Impairment of gastric accommodation induced by water-avoidance stress is mediated by 5-HT2B receptors.

BACKGROUND: Psychological stress has been shown to impair gastric accommodation (GA), but its mechanism has not been elucidated. This study was conducted to clarify the role of 5-HT2B receptors in a guinea pig model of stress-induced impairment of GA. METHODS: Gastric accommodation was evaluated by measuring the intrabag pressure in the proximal stomach after administration of a liquid meal. The guinea pigs were subjected to water-avoidance stress. The role of 5-HT2B receptors in impairment of GA was investigated by administering a 5-HT2B receptor agonist (BW723C86) or antagonist (SB215505), the traditional Japanese medicine rikkunshito (RKT), a muscarinic M3 receptor antagonist (1,1-dimethyl-4-diphenylacetoxypiperidium iodide [4-DAMP]), or a nitric oxide synthase inhibitor (Nω -nitro-L-arginine [L-NNA]). KEY RESULTS: In normal animals, liquid meal-induced GA was inhibited by BW723C86, but was not affected by SB215505. The inhibition of GA by BW723C86 was reversed by co-administration of 4-DAMP. Compared to normal animals, GA in stressed animals was significantly inhibited. SB215505 and RKT significantly suppressed stress-induced impairment of GA. After meal administration, the level of cyclic guanosine monophosphate in gastric fundus tissue increased by approximately twofold in normal animals, but did not change in stressed animals. The inhibition of GA by L-NNA was suppressed by SB215505 or RKT. At a dose that did not affect GA in normal animals, BW723C86 exacerbated the impairment of GA in stressed animals. CONCLUSIONS AND INFERENCES: Stress-induced impairment of GA may be mediated by an increased responsiveness of 5-HT2B receptors, and activation of the 5-HT2B receptor signaling pathway may have an inhibitory effect on nitric oxide function.

Effect of rikkunshito on the expression of substance P and CGRP in dorsal root ganglion neurons and voluntary movement in rats with experimental reflux esophagitis.

BACKGROUND: While there are reports that the herbal medicine rikkunshito (RKT) relieves upper gastrointestinal disease symptoms, the effect of RKT on primary afferent neurons is unknown. METHODS: A model of reflux esophagitis (RE) was implemented using male Wistar rats aged 6-7 weeks. Ten days after surgery, the total area of esophageal mucosal erosion sites was determined. Th8-10 dorsal root ganglia (DRG) were dissected out and the expression of substance P (SP), calcitonin gene-related peptide (CGRP), and phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) was determined in DRG using immunohistochemistry. RKT (0.6%/WV) or omeprazole (OME) (10 mg/kg) was administered for 10 days beginning on the day after surgery. Voluntary movement was measured with an infrared sensor for 22 h each day. KEY RESULTS: RE rats showed esophageal mucosal erosion and significantly increased number of SP/CGRP- and p-ERK1/2-immunoreactive neurons in DRG. Treatment with OME improved the size of erosive lesions in the esophageal mucosa of RE rats, while RKT did not. Treatment with RKT or OME significantly reduced the expression of SP/CGRP and p-ERK1/2 in DRG, and significantly increased voluntary movement in RE rats. CONCLUSIONS & INFERENCES: RKT inhibited the activation of ERK1/2 and decreased the expression of SP and CGRP in DRG of RE rats, which may be associated with the observed amelioration of voluntary movement.

Two amino acid substitutions in acetylcholinesterase associated with pirimicarb and organophosphorous insecticide resistance in the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae).

The complete coding sequences of two acetylcholinesterase (AChE) genes, Ace1 (orthologous to Drosophila Ace) and Ace2 (paralogous to Ace), from the cotton aphid (Aphis gossypii) were identified and sequences from carbamate resistant and susceptible strains compared. No change in the amino acid sequences was found in Ace1, while two amino acid substitutions, Ser431Phe and Ala302Ser, were detected between resistant and susceptible strains in Ace2. The position of Ser431Phe corresponds to one of fourteen aromatic residues lining the active site gorge and is located in the acyl pocket. Ala302Ser is located at one of the three residues which form the oxyanion hole in the active site of AChE. The Ser431Phe and Ala302Ser substitutions may play a role in pirimicarb and organophosphate resistance, respectively.

Fenitroxon insensitive acetylcholinesterases of the housefly, Musca domestica associated with point mutations.

The cDNA of AChE in the housefly, Musca domestica, was sequenced and individual flies were genotyped by this gene in an inhibition assay of AChE activity with an organophaspate, fenitroxon. Mutations at Gly(342) and Tyr(407), which are reportedly conserved in resistant strains of Drosophila, were associated with the insensitivity to fenitroxon. Two other mutations, Ile(162) and Val(260), did not have an apparent effect on insensitivity. However, the four mutations are located in the active site of the enzyme, and therefore the non-neutral mutations in this gene are considered to cause the insensitivity of AChE in the development of insecticide resistance of the housefly.

Tea catechins prevent the development of atherosclerosis in apoprotein E-deficient mice.

Green tea contains various antioxidative flavan-3ols (tea catechins), such as (-)-epigallocatechin gallate (EGCg, the major catechin), which exert potent inhibitory effects on LDL oxidation in vitro and ex vivo in humans. In this study, the antiatherogenic effects of tea catechins were examined in atherosclerosis-susceptible C57BL/6J, apoprotein (apo)E-deficient mice. Male apoE-deficient mice (10 wk old) were fed an atherogenic diet for 14 wk; during that time, one group (tea) was supplied drinking water supplemented with green tea extract (0.8 g/L), and another group (control) was offered the vehicle only. The tea extract consisted of the following (g/100 g): EGCg, 58.4; (-)-epigallocatechin (EGC), 11.7; (-)-epicatechin (EC), 6.6; (-)-gallocatechingallate (GCg), 1.6; (-)-epicatechin gallate (ECg), 0.5; and caffeine, 0.4. The estimated actual intake of tea catechin was 1.7 mg/(d. mouse). Tea ingestion did not influence plasma cholesterol or triglyceride concentrations. Plasma lipid peroxides were reduced in the tea group at wk 8, suggesting that the in vivo oxidative state is improved by tea ingestion. Atheromatous areas in the aorta from the arch to the femoral bifurcation and aortic weights were both significantly attenuated by 23% in the tea group compared with the control group. Aortic cholesterol and triglyceride contents were 27 and 50% lower, respectively, in the tea group than in the control group. These results suggest that chronic ingestion of tea extract prevents the development of atherosclerosis without changing the plasma lipid level in apoE-deficient mice, probably through the potent antioxidative activity of the tea.

Absence of protein polymorphism attributable to insecticide-insensitivity of acetylcholinesterase in the green rice leafhopper, Nephotettix cincticeps.

The cDNA sequence of acetylcholinesterase (AChE) from the green rice leafhopper, Nephotettix cincticeps, was amplified, based on conserved peptide sequences of AChEs. A 2.3 kb contiguous sequence, containing an ORF encoding an AChE precursor with 677 amino acid residues was obtained. The deduced protein sequence showed the most similarity to that of AChE in the Colorado potato beetle, having common features in the primary AChE structure. cDNA sequences of individual leafhoppers from an insecticide susceptible strain and the resistant strain Nakagawara, whose methylcarbamate-insensitive AChEs show 10(2) or more I(50) ratio for propoxur, were compared. No fixed inter-strain difference was identified in the protein sequence, though amino acid substitution polymorphism was found at one position in the susceptible strain. Insecticide-insensitivity of leafhopper AChE does not result from changes in the protein primary structure that is encoded by the AChE gene sequence isolated in this study.

Bactericidal activity of a fermented hot-water extract from Stevia rebaudiana Bertoni towards enterohemorrhagic Escherichia coli O157:H7 and other food-borne pathogenic bacteria.

A fermented aqueous extract from Stevia rebaudiana Bertoni showed strong bactericidal activity towards a wide range of food-borne pathogenic bacteria including enterohemorrhagic Escherichia coli O157:H7. The colony-forming ability of the food-borne pathogenic bacteria tested so far was reduced to < 10(-7) when exposed to > or = 40% (v/v) solutions of the fermented extract at 37 C for 2 hr. Secretion of verocytotoxin 1 and 2 by enterohemorrhagic E. coli was also diminished by fermented extract at a concentration of > or = 10% (v/v). In contrast, the fermented extract did not significantly kill Bifidobacteria or Lactobacilli. The active principle(s) of the fermented Stevia extract were bactericidal under acidic conditions.

The inhibitory effects of tea polyphenols (flavan-3-ol derivatives) on Cu2+ mediated oxidative modification of low density lipoprotein.

Tea polyphenols (flavan-3-ol derivatives) suppressed the oxidative modification of low density lipoprotein (LDL) which is assumed to be an important step in the pathogenesis of atherosclerosis lesions. Inhibitory experiments on the oxidative impairment of porcine serum LDL by flavan-3-ols were carried out by incubating them at 37 degrees C in the presence of 5 microM Cu2+. The oxidation of LDL was monitored either by an absorption increase at 234 nm due to the conjugated diene formation, or the formation of hydroperoxides and thiobarbituric acid reactive substances (TBARS). It was found that the oxidation was strongly inhibited by various flavan-3-ols, and a lag time over 100 min appeared, depending on the types of flavan-3-ols used. The activities based on the prolongation of the lag time were in the order of (-)-epigallocatechin (EGC) < (+)-catechin (C) < (-)-epicatechin (EC) < (-)-epicatechingallate (ECG) < (-)-epigallocatechingallate (EGCG). IC50 of flavan-3-ols on Cu2+ mediated hydroperoxides and TBARS formation of LDL were 0.90, 0.95 microM for ECG and 2.38, 2.74 microM for EGC, respectively. It was found that the Cu2+ mediated cholesterol ester degradation in LDL was almost completely inhibited by 5.0 microM C or EGCG. Cu2+ mediated apolipoprotein B-100 fragmentation was also inhibited (up to 60%) in the presence of C or EGCG.

[A case of sho-saiko-to-induced pneumonitis, diagnosed by lymphocyte stimulation test using bronchoalveolar lavage fluid].

A 66-year-old Japanese man was admitted to our hospital with fever, cough and dyspnea. He had been taking Sho-Saiko-to, a traditional Chinese medicine, for twenty days. On admission, chest X-ray examination revealed a reticular pattern in the bilateral lungs, and respiratory failure was evident. Serum levels of CRP and LDH were elevated. A differential cell count of the bronchoalveolar lavage fluid (BALF) showed that lymphocytes and eosinophils were increased. Alveolitis with lymphocyte and plasma cell infiltration was observed in a pathological specimen obtained by transbronchial lung biopsy. After all drugs had been discontinued, PaO2, serum CRP and serum LDH improved, and the reticular pattern in the bilateral lungs gradually resolved without administration of corticosteroids or antibiotics. A lymphocyte stimulation test for Sho-Saiko-to using BALF gave a positive result, although LST using blood gave a doubtful reaction. The diagnosis of Sho-Saiko-to-induced pneumonitis was made from the clinical course, laboratory findings, BALF cell analysis, pathological findings and LST using BALF. Only 13 cases of pneumonitis due to administration of traditional Chinese medical drugs have been reported. This case suggests that LST using BALF is useful for the diagnosis of drug-induced pneumonitis.

Effects of dietary vitamin E supplement on gracile axonal dystrophy (gad) mice.

We have studied the effects of dietary vitamin E supplement on the clinical signs and pathological changes in GAD (gracile axonal dystrophy) mice. The control diet contained 2 mg of dl-alpha-tocopheryl acetate (2 I.U.) and vitamin E-supplemented diet contained 58.5 mg of dl-alpha-tocopheryl nicotinate (50 I.U.), per 100 mg of feed. The diet was given to normal (gad/+) and GAD (gad/gad) mice from 21 to 130 days of age. During the feeding, there was no improvement in clinical signs in the GAD mice fed the vitamin E-supplemented diet. The gracile nucleus of the medulla oblongata and the gracile fascicules of the spinal cord were investigated for pathology at 130 days of age, and alpha-tocopherol was also assayed in the serum, liver, brain and spinal cord at that time. There were no pathological differences in the gracile nucleus and fascicules between the GAD mice fed the control and vitamin E-supplemented diet. The alpha-tocopherol levels in the serum and target organs in the control GAD mice were not significantly different from those in control normal mice, showing that GAD mice could absorb and transport alpha-tocopherol. In the supplemented GAD mice, no significant increases in alpha-tocopherol levels were observed in the liver, brain or spinal cord. Particularly, the percentage increase of alpha-tocopherol level in the liver of GAD mice was very low in comparison with that in normal mice, even though the liver can store vitamin E. Thus it may be that the capacity to store vitamin E is lowered in GAD mice. Further studies are needed to investigate in detail the vitamin E metabolism in the mutant mice.

Phosphorous compounds studied by 31P nuclear magnetic resonance spectroscopy in the taenia of guinea-pig caecum.

1. In the isolated taenia (0.4-0.6 g) of guinea-pig caecum, the intracellular phosphorous compounds and pH were investigated using 31P nuclear magnetic resonance (NMR) under various metabolic conditions. 2. The ratios of the intracellular concentration of phosphocreatine ([ PCr]) and inorganic phosphate [( Pi]) to nucleotide triphosphate ([ NTP]) were 1.71 +/- 0.14 and 0.58 +/- 0.11 (n = 25), respectively, in normal solution (32 degrees C). The intracellular pH estimated from the chemical shift of Pi was 7.05 +/- 0.06 (n = 25), agreeing well with those previously obtained. 3. In the absence of glucose, the [PCr] and [NTP] were decreased to almost a half after 150 min exposure to 40 mM-K+ solution, while [Pi] was increased 3-fold. These changes were much faster than the rate of decline in tension. When glucose was readmitted, the contractile response to K+ fully recovered in 50 min. However, this was accompanied with only a partial recovery of [PCr] and [Pi], but no recovery of [NTP]. The intracellular pH was lowered by about 0.2 of a unit, suggesting an increase in glycolysis. 4. In Ca2+-free solution, respiratory inhibition with hypoxia or CN (1 mM) only decreased [PCr], leaving [NTP] nearly unchanged. On the other hand, respiratory inhibition in excess-K+ solution containing Ca2+ (2.4 mM) severely depleted PCr and decreased [NTP] to 40%. Increasing glucose to 50 mM did not prevent these changes, although it increased tension development. 5. The simultaneous decrease of [NTP] and [PCr] during K+ contracture suggests that the activity of creatine phosphokinase is low. The recovery from respiratory inhibition was much better for [PCr] than for [NTP]. Slow, but perfect, recovery of all NTP peaks was produced by adding 1 mM-adenosine to normal solution. 6. It was suggested that tension development is closely related to the turnover rate of ATP, and not to its concentration, and that deamination of adenosine is a limiting factor in the recovery of ATP after excessive consumption.

Muscarinic cholinoceptors and choline acetyltransferase activity in the hypothalamus of spontaneously hypertensive rats.

To study the role of central cholinergic mechanisms in hypertension, we have determined muscarinic receptors using [3H] (-)quinuclidinyl benzilate (QNB) and choline acetyltransferase (ChAT) activity in the brain regions of spontaneously hypertensive rats (SHR), stroke-prone SHR (SHRSP) and renal hypertensive rats. The number of muscarinic receptors was significantly (33-38 %) elevated in the hypothalamus of SHR and SHRSP at the ages of 16 and 24 weeks compared to that of Wistar-Kyoto rats (WKY). An increased density of muscarinic receptors was consistently observed in the prehypertensive (5 weeks) and developmental (10 weeks) stages of hypertension. In contrast, in the hypothalamus of rats with renal hypertension there was no muscarinic receptor alteration. The receptor alteration in the SHRSP hypothalamus was not abolished by a chronic hypotensive treatment which prevented the development of hypertension, suggesting that an enhancement of the muscarinic receptors in spontaneous hypertension does not occur secondarily to the elevation of blood pressure. The hypothalamus of SHR and SHRSP at the ages of 5 and 24 weeks showed significantly less activity of ChAT. These data demonstrate that there is a specific increase in muscarinic receptors and a decrease in cholinergic activity in the hypothalamus of SHR and SHRSP. Thus, the present study suggests an important role for hypothalamic cholinergic receptors in the pathogenesis of spontaneous hypertension.

Clinical efficacy of niludipine in the treatment of angina pectoris.

Some Ca2+-antagonists are used for the treatment of angina pectoris. In the present study niludipine (Bay a 7168) was assessed in various types of angina pectoris cases. Niludipine, a Ca2+-antagonist of the dihydropyridine derivatives, was administered to 50 patients, 27 with effort angina pectoris, 4 with rest angina, 7 with effort plus rest angina, 4 with variant angina, 8 with angina following myocardial infarction in the doses of 60 mg/day or 120 mg/day for 4 weeks and the changes of subjective symptoms and objective findings were evaluated. Improvement was found by 69.6% for effort angina, by 75% (3/4) for rest angina, and side effects by 6% but mild degree--no facial flash, headache, hypotension were observed. The results suggest that niludipine is a safe antianginal Ca2+-antagonist with broad effectiveness for various types of angina pectoris.

Streptozotocin diabetic rats are hypertensive despite reduced hypothalamic responsiveness.

To determine whether diabetes predisposes rats to hypertension, tail-cuff systolic pressures were measured in male rats made diabetic by pretreatment with streptozotocin. From Weeks 2 through 7, diabetic rats weighed less but had higher systolic pressures than nondiabetic ones. Further comparisons made while the rats were anesthetized with urethane showed that pressor and sympathetic nerve responses to ventromedial hypothalamic stimulation, as well as pressor responses to injected vasopressin, were significantly reduced in the diabetic group. A generalized reduction of cardiovascular reactivity was considered unlikely because systemic pressor responses to norepinephrine and tyramine were unimpaired. Yet reflex bradycardia elicited by norepinephrine was enhanced indicating that baroreceptor resetting had not occurred. Thus, diabetic rats were characterized by hypertension, narrowed pulse pressure, bradycardia with increased reflex responses to norepinephrine, and reduced pressor responses to hypothalamic stimulation and to vasopressin. The successful induction of diabetes was confirmed not only by the presence of hyperglycemia, hypoinsulinemia, glycosuria, and abnormal glucose tolerance, but also by reductions in pancreatic weight, insulin, and beta-cell content. Although our results suggest that diabetic rats are predisposed to become hypertensive, other mechanisms such as hypothalamic depression may be activated to restrict further elevations in blood pressure.