The relationship between the anti-inflammatory action and drug behaviors in vivo was investigated by administering five biphenylylacetic acid derivatives to rats. 1) With five drugs, an excellent linear relationship was recognized between % inhibition of carrageenin-induced edema and logarithm of drug concentration in peripheral compartment calculated pharmacokinetically (γ=0.76-0.96). 2) A good linear relationship between areas under % inhibition versus time curves, and logarithm of drug concentration in peripheral compartment versus time curves of each drug was also recognized (γ=0.86). These results suggested that intrinsic drug activities of each drug are approximately the same and drug effect may be restricted to their transporting abilities into peripheral compartment.
In the course of studies on glucose metabolism in the brain under the condition with excessive supply of glucose, 14CO2 production from glucose-14C was examined by incubating the homogenate of the brain from control and streptozotocin-diabetic rats. The production was markedly decreased in the brain homogenate of the diabetic rats as compared with that of control rats. Administration of insulin in the diabetic rats restored the glucose oxidation activity to the control level, but about 30 min was necessary for the restoration. No difference was found between glucose-1-14C and glucose-6-14C in the change in 14CO2 production by the brain homogenate from diabetic rats before and after insulin treatment.
The extract of an Oriental medicine "bushi", Aconitum japonicum roots (raw), was fractionated monitored by the analgesic activity in the tail pressure test, leading to the isolation of a mixture of the aconitines but no other constituents as the active principles. The aconitines have been compared in a variety of animal tests for analgesic activity. As the results, the alkaloids have proved in the tail pressure method and the acetic acid-induced writhing method to show analgesic activity in decreasing order : mesaconitine > aconitine > hypaconitine, though they exhibited no significant activity in the hot plate method. Heating of the raw Aconitum roots at 100°, which is one of the processing procedures of the crude drug, has brought about a rapid decrease of the analgesic activity with concomitant decrease of the content of the aconitines, demonstrating that the benzoylaconines produced by hydrolysis of the aconitines showed little or no analgesic activity. Assay of the benzoylaconines has revealed a weak analgesic activity in the acetic acid-induced writhing test. On the basis of the present results, it is predicted that the clinical effectiveness of the crude drug is due to the aconitines (especially mesaconitine) and partly to the benzoylaconines.
Cadmium administered in vivo was an effective inhibitor of hepatic σ-aminolevulinic acid (ALA) synthetase and an effective stimulator of hepatic heme oxygenase in male mice. Cadmium inhibited the 3, 5-dicarboethoxy-1, 4-dihydrocollidine (DDC)-mediated induction of ALA synthetase when administered 1 hr prior to, or 1 hr subsequent to, the administration of DDC. Cadmium also inhibited the DDC-mediated induction of ALA synthetase when administered 3 hr following the administration of DDC. However, the degree of inhibition was lower than that obtained by administering cadmium 1 hr before or after administration of DDC. Hemin, a well known feed-back repressor of ALA synthetase, was also administered to mice for comparison with the effect of cadmium on the enzyme. Hemin inhibited the DDC-mediated induction of ALA synthetase much more effectively than cadmium when administered 3 hr following the administration of DDC. The administration of cadmium to mice significantly increased hepatic heme oxygenase activity. Pretreatment of mice with cycloheximide almost completely blocked the cadmium-mediated initial increase of heme oxygenase activity, but pretreatment with actinomycin D was less effective, suggesting that cadmium acts at a post-transcriptional step in the synthesis of the enzyme. It is shown that pretreatment of animals with cadmium reduces the toxicity against the subsequent higher dose of the metal. Such protective effect was also observed in the present investigation ; namely, pretreatment of mice with cadmium itself reduced the inhibitory effect on the DDC-mediated induction of ALA synthetase and partially inhibited the initial increase of heme oxygenase activity due to the subsequent administration of the metal. These data suggest that the decrease in cytochrome levels and the inhibition of drugmetabolizing enzyme activity seen following the administration of cadmium to rats or mice are the results of inhibition of ALA synthetase and stimulation of heme oxygenase leading to a decrease in heme levels required for the synthesis of cytochrome P-450.
The relationship between chemical structure and antitumor activity of AB ring analogues of withaferin A was examined by cell growth inhibition in mouse leukemia L5178Y cells in vitro. The 5, 6β-epoxy-4β-ol (5) and 5, 6α-epoxy-4α-ol (6) with 1-keto-2-ene function and cholesterol side chain have antitumor activity. The 4, 5-epoxy-6-hydroxyl compounds (9-16) were found to be equally or more active than corresponding 5, 6-epoxy-4-hydroxyl analogues. The antitumor activities of the 4, 5-epoxides paralleled the reactivities in ring opening reaction with acid. For the antitumor activity of withanolides, the unsaturated lactone in the side chain is important, and 1-keto-2-ene and epoxide functions were essential to elicit the activity.
Single smooth muscle cells were isolated from taenia coli of guinea pig, and calcium-and caffeine-contraction was studied. The degree of contraction of the single cells by calcium under the depolarized condition was dependent on the concentration of calcium but the sensitivity of the cells to calcium was less than that of intact tissue. However, cells which were responsive to calcium were 56% of the cells examined. Subsequent application of caffeine to the cells resulted in contraction of 85% of the single cells. These single cells examined in this experiment were not stained by trypan blue. The results indicated that, during isolation, certain trigger mechanism to produce contraction by exogenous calcium was hindered in a half of the cell preparation.
It was revealed by the Sephadex G-75 gel filtration of rat liver supernatant containing sulfobromophthalein (BSP) that the rats chronically intoxicated with CCl4 have lower BSP conjugating activities as well as lower protein contents in the Y-fraction than the control rats. Enzyme kinetic studies on the Y-fraction were carried out in order to investigate the changes induced by intoxication in the properties of glutathione S-transferases in the Y-fraction with BSP as a substrate. Since neither Km (Michaelis-Menten constant) nor Vmax (maximum velocity) value changed, no alteration by the intoxication was observed in the Y-fraction as a conjugating enzyme. It is clear that the intoxication brought about a decrease in the enzyme content in the Y-fraction, considering that protein concentration of the Y-fraction on the gel filtration decreased without the change of Vmax value. Our previous report showed that the content of endogeneous glutathione (GSH) was not altered by the intoxication. These observation led to the conclusion that the decreased BSP conjugating activity by the intoxication was due to the decreased content of enzyme in the Y-fraction. The BSP binding to the Y-fraction was measured by equilibrium dialysis. It was found that the intoxication reduced the binding constant by more than 50%, whereas the change of dissociation constant (Km) estimated from the enzyme kinetics was not observed.
The effect of colchicine on inflammatory responses in chronic, proliferative inflammation was investigated by using 8-day-old granuloma pouch induced with carrageenin in rats. Colchicine was injected directly into the granuloma pouch, and then vascular permeability of the granuloma pouch, blood volume in the granulation tissue and incorporation of 3H-proline into non-collagen protein of the granulation tissue were determined. Vascular permeability was assayed with the aid of radioiodinated human serum albumin as a tracer. The volume of the blood in the granulation tissue was also measured by using radioiodinated human serum albumin. In the early stage in the action of colchicine, it induced enhancement of the vascular permeability in the granulation tissue, and then, it induced suppression in the late stage in its action. The blood content of the granulation tissue did not change in the early stage but lowered in the late stage in advance to the suppression of the vascular permeability. Therefore, the most primary action of locally injected colchicine is to raise the vascular permeability in the local tissue, and then to decrease blood volume in the local tissues with resultant suppression of the vascular permeability. Incorporation of labeled proline into tissue protein was suppressed under the influence of colchicine regardless of its effect on the vascular permeability.
A tremorgenic mycotoxin, fumitremorgin A (FTA) produces tremor and convulsive seizure, when injected intravenously. The intravenous LD50 of this toxin was 0.185 mg/kg in mice. Neuropharmacologic agents known to be serotonergic, dopaminergic and GABAergic function in brain were used to investigate the possible relationship between these putative transmitter systems and the induction and modulation of FTA-induced tremor and tonic-clonic convulsion. The results indicate a non-involvement of dopaminergic function in central nervous system and a possible involvement of serotonergic and/or GABAergic function with FTA-induced neural signs. Dopaminergic agents, e. g. diethyldithiocarbamate, Ldopa, failed to modify tremor and convulsion ; monoamine depleting agents, e. g. reserpine reduced tremor and convulsion ; serotonin elevating agents, e. g. isocarboxazid plus L-tryptophan intensified FTA-induced tremor and convulsion. Modification of FTA-induced tremor and convulsion by some agents capable of elevating or decreasing GABA (aminooxyacetic acid, semicarbazide) was also observed. Furthermore, an elevation of serotonin (5-HT) and a decrease of GABA in FTA-treated mice were noted. These results obtained suggest a possible involvement of central serotonergic and/or GABAergic function with FTA-induced tremor and tonic-clonic convulsion.