RESUMO
In women, the association between chronic marijuana smoking and early miscarriage has long been known. Anandamide, a major endocannabinoid, mimics some of the psychotropic, hypnotic and analgesic effects of Delta(9)-tetrahydrocannabinol, the psychoactive component of marijuana. The uterus contains the highest concentrations of anandamide yet discovered in mammalian tissues and this suggests that it might play a role in reproduction. The production of small amounts of nitric oxide (NO) regulates various physiological events including implantation and myometrial relaxation, but in an inflammatory setting such as sepsis, NO has toxic effects as it is a free radical. The results presented in this study indicate that anandamide modulates NO production induced by lipopolysaccharide (LPS) in an in-vitro murine model. It was shown that LPS-induced NO synthesis and tissue damage were mediated by anandamide, as a cannabinoid receptor type I antagonist could block the effect of LPS (P < 0.001). This endotoxin inhibited anandamide uterine degradation (P < 0.05) and increased the expression of one of its synthesizing enzymes (P < 0.05). Contrary to the known anti-inflammatory and protective effects, in this model anandamide seems to act as a pro-inflammatory molecule modulating the production of NO induced by LPS. This proinflammatory effect of anandamide may be implicated in pathological reproductive events such as septic abortion.
Assuntos
Ácidos Araquidônicos/farmacologia , Lipopolissacarídeos/farmacologia , Óxido Nítrico/biossíntese , Alcamidas Poli-Insaturadas/farmacologia , Útero/efeitos dos fármacos , Amidoidrolases/metabolismo , Animais , Sequência de Bases , Western Blotting , Primers do DNA , Endocanabinoides , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Reação em Cadeia da Polimerase , Útero/metabolismoRESUMO
Endocannabinoids are an important family of lipid-signaling molecules that are widely distributed in mammalian tissues and anandamide (AEA) was the first member identified. The uterus contains the highest concentrations of AEA yet discovered in mammalian tissues and this suggests that it might play a role in reproduction. Previous results from our laboratory have shown that AEA modulated NO synthesis in rat placenta. The production of small amounts of nitric oxide regulates various physiological reproductive processes such as implantation, decidualization and myometrial relaxation. But in an inflammatory setting such as sepsis, NO is produced in big amounts and has toxic effects as it is a free radical. The results presented in this study indicate that LPS-induced NO synthesis and tissue damage were mediated by AEA. Decidual LPS-induced NO production was abrogated either by co-incubation with CB1 (AM251) or CB2 (SR144528) antagonists which suggests that both receptors could be mediating this effect. On the other hand, LPS-induced tissue damage and this deleterious effect was partially abrogated by incubating tissue explants with LPS plus CB1 receptor antagonist. Our findings suggest that AEA, probably by increasing NO synthesis, participates in the deleterious effect of LPS in implantation sites. These effects could be involved in pathological reproductive events such as septic abortion.
Assuntos
Ácidos Araquidônicos/metabolismo , Moduladores de Receptores de Canabinoides/metabolismo , Decídua , Endocanabinoides , Lipopolissacarídeos/farmacologia , Óxido Nítrico/metabolismo , Alcamidas Poli-Insaturadas/metabolismo , Aborto Séptico/imunologia , Aborto Séptico/metabolismo , Amidoidrolases/metabolismo , Animais , Ácidos Araquidônicos/farmacologia , Antagonistas de Receptores de Canabinoides , Células Cultivadas , Decídua/efeitos dos fármacos , Decídua/imunologia , Decídua/metabolismo , Feminino , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Nitratos/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Nitritos/metabolismo , Nitrogênio/metabolismo , Fosfolipase D/metabolismo , Gravidez , Receptores de Canabinoides/metabolismoRESUMO
Genital tract bacterial infections could induce abortion and are some of the most common complications of pregnancy; however, the mechanisms remain unclear. We investigated the role of prostaglandins (PGs) in the mechanism of bacterial lipopolysaccharide (LPS)-induced pregnancy loss in a mouse model, and we hypothesized that PGs might play a central role in this action. LPS increased PG production in the uterus and decidua from early pregnant mice and stimulated cyclooxygenase (COX)-II mRNA and protein expression in the decidua but not in the uterus. We also observed that COX inhibitors prevented embryonic resorption (ER). To study the possible interaction between nitric oxide (NO) and PGs, we administered aminoguanidine, an inducible NO synthase inhibitor. NO inhibited basal PGE and PGF(2alpha) production in the decidua but activated their uterine synthesis and COX-II mRNA expression under septic conditions. A NO donor (S-nitroso-N-acetylpenicillamine) produced 100% ER and increased PG levels in the uterus and decidua. LPS-stimulated protein nitration was higher in the uterus than in the decidua. Quercetin, a peroxynitrite scavenger, did not reverse LPS-induced ER. Our results suggest that in a model of septic abortion characterized by increased PG levels, NO might nitrate and thus inhibit COX catalytic activity. ER prevention by COX inhibitors adds a possible clinical application to early pregnancy complications due to infections.
Assuntos
Reabsorção do Feto/induzido quimicamente , Reabsorção do Feto/metabolismo , Lipopolissacarídeos/farmacologia , Óxido Nítrico/metabolismo , Prostaglandinas/metabolismo , Animais , Inibidores de Ciclo-Oxigenase/farmacologia , Feminino , Isoenzimas/genética , Isoenzimas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico Sintase/metabolismo , Gravidez , Prostaglandina-Endoperóxido Sintases/genética , Prostaglandina-Endoperóxido Sintases/metabolismo , RNA Mensageiro/genética , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Tirosina/metabolismoRESUMO
Nitric oxide (NO) synthesized by fetal membranes may act either directly inhibiting myometrium contractility or indirectly interacting with tocolytic agents as prostaglandins (PGs). Here we examined if NO could modulate prostaglandin E(2) 9-ketoreductase (9-KPR) activity in human fetal membranes (HFM). 9-KPR is the enzyme that converts PGE(2) into PGF(2alpha), the main PGs known to induce uterine contractility at term. Chorioamnion explants obtained from elective caesareans were incubated with aminoguanidine (AG), an iNOS inhibitor, or NOC-18, a NO donor. NOC-18 (2mM) increased PGE(2) production and diminished PGF(2alpha) synthesis in HFM. AG presented the opposite effect. When we evaluated the activity of 9-KPR by the conversion of [(3)H]-PGE(2) into [(3)H]-PGF(2alpha) and 13,14-dihidro-15-keto prostaglandin F(2alpha) (the PGF(2alpha) metabolite), we found that NOC-18 inhibited 9-KPR activity. Interestingly, AG did not elicit any effect on 9-KPR but l-NAME, a non-selective NOS inhibitor, significantly increased its activity. Our data suggests that exogenous NO inhibits 9-KPR activity in HFM, thus modulating the synthesis of important labor mediators as PGF(2alpha).
Assuntos
Membranas Extraembrionárias/enzimologia , Hidroxiprostaglandina Desidrogenases/metabolismo , Óxido Nítrico/metabolismo , Dinoprosta/metabolismo , Dinoprostona/metabolismo , Relação Dose-Resposta a Droga , Membranas Extraembrionárias/citologia , Membranas Extraembrionárias/efeitos dos fármacos , Feminino , Regulação da Expressão Gênica , Humanos , Hidroxiprostaglandina Desidrogenases/antagonistas & inibidores , Pessoa de Meia-Idade , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico Sintase/metabolismo , Gravidez , Prostaglandina-Endoperóxido Sintases/metabolismoRESUMO
Many authors hypothesize that the epidermal growth factor (EGF) is involved in the onset of labor. Previous reports from our laboratory showed that intrauterine administration of EGF delays the beginning of labor. The aims of this study were: 1) to analyze the effect of intrauterine administration of 500 ng EGF on placental prostaglandins and nitric oxide, and 2) to characterize the expression of EGF receptors (EGF-R) in pregnant rat placentae. Saline solution (sham group) and 500 ng EGF (EGF-treated group) were administered via intrauterine injection on day 21 of gestation, and both groups of animals were sacrificed on day 22 (sham rats delivered on day 22). Results showed that EGF treatment: 1) inhibited the production of prostaglandin E (p<0.001) and F(2alpha) (p<0.01), 2) increased the synthesis of nitric oxide (p<0.001), and 3) reduced the expression of cyclooxygenase-II, the enzyme responsible for PG synthesis. Placentae were found to express EGF-R and its activated form, and the expressions of both forms were higher at mid and term pregnancy. Hence, EGF is a very interesting molecule for studying the regulation of placental prostaglandin and nitric oxide production related to the parturition process.
Assuntos
Dinoprosta/biossíntese , Fator de Crescimento Epidérmico/farmacologia , Receptores ErbB/metabolismo , Óxido Nítrico Sintase/metabolismo , Placenta/efeitos dos fármacos , Placenta/metabolismo , Prostaglandinas E/biossíntese , Animais , Western Blotting , Ciclo-Oxigenase 2/biossíntese , Receptores ErbB/biossíntese , Feminino , Isoenzimas , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase/biossíntese , Placenta/enzimologia , Gravidez , RatosRESUMO
We have previously reported that intrauterine (i/u) administration of epidermal growth factor (EGF 500 ng) on day (d) 21 of pregnancy delayed 19.0 +/- 0.6 h the onset of labor. Progesterone (P) is secreted by ovarian corpora lutea (CL) throughout gestation in the rat. Prepartum CL regression due to increased uterine cyclooxygenase I and prostaglandin F(2alpha) results in P withdrawal followed by labor. The aims of the present work were (i) to study whether EGF delayed-onset of labor was mediated by a mechanism that prevented CL regression; (ii) to determine amniotic fluid (AF) EGF in pregnant rats. Rats on d21 of pregnancy received i/u EGF (500 ng) and were killed 0, 4, 8, 12, 24, and 48 h later. Control AF from rats on d13 and 18-22 of pregnancy was obtained. EGF decreased uterine prostaglandin F(2alpha) synthesis 8 h after treatment. Twelve hours after EGF injection, P reached its highest serum level and uterine cyclooxygenase I expression was undetectable. CL from rats killed 8 and 12 h after EGF were similar to those from rats on d13 of pregnancy, when serum P is maximum. EGF in AF increased throughout gestation, reached a maximum on d21, and decreased before the onset of labor. We suggest that the effect of EGF on the onset of labor was mediated by an early effect on the uterus that prevented prepartum CL regression.
Assuntos
Fator de Crescimento Epidérmico/farmacologia , Trabalho de Parto/metabolismo , Luteólise/efeitos dos fármacos , Luteólise/fisiologia , Líquido Amniótico/metabolismo , Análise de Variância , Animais , Western Blotting , Dinoprosta/sangue , Fator de Crescimento Epidérmico/metabolismo , Feminino , Técnicas Histológicas , Ovário/anatomia & histologia , Ovário/metabolismo , Gravidez , RatosRESUMO
Myometrial quiescence is a key factor in all species to accomplish a successful gestation. PGs play a crucial role in mediating parturition events, and their synthesis and metabolism are regulated by cyclooxygenases (COXs) and NAD(+)-dependent 15-hydroxy-PG dehydrogenase (PGDH), respectively. Progesterone (P(4)) is the hormone responsible for maintaining uterine smooth muscle quiescence during pregnancy. In this work, we have studied the effect of P(4) on the activity of COXs and PGDH, the uterine enzymes involved in the biosynthesis and metabolism of prostanoids in the rat. We found that during pregnancy PGF(2alpha) production and also protein levels of COX-1 and COX-2 were decreased. The exogenous administration of P(4) significantly inhibited the uterine production of PGF(2alpha) and also the protein level of COX-2. PGF(2alpha), metabolism was assessed by PGDH activity, which resulted high during pregnancy and increased as a result of P(4) administration. These results indicate that PGs levels were negatively modulated by P(4), which could be exerting its effect by increasing PGs metabolism through stimulation on PGDH activity and an inhibition on COX and that is a major mechanism for maintain uterine quiescence in pregnancy.
Assuntos
Abortivos não Esteroides/metabolismo , Dinoprosta/metabolismo , Progesterona/farmacologia , Útero/efeitos dos fármacos , Animais , Ciclo-Oxigenase 1 , Ciclo-Oxigenase 2 , Feminino , Hidroxiprostaglandina Desidrogenases/metabolismo , Isoenzimas/metabolismo , Proteínas de Membrana , Gravidez , Prostaglandina-Endoperóxido Sintases/metabolismo , Ratos , Ratos Wistar , Útero/metabolismoRESUMO
The purpose of the present work is to investigate the ability of desferrioxamine (DF) as an iron chelator to revert or decrease a severe experimental porphyria induced by hexachlorobenzene (HCB) in rats; DF treatment started after 17 weeks of HCB intoxication and was continued until the 27th week. The urinary excretions of -aminolevulinic acid (ALA), porphobilinogen and porphyrins were weekly quantitated. At the end of the experiment the animals were sacrificed and hepatic porphyrins, ALA-synthase and porphyrinogen carboxy-lyase activities were determined. The results obtained indicated that, under the present conditions, the administered iron chelator does not improve the disturbance promoted by HCB on the haem pathway. These results were compared with those obtained when the DF was given simultaneously with HCB from the beginning of fungicide administration. In this last situation the chelator was able to delay and diminish the porphyrinogenic effect of HCB.
Assuntos
Desferroxamina/uso terapêutico , Porfirias/tratamento farmacológico , Dermatopatias/tratamento farmacológico , 5-Aminolevulinato Sintetase/metabolismo , 5-Aminolevulinato Sintetase/urina , Animais , Carboxiliases/metabolismo , Hexaclorobenzeno , Fígado/enzimologia , Porfobilinogênio/urina , Porfirias/induzido quimicamente , Porfirias/enzimologia , Porfirias/urina , Porfirinas/metabolismo , Porfirinas/urina , Ratos , Ratos Endogâmicos , Indução de Remissão , Dermatopatias/induzido quimicamente , Dermatopatias/enzimologia , Dermatopatias/urinaRESUMO
The purpose of the present work is to investigate the ability of desferrioxamine (DF) as an iron chelator to revert or decrease a severe experimental porphyria induced by hexachlorobenzene (HCB) in rats; DF treatment started after 17 weeks of HCB intoxication and was continued until the 27th week. The urinary excretions of -aminolevulinic acid (ALA), porphobilinogen and porphyrins were weekly quantitated. At the end of the experiment the animals were sacrificed and hepatic porphyrins, ALA-synthase and porphyrinogen carboxy-lyase activities were determined. The results obtained indicated that, under the present conditions, the administered iron chelator does not improve the disturbance promoted by HCB on the haem pathway. These results were compared with those obtained when the DF was given simultaneously with HCB from the beginning of fungicide administration. In this last situation the chelator was able to delay and diminish the porphyrinogenic effect of HCB.
RESUMO
The present study investigates the ability of several hexachlorobenzene (HCB) metabolites to induce porphyrin accumulation in chick embryo liver cells in ovo, in order to further clarify the role of metabolites in the mechanism of HCB-induced porphyria. HCB per se had no effect on liver porphyrin content, but pretreatment assays with phenobarbital suggested that its metabolic products did. When the direct effect of phenolic, sulfur-containing, and benzenic metabolites of HCB were tested, the following results were obtained. Less chlorinated benzenes (pentachlorobenzene and 1,2,3,4- 1,2,3,5- 1,2,4,5- tetrachlorobenzene) had poor capacity to change the control porphyrin content. On the other hand, the behavior of phenolic metabolites (pentachlorophenol, 2,3,4,5- 2,3,4,6- 2,3,5,6- tetrachlorophenol, 2,3,4- 2,3,5- 2,3,6- 2,4,5- 2,4,6- 3,4,5- trichlorophenol and tetrachlorohydroquinone) as porphyrin inducers was remarkable; the stronger effects were produced by trichlorophenols and tetrachlorohydroquinone. Sulfur containing metabolites produced increases in porphyrin content that were lower than those produced by phenolic compounds and higher than those due to the action of less chlorinated benzenes; only 1-methyl-(2,3,4,5-pentachlorophenyl) sulfoxide was not able to increase porphyrin level. The extent of the effect of the other drugs was pentachlorothiophenol greater than 1-methyl-(2,3,4,5,6-pentachlorophenyl) sulfone greater than tetrachlorothioanisol greater than pentachlorothioanisol. Regarding the mechanism of HCB porphyria, the present results indicate that phenolic metabolites and, in a lower degree, sulfur-containing metabolites, can contribute to the porphyrinogenic ability of HCB.