related behavior in well-established models, including chronic corticosterone-, lipopolysaccharide-, and tumor-induced pathologically relevant depression models. Importantly, chronic stress via corticosterone treatment increased mRNA levels in PGD2-producing enzymes, such as cyclooxygenase-2 and lipocalin-type PGD2 synthase, in the brain. Furthermore, the activity of the hippocampal noradrenergic system but not the dopaminergic or serotonergic systems was increased in CRTH2(-/-) mice. Together with the observation that untreated CRTH2(-/-) mice showed antidepressant-like activity in the forced swim test, these results provide evidence that central CRTH2-mediated signaling is critically involved in depression-related behavior.

Effects of lactoferrin, soya germ and polyamine on 2-amino-1-methyl-6- phenylimidazo[4,5-b]-pyridine(PhIP)- induced breast carcinogenesis in rats.

The cancer-preventive effects of food-derived bovine lactoferrin(bLF), isoflavone-rich soya germ(SG), and spermidine(SPD) on mammary gland carcinogenesis induced by 2-amino-1- methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP), were investigated in female Sprague-Dawley(SD) rats. Two hundred and six female SD rats were divided into 8 groups. Cumulative breast cancer incidence at 43 weeks was 65.4% in the PhIP group; 80.0% and 76.0% in the 0.2% and 2.0% bLF groups, respectively; 58.3% and 20.0% in the 2% and 10% SG groups, respectively; and 80.0% and 76.9% in the 0.035% and 0.175% SPD groups, respectively. Isoflavone-rich SG significantly suppressed breast cancer, and the tumors showed fibrous or less malignant features upon histological examination.

[Associations between dietary intake and urinary excretion of sodium, potassium, phosphorus, magnesium, and calcium].

OBJECTIVES AND METHODS: The associations between dietary intake and urinary excretion of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), and phosphorus (P), and the major dietary sources derived from the urinary minerals were studied in a nutritional survey of 219 Japanese females aged 27-84 years, who completed anthropometric measurements, a one-day dietary record, and a 24 hr urine collection. RESULTS: The minerals excreted in the urine were significantly and positively correlated with each other, in which Na excretion was correlated with K and Ca excretion (r = 0.490 and r = 0.482, respectively, p < 0.01) and Ca excretion was correlated with Mg excretion (r = 0.526, p < 0.01). The ratios of urinary exertion to dietary intake of Na, K, Ca, Mg, and P were 81.5%, 62.7%, 24.5%, 21.7%, and 56.1%, respectively. The dietary intake and the urinary excretion of the minerals expressed per body weight (kg) were significantly and positively correlated (Na, r = 0.267; K, r = 0.460; Ca, r = 0.181; Mg, r = 0.245; P, r = 0.351, p < 0.01). Further examinations using chief component analysis for food intake showed several significant positive correlations, including between Na intake and the intake of vegetables, noodles, and seasonings (r = 0.332-0.381, p < 0.01); between K, Mg and P intake and the intake of vegetables, fruits, and potatoes (r = 0.332-0.533, p < 0.01); and between Ca intake and the intake of bread and dairy foods (r = 0.428, p < 0.01). In addition, significant positive associations were found between Na excretion and the intake of confectionaries, nuts, and seeds (r = 0.223, p < 0.01). Weak correlations were also found between K excretion and the intake of vegetables (r = 0.296, p < 0.01); between Ca and P excretion and the intake of meat, oil, and fats (r = 0.135, P < 0.05; r = 0.193, P < 0.01, respectively), and between Mg excretion and the intake of bread and dairy foods (r = 0.137, P < 0.05). CONCLUSIONS: Findings from this study indicate that, while urinary excretion of Ca and Mg is unlikely to be a reliable biochemical marker of dietary intake, the levels of urinary excretion of Na, K, and P can be reflective of the intake of salt, vegetables, and meats, respectively. The urinary excretion of the minerals, particularly Na, K, and Ca, may be highly linked to salt intake in Japanese females.

Behavioral characterization of mice overexpressing human dysbindin-1.

BACKGROUND: The dysbindin-1 gene (DTNBP1: dystrobrevin binding protein 1) is a promising schizophrenia susceptibility gene, known to localize almost exclusively to neurons in the brain, and participates in the regulation of neurotransmitter release, membrane-surface receptor expression, and synaptic plasticity. Sandy mice, with spontaneous Dtnbp1 deletion, display behavioral abnormalities relevant to symptoms of schizophrenia. However, it remains unknown if dysbindin-1 gain-of-function is beneficial or detrimental. RESULTS: To answer this question and gain further insight into the pathophysiology and therapeutic potential of dysbindin-1, we developed transgenic mice expressing human DTNBP1 (Dys1A-Tg) and analyzed their behavioral phenotypes. Dys1A-Tg mice were born viable in the expected Mendelian ratios, apparently normal and fertile. Primary screening of behavior and function showed a marginal change in limb grasping in Dys1A-Tg mice. In addition, Dys1A-Tg mice exhibited increased hyperlocomotion after methamphetamine injection. Transcriptomic analysis identified several up- and down-regulated genes, including the immediate-early genes Arc and Egr2, in the prefrontal cortex of Dys1A-Tg mice. CONCLUSIONS: The present findings in Dys1A-Tg mice support the role of dysbindin-1 in psychiatric disorders. The fact that either overexpression (Dys1A-Tg) or underexpression (Sandy) of dysbindin-1 leads to behavioral alterations in mice highlights the functional importance of dysbindin-1 in vivo.

Lipopolysaccharide affects exploratory behaviors toward novel objects by impairing cognition and/or motivation in mice: Possible role of activation of the central amygdala.

Lipopolysaccharide (LPS) produces a series of systemic and psychiatric changes called sickness behavior. In the present study, we characterized the LPS-induced decrease in novel object exploratory behaviors in BALB/c mice. As already reported, LPS (0.3-5 µg/mouse) induced dose- and time-dependent decreases in locomotor activity, food intake, social interaction, and exploration for novel objects, and an increase in immobility in the forced-swim test. Although the decrease in locomotor activity was ameliorated by 10h postinjection, novel object exploratory behaviors remained decreased at 24h and were observed even with the lowest dose of LPS. In an object exploration test, LPS shortened object exploration time but did not affect moving time or the frequency of object exploration. Although pre-exposure to the same object markedly decreased the duration of exploration and LPS did not change this reduction, LPS significantly impaired the exploration of a novel object that replaced the familiar one. LPS did not affect anxiety-like behaviors in open-field and elevated plus-maze tests. An LPS-induced increase in the number of c-Fos-immunoreactive cells was observed in several brain regions within 6h of LPS administration, but the number of cells quickly returned to control levels, except in the central amygdala where the increase continued for 24h. These results suggest that LPS most prominently affects object exploratory behaviors by impairing cognition and/or motivation including continuous attention and curiosity toward objects, and that this may be associated with activation of brain nuclei such as the central amygdala.

Masked function of amino acid sensors on pancreatic hormone secretion in ventromedial hypothalamic (VMH) lesioned rats with marked hyperinsulinemia.

SUMMARY: In neural regulation of the endocrine pancreas, there is much evidence to suggest that vagal efferents alter insulin and glucagon secretion, but less information on the effects of vagal afferents. In this study, we investigated the role and function of afferent fibers of the vagus nerve in normal and ventromedial hypothalamic (VMH) lesioned rats with marked hyperinsulinemia. In normal rats, hepatic vagotomy was associated with intraperitoneal (ip) arginine-induced enhancement of insulin and glucagon secretion without an accompanying change in blood glucose levels, ip leucine induced enhancement of insulin secretion accompanied by a decrease in blood glucose levels, and ip alanine-induced enhancement of glucagon secretion accompanied by an increase in blood glucose levels. In VMH lesioned rats with marked hyperinsulinemia, none of these amino acids caused significant changes in insulin and glucagon secretion. We conclude that amino acid sensors in normal rats inhibit excess release of pancreatic hormones induced directly by intake of amino acids, such as that in excess protein ingestion, and maintain blood glucose levels within the normal range. In contrast, in VMH lesioned rats with marked hyperinsulinemia, the function of the amino acid sensors is masked due to the marked hyperinsulinemia in these rats.:

Ventromedial hypothalamic lesions enhance small intestinal cell proliferation in mice.

BACKGROUND: We have found previously that ventromedial hypothalamic lesions (VMH) enhance cell proliferation in the visceral organs through vagal hyperactivity in rats. The goal of the current study was to determine the characteristics and nature of cell proliferation in the small intestine in VMH-lesioned mice. METHODS: The weight and length of the small intestine, thickness of the mucosal and muscle layers, number of proliferating cell nuclear antigen (PCNA)-positive cells, and mitotic cell count in the mucosal layer in VMH-lesioned and Sham VMH-lesioned mice were determined at 7 days after the operation. RESULTS: The weight and length of the small intestine in VMH-lesioned mice were significantly greater than those in Sham VMH-lesioned mice, by 11.6% and 15.0%, respectively. The thicknesses of the mucosal and muscle layers of the small intestine in VMH-lesioned mice were also significantly greater than those in Sham VMH-lesioned mice, by 12.7% and 12.5%, respectively. PCNA-positive cells and mitotic cells in the mucosal layer were densely present in crypts in VMH-lesioned mice, and were significantly increased by 31.9% and 71.7%, respectively, compared to Sham VMH-lesioned mice. CONCLUSIONS: These results demonstrate that VMH lesions in mice enhance cell proliferation in the mucosal layers and cause cell hypertrophy or cell proliferation in the muscle layers of the small intestine, which increases the weight and length of the small intestine. VMH lesions in mice may be a new tool for identifying growth factors and related genes involved in enlarging the small intestine mainly through cell proliferation.

Cell proliferation in ventromedial hypothalamic lesioned rats inhibits acute gastric mucosal lesions.

AIM: The role of mucosal layer thickness on prevention of acute gastric mucosal lesions (AGMLs) was examined in ventromedial hypothalamic (VMH)-lesioned rats. MATERIALS AND METHODS: The incidence of AGMLs after 48-h fasting and 60% ethanol injection into the stomach after 24-h fasting, aggressive factors (gastric acid and serum gastrin) and defensive factors [hexosamine, gastric mucosal blood flow (GMBF), serum thiobarbituric acid reacting substances (TBARS), and thickness of the gastric mucosal layer] were evaluated in VMH-lesioned rats. The effects of cell proliferation on the gastric mucosal layer of these rats were evaluated by H-E staining and immunostaining with proliferating cell nuclear antigen (PCNA). RESULTS: After 48-h fasting, no AGMLs were observed in VMH-lesioned and sham VMH-lesioned rats (controls). With 60% ethanol administration after 24-h fasting, the numbers of AGMLs were similar in the two groups, but the ulcer index, a marker of ulcer formation, was lower in VMH-lesioned rats compared to that in sham VMH-lesioned rats. VMH-lesioned rats showed increased gastric acid secretion and serum gastrin compared to sham VMH-lesioned rats, indicating an increase in aggressive factors in VMH-lesioned rats. The two groups had similar levels of gastric mucosal hexosamine, GMBF, and gastric mucosal TBARS, but VMH-lesioned rats had an increased thickness of the mucosal cell layer, indicating an increase in defensive factors in these rats. Histologically, VMH-lesioned rats had an increased total mucosal cell layer, especially for the surface epithelial cell layer, and an increased PCNA-labeling index, a marker of cell proliferation, especially in the proliferative zones of gastric mucosa, indicating increased cell proliferation in the proliferative zone of the gastric mucosa. CONCLUSION: VMH-lesioned rats are resistant to AGML formation due to increased cell proliferation in gastric mucosa through elevating the levels of defensive factors over those of aggressive factors.

Suppression of lipid-hydroperoxide and DNA-adduct formation by isoflavone-containing soy hypocotyl tea in rats.

OBJECTIVE: Phytoestrogen isoflavones (IFs) are considered to suppress estrogen-related cancers through their antiestrogenic activity. The antioxidant effect of IFs, however, has not been confirmed in anin vivo system, so suppression of hydroperoxide formation and resultant DNA adduct formation were studied. METHODS: The antioxidant effects of the soya-hypocotyl tea (SHT), which contained daidzein (14+/-1.5 mg/l) and genistein (3+/-0.5 mg/l), were examined in Wistar rats fed the AIN-76 control diet or iron deficient diet (FeD) for 4 weeks. The intake amount of the diet and IFs were measured daily. Urinary excretion of IFs was measured for 3 days before sacrifice. In addition to the serum lipid analyses, phosphatidylcholine hydroperoxide (PCOOH), and phosphatidylethanolamine hydroperoxide (PEOOH) production in red blood cells and the liver were measured as a biomarker of oxidants. Production of DNA adducts by oxidative stress was measured by the amount of 8-hydroxy-2'-deoxyguanosine (oh(8)dG) in the liver and kidney, and urine. Histological changes were checked by H&E staining and immunohistochemistry for oh(8)dG. RESULTS: FeD rats showed anemia, growth retardation, hyperlipidemia. IFs only lowered the triacylglycerol level and did not change the cholesterol level. Rats fed the normal diet did not show suppression of PCOOH and PEOOH production in either red blood cells or the liver, while groups administered SHT showed suppressed production of PCOOH and PEOOH in the liver. The cumulative intake of daidzein, genistein and the total amount of IFs showed significant inverse associations with urinary excretion of oh(8)dG. oh(8)dG in the kidney showed an inverse association with the amount of oh(8)dG in the urine. Enzymehistochemically, a strong localization of oh(8)dG was found in the epithelial cells of the bile canaliculi and proximal tubules of the kidney. CONCLUSION: IFs and SHT showed antioxidant effects at physiological concentrations in anin vivo system. The antioxidant effects of IFs decreased oxidation stress to the nuclear DNA, which was shown by the decreased oh(8)dG production. It is suggested that to prevent various cancers, in addition to the known antiestrogenie, antityrosin kinase, and other effects. IFs appeared to promote excretion of oh(8)dG.