Sodium picosulfate, a laxative, was biotransformed to 4, 4''-dihydroxydiphenyl-(2 pyridyl)-methane by intestinal flora that produced a novel sulfotransferase (not sulfatase). The biotransformation was activated by adding phenolic compounds such as phenol, acetaminophen and flavonoids. The enzyme activity related to this biotransformation was the highest in the contents of the caecum region of the intestine. The enzyme activity was 3.0 μmole/hr/g wet feces in humans and 0.75 in rats (pH 8.0). The optimal pH was 9.0.

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The effect of basic fibroblast growth factor (bFGF) treatment on memory and learning performance ability was investigated in basal forebrain (BF)-lesioned mice. Eight-week-old male ddY mice underwent bilateral BF lesions by delivery of radiofrequency current. Basic FGF (5 or 50 ng/side) was microinjected into the same location immediately after lesioning. From fifteen days after the treatment, a step-through type passive avoidance test was performed daily for 10 days. Lesioned animals showed severe impairment in the acquisition process in this task, but not in the retention process. Basic FGF improved the step-through performances; step-through latency was elongated in a dose-dependent manner on the first test trial day and the mean time required to reach the acquisition criterion was shorter than in the vehicle-treated control group. However, bFGF did not alter the cortical choline acetyltransferase (ChAT) activity decrement induced by BF lesion. These results suggest that bFGF ameliorates the memory deficit without affecting the cortical ChAT activity.

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Acute cerebral ischemia was produced in rats by injection of arachidonic acid (AA) into the internal carotid artery. Evans blue (EB) was intravenously injected and its extravasation into the brain was determined as an indicator of disturbances in the blood-brain barrier and endothelial cells. Control animals showed severe cerebral edema and marked blue staining of the brain. Benidipine (30 μg/kg, i.p.) suppressed the increase in cerebral water content and the extravasation of EB. Similarly, nicardipine (100 μg/kg, i.p.) suppressed the elevation of water content and the extravasation of EB. Furthermore, both benidipine (30 μg/kg, i.p.) and nicardipine (100 μg/kg, i.p.) improved, the neuronal injuries following AA-injection. An antiplatelet agent, ticlopidine (100 mg/kg, i.p.), and a thromboxane A₂ synthetase inhibitor, OKY-1581 (3 mg/kg, i.p.), also suppressed the elevation of cerebral water content. A lipoxygenase inhibitor, AA-861 (200 mg/kg, p.o.), and a cyclooxygenase inhibitor, indomethacin (10 mg/kg, i.p.), did not prevent the increase in cerebral water content. Neither benidipine (3-30 μg/kg, i.v.) nor nicardipine (100 μg/kg, i.v.) inhibited the AgNO₃-induced thrombus formation of the abdominal aorta, whereas ticlopidine (100 mg/kg, p.o.) and OKY-1581 (3 mg/kg, i.v.) prevented the thrombus formation. From the present results, it is suggested that benidipine, as well as nicardipine, may protect against AA-induced acute cerebral infarction via a mechanism independent of antithrombotic action.

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We investigated blocking effects of the selective β₁-adrenoceptor blocker atenolol (0.1-100 μg/kg, i.v.), the selective β₂-adrenoceptor blocker ICI 118, 551 (1-1000 μg/kg, i.v.) and the combination of the two drugs on positive chronotropic and dromotropic responses to norepinephrine (NE) released by stimulation of the sympathetic nerves in anesthetized, neurally decentralized, open-chest dogs after atropine was given. Stimulation of the intracardiac sympathetic nerves to the SA nodal region or to the AV nodal region selectively increased heart rate or decreased AV conduction time, respectively. ICI 118, 551 inhibited the chronotropic or dromotropic response to each stimulation in a dose-dependent manner, but its inhibition of the dromotropic response was less than that of the chronotropic response. Atenolol similarly inhibited either the positive chronotropic or dromotropic response to each stimulation in a dose-related manner. The combination of atenolol and ICI 118, 551 attenuated the responses to each stimulation more than atenolol alone. These data indicate that sympathetic nerve stimulation activates both β₁- and β₂-adrenoceptors of the SA and AV nodes and that the proportion of β₂-adrenoceptor-mediated effects on the AV node is less than that on the SA node. These results suggest that neurally released NE in part controls physiological functional cardiac responses mediated through β₂-adrenoceptors, in addition to the responses predominantly mediated through β₁-adrenoceptors.

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The effects of repeated administration of levoprotiline, a novel type of tetracyclic antide-pressant on histamine H₁, muscarinic acetylcholine and α₁-adrenergic receptors and the response of phosphoinositide hydrolysis (PI) stimulated by histamine in the cortex of the rat brain were investigated. Histamine H₁ receptors were up-regulated to 120% and PI response stimulated by histamine was enhanced to 160%-200% after repeated treatment with levoprotiline (20 mg/kg, i.p., once a day for 28 days) when compared to that of the saline-treated group. No significant alterations of muscarinic acetylcholine and α₁-adrenergic receptors were observed. This demonstrates that the repeated treatment with levoprotiline has prominent action on the regulation of histamine H₁ receptors and PI response coupling to histamine H₁ receptors in vivo.

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Phenylephrine-induced oscillatory contractions in rabbit mesenteric arteries were investigated in vitro. Adrenergic, cholinergic, or histamine antagonists as well as cyclooxygenase and lipoxygenase inhibitors had no effect on this phenylephrine-induced oscillation. The removal of extracellular calcium ions or treatment with a calcium antagonist reduced the amplitude and frequency of the oscillation. Removal of the endothelium or treatment with inhibitors of the synthesis or the target enzyme of endothelium-derived relaxing factor (EDRF) also reduced the amplitude and frequency of the oscillation. In a perfusion bioassay, the perfusate from an endothelium-intact arterial segment induced oscillation of an endothelium-denuded arterial ring recipient. These results suggest that phenylephrine-induced oscillation is mediated by an endothelium-derived factor such as EDRF and depends on the influx of extracellular calcium ions.

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We investigated the effect of intravenous taurine infusion on the electroretinogram (ERG) of taurine-deficient rats produced by treatment with guanidinoethyl sulfonate (GES), a taurine transport inhibitor. Mother rats were fed a taurine-free diet and given drinking water containing 1% GES from 2 weeks of gestation to weaning. The same feeding conditions were applied to male offspring after weaning. Both ERG measurement and continuous infusion of taurine at a dose of 10, 30 or 100 mg/animal/day were performed for 3 weeks from 7 to 10 weeks of age. GES-treatment reduced a- and b-wave amplitudes to 50% of the control levels and also increased b-wave latencies. Intravenous infusion of taurine improved these ERG abnormalities in a dose-dependent manner. Taurine concentrations in plasma, eyes and brain were also decreased by treatment with GES, and dose-dependent recovery was observed after infusion with taurine, although the concentrations of other amino acids were not affected by GES-treatment and infusion of taurine. Observations of morphological changes revealed that the retinal damage in GES-treated animals was decreased by taurine infusion. These results indicate that the changes in ERG and retinal structure observed in taurine deficiency are improved by intravenous infusion of taurine.

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The time-dependent effect of platelet-derived growth factor (PDGF) on cell proliferation was investigated to clarify whether PDGF accelerates the rate of proliferation or its start in primary cultured smooth muscle cells (SMC) of rat aorta. In synchronized SMC at the G₀ phase, 1, 10 and 100 ng/ml PDGF started DNA synthesis at 24, 15-18 and 12 hr, respectively, after stimulation by 3% fetal bovine serum (FBS) or hypophysectomized rat plasma (deficient in insulin-like growth factor-I (IGF-I)). Heparin (1, 10 or 100 μg/ml) decreased only the rate of DNA synthesis stimulated by PDGF in synchronized SMC. DNA synthesis in non-synchronized cells stimulated by PDGF with FBS was determined up to 10 days in culture. The stimulation with 1% FBS plus 30 ng/ml PDGF potentiated the DNA synthesis which was saturated with stimulation by 10% FBS alone, suggesting that prolonged treatment of PDGF transforms SMC. These results demonstrated that PDGF concentration-dependently accelerated the induction of competence independently of IGF-I, and heparin did not inhibit PDGF-induced competence but inhibited progression in primary cultured SMC of rat aorta.

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The effect of a chemically stable prostacyclin analog, OP-41483 α-cyclodextrin clathrate (OP-41483·α-CD), on vascular lesions, platelet aggregation and blood pressure were examined and compared with those of prostaglandin E₁ α-cyclodextrin clathrate (PGE₁·CD) in in vivo rat models. 1) In the laurate (1 mg/leg, i.a.)-induced arterial thrombotic model, OP-41483·α-CD (1 μg/kg/min, i.v.) prevented the progression of femoral arterial vascular lesions and enhanced the development of collaterals in the femoral artery. PGE₁·CD did not inhibit the progression of vascular damages. 2) In the model of vasoconstriction induced by epinephrine (0.05 mg/tail, s.c.) and ergotamine (2 mg/kg, s.c.), OP-41483·α-CD and PGE₁·CD, at 1 μg/kg/min, inhibited the progress of tail gangrene and lessened the decrease in tail cutaneous blood flow. 3) OP-41483·α-CD (1 μg/kg/min) suppressed the ADP (0.1 mg/kg/min, i.v.)-induced decrease in the number of circulating platelets without affecting the change in blood pressure. In contrast, PGE₁·CD (3 μg/kg/min) inhibited ADP-induced thrombocytopenia with a decrease in blood pressure. These results indicate that OP-41483·α-CD has antiplatelet and cutaneous blood flow improving activities that are greater than its hypotensive effect and may be of therapeutic potential in peripheral vascular diseases.

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Pravastatin sodium (pravastatin), a tissue-selective inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, was administered alone (50 mg/kg) or in combination with cholestyramine, a bile acid sequestrant resin, at the level of 2% in the diet to homozygous Watanabe heritable hyper-lipidemic (WHHL) rabbits for 4 weeks. The low density lipoprotein (LDL)-cholesterol levels were reduced by 29% and 56% with pravastatin alone and the combination treatment, respectively. Hepatic LDL receptor activity was increased by 11.2- and 13.9-fold with pravastatin alone and the combination treatment, respectively. The LDL receptor activity in the untreated homozygous WHHL rabbits was only 2.5% of that in the normal rabbits. mRNA for the LDL receptor in the liver was also increased by 2.1- and 3.4-fold with pravastatin alone and the combination treatment, respectively. On the other hand, mRNA for the LDL receptor in the adrenal gland was not affected by pravastatin and the combination treatment, whereas the mRNA in the intestine was increased in both groups. These results suggest the following: 1) the induction of hepatic LDL receptor activity by the treatment of pravastatin alone or in combination with cholestyramine is the main cause of the reduction of serum cholesterol levels by these treatments even in LDL receptor-deficient animals. 2) The induction of the mRNA for the LDL receptor in the liver and intestine, but not that in the adrenal gland, might be a reflection of the tissue-selective inhibition of cholesterol synthesis by pravastatin.

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Pentazocine and its related compounds were examined for their effect on the cytotoxicity of cortisone-resistant lymphocytes (CR lymphocytes) against Ehrlich carcinoma cells. The following compounds were used: pentazocine, naloxone, levallorphan, eptazocine and morphine. CR lymphocytes were obtained from the thymus or spleens of mice injected i.p. with hydrocortisone acetate (125 mg/kg) 2 days before harvesting the lymphocytes. The mixture of tumor cells and CR lymphocytes was inoculated s.c. into mice after incubation in the presence or absence of 10 μM drugs. Five weeks after the inoculation, the percentage of mice developing a solid tumor among the recipients given the pentazocine-treated cell mixture of tumor cells and thymic CR lymphocytes was significantly smaller than the percentage in recipients given the cell mixture treated with or without other drugs (percent tumor takes: 21% and about 80%, respectively). Splenic CR lymphocytes did not show any cytotoxic effect, irrespective of the drug treatment. The pretreatment of CR lymphocytes or Ehrlich cells with 10 μM pentazocine did not affect the cytotoxicity of thymic and splenic CR lymphocytes. The proportion of the lymphocyte-conjugated tumor cells was significantly increased when the mixture of CR lymphocytes and tumor cells was incubated in the presence of pentazocine. The present results indicate that the cytotoxicity of thymic CR lymphocytes is enhanced by pentazocine possibly through the increase in the proportion of the lymphocyte-conjugated tumor cells but enhanced not by the other drugs.

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The inhibitory mechanisms of immediate hypersensitivity reactions by glucocorticoid (GC) were studied in rats. Homologous passive cutaneous anaphylaxis (PCA) mediated by IgE anti-bodies and cutaneous reactions caused by histamine, serotonin and leukotriene C₄ were elicited at the same time in the same rats. Three kinds of GC, hydrocortisone, prednisolone and dexamethasone, inhibited all these reactions significantly. Although mediator-induced cutaneous reactions were inhibited transiently around 2 hours after GC administration, inhibition of PCA was more potent and lasted longer. A time lag seemed to be essential for both inhibitions. IgE antibody-mediated histamine release in vivo in the rat peritoneal cavity was also inhibited by GC administration significantly, and the inhibition was long lasting when compared to those of the mediator-induced cutaneous reactions. Tyrosine amino-transferase (TAT) activity in the rat liver increased significantly by GC administration, and the in creased TAT activity was completely abrogated by simultaneous administration of 5 mg/kg of cyclohex imide (CH). In the same experimental condition, although inhibition of histamine-induced cutaneous reaction by GC was completely abrogated, the inhibition of PCA elicited at the same time in the same rats was only partially attenuated. Furthermore, the same dose of CH little affected the dexamethasone inhibition of histamine release in the rat peritoneal cavity, although the increase of TAT activity in the liver of the same rats was completely abrogated. These results demonstrate that PCA is inhibited by GC through at least 2 mechanisms, inhibition of mediator release from mast cells and non-specific inhibition of vascular permeability increase caused by released mediators. Although the latter action of GC is dependent upon protein synthesis, the former seems to be mediated by a unique mechanism independent of protein synthesis.

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The antinephritic effect of pachyman on original-type anti-GBM nephritis in rats was investigated. Pachyman was given to original-type anti-GBM nephritic rats for 10 days from the day of anti-GBM serum injection. Pachyman prevented urinary protein excretion and the elevation of serum cholesterol content. Histopathological observations of the glomeruli indicated that although the number of nuclei and adhesion to capillary walls of Bowman''s capsule in nephritic control rats were significantly increased, pachyman reduced the degree of histopathological changes such as hypercellularity and adhesion as compared to the control group. Although the serum complement CH₅₀ ratio in control group was significantly lower than that in the normal group, the decrease in serum complement CH₅₀ was inhibited by pachyman, and rat C₃ deposition in the glomeruli in the pachyman-treated group was significantly reduced. These results suggest that pachyman was effective against original-type anti-GBM nephritis in rats and that the antinephritic mechanisms of pachyman may be partly due to the inhibitory action of this agent on C₃ deposition in the glomeruli.

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We investigated the effects of A23187 and phorbol 12, 13-dibutyrate (PDBu) on sn-1, 2-diacylglycerol (DAG) accumulation and phosphatidylcholine (PC) hydrolysis in rat parotid acinar cells. Both A23187 and PDBu, in concentration ranges of 0.001-0.1 μM, stimulated DAG accumulation and PC hydrolysis in a time- and concentration-dependent manner. Treatment with A23187 and PDBu stimulated the release of [³H]choline and [³H]phosphocholine into the medium, indicating [³H]PC hydrolysis is due to the activation of phospholipases C and D; however, [³H]phosphatidylethanolamine hydrolysis was not indicated. These releases were unaffected by the addition of glucose 6-phosphate, a phosphatase inhibitor. Staurosporine, a protein kinase C inhibitor, significantly inhibited the DAG accumulation and the PC hydrolysis stimulated by these agents. Combinations of A23187 and PDBu potentiated the stimulatory effect which each of these agents alone had on DAG accumulation and PC hydrolysis. This mode of action was additive but not synergistic. These results suggest that DAG accumulation induced by A23187 and PDBu is related to the PC hydrolysis mediated via the activation of phospholipases C and D, and that it is not related to phosphatidylethanolamine hydrolysis.

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To clarify which 5-HT_1A receptors, autoreceptors located in the raphe nuclei or post-synaptic receptors in the forebrain areas receiving a 5-HT input, mediate the anticonflict action of tandospirone (a 5-HT_1A receptor-related anxiolytics), the behavioral effects of tandospirone were studied in 5, 7-dihydroxytryptamine (5, 7-DHT) treated rats. By measuring both monoamines and their metabolite levels and densities of [³H]8-OH-DPAT binding in 5, 7-DHT-treated rat brain, we confirmed that pretreatment with 5, 7-DHT destroyed 5-HT neurons selectively without affecting postsynaptic 5-HT_1A receptors located on the postsynaptic neurons. This selective destruction produced no significant changes in the drinking behavior of rats in either punished or unpunished sessions of the Vogel conflict test. Furthermore, this destruction altered neither the effect of tandospirone on punished responding in this procedure nor the potency of tandospirone to induce a flat body posture in rats, which is known as the “serotonin behavioral syndrome”. These results suggested that the anticonflict action of tandospirone may be produced, at least in part, by binding to postsynaptic 5-HT_1A receptors and activating them as agonists, and not to 5-HT_1A autoreceptors located on the cell bodies of 5-HT neurons.

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To examine the effects of drugs on short-term memory in animals, the delayed discrimination experiment in rats and the delayed matching to sample experiment in rhesus monkeys were conducted. Nicotine at 0.125 mg/kg, s.c. in rats and at 0.5 mg/kg, s.c. in monkeys increased the percentages of correct choices. Scopolamine at 0.06-0.12 mg/kg, s.c. in rats and at 0.015 mg/kg, s.c. in monkeys decreased the percentages of correct choices. However, supposedly memory-specific, delaytime-dependent disruptive effects by scopolamine were found only in monkeys. Diazepam at 0.5-2 mg/kg, s.c. did not change the correct choices in rats. However, diazepam at 1-4 mg/kg, i.g. decreased the correct choices in monkeys regardless of the delay time. Chlorpromazine at 0.25-1.5 mg/kg, s.c. showed inconsistent effects in rats. In monkeys, chlorpromazine at 0.25-0.5 mg/kg, s.c. had no effect. These results suggested that using both rats and monkeys would be useful for evaluating the effects of drugs on memory.

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Mice were maintained under conditions of light from 7 a.m. to 7 p.m. and dark from 7 p.m. to 7 a.m. Probucol was given orally to these animals once daily at 10 a.m. or 10 p.m. for 7 days. Blood samples for serum cholesterol were obtained at 24 hours after the final dosage. Blood samples for plasma probucol were obtained just before and at 3, 6, 12, 24, 48, 72, 96 and 120 hours after the final dosage. The cholesterol lowering effect of the agent at 10 p.m. was greater than that at 10 a.m. Plasma probucol concentrations of the two trials did not differ at any observation point. These data suggest that the effect of probucol varies with its time of administration. This might not be caused by a time-dependent change in plasma probucol concentration.

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Alzheimer''s Disease (AD) patients have a severe degeneration of cholinergic neurons in their cerebral cortices. Basal forebrain (BF)-lesioned rat is used as a model animal of a cholinergic deficit in the cerebral cortex. Cholinergic markers were decreased in the cerebral cortex of BF-lesioned rats. Intracerebroventricular continuous infusion of cholecystokinin octapeptide (CCK8) following BF lesion obviously preserved these cholinergic markers. These results suggest that CCK8 prevents the degeneration of cholinergic neurons in the cerebral cortex following BF lesion.

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The effects of anti-asthma drugs, isoproterenol, aminophylline and hydrocortisone, and potassium channel openers on the contraction induced by electrical stimulation or exogenously applied acetylcholine were investigated in isolated guinea pig trachea. Isoproterenol and aminophylline non-selectively inhibited both the contraction evoked by vagus nerve- and that by transmural field-stimulation, but had no effect on the response induced by exogenously applied acetylcholine. Hydrocortisone and potassium channel openers, NIP-121 and cromakalim, preferentially inhibited vagus nerve-mediated response. These results suggest that anti-asthma drugs may have an ability to inhibit neurally-mediated contraction in the guinea pig trachea.

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Using a perfusion technique of isolated vessels, constrictor responses to vasopressin (VP) and norepinephrine (NE) were investigated in perfused dog femoral arteries. Both OPC-21268, a selective V₁-antagonist, and OPC-31260, a selective V₂-antagonist, significantly shifted the VP-induced dose response curves to the right without influencing the NE-induced ones. The blocking effects of OPC-31260 were much greater than those of OPC-21268, suggesting that there may probably be functional V₁- and V₂-receptors in isolated dog femoral arteries that mediate vasoconstriction.

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