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Effects of tryptophan, nicotinic acid and some other metabolites of the kynurenine pathway on lipid metabolism in the rat
1876
Effect of nikethamide on xenobiofic biotransformation in regenerating rat liver Bushma, M.I., Legonkova, L.F., Lukienko, P.I. and Zavodnik, L.B. Institute of Biochemistry, Byelorussian SSR Academy of Sciences, 50 Lenin KomsomolBird, Grodno 230009, U.S.S.R.
Stimulation of regenerative processes in rat liver (removal of about 70~ of its weight) was accompanied by a 18-43c$ decrease of the cytochrome bs and P-450 concentrations, the NADH-cytochrome b 5 reductase activity and the rates of NADPH oxidation, amidopyrine, ~mylmorphine and aniline hydroxylation. The nikethamide administration to partially hepatectomized rats (subcutaneously, 75 mg/kg, 5 days before the operation and during the postoperative period) exerted the nolmalizing effect which was most pronounced after 2 days following the operation. The cytochrome hs concentration, the: activities of NADH-cytochrome b5 and NADPH-cytochrome P-450 reductases and the rates of amidopyrine, ethylmorphine and aniline hydroxylation were increased by 31-80~ as compared to untreated operated animals. Under condi~ons of liver regeneration, in contrast with the microsomal oxidation enzymes, the activities of glutathione-S- and UDP-glucurenyltransferases were compensatory increased by 31-44~. Nikethamide induced their further activation. The conjugation rate of glucuronic acid wi'.h paranitrophenol in microsomes, those of glutathione with sulfobromophthaleine (cytosol) and 1-chloro-2,4-dinitrobenzene (cytosol and microsomes) were increased by 30-.54~$, 36-76~ and 13-70~$ (2, 4 and 8 days after the operation, respectively). Under the action of nikethamide the rate of UDP-glucuronic acid biosynthesis (UDPG-dehydrogenase) was increased by 30~ (2 days) compared to untreated operated rats. Nikethamide accelerated the recovery of the liver weight. Substrate induction of microsomal monooxygenases (Bushma, Lukienko, 1982) and enhanced biosynthesis of nicotinamide coenzymes (Stepanyan, Tscitlin, 1968) play the main role in the mechanism of the nikethamide stimulatory effect on the activities of the enzyme system of xenobiotic biotransformation. The accelerated recovew of the liver weight was mainly due to proliferation in membranes hepatocytes of the endoplasmic reticulum with the enz}~aes of xenobiotic oxidation and conjugation localized in them (Lukienko et al., 1983).
References Bushma M.I., Luldenko P.I., 1982, Farmakologiya i Toksikologiya 5, 80. Stepanyan H.O., Tseitlin L,A., 1968, Byulleten Eksperimentalnoj Biologii i Meditsiny 7, 51. Lukienko P.I., Bushma M.I., Nikitin V.S., 1983, Farmakologiya i Toksikologiya 6, 74. P.th.254 [
Effects of tryptophan, nicotinic acid and some other metabolites of the kynurenine pathway on lipid metabolism in the rat Sainio, E.-L. a n d Penttil~i, I.M. Department of Pharmacology and Toxicology and Department of Clinical Chemistry, University of Kuopio, P.O.B. 6, SF-70210 Kuopio, Finland
It is wall imown that nicotirfi,: acid affc-cis the metabolism of lipids by lowering ~he concentrations of serum cholesterol, triglyeerides and free fatty acids both in man and in rat (Nikkil/~, 1971). Nicotinic acid itself is one degradation product of tryptophan and is formed from this amino acid through the kynurenine pathway via 3-hydroxyanthralinic acid. Tryptophan itself has some effects to the lipid metabolism by increasing the hepatic fatty acid synthesis in the rat (Fears and Murrell, 1980). To investigate more thoroughly the effects of this amino acid and its normal degradation products to serum lipids and their composition we purchased the compounds needed from Fluka Ag. (L-g+)-tryptophan) and from Sigma Chemical Co. (all other compounds tested). Especially we were
1877 interested about the effects of these compounds to the ratio of unsaturated and saturated free and esterified fatty acids (P/S-ratio) in serum. In the preliminary study we investigated the effects of tryptophan and its degradation products kynurenine, anthranilic acid, kynurenic acid, xanturenic acid, 3-OH-anthranilic acid, quinolinic acid, picolinic acid and nicotinic acid on serum cholesterol, triglycerides, phospholipids, high-density lipoprotein (HDL) cholesterol, HDL-phospholipids, HDL-triglycerides, free fatty acids and esterified fatty acids in rat serum (5-10 animals in each group) after peroral administration of 0,5 mmol/kg of each compound to the fasted animals and the second dose (nicotinic acid excluded) after three hours from the first meal. The blood samples were taken after five hours from the first meal by decapitating the animals, sera were separated after one hour and stored at - 2 0 ° C ~tntil anaLw.edo The results showed that nicotinic acid, as expected, lowered both serum total and HDL-cholesterol as well as triglycerides. Kynurenic acid increased total cholesterol, anthranilic acid decreased phospholipids and increased triglycerides. Tryptophan itself had a tendency to lower total cholesterol and increase triglycerides. After tryptophan, quinolinic acid and nicotinic acid there was most clear increases in serum free fatty acids, the corresponding changes were also observed in the values of serum esterified fatty acids except of nicotinic acid~ after which a clear decrease was usually found. The P/S-ratio has a tendency to increase for serum free fatty acids after tryptophan, nicotinic acid, quinolinic acid and picolinic acid, while there was no change in P/S-ratios of serum esterified fatty acids. These preliminary results will be established with bigger material.
References Nikkil& E.A., 1971, In Metabolic Effects of Nicotinic Acid and Its Derivatives, Hans Huber, Bern, 488. Fears, R., Murrell, E.A., 1980, Br. J. Nutr. 43, 349. I P-th.255 I
Effect of antiandrogens of heme content and metabolic processes in rat testis Clos, V. and Esteve, A. Departament de Farmacologia i Psiquiatria, Divisi~ Farmacologia, Unitat de Farmacologia Veterinaria, Universitat Aut~noma de Barcelona, Beilaterra, Spain
The antiandrogen Cyproterone Acetate (CA) and Flutamide (FL) modify LH and Testosterone (T) secretion differentially. CA reduces plasma levels of both hormones, while FL produces an increase in LH and T blood concentrations. Moreover, CA causes a decrease in testicular cytochrome P-450 levels, while FL induces a marked increase in this parameter (Closet al., 1988). Cytochrome P-450 is involved in testicular androgen biosynthesis and it has been found a close relationship between LH plasma levels and testicular microsomal system activity (Lee et al., 1980). In the present study we have explored if modifications in testicular cytochrome P-450 depend on heine metabolic processes. Therefore, microsomal heme content and ALA synthase and heme oxygenase activities, were determined. Male Sprague-Dawley rats were decapitated 24 o 48 hours after the last administration of antiandrogens (CA 100 mg/kg~ FL 50 mg/kg during 3 days) .~nd 12 hr after the last admi,~stration of hCG (100 units/12 hr-interval/5 days). To obtain the ,'nicrosomal and mitochondrial fractions two and three pairs of testis respectively were pooled and processed. T¢stieu!ar heme content of microsomal fraction was determined by difference spectrum from oxydated/reduced py~dJne hemecromogen between 541 and 557 nm, using an extinction coefficient of 32.4 nM cm -1. The testicular heme oxygenase activity was evaluated in an incubation mixture containing microsomal and witocondci~1 fraction by bilirubin formation (extinction coefficient of 40 nM cm-1). Mitochondrial ALA synthase activity was de~ermined by moaification of a radioisotopic method emplo~ng (2~3-~4C) succinate and succinil CoA generation system. The samples were washed in AG 50 w × 8 columns and finally eluted with 1N NaOH. The interfering substances were eliminated from the ~4C-ALA by formation of ALA-pyrole, which was purified by ion-exchange chromatografy using AG 1-× 8 columns. After CA administration a significant reduction in heme content (control- 0.219 ± 0.0045, CA = 0.170 ± 0.0089 nmol/mg prot.; p < 0.001; n = 5) was observed. In contrast, FL treatment induced an increase in heme content
Effect of nikethamide on xenobiofic biotransformation in regenerating rat liver Bushma, M.I., Legonkova, L.F., Lukienko, P.I. and Zavodnik, L.B. Institute of Biochemistry, Byelorussian SSR Academy of Sciences, 50 Lenin KomsomolBird, Grodno 230009, U.S.S.R.
Stimulation of regenerative processes in rat liver (removal of about 70~ of its weight) was accompanied by a 18-43c$ decrease of the cytochrome bs and P-450 concentrations, the NADH-cytochrome b 5 reductase activity and the rates of NADPH oxidation, amidopyrine, ~mylmorphine and aniline hydroxylation. The nikethamide administration to partially hepatectomized rats (subcutaneously, 75 mg/kg, 5 days before the operation and during the postoperative period) exerted the nolmalizing effect which was most pronounced after 2 days following the operation. The cytochrome hs concentration, the: activities of NADH-cytochrome b5 and NADPH-cytochrome P-450 reductases and the rates of amidopyrine, ethylmorphine and aniline hydroxylation were increased by 31-80~ as compared to untreated operated animals. Under condi~ons of liver regeneration, in contrast with the microsomal oxidation enzymes, the activities of glutathione-S- and UDP-glucurenyltransferases were compensatory increased by 31-44~. Nikethamide induced their further activation. The conjugation rate of glucuronic acid wi'.h paranitrophenol in microsomes, those of glutathione with sulfobromophthaleine (cytosol) and 1-chloro-2,4-dinitrobenzene (cytosol and microsomes) were increased by 30-.54~$, 36-76~ and 13-70~$ (2, 4 and 8 days after the operation, respectively). Under the action of nikethamide the rate of UDP-glucuronic acid biosynthesis (UDPG-dehydrogenase) was increased by 30~ (2 days) compared to untreated operated rats. Nikethamide accelerated the recovery of the liver weight. Substrate induction of microsomal monooxygenases (Bushma, Lukienko, 1982) and enhanced biosynthesis of nicotinamide coenzymes (Stepanyan, Tscitlin, 1968) play the main role in the mechanism of the nikethamide stimulatory effect on the activities of the enzyme system of xenobiotic biotransformation. The accelerated recovew of the liver weight was mainly due to proliferation in membranes hepatocytes of the endoplasmic reticulum with the enz}~aes of xenobiotic oxidation and conjugation localized in them (Lukienko et al., 1983).
References Bushma M.I., Luldenko P.I., 1982, Farmakologiya i Toksikologiya 5, 80. Stepanyan H.O., Tseitlin L,A., 1968, Byulleten Eksperimentalnoj Biologii i Meditsiny 7, 51. Lukienko P.I., Bushma M.I., Nikitin V.S., 1983, Farmakologiya i Toksikologiya 6, 74. P.th.254 [
Effects of tryptophan, nicotinic acid and some other metabolites of the kynurenine pathway on lipid metabolism in the rat Sainio, E.-L. a n d Penttil~i, I.M. Department of Pharmacology and Toxicology and Department of Clinical Chemistry, University of Kuopio, P.O.B. 6, SF-70210 Kuopio, Finland
It is wall imown that nicotirfi,: acid affc-cis the metabolism of lipids by lowering ~he concentrations of serum cholesterol, triglyeerides and free fatty acids both in man and in rat (Nikkil/~, 1971). Nicotinic acid itself is one degradation product of tryptophan and is formed from this amino acid through the kynurenine pathway via 3-hydroxyanthralinic acid. Tryptophan itself has some effects to the lipid metabolism by increasing the hepatic fatty acid synthesis in the rat (Fears and Murrell, 1980). To investigate more thoroughly the effects of this amino acid and its normal degradation products to serum lipids and their composition we purchased the compounds needed from Fluka Ag. (L-g+)-tryptophan) and from Sigma Chemical Co. (all other compounds tested). Especially we were
1877 interested about the effects of these compounds to the ratio of unsaturated and saturated free and esterified fatty acids (P/S-ratio) in serum. In the preliminary study we investigated the effects of tryptophan and its degradation products kynurenine, anthranilic acid, kynurenic acid, xanturenic acid, 3-OH-anthranilic acid, quinolinic acid, picolinic acid and nicotinic acid on serum cholesterol, triglycerides, phospholipids, high-density lipoprotein (HDL) cholesterol, HDL-phospholipids, HDL-triglycerides, free fatty acids and esterified fatty acids in rat serum (5-10 animals in each group) after peroral administration of 0,5 mmol/kg of each compound to the fasted animals and the second dose (nicotinic acid excluded) after three hours from the first meal. The blood samples were taken after five hours from the first meal by decapitating the animals, sera were separated after one hour and stored at - 2 0 ° C ~tntil anaLw.edo The results showed that nicotinic acid, as expected, lowered both serum total and HDL-cholesterol as well as triglycerides. Kynurenic acid increased total cholesterol, anthranilic acid decreased phospholipids and increased triglycerides. Tryptophan itself had a tendency to lower total cholesterol and increase triglycerides. After tryptophan, quinolinic acid and nicotinic acid there was most clear increases in serum free fatty acids, the corresponding changes were also observed in the values of serum esterified fatty acids except of nicotinic acid~ after which a clear decrease was usually found. The P/S-ratio has a tendency to increase for serum free fatty acids after tryptophan, nicotinic acid, quinolinic acid and picolinic acid, while there was no change in P/S-ratios of serum esterified fatty acids. These preliminary results will be established with bigger material.
References Nikkil& E.A., 1971, In Metabolic Effects of Nicotinic Acid and Its Derivatives, Hans Huber, Bern, 488. Fears, R., Murrell, E.A., 1980, Br. J. Nutr. 43, 349. I P-th.255 I
Effect of antiandrogens of heme content and metabolic processes in rat testis Clos, V. and Esteve, A. Departament de Farmacologia i Psiquiatria, Divisi~ Farmacologia, Unitat de Farmacologia Veterinaria, Universitat Aut~noma de Barcelona, Beilaterra, Spain
The antiandrogen Cyproterone Acetate (CA) and Flutamide (FL) modify LH and Testosterone (T) secretion differentially. CA reduces plasma levels of both hormones, while FL produces an increase in LH and T blood concentrations. Moreover, CA causes a decrease in testicular cytochrome P-450 levels, while FL induces a marked increase in this parameter (Closet al., 1988). Cytochrome P-450 is involved in testicular androgen biosynthesis and it has been found a close relationship between LH plasma levels and testicular microsomal system activity (Lee et al., 1980). In the present study we have explored if modifications in testicular cytochrome P-450 depend on heine metabolic processes. Therefore, microsomal heme content and ALA synthase and heme oxygenase activities, were determined. Male Sprague-Dawley rats were decapitated 24 o 48 hours after the last administration of antiandrogens (CA 100 mg/kg~ FL 50 mg/kg during 3 days) .~nd 12 hr after the last admi,~stration of hCG (100 units/12 hr-interval/5 days). To obtain the ,'nicrosomal and mitochondrial fractions two and three pairs of testis respectively were pooled and processed. T¢stieu!ar heme content of microsomal fraction was determined by difference spectrum from oxydated/reduced py~dJne hemecromogen between 541 and 557 nm, using an extinction coefficient of 32.4 nM cm -1. The testicular heme oxygenase activity was evaluated in an incubation mixture containing microsomal and witocondci~1 fraction by bilirubin formation (extinction coefficient of 40 nM cm-1). Mitochondrial ALA synthase activity was de~ermined by moaification of a radioisotopic method emplo~ng (2~3-~4C) succinate and succinil CoA generation system. The samples were washed in AG 50 w × 8 columns and finally eluted with 1N NaOH. The interfering substances were eliminated from the ~4C-ALA by formation of ALA-pyrole, which was purified by ion-exchange chromatografy using AG 1-× 8 columns. After CA administration a significant reduction in heme content (control- 0.219 ± 0.0045, CA = 0.170 ± 0.0089 nmol/mg prot.; p < 0.001; n = 5) was observed. In contrast, FL treatment induced an increase in heme content