Comparative Biochemistry and Physiology Part C Comparative Pharmacology and Toxicology

Published by Elsevier
Print ISSN: 0742-8413
Pregnant F-344 rats were exposed by intubation to a single dose (35 mg/kg) of 1,2-dimethylhydrazine dihydrochloride or to an acetate buffer on day 14 of gestation. A detailed examination of the effects of this dose of 1,2-dimethylhydrazine on brush border enzymes in the offspring was performed. Changes in the liver and colon levels of the alpha-glycerophosphate and malate/aspartate substrate cycle enzymes were measured during the development; at days 17 and 20 of gestation and at 2, 6, 13, 20, 27, 55, 110 days and 1 year after birth. It is concluded that metabolic energy enzymes, glutamate oxaloacetate transaminase and malate dehydrogenase, are more sensitive to 1,2-dimethylhydrazine treatment than are the brush border hydrolases or NAD- and Fp-linked alpha-glycerophosphate dehydrogenases.
1. The effect of a single injection of ethane-1,2-dimethane sulfonate (EDS) was studied in the teleost fish, Gobius paganellus in two different periods of the year. 2. During June EDS did not induce any change, while during December the drug was highly effective in promoting testicular activity. 3. Nucleus/cytoplasm ratio of interstitial cells strongly decreased concomitantly with the detection of high testicular androgen levels. 4. The germinal compartment was well developed showing the appearance of all spermatogenic stages and the cavity of lobular compartments filled of spermatozoa. 5. Our data are the first evidence of a stimulatory activity of EDS on testes of a vertebrate species.
1. MPTP significantly lowered Kd of the binding of [3H]QNB to muscarine receptor without affecting Bmax values compared with those of control. Hill coefficients (nH) of control and MPTP (250 microM) added group were 1.15 +/- 0.127 and 0.56 +/- 0.202, respectively. 2. Prior addition of pargyline to MPTP did not prevent the decrease of [3H]QNB binding. The patterns of displacement of [3H]QNB by MPTP and MPP+ were similar to those by some muscarinic agonists, such as acetylcholine, carbamyl choline and methacholine. 3. These results suggest that MPTP might be muscarinic agonist and might play a role to produce Parkinsonism through directly affecting the muscarinic cholinergic receptors in vivo.
Glutathione S-transferase in the cytosol of rainbow trout liver was partially purified by affinity chromatography on a column with glutathione coupled to epoxy-activated Sepharose 6B, which retained 94% of the total activity. Chromatofocussing on a Polybuffer exchanger 118 column separated the glutathione S-transferase into six major cationic isoenzymes (K1-K6), and some minor fractions. SDS-polyacrylamide slab gel electrophoresis showed K1-K3 to be heterodimers with subunits of Mr 25,000 and 26,500, and K4-K6 to be homodimers with subunits of Mr 25,000. The glutathione S-transferase isoenzymes were partially characterized by different biochemical parameters. The hepatic rainbow trout glutathione S-transferases were inhibited by the organic water pollutants, 1,4-benzoquinone and 2,4-dichlorophenoxyacetic acid. The same kinetic inhibition patterns were observed with these inhibitors as for rat liver glutathione S-transferases. It is concluded that rainbow trout glutathione S-transferases can play a key role in the detoxication of organic micropollutants in the aquatic environment.
1. The activity of inositol 1,4,5-trisphosphate 3-kinase in subcellular fractions of smooth muscles of the pig coronary artery was examined. 2. Incubation of [3H]inositol 1,4,5-trisphosphate (IP3) with muscle homogenates produced more polar 3H-radioactivity (probably as inositol 1,3,4,5-tetrakisphosphate, IP4) than IP3, in the Mg2+- and ATP-dependent manner, thereby indicating the presence of IP3 3-kinase activity in homogenates of the muscle. 3. Most of the kinase activity was present in the cytosol fraction. The enzyme activity was reversibly activated by Ca2+ with a half-maximal effective concentration of 2.5 x 10(-7) M. 4. The calmodulin antagonists, W-7 and chlorpromazine inhibited the Ca2+-activated enzyme activity.
1. The possible involvement of eicosanoids, cyclic adenosine monophosphate (c-AMP), and inositol 1,4,5-trisphosphate (IP3) in serotonin-(5-hydroxytryptamine-) induced secretion in rat ileum in vivo was studied. 2. Serotonin caused a significant increase in mean IP3 levels. Indomethacin reduced serotonin-induced secretion of water by 28%. Thus, IP3 and eicosanoids appear to be intracellular mediators of serotonin-induced secretion in rat ileum. 3. Serotonin, BRL 24924, and cisapride all inhibited theophylline-induced increases in c-AMP concentrations in rat ileal segments. Neither BRL 24924 nor cisapride caused any change in IP3 levels. 4. These data suggest that a 5-HT2 receptor dependent on IP3 and eicosanoids is involved in mediating in serotonin-induced secretion in rat small intestine.
1. Cytoplasmic Ca2+ concentration ICaIin and membrane potential of single Helix pomatia neurons was studied by Fura-2 fluorescence measurement and conventional current clamp methods. 2. Intracellular injection of inositol-1,4,5-trisphosphate (IP3) and nonhydrolysable GTP analogue (Gpp/NH/p) led to a rise of ICaIin; in contrast, GTP injection did not cause significant ICaIin changes. 3. We suggest that both IP3 and Gpp/NH/p directly activated Ca release from intracellular stores.
1. The effects of the herbicide 1.1.1. trifluoro-N-(2-methyl-4-phenyl sulfonyl phenyl) methane sulfonamide on the drug metabolising enzyme activities in livers of rat, mouse and guinea pig have been compared. 2. In all three animal models, the herbicide increased the activities of both aniline hydroxylase and p-aminopyrine demethylase. The greatest inductive effect was seen in the rat, while the least effect was evident in the guinea pig. 3. In mouse and guinea pig, 1.1.1. trifluoro-N-(2-methyl-4-phenyl sulfonyl phenyl) methane sulfonamide had no effect on the soluble or microsomal epoxide hydratases or the glutathione S-transferases. In the rat, however, the herbicide significantly decreased the microsomal epoxide hydratase activity, as well as the soluble and microsomal glutathione S-transferase activities. 4. These results are discussed in relation to factors responsible for species differences in the response to foreign compounds.
1. The activity of tyrosine hydroxylase (TH; EC was estimated in vitro in crude tissue homogenates from the posterior cardinal veins (chromaffin tissue) and the coeliac ganglion (adrenergic neurons) of the Atlantic cod, Gadus morhua. 2. TH from the chromaffin tissue showed its highest activity at pH = 6.0 and a temperature of 30-35 degrees C, and was stimulated by low concentrations of catalase (20 micrograms/ml). 3. Estimations of the absolute TH activity in vitro showed values of 110 +/- 30 nmol/g X hr for the chromaffin tissue and 1120 +/- 280 nmol/g X hr for the coeliac ganglion.
The catecholamine content (noradrenaline, NA; adrenaline, A; dopamine, DA, and its metabolite, DOPAC) was measured, by the HPLC method, in brain and blood plasma of eels studied at atmospheric pressure (1 ATA) or at 101 ATA of hydrostatic pressure (HP). In the brain, HP induces a slight but significant increase (P less than 0.05) in A and DA contents but NA and DOPAC levels are not modified at 101 ATA when compared to 1 ATA. In the plasma, only A and NA are detected, adrenaline being the predominant amine. In eels exposed to 101 ATA HP, A and NA are strongly increased (+100%; P less than 0.01). The significance of the catecholamine increase in brain and plasma of the eels under HP is discussed.
1. The characteristics of hepatic ethoxycoumarin and ethoxyresorufin O-de-ethylases in juvenile cod (Gadus morhua) from the North Sea are described. 2. Feeding Aroclor 1254 to juvenile cod to produce liver concentrations of approx 900 microgram X g-1 (wet wt) induced ethoxycoumarin O-de-ethylase approx 30-fold, but had no effect on ethoxyresorufin O-deethylase activity. 3. Feeding Aroclor 1016 to juvenile cod to produce liver concentrations of approx 300 micrograms X g-1 (wet wt.) did not induce ethoxycoumarin O-de-ethylase activity.
1. Groups of lean, obese, and obese-non-insulin-dependent diabetic LA/N-cp and SHR/N-cp rats were administered the a-glucosidase inhibitor Miglitol (150 mg/kg diet, ad libitum) from 8 until 15 weeks of age. 2. Phenotype effects (obese greater than lean) were present for weight gain, adiposity, serum glycemic and lipid parameters, and for liver glucokinase, glucose-6-phosphate dehydrogenase, and malic enzyme activity. Miglitol treatment was associated with improvements in glucokinase and malic enzyme in both strains, and in improvements in glycemic parameters in obese rats. 3. These results are consistent with variable improvements in glycemic control and insulin action following low dose Miglitol treatment, and indicate that indirect effects of the drug on insulin sensitivity in peripheral tissues and on glucoregulatory enzymes may contribute to the glycemic improvements observed with this drug, while greater dosages or longer treatment may be required to observe comparable improvements in adiposity or plasma lipid profiles.
1. Liver microsomes were prepared from rats, rabbits, guinea pigs, hamsters, gerbils, a cat and three strains of mice, and were incubated with delta-11-tetrahydrocannabinol (delta-11-THC). The extracted metabolites were separated by chromatography on Sephadex LH-20 and examined by gas chromatography and combined gas chromatography/mass spectrometry. 2. Eleven metabolites were identified; these were formed by aliphatic hydroxylation of all positions of the pentyl chain, allylic hydroxylation at C-10 and C-8 (alpha and beta), and by the epoxide-diol pathway. 3. The ratio of the metabolites varied considerably between the species. Mice and rats favoured hydroxylation at C-8-alpha with very little hydroxylation of the pentyl chain. 4. In the guinea pig, however, hydroxylation of the pentyl chain, particularly at C-4', produced the major metabolites; very little hydroxylation occurred at C-8. 5. Side-chain hydroxylation was also favoured by the gerbil. 6. In the cat and hamster, 8-beta-hydroxylation was by far the major metabolic route, accounting, in the cat, for nearly 70% of the recovered metabolites. 7. The rabbit, on the other hand, favoured the epoxide-diol pathway with over 70% of the recovered metabolites being accounted for by the 9,11-dihydro-diols. 8. The results emphasise the need to make appropriate choices of animal models for metabolic and toxicological studies in humans.
1. In order to determine the selectivity of classical and novel adrenergic agents for alpha 1- and beta-adrenergic receptors in brown adipose tissue, the ability of these agents to compete for binding sites labelled with [3H]prazosin and [3H]CGP-12177, respectively, was investigated. 2. The beta-antagonist propranolol, known to inhibit norepinephrine-induced respiration in micromolar concentrations, bound to the [3H]CGP-12177 site with nanomolar affinity. 3. Among agonists, only isoprenaline showed high selectivity for beta-receptors, and only oxymetazoline for alpha 1-receptors. 4. Unexpectedly, the novel thermogenic agonists (BRL-agonists), shown to be potent and selective stimulators of brown fat thermogenesis, were unselective and bound only with low affinity to the [3H]CGP-12177 binding sites. 5. These results suggest that the beta-adrenergic binding site in brown adipose tissue identified here with [3H]CGP-12177 may not be the one (or not the only one) coupled to thermogenesis.
1. Aroclor 1242 (500 mg/kg, p.o.) produced a marked increase in porphyrin content of quail kidney (1800-fold), and of rat kidney but to a lesser extent (6-fold). 2. delta-Aminolevulinic acid synthetase activity was increased 12-fold in quail kidney but was unchanged in rat kidney following Aroclor 1242 treatment. 3. Uroporphyrinogen decarboxylase activity was significantly inhibited in quail kidney but not in rat kidney. 4. Renal ethoxyresorufin O-deethylase activity was induced in rat and quail whereas renal ethoxycoumarin O-deethylase and glutathione S-transferase activities were induced only in rats by Aroclor 1242.
1. The metabolism of a wide range of di-, tri-, tetra-, penta- and hexachlorobiphenyls by hepatic microsomes isolated from control animals and animals treated with Aroclor 1254 was studied. 2. Hepatic microsomes isolated from control rats expressed higher rates of oxidations than avians. 3. Treatment of rats and pigeons with Aroclor 1254 induced cytochrome P450 dependent monooxygenases leading to an increased regioselective metabolism of PCB isomer and congeneres. 4. There was an inverse relationship between the degree of halosubstitution and microsomal oxidation. Meta-para carbon atoms free of halosubstitution were the preferred side for oxidation. 5. A good correlation was found between the in vitro metabolism of PCBs and their relative abundance in tissue extracts, thus suggesting oxidative metabolism to be the major route of metabolic disposal.
The in vitro metabolism of the volatile aromatic hydrocarbon toluene by enzymes associated with the 12,000 g supernatant fraction of hybrid sunfish (Lepomis macrochirus X L. cyanellus X L. gibbosus) liver homogenates was studied. Aminopyrine demethylase (APDM) and aniline hydroxylase (AH) activities were measured. Intramuscular injections of Aroclor 1254 (a polychlorinated biphenyl) produced significant increases in APDM and AH activities (P less than or equal to 0.1, ANOVA). There were no significant changes in the metabolism of toluene, liver wet weights, or liver protein concentrations following treatment.
Postnatal changes in content and activity of the mixed-function oxidase system in nestling barn owls and baby chicks showed the following: 1. Increase in liver weight in both. 2. Significantly higher cytochrome P-450 level in 1-day old chicks but lower in 1-day old owls than at any other age. 3. Ratio of cytochrome b5 to P-450 was lower than one in nestling owls but higher than one in chicks. 4. Aroclor 1254 (PCBs) increased the level and catalytic activity of cytochrome P-450 more in the owl than in the chick. 5. The ratio 455:430 nm characteristic of ethylisocyanide binding was not altered in the barn owl due to PCB treatment but changed significantly in the treated chicken.
The mean level of PCB residues in the liver of the Caspian turtle collected in nature was 23 ppm, or approximately 20-fold greater than that detected in the two bird species tested. Treatment of the turtles with aroclor 1254 resulted in a 30-fold increase in the level of PCB residues in the liver but did not cause any increase in the content of cytochrome P-450 and the desulfurase activity of this hemoprotein. The Ki value for acetylcholinesterase inhibition by paraoxon in brain homogenate of the Caspain terrapin was 3 and 2 orders of magnitude higher than that found in the African bulbul and the barn owl, respectively.
1. Treatment with a commercial mixture of polychlorinated biphenyls (PCBs) resulted in highly significant increases in pigeon hepatic microsomal proteins (100-fold), cytochrome P-450 (11-fold), cytochrome b5 (7-fold), NADPH-cytochrome c-(P450) reductase (7-fold), ethoxycoumarin-O-deethylation (9-fold), aldrin epoxidase (22-fold), ethoxyresorufin-O-deethylation (48-fold), N-demethylation of dimethylnitrosamine (28-fold) but not of lauric acid 12-hydroxylation. 2. SDS-PAGE analysis of pigeon hepatic microsomal proteins induced by Aroclor 1254 suggested highly significant increases in the density of staining in bands of estimated Mr 51-52 kD, 54-54.5 kD, 57-58 kD, 59-60 kD and of 77.5-78.5 kD. 3. The induction of cytochrome P-450IA1 was confirmed by Western immunoblotting using the monoclonal antibodies MAB 1-12-3 and MAB 1-8-4. 4. There was agreement between the 8-fold increase in cytochrome P-450IA1 increased staining of microsomal proteins, as judged by SDS-PAGE, and the 24-fold increase in the amount of protein that reacted with the monoclonal antibodies MAB 1-12-3 and MAB 1-8-4, as judged by Western immunoblotting. 5. It is concluded that treatment with a commercial PCB mixture resulted in the induction of several isoforms of pigeon hepatic cytochrome P-450 in a fashion that is likely to be similar to that reported for mammals.
Daily oral exposure of rats to 30 mg/kg of Aroclor 1254 for 1 month caused deleterious effects on the reproductive process, which were reflected in a decrease in the reproductive potential. The following disturbances were observed: prolongation of the estrous cycle; decrease in sexual receptivity; delay in timing of copulation; vaginal bleeding during gestation; decrease in litter size and delay in the time of parturition. The offspring, whether exposed to PCBs either prenatally and/or postnatally, showed a slower rate of body weight gain than controls. This was accompanied by high mortality until weaning of treated pups. Vaginal opening in the PCB-treated (as young) females occurred precociously, while other reproductive parameters were not affected at adulthood. Discontinuance of PCB treatment reversed the above symptoms.
1. Constitutive and Aroclor 1254-induced hepatic glutathione (GSH) S-transferases, GSH peroxidase and GSH reductase activities were determined in 12 strains of 8-10 week-old inbred male mice. 2. The constitutive GSH S-transferase activity varied from 2.5 (SJL/JCR) to 8.9 (C57BL/6N) mumol/min/mg protein and the corresponding values for the Aroclor 1254-treated mice were in the range of 7.1-23.0 mumol/min/mg protein. Aroclor 1254 significantly induced GSH S-transferase activity in all mice, however, significant interstrain differences were found in inducibility. 3. Aroclor 1254-treatment caused a 4.2-fold induction of GSH S-transferase in NFS/NCR but only a 1.4-fold increase in AKR/NCR mice. Aroclor 1254 significantly induced GSH reductase in all strains studied while GSH peroxidase activity decreased in these mice. 4. The range of hepatic GSH levels in control and Aroclor 1254-treated mice was relatively narrow for both groups (6.59-11.25 microM/g wet tissue).
1. In the optic ganglion of Loligo pealii, binding sites for [3H]-acetylcholine (KD: 5.2 x 10(-7) M; Bmax: 1.7 x 10(-11) mol/g tissue) and 125I-alpha-bungarotoxin (KD: 3.3 x 10(-9) M; Bmax: 9.7 x 10(-11) mol/g tissue) were observed. 2. Both sites are blocked by nicotinic compounds, but differ significantly in their affinity for individual ligands, with the acetylcholine site preferentially binding agonists, and the toxin site, antagonists. 3. The acetylcholine site is substantially more thermolabile than the toxin site. 4. A partial separation of the two binding activities is accomplished by sucrose density centrifugation. 5. These observations and a comparison with other tissues (Torpedo californica electroplaque; chick optic lobe; rat brain) suggest the presence, in the squid, of more than one kind of neuronal nicotinic receptor.
1. Cytochrome P-450 concentrations were similar in male and female carrier (db/+) and diabetic (db/db) mice. Benzphetamine N-demethylase and styrene oxide hydrolase activities were 47 and 65% lower in db/+ than in db/db mice. 2. UDP-Glucuronosyltransferase activity toward 1-naphthol, estrone and diethylstilbestrol was not different between db/db and db/+, but was 40% higher in db/db mice toward testosterone. 3. Glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene and ethacrynic acid was 47 and 59% lower in db/db mice than in male db/+ mice. Female db/+ mice had similar activities to those found in diabetic animals. 4. The differences in enzyme activity between hyperinsulinemic and normal animals suggest that insulin can influence both phase I and phase II biotransformations. 5. Enzyme activities in db/+ and db/db mice were compared to those in 129 REJ and Swiss Webster mice.
1. Fenoxycarb (RO-13-5223) exhibits a strong juvenile hormone type of activity against Triatoma infestans. 2. Topical treatment of last-stadium nymph with the juvenoid caused the formation of superlarvae, adult-larvae intermediates and adultoids. The ED50 was 0.02 microgram/insect. 3. Taking into account abnormalities in oceli, head, thorax, legs, wings, abdomen, conexivo and external genitalia, a scoring system to evaluate the retention of juvenile characters after moulting was developed. 4. Intermediate dose of the juvenoid produced the prolongation of the last instar nymph. 5. Abnormal individuals formed composite cuticles possessing both nymph and adult morphological features.
Metabolic rates associated with sustained, prolonged and critical swimming speeds were examined in 10 g trout exposed to 5% 96 hr LC50 (0.75 microgram X l-1) and 10% 96 hr LC50 (1.50 micrograms X l-1) at 12 degrees C. Permethrin did not influence the metabolic cost for swimming at sustained and prolonged speeds. Basal metabolic rate increased on initial exposure to permethrin reaching maximum values after 7 days and declined to the control level after 13 days in 5% and after 32 days in 10% 96 hr LC50. Critical swimming speeds were adversely affected in a manner reflective of the effects of permethrin on basal metabolic rate. Elevation in basal metabolic rate in fish exposed to permethrin was a result of increased energy requirements due to physiological stress, detoxication and tissue repair.
1-[14C]Phenyl-1-(3,4-dimethyl)phenylethane ([14C]PXE), a labelled analogue of a component of some commercial PCB replacement materials, was cleared rapidly from plasma of the thorny skate, Raja radiata, after i.v. injection. A polyexponential fit to the clearance data yielded three linear components with half-lives of 7, 128 and 924 min. The metabolic clearance rate for the mean animal was approximately 41 X kg-1 X d-1. The main storage site for [14C]PXE was the liver, which contained about 40% of the injected dose. Approximately 25% of the injected radioactivity was recovered from the bile within 36 hr of injection in the form of polar metabolites, indicating rapid degradation of [14C]PXE.
1. Oral administration of [14C]histamine induced the presence of small amounts of [14C]histamine in stomach and ileal tissues of control guinea-pigs. In contrast, much larger amounts were found after 8 h infusion. 2. Similar amounts of [14C]histamine were found in the tissues when [14C]histamine was given by intravenous infusion from 24-30 h after chlorpromazine injection.
1. The rate of penetration 14C malathion into the larvae of the diamondback moth, Plutella xylostella L., was found to be significantly different in an R-strain and S-strain. The rate of penetration was more rapid in the R-strain during the first hour after treatment. 2. The rate of metabolism in vivo and the rate of excretion were also higher in the R-strain compared with the S-strain. 3. The main metabolites produced in both strains were malathion dicarboxylic acid and desmethyl malathion. 4. The mechanism of insecticide resistance in Plutella xylostella L. is multifactorial, and involves a higher rate of penetration into the larvae of the R-strain, a higher activity of enzymes involved in its metabolism, and a higher level of excretion of the toxic compounds from the body of the R-strain compared with the S-strain.
The degree of tissue covalent binding of 14C-3-methylindole metabolite in goat and rat pretreated with phenobarbital or 3-methylcholanthrene was compared. The effect of conjugating agents, i.e. glutathione (GSH), cysteine and sulfate, in reducing the degree of tissue covalent binding was measured. The degree of tissue covalent binding was significantly higher in the lung than the liver of goats. In rats, covalent binding was higher in the liver than the lung. Glutathione and cysteine were effective in decreasing the degree of in vitro covalent binding in both liver and lung tissues of goat and rat.
1. Binding of [14C] DDT by submitochondrial particles and by liposomes prepared from lipids extracted from the particles was studied by the discontinuous sucrose gradient method. 2. Binding of the insecticide was a biphasic linear function of the biomembrane- and liposome-concentration with a break in the binding curve occurring at identical concentrations of phospholipid for both the biomembrane and vesicle. The biphasic binding curve is interpreted in terms of decreased availability of binding sites as a result of particle-particle interaction. 3. [14C] DDT was bound mainly by the membrane lipids and only negligible binding was detected for the delipidated membrane. 4. A 100-200-fold excess of unlabeled DDT had no effect on the binding of [14C] DDT and a 600-fold excess of unlabeled DDT reduced the binding by 20% suggesting that binding of [14C] DDT by lipids was nonspecific. 5. These results are discussed in relation to the strong inhibition by DDT of mitochondrial bioenergetics.
Rainbow trout were exposed to aqueous [14C]2-methylnaphthalene and their bile was examined for metabolites of [14C]2-methylnaphthalene. Trout which were pretreated with the monooxygenase inducer beta-naphthoflavone exhibited greater levels of total metabolites, glucuronide conjugates and dihydrodiol metabolites of [14C]2-methylnaphthalene in bile as compared to non-induced trout. The ratio of 2-hydroxymethyl-naphthalene to dihydrodiols found was greater in non-induced than in induced trout. These results are consistent with previously published studies on the metabolism of [14C]2-methylnaphthalene by rat and trout hepatic microsomes in vitro.
Sexually immature Shasta strain rainbow trout (Salmo gairdneri) of either sex were acclimated at 10, 14 or 18 degrees C for at least 4 weeks and plasma pharmacokinetics and biliary excretion of i.p. injected [14C]taurocholate (TC) examined in spinally transected or free-swimming fish, respectively. Plasma elimination half-lives but not absorption rate constants for [14C]TC (10 mumol/kg) were about two-fold reduced in 18 as compared to 10 or 14 degrees C acclimated fish. Distribution of [14C]TC to tissues other than plasma, liver, bile and small intestine was not different in 10, 14 or 18 degrees C acclimated free-swimming fish at 1 or 4 hr post-injection. Biliary excretion of [14C]TC (7.5-10 mumol/kg) at 1 hr post-injection was significantly higher in 14 and 18 as compared to 10 degrees C acclimated fish.
1. Analysis of individual PCB-isomers and congeners in extracts of adipose tissue from N = 12 razorbills suggested that 4-chlorobiphenyl was subjected to metabolism. 2. In vitro metabolism studies using [14C]-4-chlorobiphenyl as substrate showed that razorbills metabolise this substrate to [14C]4-chloro-4'-hydroxybiphenyl at an average rate of 20 pmol/mg microsomal protein/min. For comparison, the metabolism of [14C]-4-chlorobiphenyl by pigeons and rats was also studied, and average rates in the formation of [14C]-4-chloro-4'-hydroxybiphenyl of 12 pmol/mg microsomal protein min and 342 pmol/mg microsomal protein min were estimated. 3. A comparison of the hepatic drug metabolising enzyme system of razorbills and pigeons showed similar concentrations of cytochrome P-450, cytochrome b5 and comparable catalytic activities of cytochrome P-450-dependent monooxygenase, when assessed for HHDN epoxidase, PROD, EROD and the Phase II enzymes glutathiones-S-transferase, but were significantly lower, when compared with rats. The results obtained suggest fundamental differences in the catalytic activities of cytochrome P-450-dependent monooxygenase between avian and mammalian species. 4. The present study, however, provides evidence that fish-eating seabirds have the ability to metabolically dispose of certain PCB isomers and congeners, which are amongst the most ubiquitously distributed pollutants in the ecosystem.
1. Some studies of cyclophosphamide (CP) and its metabolite acrolein in chick embryo liver were carried out in order to investigate the mechanism of the porphyrinogenic action of CP. 2. In vitro and in vivo studies revealed that CP induced but did not activate delta-aminolaevulinic acid (ALA) synthase. 3. Pretreatments with phenobarbital (PB) or SKF-525A did not modify ALA-synthase induction produced by CP. 4. Acrolein administration neither induced ALA-synthase activity nor increased cytochrome P-450 content or led to hepatic porphyrin accumulation. 5. Time course induction of cytochrome P-450 content after administration of CP or PB was similar. 6. The results obtained would indicate that CP is a strong inducer of both ALA-synthase activity and microsomal cytochrome P-450 content in liver of 17 day-old chick embryos and that its porphyrinogenic activity is not mediated by its metabolite acrolein.
Beside the known existence of cyanoglucosides (linamarin and lotaustralin) and proteins the neurotoxin beta-cyanoalanine has been demonstrated for the first time in the defensive secretions of animals. It is proposed that beta-cyanoalanine is produced by metabolizing cyanide from the cyanoglucosides. The methanolic precipitated protein fraction contains high amounts of aspartic acid, glycine, alanine, leucine and serine, thus being similar to the composition of larval silks in Lepidoptera. The defensive secretion contains 85% water, 8% proteins, 7% cyanoglucosides, 0.3% beta-cyanoalanine and beta-glucosidase while beta-cyanoalanine-synthetase could only be detected in the haemolymph.
1. We have studied the binding of [3H]-RO 15-1788 to membrane preparations of the retina of rabbit (Lepus cunicula) and turtle (Pseudemys scripta elegans). 2. In both species, [3H]-RO 15-1788 binding was maximal at 0 degrees C and decreased with increasing temperature. It was saturable, protein concentration-dependent and specific. Flunitrazepam, unlabelled RO 15-1788 and ethyl-beta-carboline were the most effective displacers, whereas RO 5,4864 was ineffective. 3. In both turtle and rabbit retina, Scatchard analysis indicated the presence of a single binding site for [3H]-RO 15-1788. The KD was 0.75 nM in both turtle and rabbit, while the Bmax were 520 and 250 fmol/mg protein in turtle and rabbit respectively. A study of the association rate of [3H]-RO 15-1788 binding revealed faster kinetics in turtle, as compared to rabbit.
1. Male Japanese quail were given 2.20 x 10(-4)-14.53 mg uranium/kg intravenously as uranyl ion (235U label). 2. The relationship between dosage and the 18-hr accumulation of U in leg bones, liver, kidneys and testes was linear. 3. Increases in U deposition with increased dosage were approximately 1:1, except for kidneys where 10-fold increases in dosage resulted in 25-fold increases in deposition. 4. Estradiol-17 beta increased U deposition in bones by 15-fold thereby providing some protection for the kidneys as now the ratio of dosage to accumulation was 1:1.
1. The administration of crude venom of the parotoid glands of the toad Bufo ictericus ictericus to the in situ (via abdominal vein) or isolated heart of this anuran causes both chronotropic and inotropic effects. 2. While under action of parotoid venom, the heart of the animal is insensitive to vagus nerve stimulation. 3. This blocking of vagal action is dose dependent and it is suggested that it results from a functional antagonism between the venom constituents and the acetylcholine liberated by the nerve endings on stimulation. 4. The venom constituents probably involved in this antagonism are catecholamines (adrenaline and noradrenaline), tryptamine derivatives (serotonin and bufotenidin) and genins (bufagin and bufotoxin), possibly also ATP. 5. Adrenaline, noradrenaline and serotonin, or a mixture of the three, mimic, at least partially, the blocking of vagal action caused by crude venom. 6. The blocking action of crude venom can be prevented by previously or simultaneously adding acetylcholine to the infused crude venom. This prevention is dose dependent. 7. The blocking action persists in the boiled venom and in the material dialysed from crude venom.
Body wall strips and oral rings of Bunodosoma caissarum respond to the application of at least four categories of drugs with sustained contractions. Propionylcholine, butyrylcholine and nicotine never failed to evoke a response; acetylcholine eventually was inactive. Occasionally, a correlation between dose and response was possible. Adrenaline and noradrenaline also elicited responses, although, occasionally, both were ineffective. Tryptamine and serotonin (less) were also effective. L-Glutamate was particularly effective and its action could be depressed by GABA. Histamine, betaine, taurine and aspartate were ineffective. The results are discussed in terms of depolarization due to specific membrane receptors or to unspecific causes.
Quantitation of immunoblots for P450 1Al (upper panel) and P,,, 3A (lower panel) of control (C, open bars) and dexamethasone treated (DX, solid bars) in trout liver microsomes at 24 and 48 hr after treatment. Values are mean + SD from at least four separate fish. Asterisks indicate values that are significantly different from corresponding control values.
Autoradiogram of Northern blot of P7450 1Al mRNA in control (C) and dexamethasone treated (DX) trout liver at various times after treatment. Arrows represent the location of 28s and 18s ribosomal RNA.
Quantitation of Northern blots of Pd5,, 1Al mRNA in control (C, open bar) and dexamethasone treated (DX, solid bars) trout liver at various times after treatment. Values are mean + SD from at least four separate samples. Asterisks indicate values that are significantly different from corresponding control values.
1. In rainbow trout liver, dexamethasone caused a reduction in cytochrome P450 1A1 proteins but no change in P450 3A proteins as measured by Western blots using specific anti P450 1A1 and P450 3A sera. 2. After dexamethasone administration, the level of P450 1A1 was down to 14% and 8% of the control values at 24 and 48 hr, respectively. 3. There was no change in P450 1A1 mRNA abundance at 24 hr but a decrease to 45% of the control value was observed at 48 hr after dexamethasone. 4. There is, therefore, a differential response between P450 1A1 and P450 3A to dexamethasone in the trout liver. 5. The initial decrease in P450 1A1 protein probably occurs at the translational level while both translational and transcriptional levels are involved 48 hr after dexamethasone administration.
1. In the course of the present investigation, three chelating agents (2,3,2 tet, cyclam or EDTA) were tested for their therapeutic effect on nickel and cobalt poisoned toad. 2. Our results showed that EDTA appears to be superior to the two other ligands, which have been proved to be chemical ligands for Ni and Co in vitro. 3. EDTA was able to prevent disturbances in the activities of serum aspartate and alanine aminotransferases, alkaline phosphatase, total protein, urea, uric acid and blood glucose level. 4. Our results suggest caution in the use of 2,3,2 tet or cyclam in human Ni and Co intoxication.
1. Adipose tissue lipoprotein lipase (LPL) activity of several different animal species was determined after i.p. administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). 2. TCDD caused a significant reduction in LPL activity and an increase in serum triglyceride concentration in guinea pigs, rabbits, and hamsters but not rats. 3. TCDD increased adipose tissue LPL activity of mink and lowered their serum triglyceride concentration. 4. Results of this study indicate that profound differences occur in lipid metabolism between various species in response to TCDD and these changes do not appear to be related to generalized toxicity such as wasting.
1. 3,3',4,4'-Tetrachlorobiphenyl (TCB) was 20-100 times more toxic in chick embryos than in turkey embryos when injected into eggs. 2. The ED50-value for induction of AHH activity by TCB in the liver of early chick and turkey embryos was estimated to be 0.6 and 6 micrograms/kg egg, respectively. 3. In both species alpha-naphthoflavone was more effective than metyrapone at inhibiting basal and TCB-induced AHH activities. 4. The TCDD receptor was detected in the liver of 7-day-old chick embryos, while it was not found in 9-day-old turkey embryo liver.
At toxic doses in rats, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) caused injuries in blood vessels in the brain. 2. 2,4-D caused extravasations of the circulating Evans blue-albumin complex also in the spinal cord. 3. By contrast, potency in damaging cerebral vessels was almost non-existent with 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). 4. None of the three chlorophenoxyacetic acids caused such cerebrovascular injuries in mice, guinea pigs, Syrian hamsters, rabbits and chickens.
Bioassay experiments were performed after exposure for 96 hr to various concentrations of trichlorophenoxyacetic acid (2,4,5.T). The sensitivity of juvenile trout was considerably higher than that of mature animals. The activity of the microsomal Ca2+ ATPase in trout gill under the effect of 2,4,5.T was investigated. In vitro studies showed an inhibitory effect on the Ca2+ ATPase, occurring at sublethal concentrations of the herbicide. In vivo exposure to various sublethal concentrations of 2,4,5.T during 96 hr involved a significant inhibition of the microsomal Ca2+ ATPase. The sensitivity of the microsomal Ca2+ ATPase from gills to 2,4,5.T is related to the toxicity of this herbicide.
The optimum conditions (pH, microsomal protein amount and substrate concentration) of guinea-pig liver, lung and kidney microsomal aniline 4-hydroxylase, ethylmorphine N-demethylase and benzo[a]pyrene hydroxylase activities were determined. Male guinea-pigs weighing 500-700 g were administered 3-methylcholanthrene (25 mg/kg, i.p. 3 days), phenobarbital (75 mg/kg, i.p. 3 days), pyrethrum (120 mg/kg, i.p. 2 days) and 2,4,5-T isooctylester (200 mg/kg, i.p. 3 days). 3-Methylcholanthrene treatment caused significant increases in liver microsomal benzo[a]pyrene hydroxylase and kidney microsomal aniline 4-hydroxylase activities. However, with phenobarbital treatment the only significant increase was observed in liver microsomal ethylmorphine N-demethylase activity. Pyrethrum treatment decreased kidney microsomal ethylmorphine N-demethylase activity significantly. 2,4,5-T isooctylester treatment increased liver microsomal aniline 4-hydroxylase and lung microsomal ethylmorphine N-demethylase activities significantly. Liver microsomal NADPH-cytochrome c reductase activity was increased significantly by phenobarbital and pyrethrum treatment. The other treatments did not cause any significant changes in microsomal NADPH-cytochrome c reductase activities of liver, lung and kidney. Cytochrome P-450 content of guinea-pig liver microsomes were increased significantly about 2.5-fold and 2-fold by treatment with 3-methylcholanthrene and phenobarbital, respectively. 3-Methylcholanthrene also caused 1 nm spectral shift in the absorption maxima of CO difference spectrum of the dithionite-reduced liver microsomal cytochrome P-450, forming P-449.
1. Accumulation of 2,4,6-trichlorophenyl-4'-aminophenyl ether (CNP-amino) in carp was investigated for 14 days. CNP-amino in carp could be divided into free CNP-amino [CNP-amino(I)] and bound CNP-amino [CNP-amino(II)]. 2. The bioconcentration factors (BCF) of CNP-amino(I + II) in carp were 90 +/- 38 (mean +/- SD, n = 3) for muscle, 402 for liver, 501 for kidney and 5368 for gallbladder after 14 days exposure. 3. 2,4,6-Trichlorophenyl-4'-acetamide phenyl ether (CNP-acetamide) was detected as metabolites of CNP-amino in muscle and viscera of carp.
Metallothioneins are low molecular weight proteins rich in sulfhydryl groups (cysteinyl) which readily bind various heavy metal cations, e.g. cadmium, copper, gold, mercury, silver and zinc. Mercury has a particular affinity for sulfhydryl groups and mercury-203 has been used as the basis of a rapid, sensitive, radiometric assay for metallothionein. The potential of 16 metals and oxygen for interfering with this test was examined. The mercury-203 test appears to be sensitive to the presence of copper, mercury, oxygen, selenium and silver.
1. The effect of 70 mg/l and 35 mg/l MS 222 an anaesthetic on the enzymes: superoxide dismutase (SOD), catalase (C) and peroxidase (P) were estimated in erythrocytes of Cyprinus carpo, a freshwater fish and Dicentrarchus labrax, a marine fish. 2. The end of the summer, at 16 degrees C MS 222 in concentration 70 mg/l caused an enhancement of the SOD and peroxidase activities and a decrease of the catalase activity. 3. In the autumn at 22 degrees C SOD and peroxidase activities in erythrocytes of Dicentrarchus labrax are normally higher than at 16 degrees C. On the contrary MS 222 causes no significant modification of enzymatic activities measured, but an increase in the dispersion of the results. 4. At 13 degrees C in the spring, MS 222 has no immediate influence on the activity of these enzymes, whilst at the same temperature at the beginning of winter, SOD is the only one activated. 5. It seems that in experiments concerning peroxide metabolism enzymes the use of anaesthetic MS 222 is not advisable.
Top-cited authors
Peter Calow
  • University of Minnesota Twin Cities
Gary Winston
  • University of Colorado
Johan HJ van Vuren
  • University of Johannesburg
Edward L Porter
  • ENNREGS Environmental Limited
Robert James Walker
  • University of Southampton