Age-related insulin resistance in hypothalamus and peripheral tissues of orexin knockout mice.

AIMS/HYPOTHESIS: Orexin/hypocretin is a hypothalamic neuropeptide that regulates motivated behaviours, such as feeding and arousal, and, importantly, is also involved in energy homeostasis. The aim of this study was to reveal the role of orexin in the regulation of insulin sensitivity for glucose metabolism. METHODS: Orexin knockout mice fasted overnight underwent oral glucose tolerance testing and insulin tolerance testing. The impact of orexin deficiency on insulin signalling was studied by Western blotting to measure levels of Akt phosphorylation and its upstream and downstream molecules in the hypothalamus, muscle and liver in orexin knockout mice. RESULTS: We found that orexin deficiency caused the age-related development of impaired glucose tolerance and insulin resistance in both male mice without obesity and female mice with mild obesity, fed a normal chow diet. When maintained on a high-fat diet, these abnormalities became more pronounced exclusively in female orexin knockout mice that developed severe obesity. Insulin signalling through Akt was disrupted in peripheral tissues of middle-aged (9-month-old) but not young adult (2-to-3-month-old) orexin knockout mice fed a normal chow diet. Moreover, basal levels of hypothalamic Akt phosphorylation were abnormally elevated in orexin knockout mice at every age studied, and insulin stimulation failed to increase the level of phosphorylation. Similar abnormalities were observed with respect to GSK3beta phosphorylation in the hypothalamus and peripheral tissues of middle-aged orexin knockout mice. CONCLUSIONS/INTERPRETATION: Our results demonstrate a novel role for orexin in hypothalamic insulin signalling, which is likely to be responsible for preventing the development of peripheral insulin resistance with age.

New triterpenes, myrrhanol A and myrrhanone A, from guggul-gum resins, and their potent anti-inflammatory effect on adjuvant-induced air-pouch granuloma of mice.

Myrrhanol A, a new triterpene isolated from guggul (Balsamodendron or Commiphora mukul Hook.)-gum resin, displays a potent anti-inflammatory effect on exudative pouch fluid, angiogenesis, and granuloma weights in adjuvant-induced air-pouch granuloma of mice. Its effects were more marked than those of hydrocortisone and the 50% aqueous methanolic extract of the crude drug. Myrrhanol A is a plausible candidate for a potent anti-inflammatory agent.

Blood-pressure lowering, positive chronotropy and inotropy by the Veratrum alkaloids germidine and germerine but negative chronotropy by veratridine in mice.

Germidine and germerine, the Veratrum alkaloids lowered blood pressure accompanied with positive chronotropy and inotropy in mice. Germerine was more potent than germidine in both blood-pressure lowering and positive inotropy, whereas veratridine produced negative chronotropy and positive inotropy. An acyl group (an acetyl or a 2-methylbutyroyl group) at 3-O-R1 position and a 2-methylbutyroyl group at 15-O-R2 position in germine were important to produce the positive inotropy and chronotropy. The presence of a veratroyl group at 3-O-R1 position and a free hydroxyl group at 15-O-R2 position may be essential to produce the negative chronotropy by veratridine. The positive inotropy by germidine and veratridine may be due to TTX-resistant Na+ channel activation.

Antihyperglycemic effects of gymnemic acid IV, a compound derived from Gymnema sylvestre leaves in streptozotocin-diabetic mice.

We investigated the antihyperglycemic action of a crude saponin fraction and five triterpene glycosides (gymnemic acids I-IV and gymnemasaponin V) derived from the methanol extract of leaves of Gymnema sylvestre R. BR. (Asclepiadaceae) in streptozotocin (STZ)-diabetic mice. The saponin fraction (60mg/kg) reduced blood glucose levels 2 4h after the intraperitoneal administration. Gymnemic acid IV, not the other 4 glycosides at doses of 3.4-13.4mg/kg reduced the blood glucose levels by 13.5-60.0% 6h after the administration comparable to the potency of glibenclamide, and did not change the blood glucose levels of normal mice. Gymnemic acid IV at 13.4 mg/kg increased plasma insulin levels in STZ-diabetic mice. Gymnemic acid IV (1 mg/mL) did not inhibit alpha-glycosidase activity in the brush border membrane vesicles of normal rat small intestines. These results indicate that insulin-releasing action of gymnemic acid IV may contribute to the antihyperglycemic effect by the leaves of G. sylvestre. Gymnemic acid IV may be an anti-obese and antihyperglycemic pro-drug.

[A survey of current nutrition therapy for the ALS patients in Japanese national sanatoriums].

To evaluate the current nutrition therapy for the patients of amyotrophic lateral sclerosis (ALS) in Japan, we sent questionnaires to 53 Japanese national sanatoriums (hospitals) and were able to collect replies from 42 institutes. In these replies, information on 466 patients (262 inpatients and 204 outpatients) was reported, accounting for about 10% of all Japanese ALS patients. Patients who ate orally were more frequent (p < 0.001, chi 2 test) in the outpatients (76.0%) than in the inpatients (39.7%). When the subjects were limited to non-orally nourished cases, gastrostomy was more frequently performed (p < 0.05, chi 2 test) in the outpatients (49%) than in the inpatients (29.1%), but no significant differences were observed between the above two groups as to the quantity of daily caloric intake; the mode was 1000-1200 Cal. About a quarter of non-orally nourished patients received supplemental sodium chloride, and fewer were supplemented copper and/or zinc. The consent of the patients as well as the clinical findings weighed heavily in the determination of the feeding route. Most physicians were disinclined to encourage tube feeding in the early stage of dysphagia, but were supportive of the operation of percutaneous endoscopic gastrostomy when non-oral nutrition therapy became necessary. Although the efficacy of vitamins for ALS has not been proved, 45 of 58 physicians agreed to subscribe vitamins to their patients, especially vitamin B12, E and C.

The antihyperglycaemic blend effect of traditional chinese medicine byakko-ka-ninjin-to on alloxan and diabetic KK-CA(y) mice.

The antihyperglycaemic interaction (blend effect) of component crude drugs included in a traditional Chinese prescription, Byakko-ka-ninjin-to (BN; consisted of five crude drugs, ginseng, anemarrhena,-licorice, gypsum and rice) was investigated using genetically obese diabetic KK-CA(y) mice and alloxan-diabetic mice. The water extract of ginseng, anemarrhena, licorice and gypsum when individually tested markedly lowered blood glucose levels in diabetic animals. Antihyperglycaemic effects of ginseng-anemarrhena and ginseng-licorice combinations were decreased compared with the respective individual-effects. Such decreased effects were partially reversed by adding gypsum or by substituting CaCl(2) for gypsum. The combination of D-O-ANa and glycyrrhizin, respectively the main constituents from ginseng and licorice, also demonstrated a decreased effect compared with the respective individual effects. The CaCl(2) at 0.5 mg/kg (i.p.) was sufficient to partially reverse these effects. These results indicate that antihyperglycaemic effects of BN depend on four crude drugs and Ca(2+) in the blend.

Inhibitory effects of tetrandrine and related synthetic compounds on angiogenesis in streptozotocin-diabetic rodents.

Structure-activity relationships of tetrandrine, isolated from a Kampo medicine, Stephania tetrandrae S. MOORE (root), and related synthetic compounds, were investigated in in vitro fetal bovine serum (FBS)-stimulated angiogenesis of cultured choroids in streptozotocin-diabetic Wistar rats, and air-pouch granuloma angiogenesis in vivo in diabetic mice. Tetrandrine, KS-1-1 (6,7-dimethoxy-1-[[4-[5-(6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroiso quinolinyl)methyl-2-methoxy]phenoxy]benzyl]-2-methyl-1,2,3,4-tetrahyd roisoquinoline), and KS-1-4 (6,7-dimethoxy-1-[[4-[4-(6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroiso quinolinyl)methyl]phenoxy]benzyl]-2-methyl-1,2,3,4-tetrahydroisoquino line), potently inhibited choroidal angiogenesis and air-pouch granuloma angiogenesis in the diabetic state. Their inhibitory effects on diabetic choroids were greater than those on normal choroids. Among these compounds, KS-1-4 inhibited only diabetic angiogenesis. These compounds significantly inhibited FBS-stimulated tube formation in vascular endothelial cells from normal rats. Tetrandrine and KS-1-4, but not KS-1-1, inhibited vascular endothelial growth factor- and platelet-derived growth factor-BB-stimulated angiogenesis in normal choroids. The bis[tetrahydroisoquinoline] moiety, connected by oxy-bis[phenylenemethylene] and 2,2'-dimethyl groups in tetrandrine, contributes to the inhibition of diabetic choroidal angiogenesis. KS-1-4 may be a candidate for anti-choroidopathy and retinopathy drugs in the diabetic state.

Acetylcholine-induced biphasic effect on the maximum upstroke velocity of action potential in mouse right atria: interaction with beta-adrenergic signaling cascade.

Several lines of evidence suggest the molecular and functional entity of muscarinic M1 receptors in mammalian heart. We have reported that acetylcholine (ACh) reduces the maximum upstroke velocity of action potential (Vmax) through activation of muscarinic M1 receptors, which is followed by a muscarinic M2 receptor-mediated increase. The present study sought to determine whether activation of beta-adrenergic receptors modulates the muscarinic M1 and M2 receptor-mediated effects on Vmax in isolated mouse right atria. Intracellular recordings of spontaneous action potential were done using the conventional glass microelectrode technique. Isoproterenol (3 nM) completely antagonized ACh (5 microM)-induced reduction in Vmax. The antagonism was accompanied by a subsequent increase in Vmax. Propranolol (0.3 microM) abolished the effects of isoproterenol on ACh-induced changes in Vmax. Isoproterenol antagonized McN-A-343 (4-(m-chlorophenyl-carbamoyloxy)-2-butynyltrimethylammonium chloride) (300 microM, a muscarinic M1 receptor agonist)-induced reduction in Vmax. Oxotremorine (0.03 microM), a muscarinic M2 receptor agonist, did not affect Vmax by itself, but significantly increased it in the presence of 3 nM isoproterenol. The effects of isoproterenol were mimicked by cholera toxin (100 nM, 1 hr), a Gs-protein activator, and forskolin (10 nM), a direct activator of adenylyl cyclase. H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulphonamide++ +, 1 microM), a selective protein kinase (PK)-A inhibitor, abolished the antagonism by isoproterenol of ACh-induced reduction in Vmax. The present results suggest that activation of the beta-adrenergic-Gs-adenylyl cyclase system antagonizes ACh-induced reduction (muscarinic M1-mediated) and potentiates the subsequent increase (muscarinic M2 receptor-mediated) in Vmax. The beta-adrenergic antagonism of ACh-induced reduction in Vmax may involve cross-talk between PK-A and PK-C signaling pathways.

A mixture of synthetic oligonucleotide probes labeled with biotin for the sensitive detection of potato spindle tuber viroid.

Five kinds of synthetic oligonucleotide probes labeled with biotin (BIO) were designed for the detection of potato spindle tuber viroid (PSTVd), and their sensitivities were compared with that of a digoxigenin (DIG)- or BIO-labeled cDNA probe. Although each oligonucleotide probe alone was less sensitive than the DIG-cDNA probe, sensitivity was increased by using a mixture of two or all of the five oligonucleotide probes. The sensitivity of a PSmix1-5 probe, which was a mixture of five oligonucleotides, was the same as that of a DIG-labeled cDNA probe, which can detect 7.8 pg of purified PSTVd and PSTVd in nucleic acids, equivalent to extracts from 20 microg of infected potato leaf and 310 microg of infected potato tuber. Using the PSmix1-5 probe, PSTVd in all leaves and tubers of seven potato cultivars could be detected without any background. Moreover, with the PSmix1-5 probe, the hybridization time could be shortened to 2 h without any decrease in sensitivity, whereas the sensitivity of the cDNA probes clearly decreased when the hybridization time was shortened. Hybridization using a mixture of several oligonucleotide probes may be applicable to the gene diagnosis of other viroids and viruses.

Inhibitory effects of tetrandrine on angiogenesis in adjuvant-induced chronic inflammation and tube formation of vascular endothelial cells.

The inhibitory effects of tetrandrine (an alkaloid isolated from the Chinese medicine Stephania tetrandrae S. Moore) were investigated in terms of the angiogenesis in an adjuvant-induced chronic inflammation model of mouse and tube formation of rat vascular endothelial cells (EC). Tetrandrine (7.5-30 mg/kg) reduced the carmine content, granuloma weight, inflammatory cell count and pouch fluid weight in the inflammation model in a dose-dependent manner. The inhibitory pattern of tetrandrine on these parameters was similar to that of hydrocortisone. The inhibitory effect of tetrandrine on carmine content was 0.56-fold smaller than that of hydrocortisone. Tetrandrine (0.1-10 microM) also inhibited 2% fetal bovine serum (FBS)-stimulated tube formation of vascular EC. The inhibitory effect of tetrandrine on tube formation was more than 100-fold greater than that of hydrocortisone. Tetrandrine (10-30 nM) inhibited the tube formation stimulated by interleukin (IL)-1alpha and platelet-derived growth factor (PDGF)-BB to a greater extent than FBS-stimulated tube formation. The inhibitory effects of tetrandrine on the action of IL-1alpha and PDGF-BB were non-competitive. These results demonstrate that tetrandrine may reduce the tube formation of EC in the angiogenic process through inhibition on the post-receptor pathway of IL-1alpha and PDGF-BB in chronic inflammation.

Antihyperglycemic effects of N-containing sugars from Xanthocercis zambesiaca, Morus bombycis, Aglaonema treubii, and Castanospermum australe in streptozotocin-diabetic mice.

The aqueous MeOH extract of the leaves and root of Xanthocercis zambesiaca (Leguminosae) and eight structurally related nitrogen-containing sugars, fagomine (1), 4-O-beta-D-glucopyranosylfagomine (2), 3-O-beta-D-glucopyranosylfagomine (3), 3-epifagomine (4), 2,5-dideoxy-2,5-imino-D-mannitol (5), castanospermine (6), alpha-homonojirimycin (7), and 1-deoxynojirimycin (8) were evaluated for antihyperglycemic effects in streptozotocin (STZ)-diabetic mice. The insulin-releasing effects of 1 were also investigated. The blood glucose level fell after i.p. injection of the extract (50 mg/kg). Compounds 1, 2, 5, and 6 reduced the blood glucose level after i.p. injection of 150 mumol/kg. Compound 1 increased plasma insulin level in STZ-diabetic mice and potentiated the 8.3-mM glucose-induced insulin release from the rat isolated-perfused pancreas. The 1-induced potentiation of insulin release may partly contribute to antihyperglycemic action.

Choto-san in the treatment of vascular dementia: a double-blind, placebo-controlled study.

In an earlier placebo-controlled study, we demonstrated that a kampo (Japanese herbal) medicine called Choto-san (Diao-Teng-San in Chinese) was effective in treating vascular dementia. To evaluate its efficacy using more objective criteria, we carried out a multi-center, double-blind study of Choto-san extract (7.5 g/day) and a placebo, each given three times a day for 12 weeks to patients suffering from this condition. The study enrolled and analyzed 139 patients, 50 males and 89 females, with a mean age of 76.6 years. Choto-san was statistically superior to the placebo in global improvement rating, utility rating, global improvement rating of subjective symptoms, global improvement rating of psychiatric symptoms and global improvement rating of disturbance in daily living activities. Such items as spontaneity of conversation, lack of facial expression, decline in simple mathematical ability, global intellectual ability, nocturnal delirium, sleep disturbance, hallucination or delusion, and putting on and taking off clothes were significantly improved at one or more evaluation points in those taking Choto-san compared to those taking the placebo. Furthermore, the change in revised version of Hasegawa's dementia scale from the beginning point in Choto-san group was tended to be higher than that in placebo group with no statistical significance. These results suggest that Choto-san is effective in the treatment of vascular dementia.

Aconitine, a main component of aconite, increases spontaneous acetylcholine release from the frontal cerebral cortex of freely moving rats.

We investigated whether peripherally administered aconitine increases spontaneous acetylcholine (ACh) release from the frontal cerebral cortex in freely moving rats using in vivo microdialysis, as it relates to aconitine-induced bradycardia estimated by a tail-artery cuff technique in unilateral anterior hypothalamus (AH)-lesion mice. Intraperitoneally administered aconitine significantly increased cortical ACh release within 15 min at 10 and 30 micrograms/kg. The increasing effect disappeared 30 min after the administration of aconitine. Aconitine-induced ACh release was not inhibited by intracerebroventricularly preadministered atropine (1 and 3 micrograms/rat). Atropine (1 micrograms/mouse) preadministered into the contralateral intact AH in mice did not affect aconitine (30 micrograms/kg, i.p.)-induced bradycardia. These results indicate that the cortical ACh release caused by peripherally administered aconitine does not occur through activation of the central muscarine receptor, and thus its ACh release may not be concerned with the occurrence of bradycardia.

Combined potentiating effect of byakko-ka-ninjin-to, its constituents, rhizomes of Anemarrhena asphodeloides, tomosaponin A-III, and calcium on pilocarpine-induced saliva secretion in streptozocin-diabetic mice.

The effects on pilocarpine-induced saliva secretion by a hot aqueous extract of Byakko-ka-ninjin-to (BN), its constituents, rhizomes of Anemarrhena asphodeloides, three saponins (pseudoproto-timosaponin-AIII (An-S-1), proto-timosaponin-AIII (An-S-2) and timosaponin-AIII (An-S-3)) and calcium were examined in streptozocin (STZ)-induced diabetic and normal mice. The hot aqueous extracts of BN (250 and 500 mg/kg, i.p.) and Anemarrhena (170 and 340) mg/kg, i.p.) significantly promoted salivary flow in the diabetic animals, but suppressed it in the normal controls. An-S-2 and An-S-3 but not An-S-1 (10 mg/kg, i.p.), significantly promoted salivary How in the diabetic animals. The potency order was An-S-3 >> An-S-2 >> extract. The hot aqueous extracts of BN and Anemarrhena increased the protein content of saliva in a dose-dependent manner. Combination of An-S-3 (0.1 mg/kg, i.p.) with CaCl2 (2 and 4 mg/kg, i.p.) potentiated salivary flow compared with the respective effect of each on its own. These results demonstrated that 1) An-S-3 was mainly responsible for saliva secretion of the hot aqueous extract, and 2) the effect of An-S-3 was potentiated by combination with calcium, suggesting combined effects of Byakko-ka-ninjin-to containing Anemarrhena asphodeloides and gypsum fiber (calcium).

Various treatment techniques on signs and symptoms of delayed onset muscle soreness.

Eccentric activities are an important component of physical conditioning and everyday activities. Delayed onset muscle soreness (DOMS) can result from strenuous eccentric tasks and can be a limiting factor in motor performance for several days after exercise. An efficacious method of treatment for DOMS would enhance athletic performance and hasten the return to activities of daily living. The purpose of this study was to identify a treatment method which could assist in the recovery of DOMS. In the selection of treatment methods, emphasis was directed toward treatments that could be rendered independently by an individual, therefore making the treatment valuable to an athletic trainer in team setting. DOMS was induced in 70 untrained volunteers via 15 sets of 15 eccentric contractions of the forearm extensor muscles on a Lido isokinetic dynamometer. All subjects performed a pilot exercise bout for a minimum of 9 weeks before data collection to assure that DOMS would be produced. Data were collected on 15 dependent variables: active and passive wrist flexion and extension, forearm girth, limb volume, visual analogue pain scale, muscle soreness index, isometric strength, concentric and eccentric wrist total work, concentric and eccentric angle of peak torque. Data were collected on six occasions: pre- and post-induced DOMS, 20 minutes after treatment, and 24, 48, and 72 hours after treatment. Subjects were randomly assigned to 1 of 7 groups (6 treatment and 1 control). Treatments included a nonsteroidal anti-inflammatory drug, high velocity concentric muscle contractions on an upper extremity ergometer, ice massage, 10-minute static stretching, topical Amica montana ointment, and sublingual A. montana pellets. A 7 x 6 ANOVA with repeated measures on time was performed on the delta values of each of the 15 dependent variables. Significant main effects (p < .05) were found for all of the dependent variables on time only. There were no significant differences between treatments. Therefore, we conclude that none of the treatments were effective in abating the signs and symptoms of DOMS. In fact, the NSAID and A. montana treatments appeared to impede recovery of muscle function.

Potentiating effects on pilocarpine-induced saliva secretion, by extracts and N-containing sugars derived from mulberry leaves, in streptozocin-diabetic mice.

The effects of hot water extracts and six compounds of N-containing sugars, 1-deoxynojirimycin (DNJ), N-methyl-DNJ (N-Me-DNJ), 2-O-alpha-D-galactopyranosyl-DNJ (GAL-DNJ), fagomine, 1,4-dideoxy-1,4-imino-D-arabinitol (DAB), and 1,2 alpha,3 beta,4 alpha-tetrahydroxynortropane (calystegin B2), derived from mulberry leaves (Morus alba L.), were investigated on pilocarpine-induced saliva secretion in streptozocin (STZ)-induced diabetic mice. The extracts (100 and 200 mg/kg, i.p.) significantly potentiated the pilocarpine-induced salivary flow but not the protein content. The component compounds (37.5-300 mumol/kg) potentiated the saliva secretion, and the potency order was DAB > fagomine > GAL-DNJ. Only fagomine significantly increased the protein content in the saliva. The potentiation of pilocarpine-induced salivary flow was correlated with anti-hyperglycemic effects by the extract and GAL-DNJ from mulberry leaves in the same dose ranges.

Complementary effects of paeoniflorin and glycyrrhizin on intracellular Ca2+ mobilization in the nerve-stimulated skeletal muscle of mice.

Effects of paeoniflorin (PF) and glycyrrhizin (GLR), contained in paeony and licorice roots, respectively, on contractile and non-contractile Ca2+ mobilization were examined by measuring the Ca(2+)-aequorin luminescence (Ca2+ transients) of the nerve-stimulated skeletal muscle of mice in the presence of neostigmine (0.3 microM). PF (0.1-1 mM) prolonged the duration of non-contractile Ca2+ transients, which may induce the desensitization of nicotinic acetylcholine receptor, but did not affect contractile Ca2+ transients. GLR (0.3-1 mM) depressed contractile Ca2+ transients without affecting non-contractile transients. These results suggest that PF and GLR may have complementary effects on intracellular Ca2+ mobilization to block the neuromuscular transmission.

Inhibitory effect of isoliquiritin, a compound in licorice root, on angiogenesis in vivo and tube formation in vitro.

A water extract of licorice root inhibits granuloma angiogenesis in adjuvant-induced chronic inflammation (Phytother. Res., 5, 195. 1991). The present study has investigated the effects of licorice-derived compounds on granuloma angiogenesis. Isoliquiritin (0.31-3.1 mg/kg), a licorice-derived flavonoid, inhibited the carmine content of granuloma tissue 50-fold greater than licorice extract. Glyeyrrhizin (20-80 mg/kg), a licorice-derived saponin, inhibited carmine content with a weak potency. The licorice extract (0.01-1 mg/ml) also inhibited tube formation from vascular endothelial cells in a concentration-dependent manner. From the chemical structure-activities of used licorice-derived flavonoids (0.1-100 microM), their potencies for anti-tube formation were in the order isoliquiritigenin > isoliquiritin > liquiritigenin >> isoliquiritin-apioside. Glycyrrhizin (0.1-100 microM) and glycyrrhetinic acid (0.1-10 microM) increased tube formation. A glycyrrhizin (82 micrograms/ml)-induced increase in tube formation was inhibited by isoliquiritin. The combined effect of a mixture of 82 micrograms/ml glycyrrhizin and 4.2 micrograms/ml isoliquiritin, a similar concentration ratio to their yield ratio in the licorice extract, corresponded to the effect of 100 micrograms/ml extract. In conclusion, the anti-angiogenic effect of licorice extract depended on the anti-tube formation effect of isoliquiritin.

[Hypoglycemic activity and mechanisms of extracts from mulberry leaves (folium mori) and cortex mori radicis in streptozotocin-induced diabetic mice].

Averaged blood glucose levels were 400 mg/dl in nonfasted mice, and 250 mg/dl in fasted mice in 4 weeks after injection with streptozotocin (STZ, 150 mg/kg, i.v.). These mice were used for experiments. Hypoglycemic effects of hot water extracts (W) from Folium Mori (Mulberry leaves, Morus alba L., China and Japan) or Cortex Mori Radicis (Morus alba L., China) were observed in fasted and nonfasted STZ-induced diabetic mice at a single dose of 200 mg/kg (i.p.). The W from Folium Mori exhibited most potent hypoglycemic effects. The most potent fractions of Folium Mori and Cortex Mori Radicis were ethanol-insoluble extracts (A2). These A2 fractions demonstrated a fall in blood glucose levels of 24.6 +/- 6.0% and 60.5 +/- 9.1% at nonfasted STZ-mice, and 81.4 +/- 7.9% and 77.3 +/- 5.8% at fasted STZ-mice, respectively. The increase in glucose uptake was a mechanism of hypoglycemic actions by W and A2 of Folium Mori.

Depolarizing neuromuscular blocking action of coryneine derived from aconite root in isolated mouse phrenic nerve-diaphragm muscles.

The mode of the neuromuscular blocking action of coryneine (a quaternary ammonium derivative of dopamine) derived from aconite root was investigated in isolated phrenic nerve-diaphragm muscles and denervated diaphragm muscles of mice. Coryneine (20-150 microM) blocked the nerve-evoked twitch response without affecting the contraction evoked by electrical stimulation of the muscle. The blocking effect was reversed by neostigmine, a cholinesterase inhibitor. The electrical charge-response curve on depolarization produced by iontophoretically applied acetylcholine (ACh) at the endplate regions in normal muscles was shifted to the right on decreasing the maximal response by 40 microM coryneine. The double-reciprocal plot revealed that coryneine reduced the apparent affinity of ACh for its receptor on decreasing the maximal response. Coryneine (20 microM-2mM) itself depolarized the endplate membrane and this effect was reversibly suppressed by 1 and 5 microM pancuronium. Coryneine 30 microM-10mM) produced contractions of denervated muscles in a concentration-dependent manner and the effects were reduced by 70nM pancuronium. These results indicate that coryneine is a depolarizing agent and a mixed-type competitive and noncompetitive neuromuscular blocker.