An attempt has been made to clarify immunosuppressive properties of antitumor agents by studying the effect of the agents on the thymus, the reticulo-endothelial system (RES) and hepatic drug-metabolizing enzyme activities of tumor (an ascites hepatoma, AH 130 cells)-bearing rats. A drastic decrease in the thymus weight and the total number of the lymphocytes and an enhanced activity of thymus alkaline phosphatase were detected by injecting either 5-fluorouracil (5FU) or cyclophosphamide (CP) (30 mg each/kg weight, i.p.) daily for 5 days to tumor-bearing rats. The agents, however, did not induce any conspicuous damage in microsomal mixed function oxidase system or the RES. The presence of 10-day-old tumor resulted in an extreme decrease in the weight and lymphocytes of thymus and a partial decrease in the microsomal drug metabolizing enzyme activities and the RES. Thus, these antitumor agents may lead to the decline of host-mediated immune mechanism. The multiplication of the tumor cells also appears to depress the immune functions and the host resistance.
We imestigated the influences of imidazole on the basal and the secretagogue-stimulated gastric acid secretion in isolated bullfrog gastric mucosa preparations and in anesthetized young chickens. Imidazole (1×10-4 g/ml) readily depressed the basal acid secretion in gastric mucosa in vitro. The inhibitory effect of imidazole was diminished considerably after washing out of the drug. The maximum acid secretion elicited by tetragastrin or bethanechol was completely antagonized by imidazole (1×10-4 g/ml). The stimulatory action of histamine or dibutyryl cyclic AMP was also remarkably depressed in the presence of imidazole (3×10-4 g/ml). After dibenamine pretreatment (5×10-5 g/ml) for 60 min, the isolated gastric mucosa preparation became refractory to tetragastrin, bethanechol and histamine, but responded to dibutyryl cyclic AMP. Imidazole protected the histamine sensitivity against dibenamine blockade in the concentration of 5×10-4 g/ml. In anesthetized young chickens, imidazole (200 mg/kg, s.c.) depressed tetragastrin- and histamine-stimulated gastric acid secretion. The effects of the imidazole derivatives and several antagonists (metiamide, atropine, diphenhydramine, acetazolamide and 2, 4-dinitrophenol) on acid production were compared with that of imidazole. From these results, it is concluded that imidazole has a potent antisecretory effect on the basal and the secretagogue-stimulated acid secretion.
Masugi's nephritis was induced in rats by a single i.v. injection of antikidney serum from rabbits immunized with the homogenate of rat whole kidneys. The antinephritic effect of drugs was evaluated through determination of biochemical parameters such as contents of protein and enzymes excreted into the urine and serum cholesterol content by the preadministration and intermittent administration tests. In the preadministration test, of test drugs, betamethasone (0.2 mg/kg±3 p.o.) and azathioprine (25 mg/kg±3 p.o.) showed an antinephritic effect. Betamethasone in particular resulted in normalization of urine and serum parameters. In the intermittent test, all drugs tested were effective. Significant recovery effects were observed with betamethasone (0.1 mg/kg±6 p.o.), prednisolone (5 mg/kg±6 p.o.), azathioprine (30 mg/kg±6 p.o.), trancxaYnic acid (200 mg/kg±6 i.p.) and cetraxate (100 mg/kg±6 i.p.) on urinary protein excretion and with all test drugs including indomethacin (5 mg/ kg±6 p.o.) and cyclophosphamide (2.5 mg/kg±6 p.o.) on urinary enzyme excretions. Serum cholesterol levels reverted to normal levels after administration of betamethasone. Using this nephritic model, the antinephritic effect of drugs could be tentatively evaluated.
Effects of 1-methyl-2-(β-naphthyl)-aziridine (250059-S), which possesses characteristic tranquilizing actions, on levels of blood glucose and liver glycogen, and on adrenaline release from the adrenal gland were studied in rats. While there was no elevation of blood glucose, a decrease of liver glycogen was detected after an s.c. injection of 250059-S (5 or 25 mg/kg). Marked decrease of adrenaline content in adrenal glands was observed 2 hours after subcutaneous administration of 50 mg/kg of this compound. This result is consistent with the marked adrenaline secretion from the adrenal gland into adrenal-venous blood after injection of 25 mg/kg or more of 250059-S. In splanchnicotornized rats, however, 250059-S-induced adrenaline release was not clearly observed. Pretreatment with 250059-S prevented adrenaline-induced hyperglycemia. 250059-S, at doses of 10 and 25 mg/kg, elevated the plasma insulin level to about twice that of the control. The 250059-S-induced depletion of liver glycogen was not completely blocked by adrenal demedullation, although it completely disappeared with pretreatment with 10 mg/kg of propranolol. In conclusion, 250059-S causes hypersecretion of adrenaline from the adrenal glands through excitation of the splanchnic nerves, though it causes no elevation of blood glucose, mainly because of its direct or indirect blocking action on adrenaline hyperglycemia.
Effects of benzphetamine, acetone, metyrapone and dimethylsulfoxide administration to rats on the metabolism of drugs by liver 9, 000×g supernatant fraction were studied herein. Activities for aniline hydroxylation and phenacetin O-deethylation were increased while ethylmorphine and benzphetamine N-demethylations were unchanged by the single administration of acetone, metyrapone or dimethylsulfoxide. Increase in aniline hydroxylase activity by about 53.4% and in phenacetin O-deethylase activity by about 44.4% were observed at 30 min after the single administration of benzphetamine whereas ethylmorphine N-demethylase activity was slightly decreased. NADPH-cytochrome P-450 reductase activity and cytochrome P-450 content were unaltered until 12 hr after the single administration of benzphetamine. Aniline hydroxylation was increased by the addition of benzphetamine to the incubation mixture and the increase in aniline hydroxylation caused by benzphetamine could be reversed by washing the microsomes.
Using the isolated Langendorff rat heart preparation perfused at a constant flow rate (about 6 ml·min-1 pro heart) with a modified Krebs-Henseleit solution, methods for recording left ventricular cavity pressure and electrocardiogram (ECG) changes were devised. Stable levels of mechanical activities were reached 60-90 min after start of perfusion and were maintained for at least 4 hr. When either norepinephrine (0.05-0.15 μg) or quinidine (50-200 μg) was injected into the aortic bulb of the heart, sensitive changes in the measurable cardiac parameters were observed and changes in ECG patterns were particularly characteristic. Our results indicate that this experimental model may be useful for evaluating numerous functions of the isolated heart.
To investigate the role of the striatum and nucleus accumbens in neurolepticinduced catalepsy, bilateral electrocoagulations were made or microinjections of 6-hydroxydopamine (6-OHDA) were given to rats in these brain regions, and the cataleptogenic activity of neuroleptics was measured. Electrocoagulation in these regions caused a highly specific destruction of brain tissue, and 6-OHDA decreased the levels of dopamine in the injected region with little effect on these levels in other regions. The cataleptogenic activity of haloperidol was enhanced by the electrocoagulation in the striatum at 2 days after the operation, but was weakened from 7 days on. The electrocoagulation weakened the catalepsy induced by chlorpromazine, thioridazine, and ID-4708 (a new butyrophenone derivative), but enhanced that by clozapine at 2 weeks after the operation. Microinjection of 6-OHDA into the striatum enhanced the catalepsy induced by the five neuroleptics used. The lesions in the nucleus accumbens had fewer effects on catalepsy than did those in the striatum. It was concluded that the striatum more than the nucleus accumbens is involved in producing catalepsy with neuroleptics, and that the enhancement of catalepsy by electrocoagulation in the striatum is characteristic of clozapine.
Cytochrome b5 was isolated from liver microsomes using a detergent-method. The hemoprotein was found to bind to liver plasma membranes in vitro and was accompanied by an increase in NADH-cytochrome c reductase activity, but not NADH-ferricyanide reductase activity. As in the case of microsomes, the binding to plasma membranes was temperature-dependent and was tight to the extent that the bound cytochrome b5 was little released under high ionic strength. The capacity of plasma membranes for the binding was less than that of microsomes. Administration of CCl4 did not significantly affect the binding of the hemoprotein in both fractions. These results add support to our previous proposal that the elevation of NADH-cytochrome c reductase activity of liver plasma membranes observed early after administration of CCl4 may be caused by the binding of cytochrome b5 which has probably migrated from the endoplasmic reticulum.
An investigation was made of monoamine-related agents on the Straub tail reaction (STR) due to central excitatory effect of morphine (10 mg/kg). Apomorphine (10 mg/kg) showed a tendency to enhance the STR, and L-dopa (150 mg/kg) and methamphetamine (5 and 10 mg/kg) produced a significant increase in the STR. Phenoxybenzamine and propranolol induced the inhibition of the STR to a large extent. Diethyldithiocarbamatc (250 mg/kg) and disulfiram (200 and 400 mg/kg) had no influence on the STR. α-Methyl-p-tyrosine (100 and 400 mg/kg) reduced the STR. L-5-Hydroxytryptophan [L-5-HTP] (100 mg/kg) inhibited the STR significantly. Isocarboxazid (50 mg/kg), nialamide (50 and 100 mg/kg) and tranylcypromine (10 and 25 mg, kg) did not influence the STR. On the contrary, biochemical investigations showed that morphine (10 and 20 mg/kg) decreased the 5-hydroxytryptamine (5-HT) content of the lumbosacral cord significantly, although no alteration of 5-HT content occurred in various sites of the brain, compared to a vehicle-treated group. Morphine (10 and 20 mg, /kg) did not act on the dopamine or norepinephrine content of various sites of the brain and spinal cord. Our results suggest that the STR is, at least to some extent, the result of an increase in catecholarninergic activity and/or a decrease in tryptaminergic activity in the central nervous system of mice.
Effects of taurine (2-aminoethanesulfonic acid) on the uptake and release of 14C-acetylcholine (14C-ACh) and 3H-norepinephrine (3H-NE) in the superior cervical ganglion and cerebral cortex of the rat were studied. Taurine suppressed high potassium evoked release of 14C-ACh and 3H-NE from the rat superior cervical ganglia and cerebral cortical slices, while the drug did not modify per se the uptake and unstimulated (spontaneous) release of 14C-ACh and 3H-NE in these tissues. Furthermore, taurine inhibited the release of 3H-NE from the crude synaptosomal (P2) fraction of the rat brain without affecting the uptake. These results suggest that taurine may act as a modulator of neuronal activity, possibly by stabilizing excitable membrane and by suppressing the release of neurotransmitter at synapses.
Using a modified type of Masugi's nephritis, quantitative changes in several connective tissue components of renal cortex during the process of nephritis were compared with those of the contents of urinary protein and serum cholesterol. Levels of urinary protein and serum cholesterol were highest 10 days after anti-kidney serum injection and nearly normal levels were reverted to on the 30th day. The levels of sialic acid, uronic acid and hydroxyproline in the renal cortex of the nephritic group significantly increased from the 1st, 5th and 10th days, respectively compared with the normal group. The sialic acid content reached a peak with an increase of approx. 40% on the 15th day, reverting to almost the normal level on the 30th day, while the uronic acid and hydroxyproline levels continued to increase slowly after the 15th day, reaching rates of approx. 70%, and 40%, respectively on the 30th day. The hexosamine content reached a maximum of 20% on the 20th day. Quantitative changes in connective tissue components of the renal cortex due to nephritis appear to reflect the degree of the repair of injured renal tissue.
Prolonged ischemia by bilateral carotid artery ligation in rats resulted in cerebral edema with a reduced energy state. Mitochondria isolated from the ischemic brain showed an impairment of oxidative phosphorylation. The ischemic brain was also characterized by a remarkable accumulation of free fatty acids known to have properties as an uncoupling factor. The major components of increased free fatty acids were palmitic, stearic, oleic and arachidonic acids. The analysis of saponified myelin and mitochondrial lipids from the ischemic brain showed a decrease in fatty acid contents. The main components of decreased fatty acids in these subcellular fractions corresponded to those of free fatty acids accumulating in the ischemic brain. These results indicate that cerebral energy failure in the ischemic brain is related to the accumulation of free fatty acids, which are derived from endogenous brain lipids.
Spontaneous electrical activity of the isolated frog spinal cord was examined in Ca2+ -free environment. Spontaneous discharges from the central root altered in four distinguishable steps. The first step was an immediate increase in the rate of spontaneous discharges and the second was a gradual decrease. The third was the occurrence of rhythmical bursts, and the last, the appearance of continuous firing. The rhythmical bursts could be depressed by the addition of metabolic inhibitors (ouabain or dinitrophenol in a concentration of 5×10-5 M) as well as of Ca2+ -chelating agents (EDTA or EGTA in a concentration of 10-3 M). Our results suggest that the occurrence of the rhythmical bursts requires a metabolic pumping process to redistribute Na+ and K+ across the membrane and a small amount of Ca2+ for transmitter secretion.
The influences of sympathectomy on gastrointestinal mucosa, gastric secretion, acute or chronic gastric ulcers were studied in rats. Under ether anesthesia, sympathectomy was performed by surgical removal of the celiac ganglion. Surgical sympathectomy per se produced no pathological changes in the gastrointestinal tract as determined by macroscopical observation 3, 10 or 20 days after operation. The volume of gastric juice and pepsin output were not influenced by the sympathectomy but gastric acid output was significantly increased in pylorus-ligated rats. The sympathectomy worsened the stress- and the indomethacin-induced ulcer and delayed the healing of chronic gastric ulcers a little but not significantly, and had no deteriorative influence on the reserpine-induced ulcers. In contrast, Shay ulcers, aspirin- or serotonin-induced ulcers were significantly aggravated by sympathectomy. The loss of H+ ions and gain of Na+ ions in the gastric juice of pylorus-ligated and aspirin-treated rats were not affected by sympathectomy.
The effects of polychlorinated dibenzofurans (PCDFs), trace toxic contaminants of commercial polychlorinated biphenyl preparations ( PCBs), on the induction of hepatic drug-metabolizing enzymes were studied in the rat. PCDFs were about a thousand times more potent than PCBs (Kanechlor-500) as inducers of cytochrome P-450. Rats given 10 μg/kg of PCDFs intraperitoneally for 3 days showed significantly increased hepatic cytochrome P-450 levels. At the highest dose tested, 1000 μg/kg, a two-fold increase of cytochrome P-450 and a three-fold increase of p-nitroanisole demethylase activity were observed. PCDFs and 3-methylcholanthrene had quite similar effects on microsornal drug-metabolizing enzymes. Both drugs increased p-nitroanisole demethylase activity strikingly and aniline hydroxylase activity moderately, but produced little change in aminopyrine demethylase activity. α-Naphthoflavone, which is known to be a specific inhibitor of aryl hydrocarbon hydroxylase induced by polycyclic aromatic hydrocarbons, inhibited at low concentrations p-nitroanisole demethylase activity of rats previously treated with both drugs. Further, both drugs increased the 455 nm to 430 nm peak ratios of ethyl isocyanide difference spectra. Following three daily doses of PCDFs (100 μg/kg), cytochrome P-450 level and p-nitroanisole demethylase activity remained elevated for over 15 days, with a decrease to control levels after 30 days. Such indicates the slow excretion of PCDFs.
Effects of several monoamine-related compounds on the reserpine-induced spikes recorded from the medial nucleus Trapezoides (reserpine-induced Tr spikes) in rabbits were investigated. 5HTP (30-50 mg/kg, i.p.) showed marked suppression of reserpine-induced Tr spikes. Parachlorophenylalanine (PCPA) alone induced spikes similar to reserpine-induced Tr spikes after repeated doses (250 mg/kg twice daily for 3 successive days). A marked enhancement of the generation of reserpinc-induced Tr spikes was elicited, when reserpine was given to rabbits pretreated with PCPA. L-DOPA (30-50 mg/kg, i.p.) showed a slight but significant suppressive action 20 to 40 min after injection. α-methyl-p-tyrosine (α-MT) (200 mg/kg, i.p.) produced no significant change within 6 hr, but did show a marked facilitatory effect on the generation oft he spikes when reserpine was given to rabbits pretreated with α-MT. α-methyl-metatyrosine (α-M MT) (100 mg/kg, i.v.) caused a long-lasting, marked suppression. These findings suggest that both catechotamines and 5HT have a suppressive action on the generation of reserpine-induced Tr spikes.