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1.
J Dairy Sci ; 99(11): 8831-8846, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27614839

RESUMO

The response of transition dairy cows to dietary supplementation with fat sources of various fatty acid profiles could affect hepatic fat metabolism differently. Twenty-eight Holstein cows were blocked for similar calving date 4wk before expected parturition to compare the effects of feeding sources of n-3 and n-6 fatty acids on milk production and composition, plasma metabolites, and liver parameters. Cows within each block were assigned to 1 of 3 isonitrogenous and isoenergetic diets: control with a source of calcium salts of palm oil (MEG; 1.1 and 2.6% of the dry matter in prepartum and postpartum diets, respectively); n-3 fatty acids supplied as whole flaxseed (WFL; 4.8 and 7.7% of the dry matter in prepartum and postpartum diets, respectively); and n-6 fatty acids supplied as whole linola (WLO; 4.8 and 7.7% of the dry matter in prepartum and postpartum diets, respectively). Diets were fed until wk 14 of lactation. Contrasts of WFL versus WLO and polyunsaturated fatty acids versus MEG were compared. Cows fed polyunsaturated fatty acids increased dry matter intake over time at a greater extent than those fed MEG, which resulted in enhanced energy balance. Cows fed MEG produced more milk compared with those fed polyunsaturated fatty acids, and there was no difference between those fed WFL and WLO. We found no effect on body condition score and body weight. Plasma concentrations of glucose, fatty acids, and BHB were similar among diets. There was no effect of diet on concentration of glycogen and activities of superoxide dismutase and glutathione peroxidase in the liver. We observed higher concentrations of hepatic lipids and triacylglycerol in cows fed MEG compared with those fed polyunsaturated fatty acids, and no difference between WFL and WLO. Hepatic catalase activity tended to be higher on wk 4 after calving for cows supplemented with WFL compared with those fed WLO. Feeding linoleic and linolenic acids as unprotected oilseeds increased dry matter intake over time at a greater extent for cows fed MEG, improved the energy status, and lowered hepatic lipids and triacylglycerol contents, which may contribute to enhance the health status of transition dairy cows.


Assuntos
Linho/metabolismo , Leite , Animais , Bovinos , Dieta/veterinária , Metabolismo Energético , Feminino , Lactação , Metabolismo dos Lipídeos
2.
J Anim Sci ; 92(7): 2922-30, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24504042

RESUMO

The impacts of supplementing the diet of gestating gilts twice daily with 4 g of the plant extract silymarin on circulating hormonal concentrations, oxidative status, mammary development, and mammary gene expression at the end of gestation were determined. Gilts were fed conventional diets during gestation and on d 90 they were assigned as controls (CTL; n = 16) or treated (TRT; n = 17) animals. Treatment consisted of providing 4 g of silymarin twice daily until d 110, at which time all gilts were slaughtered to collect mammary tissue for compositional analyses and measures of gene expression and oxidative status, and liver and corpora lutea for measures of oxidative stress variables. Blood samples for hormonal assays and evaluation of oxidative stress biomarkers were obtained on d 89, 94, and 109 of gestation. Silymarin increased (P = 0.05) circulating concentrations of prolactin over all samples in the repeated in time analysis. In separate analyses for each sampling time, prolactin concentrations in TRT gilts tended (P < 0.10) to be greater than in CTL gilts on d 94 of gestation. Repeated in time analysis also revealed that silymarin reduced (P ≤ 0.05) plasmatic accumulation of biomarkers of oxidative damage to protein (protein carbonyls) between d 89 and 109. There was no effect (P > 0.10) of treatment on progesterone, estradiol, leptin, or 8-hydroxy-2'-deoxyguanosine concentrations. Percent fat in mammary parenchyma was greater (P ≤ 0.05), percent protein was lesser (P ≤ 0.05), and concentrations of both RNA (P ≤ 0.01) and DNA (P < 0.05) were lesser in TRT than CTL gilts. Mammary parenchyma from TRT gilts had lower (P ≤ 0.05) mRNA abundance for STAT5A and leptin and tended to have lower (P ≤ 0.10) abundance for STAT5B than CTL gilts. Silymarin reduced (P ≤ 0.001) protein carbonyls concentrations in liver of TRT gilts. No effect of treatment was observed on antioxidant gene expression and enzymatic activities in liver samples while total superoxide dismutase activity tended to be higher (P ≤ 0.10) in the corpora lutea of TRT animals when compared with CTL. This is the first demonstration that, in female pigs, silymarin can increase prolactin concentrations and protect against oxidative stress, yet the increase in prolactin was not enough to have beneficial effects on mammary gland development in late gestation.


Assuntos
Glândulas Mamárias Animais/efeitos dos fármacos , Extratos Vegetais/farmacologia , Prenhez/efeitos dos fármacos , Prolactina/sangue , Silimarina/farmacologia , Animais , Estradiol/sangue , Feminino , Leptina/sangue , Glândulas Mamárias Animais/crescimento & desenvolvimento , Estresse Oxidativo/efeitos dos fármacos , Gravidez , Prenhez/sangue , Prenhez/fisiologia , Progesterona/sangue , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Suínos/sangue , Suínos/metabolismo , Suínos/fisiologia
3.
J Dairy Sci ; 93(5): 2130-42, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20412928

RESUMO

The present experiment was undertaken to study the interactions between dietary supplements of rumen-protected methionine (RPM) and intramuscular injections of folic acid and vitamin B(12), given from 3 wk before calving to 16 wk of lactation, on hepatic metabolism of lactating dairy cows. Sixty multiparous Holstein cows were assigned to 10 blocks of 6 cows each according to their previous milk production. Within each block, 3 cows were fed a diet calculated to supply Met as 1.83% of metabolizable protein, whereas the 3 other cows were fed the same diet supplemented with 18g of RPM calculated to provide Met as 2.23% of metabolizable protein. Within each level of Met, the cows received no vitamin supplement or weekly intramuscular injections of 160mg of folic acid alone or combined with 10mg of vitamin B(12). Liver biopsies were taken at 2, 4, 8, and 16 wk of lactation. Liver concentrations of folates and vitamin B(12) were increased by their respective supplements but this response to vitamin supplements was altered by methionine supply. Concentrations of total lipids and triglycerides increased in livers of cows fed RPM, whereas concentrations of cholesterol ester, cholesterol, diglycerides, phosphatidylethanolamine, and phosphatidylcholine were not affected. Folic acid, alone or combined with vitamin B(12), tended to increase the ratio of phosphatidylcholine to phosphatidylethanolamine. Gene expression of 5,10-methylene-tetrahydrofolate reductase, microsomal transfer protein, and phosphatidylethanolamine methyltransferase were higher in liver of cows fed RPM supplements. The relative mRNA abundance of 5,10-methylene-tetrahydrofolate reductase and methylmalonyl-CoA mutase were increased by the combined injections of folic acid and vitamin B(12), whereas those of methionine synthase and methionine synthase reductase were not affected by treatments. These results suggest that increasing supply of methyl groups, as preformed labile methyl groups or through methylneogenesis, affected the methylation cycle but had a limited effect on dairy cow performance. The observed effects of the combined supplement of folic acid and vitamin B(12) on lactational performance of dairy cows probably result from an improvement of energy metabolism during early lactation.


Assuntos
Dieta/veterinária , Suplementos Nutricionais , Ácido Fólico/farmacologia , Fígado/efeitos dos fármacos , Metionina/metabolismo , Vitamina B 12/farmacologia , Indústria de Laticínios , Ácido Fólico/administração & dosagem , Regulação da Expressão Gênica/efeitos dos fármacos , Injeções Intramusculares , Lipídeo A/metabolismo , Fígado/metabolismo , Distribuição Aleatória , Fatores de Tempo , Vitamina B 12/administração & dosagem
4.
J Dairy Sci ; 92(4): 1685-95, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19307650

RESUMO

The present experiment was undertaken to determine if the effects of supplementary folic acid on lactational performance were caused by improved methylneogenesis and if the supply in vitamin B(12) could affect this metabolic pathway. In this eventuality, supplementary Met, a major source of preformed methyl groups, should reduce the requirements for these vitamins. Sixty multiparous Holstein cows were assigned to 10 blocks of 6 cows each according to their previous milk production. Within each block, 3 cows were fed a diet estimated to supply Met as 1.83% metabolizable protein and 3 cows were fed the same diet supplemented with 18 g of rumen-protected methionine (RPM) to supply Met as 2.23% of metabolizable protein. Within each level of Met, cows received no vitamin supplement or weekly intramuscular injections of 160 mg of folic acid alone or combined with 10 mg of vitamin B(12) from 3 wk before to 16 wk after calving. There was no treatment effect on dry matter intake during pre- and postcalving periods: 13.4 +/- 0.4 and 21.8 +/- 0.4 kg/d, respectively. Milk production was not affected by RPM supplementation. Folic acid and vitamin B(12) given together tended to increase milk production during the 16 wk of lactation. This effect was more pronounced during the first 4 wk of lactation: 37.5, 37.7, and 40.3 +/- 0.9 kg/d for cows receiving no vitamin supplement, folic acid alone, or folic acid combined with vitamin B(12), respectively. Milk fat yield was not affected by treatments. Lactose, crude protein, and total solid yields were greater, in early lactation, in cows injected with folic acid and vitamin B(12) together but this effect diminished as lactation progressed. Intramuscular injections of folic acid alone or combined with vitamin B(12) tended to decrease plasma concentrations of homocysteine from 5.51 microM with no vitamin supplement to 4.54 and 4.77 +/- 0.37 microM, respectively. Results of the present experiment suggest that the effects of the combined supplement of folic acid and vitamin B(12) on lactational performance of dairy cows were not due to an improvement in methyl groups supply, because RPM supplement, a source of preformed methyl groups, did not alter the cow responsiveness to vitamin supplements.


Assuntos
Bovinos/fisiologia , Dieta/veterinária , Ácido Fólico/farmacologia , Lactação/fisiologia , Metionina/metabolismo , Vitamina B 12/farmacologia , Complexo Vitamínico B/farmacologia , Aminoácidos/sangue , Animais , Análise Química do Sangue , Bovinos/metabolismo , Indústria de Laticínios , Feminino , Ácido Fólico/administração & dosagem , Injeções Intramusculares , Distribuição Aleatória , Vitamina B 12/administração & dosagem , Complexo Vitamínico B/administração & dosagem
5.
J Dairy Sci ; 92(2): 677-89, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19164680

RESUMO

The present experiment was undertaken to determine the effects of dietary supplements of rumen-protected methionine and intramuscular injections of folic acid and vitamin B(12), given 3 wk before to 16 wk after calving, on glucose and methionine metabolism of lactating dairy cows. Twenty-four multiparous Holstein cows were assigned to 6 blocks of 4 cows each according to their previous milk production. Within each block, 2 cows were fed a diet estimated to supply methionine as 1.83% metabolizable protein, equivalent to 76% of methionine requirement, whereas the 2 other cows were fed the same diet supplemented daily with 18 g of rumen-protected methionine. Within each diet, the cows were administrated either no vitamin supplement or weekly intramuscular injections of 160 mg of folic acid plus 10 mg of vitamin B(12.) To investigate metabolic changes at 12 wk of lactation, glucose and methionine kinetics were measured by isotope dilution using infusions of 3[U-(13)C]glucose, [(13)C]NaHCO(3) and 3[1-(13)C,(2)H(3)] methionine. Milk and plasma concentrations of folic acid and vitamin B(12) increased with vitamin injections. Supplementary B-vitamins increased milk production from 34.7 to 38.9 +/- 1.0 kg/d and increased milk lactose, protein, and total solids yields. Whole-body glucose flux tended to increase with vitamin supplementation with a similar quantitative magnitude as the milk lactose yield increase. Vitamin supplementation increased methionine utilization for protein synthesis through increased protein turnover when methionine was deficient and through decreased methionine oxidation when rumen-protected methionine was fed. Vitamin supplementation decreased plasma concentrations of homocysteine independently of rumen-protected methionine feeding, although no effect of vitamin supplementation was measured on methionine remethylation, but this could be due to the limitation of the technique used. Therefore, the effects of these B-vitamins on lactation performance were not mainly explained by methionine economy because of a more efficient methylneogenesis but were rather related to increased glucose availability and changes in methionine metabolism.


Assuntos
Bovinos/metabolismo , Suplementos Nutricionais , Ácido Fólico/administração & dosagem , Glucose/metabolismo , Metionina , Rúmen/metabolismo , Vitamina B 12/administração & dosagem , Animais , Peso Corporal/fisiologia , Indústria de Laticínios , Feminino , Injeções Intramusculares/veterinária , Lactação , Metionina/administração & dosagem , Metionina/metabolismo , Gravidez , Vitamina B 12/sangue
6.
J Dairy Sci ; 90(10): 4780-92, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17881701

RESUMO

Thirty-three Holstein cows averaging 687 kg of body weight were allotted 6 wk before the expected date of parturition to 11 groups of 3 cows blocked within parity for similar calving dates to determine the effects of feeding different sources of fatty acids on blood parameters related to fatty liver and profile of fatty acids in plasma and liver. Cows were fed lipid supplements from 6 wk before the expected date of parturition until d 28 of lactation. Cows within each block were assigned to 1 of 3 isonitrogenous and isoenergetic dietary supplements: control with no added lipids (CO); unsaturated lipids supplied as whole flaxseed (FL; 3.3 and 11.0% of the dry matter in prepartum and postpartum diets, respectively); and saturated lipids supplied as Energy Booster (EB; 1.7 and 3.5% of the DM in prepartum and postpartum diets, respectively). Diets EB and FL had similar ether extract concentrations. Multiparous cows fed EB had lower dry matter intake and milk production, higher concentrations of nonesterified fatty acids and beta-hydroxybutyrate in plasma and triglycerides (TG) and total lipids in liver, and lower concentrations of plasma glucose and liver glycogen than those fed FL and CO. Production of 4% fat-corrected milk was similar among treatments. Multiparous cows fed FL had the highest liver concentrations of glycogen on wk 2 and 4 after calving and lowest concentrations of TG on wk 4 after calving. Liver C16:0 relative percentages in multiparous cows increased after calving whereas those of C18:0 decreased. Relative percentages of liver C16:0 were higher in wk 2 and 4 postpartum for multiparous cows fed EB compared with those fed CO and FL; those of C18:0 were lower in wk 4 postpartum for cows fed EB compared with those fed CO and FL. Liver C18:1 relative percentages of multiparous cows increased after calving and were higher in wk 4 for cows fed EB compared with those fed CO and FL. The inverse was observed for liver C18:2 relative percentages. In general, diets had more significant effects on plasma concentrations of nonesterified fatty acids, beta-hydroxybutyrate, and glucose and liver profiles of fatty acids, TG, total lipids, and glycogen of multiparous than primiparous cows. These data suggest that feeding a source of saturated fatty acids increased the risk of fatty liver in the transition cow compared with feeding no lipids or whole flaxseed. Feeding flaxseed compared with no lipids or a source of saturated fatty acids from 6 wk before calving could be a useful strategy to increase liver concentrations of glycogen and decrease liver concentrations of TG after calving, which may prevent the development of fatty liver in the transition dairy cow.


Assuntos
Bovinos/metabolismo , Dieta/veterinária , Suplementos Nutricionais , Linho/metabolismo , Metabolismo dos Lipídeos , Fígado/metabolismo , Animais , Glicemia/metabolismo , Peso Corporal , Doenças dos Bovinos/fisiopatologia , Ácidos Graxos/metabolismo , Ácidos Graxos não Esterificados/sangue , Feminino , Glicogênio/metabolismo , Lactação/fisiologia , Lipídeos/análise , Fígado/química , Leite/química , Leite/metabolismo , Gravidez , Transtornos Puerperais/fisiopatologia , Transtornos Puerperais/veterinária , Fatores de Tempo
7.
J Dairy Sci ; 90(7): 3442-55, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17582128

RESUMO

The present experiment was undertaken to determine the effects of dietary supplements of folic acid and vitamin B12 given from 3 wk before to 8 wk after calving on lactational performance and metabolism of 24 multiparous Holstein cows assigned to 6 blocks of 4 cows each according to their previous milk production. Supplementary folic acid at 0 or 2.6 g/d and vitamin B12 at 0 or 0.5 g/d were used in a 2 x 2 factorial arrangement. Supplementary folic acid increased milk production from 38.0 +/- 0.9 to 41.4 +/- 1.0 kg/d and milk crude protein yield from 1.17 +/- 0.02 to 1.25 +/- 0.03 kg/d. It also increased plasma Gly, Ser, Thr, and total sulfur AA, decreased Asp, and tended to increase plasma Met. Supplementary B12 decreased milk urea N, plasma Ile, and Leu and tended to decrease Val but increased homocysteine, Cys, and total sulfur AA. Liver concentration of phospholipids was higher in cows fed supplementary B12. Plasma and liver concentrations of folates and B12 were increased by their respective supplements, but the increase in plasma folates and plasma and liver B12 was smaller for cows fed the 2 vitamins together. In cows fed folic acid supplements, supplementary B12 increased plasma glucose and alanine, tended to decrease plasma biotin, and decreased Km of the methylmalonyl-coenzyme A mutase in hepatic tissues following addition of deoxyadenosylcobalamin, whereas it had no effect when cows were not fed folic acid supplements. There was no treatment effect on plasma nonesterified fatty acids as well as specific activity and gene expression of Met synthase and methylmalonyl-coenzyme A mutase in the liver. Ingestion of folic acid supplements by cows fed no supplementary B12 increased total lipid and triacylglycerols in liver, whereas these supplements had no effect in cows supplemented with B12. The increases in milk and milk protein yields due to folic acid supplements did not seem to be dependent on the vitamin B12 supply. However, when vitamin B12 was given in combination with folic acid, utilization of the 2 vitamins seems to be increased, probably more so in extrahepatic tissues. Metabolic efficiency seems also to be improved as suggested by similar lactational performance and dry matter intake for cows fed supplementary folic acid but increased plasma glucose and decreased hepatic lipids in cows fed folic acid and vitamin B12 together.


Assuntos
Bovinos/metabolismo , Suplementos Nutricionais , Ácido Fólico/administração & dosagem , Lactação/metabolismo , Vitamina B 12/administração & dosagem , 5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/análise , 5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/biossíntese , 5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/genética , Ração Animal/análise , Animais , Dieta , Feminino , Expressão Gênica/fisiologia , Fígado/química , Metilmalonil-CoA Mutase/análise , Metilmalonil-CoA Mutase/biossíntese , Leite/química , Dados de Sequência Molecular , Gravidez , RNA Mensageiro/química , Distribuição Aleatória , Fatores de Tempo , Vitamina B 12/análise
8.
J Anim Sci ; 80(8): 2134-43, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12211383

RESUMO

The present work aimed to determine if different levels of prolificacy either by parity or by genetic origin are linked to folate metabolism. Nulliparous Yorkshire-Landrace (YL) and multiparous YL, and multiparous Meishan-Landrace (ML) sows were randomly assigned to two treatments: 0 ppm or 15 ppm folic acid+0.6% glycine. Supplements were given from the estrus before mating until slaughter on d 25 of gestation. At slaughter, embryo and endometrial tissues were collected to determine concentrations of DNA, protein, and homocysteine. Allantoic fluid samples were also collected to determine concentrations of folates, vitamin B12 and amino acids. Blood samples were taken at first estrus, at mating, and on d 8, 16, and 25 of gestation to determine serum concentrations of folates, vitamin B12, and relative total folate binding capacity (TFBC). Over the entire experiment, multiparous YL sows had higher average serum concentrations of folates than nulliparous YL sows (P < 0.05) but had similar serum concentrations of relative TFBC. Concentrations of folates and relative TFBC averaged higher in ML measured over the entire experiment than in multiparous YL sows (P < 0.05). Concentrations of serum vitamin B12 were higher in multiparous YL than in ML sows or YL nulliparous sows (P < 0.05) over the entire experiment. In allantoic fluid, folates, vitamin B12, and essential amino acids contents were significantly lower in ML than in YL multiparous sows (P < 0.05). The folic acid+glycine supplement increased concentrations of serum folates, but the increase was more marked in nulliparous YL sows (nulliparous x folic acid+glycine, P < 0.05). The folic acid+glycine supplement had no effect on litter size and embryo survival, but it tended to increase embryo DNA in multiparous YL sows (P = 0.06) but not in ML and nulliparous YL sows. Homocysteine was decreased by folic acid+glycine supplement in embryos from all sows, but in endometrium, the folic acid+glycine effect was dependent on parity (nulliparous x folic acid+glycine, P < 0.05). The effects of folic acid+glycine on litter size and embryo development and survival and some aspects of folate metabolism suggest that the basal dietary content of folic acid+glycine was adequate for ML and nulliparous YL sows but not to optimize embryo development in YL multiparous sows.


Assuntos
Desenvolvimento Embrionário e Fetal/efeitos dos fármacos , Ácido Fólico/farmacologia , Glicina/farmacologia , Tamanho da Ninhada de Vivíparos/efeitos dos fármacos , Paridade , Suínos/embriologia , Alantoide , Aminoácidos Essenciais/análise , Animais , Cruzamentos Genéticos , Suplementos Nutricionais , Feminino , Ácido Fólico/sangue , Hematínicos/farmacologia , Necessidades Nutricionais , Gravidez , Distribuição Aleatória , Suínos/fisiologia , Fatores de Tempo , Vitamina B 12/análise , Vitamina B 12/sangue
9.
Biol Reprod ; 65(3): 921-7, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11514359

RESUMO

Recent evidence has pointed toward a possible role of leptin (Lep) and its receptor (Lepr) in early gestation materno-fetal cross-talk. However, in gestating sows, exhaustive characterization of leptin mRNA expression in backfat and leptin-receptor mRNA expression in endometrial and embryonic tissues is still pending. The objectives of this study were to characterize the Lep, Lepr, and long Lepr-L isoform mRNA expression according to the breed and parity of gestating sows or to specific folic acid (B(9)) + glycine dietary treatments. To this end, nulliparous (GT) and multiparous occidental Yorkshire-Landrace (YL) sows as well as multiparous Chinese Meishan-Landrace (ML) sows were used. These sows were randomly assigned to two different dietary treatments: 0 or 15 ppm of B(9) + 0.6% glycine, given from the estrous preceding mating until slaughter on Day 25 of gestation. Jugular blood samples were collected at mating and on Day 25 of gestation and assayed for circulating leptin concentrations. Expression levels of Lep in backfat and of Lepr and Lepr-L in endometrial and embryonic tissues were performed using semiquantitative reverse transcription-polymerase chain reaction. Results demonstrated that on Day 25 of pregnancy, the ML sows showed higher concentrations of circulating leptin along with higher backfat thickness and higher expression of Lep in backfat tissue. Moreover, in embryonic tissues, the mRNA expression levels of Lepr and Lepr-L genes were higher in ML than in YL sows. Parity effects were observed for mRNA expression of Lepr in both endometrial and embryonic tissues, whereas mRNA levels were higher in YL than in GT sows. In addition, embryonic Lepr-L mRNA levels were higher in GT than in YL sows, and B(9) + glycine dietary supplement decreased the mRNA expression levels of Lep in backfat and of Lepr in embryonic tissues. These decreases were independent of breed or parity of the sows. The effect of B(9) + glycine on Lepr-L mRNA expression levels was only seen in YL sows, whereas the treatment lowered Lepr-L expression levels in both endometrial and embryonic tissues. These results indicate that leptin and its receptor may play a role during early stages of development of the pig embryo-fetus, and that these roles could be modulated according to the breed and parity of the sows. Moreover, the effects of B(9) + glycine on expression levels of embryonic and endometrial Lepr-L mRNA in YL sows may explain the previously reported effects of B(9) on embryo survival rate and litter size observed in occidental multiparous sows.


Assuntos
Proteínas de Transporte/genética , Endométrio/metabolismo , Ácido Fólico/administração & dosagem , Leptina/genética , Paridade , Receptores de Superfície Celular , Suínos/genética , Tecido Adiposo/química , Animais , Composição Corporal , Dieta , Embrião de Mamíferos/química , Embrião de Mamíferos/metabolismo , Endométrio/química , Feminino , Expressão Gênica/efeitos dos fármacos , Idade Gestacional , Glicina/administração & dosagem , Leptina/metabolismo , Tamanho da Ninhada de Vivíparos , Gravidez , RNA Mensageiro/análise , Receptores para Leptina , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Especificidade da Espécie , Suínos/embriologia
10.
Endocrine ; 9(1): 65-9, 1998 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9798732

RESUMO

The pathogenesis of benign prostatic hyperplasia is linked to the accumulation of dihydrotestosterone (DHT), the active form of testosterone (T), in prostatic tissue. We have defined characteristics of 5alpha-reductase enzyme which catalyzes the conversion of T into DHT in prostatic microsomes of growing pigs. Peaks for the 5alpha-reductase activity were found at pH 5.5 and 8.0, which indicates the presence of both type 1 and type 2 isozymes. Kinetic parameters of porcine 5alpha-reductase in the presence of Serenoa repens extracts revealed uncompetitive, noncompetitive, and mixed types of inhibitions. Our results show the inhibitory action of S. repens on prostate porcine microsomal 5alpha-reductase activity.


Assuntos
3-Oxo-5-alfa-Esteroide 4-Desidrogenase/metabolismo , Inibidores Enzimáticos/farmacologia , Microssomos/enzimologia , Extratos Vegetais/farmacologia , Próstata/enzimologia , Inibidores de 5-alfa Redutase , Animais , Cinética , Masculino , Próstata/ultraestrutura , Suínos
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