This report describes the features of the anti-ulcer effect of Oren-gedoku-to (OGT, a traditional Chinese medicine) and its component herb drugs. Coptidis rhizoma and Phellodendri cortex given orally dose-dependently inhibited the appearance of ethanol-induced gastric hemorrhagic lesions in a dose range of 25-100 mg/kg, but the formation of the lesions was not prevented by Scutellariae radix or Gardeniae fructus at the same doses. Coptidis rhizoma, Phellodendri cortex and Gardeniae fructus inhibited the gastric potential difference (PD) reduction induced by ethanol, whereas Scutellariae radix did not prevent the decrease in the PD reduction caused by ethanol. Phellodendri cortex, Scutellariae radix and Gardeniae fructus had no significant influence on the basal PD, while Coptidis rhizoma increased the basal PD. The four herb drugs prevented gastric acid secretion induced by 2-deoxy-D-glucose, but the three drugs except for Phellodendri cortex showed little effect on pentagastrin-stimulation. These results suggest that the gastric mucosal protection by OGT is ascribed to Coptidis rhizoma and Phellodendri cortex, and its antisecretory effect is due to the four drugs.
5-Phenylmethylenehydantoin (5-PMH) and 5 (o-methoxyphenyl)-methylenehydantoin (5-o-MPMH) were found to have anticonvulsant activities with ED50 values of 48 and 73 mg/kg as compared to 11 mg/kg for phenytoin. The log dose-logit plots yielded nearly parallel straight lines for all three compounds, indicating that they may have the same mechanism of action. The meta and paramethoxy isomers of 5-o-MPMH, 5-m-MPMH and 5-p-MPMH, did not show any anticonvulsant activity up to 200 mg/kg. In addition, 5-o-MPMH induced neurological deficits as shown by marked effects on rota-rod performance in the dose range of 50-90 mg/kg. Above 100 mg/kg, 5-o-MPMH caused a loss of the righting reflex in mice for up to 2.3 hr at 200 mg/kg. In contrast, 5-PMH, 5-m-MPMH and 5-p-MPMH may have slight sedative effects, but only 5-m-MPMH decreased rota-rod performance significantly at 90 mg/kg. None of the three was hypnotic up to 200 mg/kg in dose. It is therefore inferred that 5-o-MPMH causes general CNS depression via a mechanism distinct from that of its anticonvulsant effects which is shared by phenytoin and 5-PMH. 5-o-MPMH increased jumping latency in the hot plate test in the same dose range as it causes neurological deficit. 5-o-MPMH also appeared to have a similar degree of toxicity in mice as diazepam judging from rough estimates of their LD50/HD85 ratios.
Our previous study showed that FK973 (11-acetyl-8-carbamoyloxymethyl-4-formyl-14-oxa-1, 11 diazatetracyclo [7.4.1.02, 7010, 12]tetradeca-2, 4, 6-trien-6, 9-diyl diacetate), a novel substituted dihydrobenzoxazine, which is a derivative of the fermentation product of Streptomyces sandaensis No. 6897, had strong antitumor effects on experimental tumors in vitro and in vivo. In this report, we investigated its effect on the cell cycle of murine leukemia L1210 cells in vitro by means of DNA/5-bromo-2'-deoxyuridine double staining and compared these effects with those of other antitumor drugs. Both FK973 and mitomycin C arrested the cells in the G2 phase. Vinblastine arrested the cells in the M phase and cytosine arabinoside, in the G1 phase. Although FK973 and mitomycin C were shown to act on the cell cycle in a similar way, FK973 was slower in producing its effect. From the results, FK973 arrests the cells in the G2 phase, and it appears that FK973 must be converted into the activated form in the cells for the development of its antitumor effects.
The role of histamine H2-receptors in AV nodal conduction was estimated in the blood-perfused AV node preparation of the dog. Histamine injected into the AV node artery caused an initial, predominant, dose-related prolongation of the AH interval, which was followed by a slight but significant shortening. Diphenhydramine, an H1-antagonist, abolished the initial prolongation, but the shortening was slightly enhanced. Cimetidine, an H2-antagonist, abolished the shortening and potentiated the initial prolongation. Dimaprit, an H2-agonist, caused only a slight, dose-related shortening of the AH interval, which was abolished by cimetidine. The shortening induced by either histamine or dimaprit was slightly suppressed, but was never abolished by atenolol, a beta-blocker, which completely abolished the noradrenaline-induced shortening. These results indicate that a positive dromotropic effect via H2-receptors exists in the canine AV node, although the main effect of histamine on AV nodal conduction is a negative one via H1-receptors.
DN-2327, 2-(7-chloro-1, 8-naphthyridin-2-yl)-3-[(1, 4-dioxa-8-azaspiro-[4, 5]dec-8-yl)carbonylmethyl]isoindolin-1-one, produced anxiolytic, taming and anti-convulsive effects when administered orally to several species of animals. DN-2327 produced few of the sedative-hypnotic and muscle-relaxant effects observed with diazepam. The durations of the anxiolytic and anti-convulsive activities of DN-2327 were much longer than those of diazepam. Tolerance to DN-2327 did not develop when it was administered daily for 14 days in an anti-conflict test (Vogel conflict test). DN-2327 showed potent displacement activity against[3H]diazepam binding. The binding affinity of DN-2327 for benzodiazepine receptors was about twenty times that of diazepam. Furthermore, the affinity of DN-2327 for benzodiazepine receptors was not enhanced by the presence of GABA. There is a wide margin between the doses of DN-2327 that cause the anxiolytic effects and its sedative-hypnotic/muscle-relaxant effects. These results suggest that DN-2327 has more marked anxioselective properties compared with the benzodiazepines.
The [3H]mepyramine binding to rat liver membranes was about 2-fold higher in the presence of 2 mM CaCl2 than in the absence. However, the [3H]-mepyramine binding to rat brain membranes was not affected by the presence of 2 mM CaCl2. Scatchard analysis showed that 2 mM CaCl2 did not change the affinity (KD) of liver membranes to [3H]mepyramine, but increased the binding capacity (Bmax). CaCl2 had a half maximal effect (ED50) at 3 μM and a maximal effect at concentrations of more than 10 μM. Other divalent cations, Mg++, Mn++, Sr++ and Ba++, also increased the [3H]mepyramine binding, whereas monovalent cations, Na+, K+, Li+ and Rb+, had no effect.
Microinjection of the muscarinic agonist oxotremorine into the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei which contain cell bodies of vasopressinergic neurons induced potent antidiuretic effects in waterloaded and ethanol-anesthetized rats. The effects included both decreases in urine outflow and increases in urine osmotic pressure. However, no significant changes in various visceral functions other than antidiuresis such as mean blood pressure, heart rate, respiration rate and rectal temperature were observed when oxotremorine was microinjected into the SON. Only a slight change in mean blood pressure (approx. 10 mmHg decrease) was observed by the microinjection into the PVN. Intravenous preinjection of a vasopressin (AVP) V1 V2 antagonist that has one of the most potent V2 (antidiuretic)-antagonist activities, d(CH2)5-D-Tyr(Et)VAVP, inhibited nearly completely the antidiuretic effects induced by the microinjection of oxotremorine. The results demonstrated that oxotremorine stimulated muscarinic receptors in the hypothalamic SON and PVN, released AVP and induced an antidiuretic effect through AVP-receptors in the kidney.
P-450-male is one of the male-specific forms of cytochrome P-450 in liver microsomes of adult rats and functions as testosterone 2α- and 16α-hydroxylases. The purpose of this study was to examine whether forms of cytochrome P-450 cross-reactive with anti-P-450-male antibodies are present in liver microsomes of other animal species, such as male and female mice, rabbits, guinea pigs, hamsters, dogs and humans. The antibodies cross-reacted with a protein(s) in the liver microsomes of all animal species to show one or more bands on nitrocellulose paper by Western blot peroxidase-anti-peroxidase staining analysis. Qualitative as well as quantitative species differences were noted in the testosterone hydroxylases. The antibodies inhibited 2α-hydroxylase in male rats, 16α-hydroxylase in male rats and male and female dogs, 7α-hydroxylase in female rats and male and female mice and hamsters, and 15α-hydroxylase in female mice and hamsters. No clear inhibition of 6β-hydroxylase, which was present in all animal species, was observed. These results indicate that forms of cytochrome P-450 that are immunochemically related with P-450-male catalyze the hydroxylation of testosterone at varying positions depending on the animal species, with the exception of 6β-hydroxylation, which may be catalyzed by a distinct form of cytochrome P-450.
Little is known about the physiological role of surface active phospholipids (SAP) in the central respiratory tract. In the present study, the effect of SAP on acid-inducing inhibition of particle transport by the tracheal mucociliary function was investigated in unanesthetized pigeons. SAP and acids were directly nebulized to the surface of the trachea. The composition of SAP was based on that of the pulmonary surfactant. The experiment was carried out under application of acetylcholine providing a constant mucociliary transport. SAP significantly diminished HCl- and H2SO4-inducing inhibitions of the mucociliary transport. Benzalkonium chloride also reduced the inhibition. The results suggest that SAP may be a protecting factor of the mucociliary clearance and that SAP may be connected with hydrophobicity not only of the alveolar surface but of the tracheal epithelium.
The effect of a high-cholesterol (CHOL) diet and corticosteroids on the toxicity of vitamin D2 (VD2) in rats was studied. VD2 was administered orally at the dosage of 5-60×104 IU/kg, once daily for 4 days. Animals fed CHOL showed a decrease in mortality due to VD2 treatment. Dietary CHOL inhibited toxic responses such as a diminished growth rate following anorexia, elevated serum calcium level and calcium deposition in tissues, which were produced by a sublethal dose of VD2 (20×104 IU/kg, once daily for 4 days). Animals pretreated with the high-CHOL diet from 2 weeks before the first VD2 administration showed much more symptomatic relief than those given this diet after the first VD2 administration. On the other hand, dexamethasone (DEX) as well as corticosterone remarkably increased the mortality due to VD2. The degree of VD2 toxicity, enhanced by DEX, was correlated with the degree of hypercalcemia and tissue calcification. Therefore, the inhibitory effect of CHOL is not likely to be due to activation of the CHOL-corticosterone system in the adrenal gland.
The plasma extravasation inducing activities of several chemical mediators (allergic agents: histamine, leukotriene C4 (LTC4) and platelet activating factor (PAF); neurogenic agents: substance P, capsaicin and carbachol) have been investigated and characterized in rat skin and trachea. Substance P, histamine, LTC4 and PAF induced dose-dependent plasma extravasation in rat skin. The activities of these mediators in inducing tracheal plasma extravasation were very different from those in the skin reactions. When these mediators were injected intravenously, substance P induced severe plasma extravasation, and the activities of histamine and PAF were weaker than that of substance P. When injected intratracheally, only substance P and capsaicin induced tracheal plasma extravasation, while none of the allergic mediators tested caused any plasma extravasation in the trachea. Carbachol did not induce any plasma extravasation in either skin or trachea. These results indicate that the stimulation of afferent substance P-containing nerve fibers has a more important role in the induction of tracheal plasma extravasation than that of allergic chemical mediators.
In vitro cardiac effects of a cardiotonic drug, MCI-154, for which the main action mechanism was proposed to be the enhancement of Ca2+ sensitivity of cardiac contractile proteins, were investigated. MCI-154 (3×10-8-3×10-4 M) increased the developed tension in isolated ventricular muscles from cats, dogs, guinea pigs and rats and increased that of isolated left atrial muscles of guinea pigs and rats. However, species differences were observed in the responses to MCI-154. The positive inotropic potency of MCI-154 was stronger than those of amrinone and milrinone. In the isolated right atria from guinea pigs and rats, properties of the chronotropic effect of MCI-154 were different from those of amrinone and milrinone. The positive inotropic action of MCI-154 was not affected by phentolamine, propranolol, cimetidine and tetrodotoxin. MCI-154 did not inhibit cardiac Na+, K+-ATPase. MCI-154 modelately stimulated Ca2+-uptake of isolated cardiac sarcoplasmic reticulum (SR), but induced no release of Ca2+ the SR. These results support the view that the main mechanism for the action of MCI-154 is the enhancement of Ca2+ sensitivity of cardiac contractile proteins.
Studies were made on the effects of in vivo administration of an "antidementia drug", pantoyl-GABA, on choline acetyltransferase (ChAT) activity in mouse brain. Male ICR mice were treated intraperitoneally with 500 mg/kg of pantoyl-GABA, once a day, for various periods. Then they were killed, and the ChAT activities of their cerebral cortex, hippocampus and striatum were measured. Results showed that ChAT activity increased significantly in the cerebral cortex and hippocampus from day 5 and 7, respectively, of treatment, but did not increase in the striatum even after treatment for 14 days. The kinetics of ChAT activity were investigated in tissues from the cerebral cortex and hippocampus of mice treated with the drug for 7 days. Drug-treatment increased the Vmax value, but did not affect the Km values for choline and acetyl-CoA. These results indicate that longterm treatment with pantoyl-GABA enhanced ChAT activity, without altering the affinity of the enzyme for either substrate.
Effect of (±)-methyl 3-ethyl-2, 3, 3a, 4-tetrahydro-1H-indolo[3, 2, 1-de] [1, 5] naphthyridine-6-carboxylate hydrochloride (OM-853), a new vincamine analogue, on the metabolism and function of cerebral 5-hydroxytryptamine (5-HT) neurons was investigated using male Wistar rats. The single administration of OM-853 (200 mg/kg, p.o.) induced the facilitation of metabolic turnover of 5-HT in various brain areas except the cerebral cortex, pons-medulla and cerebellum. In vitro addition of OM-853 inhibited the uptake of [14C]5-HT in striatal slices only at a high concentration (10-4 M). On the other hand, a low concentration of OM-853 (10-8-10-6 M) induced the increase of the spontaneous and high K+ (30 mM)-evoked releases of [14C]5-HT from striatal slices. OM-853 had more potent inhibitory effect on the binding of [3H]8-hydroxy-2-(di-n-propylamino)tetralin (8-hydroxy DPAT) to 5-HT1A receptors and/or 5-HT autoreceptors than that of [3H]-ketanserin to 5-HT2 receptors. The stimulatory effect of OM-853 (10-7 M) on [14C]5-HT release was antagonized by 10-7 M 8-hydroxy DPAT, which is known to act at presynaptic 5-HT autoreceptors as an agonist. These results suggest that OM-853 may induce facilitation of 5-HT turnover by enhancing 5-HT release, probably via the inhibition of presynaptic 5-HT autoreceptor.
Previously we reported the antitumor activity of 4 kinds of Chinese herbs: A. capillaris, S. doederleinii, A. macrocephala and S. subprostrata. Evidence has been also presented that A. capillaris shows the activity mainly through a direct tumoricidal action and the others display the activity through the enhancement of tumor-immune response. The present results are as follows: A. capillaris did not affect Meth A tumor-neutralizing activity (Winn's assay) in spleen cells of BALB/c mice bearing the primary tumor. The other herbs enhanced the activity on days 10 and 15 and prevented the decay of the activity on day 20 after the Meth A tumor transplantation. However, none of them enhanced the local graft versus host reaction (GvHR) induced in CBF1 mice by spleen cells of BALB/c mice. A. capillaris hardly affected the humoral antibody formation against sheep red blood cells in mice. On the contrary, the other 3 herbs enhanced the formation. Blast transformation of murine lymphocytes with PHA-P or LPS was suppressed by 10-5 to 10-4 g/ml of A. capillaris. A. macrocephala enhanced the response by LPS. It should be noted that A. capillaris showed no immunosuppressive action in spite of having a direct tumoricidal action in vitro. Further investigations will be required on the latter 3 herbs to clarify the relationship between their humoral immunity-stimulating activity and their tumor immunity-enhancing activity.
The metabolism of antipyrine (AP) was investigated in female rats of the Dark Agouti (DA) and Lewis (L) strains, which have been proposed as models for human poor and extensive metabolizers of debrisoquine (DB), respectively. Following i.p. injection of 50 mg/kg of AP, the rate of production of 4-hydroxy-antipyrine in 24-hr urine was increased significantly in the L strain. The results suggested that different cytochrome P-450 isozymes were responsible for hydroxylation of AP and DB and showed interphenotype differences between the two strains.
In SART-stressed (repeated cold-stressed) rats, shuttle-avoidance response was examined. The rats exposed to SART stress prior to training showed a high avoidance rate and no change in the intertrial response. Upon exposure to SART stress after completion of learning, the rats showed no change in the avoidance rate and an increase in the intertrial response in the retention test. These results are in contrast to the previous observations of passive avoidance response, and the abnormal behavior in such animals may be based on excessive emotionality and/or hyperreactivity rather than alterations in the process of learning and memory.