RESUMEN
Obesity constitutes a health problem of increasing worldwide prevalence. Among the health detriments caused by obesity, reproduction is disrupted. However, the mechanisms involved in this disruption are not fully understood. Animals fed a cafeteria diet constitute the model for the study of obesity that most closely reflects Western diet habits. The aims of this study were to evaluate whether a cafeteria diet affects ovarian function and to contribute to the understanding of the mechanisms involved. For that purpose, 22-day-old female Wistar rats were fed ad libitum with a standard diet (control group; n = 20) or cafeteria diet (CAF group; n = 20). The cafeteria diet induced obesity and hyperglycaemia, without altering serum triglycerides, cholesterol or C-reactive protein concentrations. This diet also altered ovarian function: the rats showed prolonged dioestrous phases, decreased serum oestradiol concentrations and increased number of antral atretic follicles. Moreover, follicular cysts were detected in the CAF group, concomitantly with a decrease in the number of anti-Müllerian hormone immunoreactive pre-antral follicles and COX-2-positive antral and pre-ovulatory follicles. The authors conclude that a cafeteria diet reduces ovarian reserve, induces the presence of follicular cysts and disturbs the ovulatory process, leading to the delayed pregnancy observed in these animals.
Asunto(s)
Dieta Occidental/efectos adversos , Infertilidad Femenina/etiología , Obesidad/complicaciones , Ovario/metabolismo , Animales , Hormona Antimülleriana/metabolismo , Colesterol/sangre , Ciclooxigenasa 2/metabolismo , Femenino , Hiperglucemia/complicaciones , Hiperglucemia/metabolismo , Infertilidad Femenina/metabolismo , Obesidad/metabolismo , Embarazo , Ratas , Ratas Wistar , Triglicéridos/sangreRESUMEN
BACKGROUND: Maternal diabetes is associated with morphological placental abnormalities and foeto-placental impairments. These alterations are linked with a dysregulation of the activity of matrix metalloproteinases (MMPs). We investigated the action of 15deoxyDelta(12,14) prostaglandin J(2) (15dPGJ(2)), a natural ligand of the peroxisome proliferator activated receptor (PPAR) gamma, on MMP-2 and MMP-9 activities and tissue inhibitors of matrix metalloproteinases (TIMP) levels in foetuses and placentas from diabetic rats. MATERIALS AND METHODS: Diabetes was induced in rat neonates by a single streptozotocin administration (90 mg kg(-1) s.c.). At 13.5 days of gestation, foetal and placental homogenates were prepared for the determination of PPARgamma levels (western blot) and 15dPGJ(2) concentration (enzyme-immunoassay), whereas the in vitro effect of 15dPGJ(2) (2 microM) was evaluated on placental and foetal MMPs and TIMP activities (zymography and reverse zymography), nitrate/nitrite concentrations (Griess method) and thiobarbituric acid reactive substances (TBARS). RESULTS: PPARgamma was increased while 15dPGJ(2) was decreased in placentas and foetuses from diabetic rats. 15dPGJ(2) additions were able to reduce the high activities of MMP-2 and MMP-9 present in diabetic placental tissues. 15dPGJ(2) additions reduced MMP-2 activity in control and diabetic foetuses. TIMP-3 levels were decreased in diabetic placentas and 15dPGJ(2) was able to enhance them to control values. Nitrates/nitrites and TBARS, metabolites of MMPs activators, were increased in the diabetic placenta and reduced by 15dPGJ(2). CONCLUSIONS: This study demonstrates that 15dPGJ(2) is a potent modulator of the balance between MMP activities and TIMP levels, which is needed in the correct formation and function of the placenta and foetal organs.
Asunto(s)
Diabetes Mellitus/metabolismo , Feto/efectos de los fármacos , Metaloproteinasas de la Matriz/efectos de los fármacos , PPAR gamma/antagonistas & inhibidores , Placenta/efectos de los fármacos , Prostaglandina D2/análogos & derivados , Animales , Diabetes Mellitus/enzimología , Modelos Animales de Enfermedad , Femenino , Feto/metabolismo , Gelatinasas/metabolismo , Metaloproteinasas de la Matriz/metabolismo , Óxido Nítrico/metabolismo , PPAR gamma/metabolismo , Placenta/metabolismo , Embarazo , Prostaglandina D2/metabolismo , Prostaglandina D2/farmacología , Ratas , Ratas Wistar , Inhibidores Tisulares de Metaloproteinasas/efectos de los fármacos , Inhibidores Tisulares de Metaloproteinasas/metabolismoRESUMEN
To investigate the expression of leptin receptors (Ob-R) in the rat hypothalamus-pituitary-ovarian axis, immature rats were treated with eCG/hCG and Ob-R expression was evaluated by western blot analysis. The Ob-R expression increased 24 h after eCG administration in all the tissues assayed. In the hypothalamus, these levels immediately decreased to those obtained without treatment. In the pituitary, the Ob-R expression continued to be elevated 48 h after eCG administration, whereas the hCG injection did not modify these levels. Similar results were obtained with the ovarian long isoform. To assess the effect of leptin on its receptors, Ob-R was assessed in hypothalamus, pituitary and ovarian explants cultured in the presence or absence of leptin (0.3-500 ng/ml). In the hypothalamus, we found a biphasic effect: the Ob-R expression was either reduced or increased at low or high concentrations of leptin respectively. LH-releasing hormone secretion increased at 1 ng/ml. In the pituitary, Ob-R increased at 10 or 30 ng/ml of leptin for the long and short isoforms respectively. Leptin also induced an increase in LH release at 30 ng/ml. In the ovarian culture, the presence of leptin produced an increase in Ob-R expression at different ranges of concentrations and a dose-dependent biphasic effect on the progesterone production. In conclusion, all these results clearly suggest that leptin is able to modulate the expression of its own receptors in the reproductive axis in a differential way. Moreover, the positive or negative effect that leptin exerts on the ovulatory process may be dependent on this regulation.
Asunto(s)
Expresión Génica/efectos de los fármacos , Hipotálamo/metabolismo , Leptina/farmacología , Ovario/metabolismo , Hipófisis/metabolismo , Receptores de Leptina/genética , Receptores de Leptina/metabolismo , Animales , Western Blotting , Gonadotropina Coriónica/farmacología , Femenino , Hormona Liberadora de Gonadotropina/metabolismo , Hipotálamo/efectos de los fármacos , Inmunohistoquímica , Técnicas In Vitro , Ovario/efectos de los fármacos , Hipófisis/efectos de los fármacos , Ratas , Ratas Sprague-DawleyRESUMEN
Maternal diabetes promotes an overaccumulation of lipids in the feto-placental unit and impairs feto-placental development and growth. Here, we investigated the role played by the nuclear receptor peroxisome proliferator-activated receptor (PPAR)alpha in lipid metabolism in fetuses and placentas from control and neonatal streptozotocin-induced diabetic rats. Placentas and fetuses were studied on day 13.5 of gestation. The concentrations of PPARalpha (by Western blot) and its endogenous agonist leukotriene B(4) (LTB(4)) (by enzyme immunoassay) were analysed. Placental explants and fetuses were cultured with LTB(4) or clofibrate, and then lipid metabolism analysed (concentrations and synthesis from (14)C-acetate of triglycerides, phospholipids, cholesterol and cholesteryl esters; release of glycerol and free fatty acids (FFAs)). We found that maternal diabetes led to increases in placental concentrations of triglycerides and cholesteryl esters, and fetal concentrations of phospholipids. PPARalpha agonists downregulated fetal and placental lipid concentrations in control and diabetic rats. The synthesis of lipids was reduced in the diabetic placenta but increased in fetuses from diabetic animals. PPARalpha agonists reduced the synthesis of lipids in control placenta and in the fetuses from control and diabetic rats. Glycerol and FFA release was enhanced in the diabetic placenta and in control placenta cultured with PPARalpha agonists. Maternal diabetes led to reductions in fetal and placental LTB(4) concentrations and to increases in placental PPARalpha concentrations. Overall, these data support a novel role of PPARalpha as a regulator of lipid metabolism in the feto-placental unit, relevant in maternal diabetes where fetal and placental PPARalpha, LTB(4) and lipid concentrations are altered.
Asunto(s)
Diabetes Gestacional/metabolismo , Feto/metabolismo , Metabolismo de los Lípidos , PPAR alfa/metabolismo , Placenta/metabolismo , Animales , Ácidos Grasos no Esterificados/análisis , Femenino , Glicerol/análisis , Leucotrieno B4/análisis , Leucotrieno B4/metabolismo , Lípidos/análisis , Lípidos/biosíntesis , PPAR alfa/análisis , Embarazo , Ratas , Ratas WistarRESUMEN
Matrix metalloproteinases (MMPs) play an important role in tissue remodeling that accompanies the rapid growth, differentiation, and structural changes of the placenta and several fetal organs. In the present study, we investigated whether the diabetic maternal environment may alter the regulatory homeostasis exerted by nitric oxide (NO) on MMPs activity in the feto-placental unit from rats at midgestation. We found that NADPH-diaphorase activity, which reflects the distribution and activity of NO synthases (NOS), was increased in both placenta and fetuses from diabetic rats when compared with controls. In addition, while a NO donor enhanced MMP2 and MMP9 activities, a NOS inhibitor reduced these activities in the maternal side of the placenta from control rats. This regulatory effect of NO was only observed on MMP9 in the diabetic group. On the other hand, the NO donor did not modify MMP2 and MMP9 activities, while the NOS inhibitor reduced MMP9 activity in the fetal side of both control and diabetic placentas. In the fetuses, MMP2 was enhanced by the NO donor and reduced by the NO inhibitor in both fetuses from control and diabetic rats. Overall, this study demonstrates that NO is able to modulate the activation of MMPs in the feto-placental unit, and provides supportive evidence that increased NOS activity leads to NO overproduction in the feto-placental unit from diabetic rats, an alteration closely related to the observed MMPs dysregulation that may have profound implications in the formation and function of the placenta and the fetal organs.
Asunto(s)
Diabetes Mellitus Experimental/metabolismo , Feto/enzimología , Metaloproteinasas de la Matriz/metabolismo , Óxido Nítrico/fisiología , Placenta/enzimología , Animales , Western Blotting/métodos , Electroforesis en Gel de Poliacrilamida , Femenino , Feto/efectos de los fármacos , Metaloproteinasa 2 de la Matriz/análisis , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/análisis , Metaloproteinasa 9 de la Matriz/metabolismo , Metaloproteinasas de la Matriz/análisis , NG-Nitroarginina Metil Éster/farmacología , Donantes de Óxido Nítrico/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa de Tipo II/análisis , Óxido Nítrico Sintasa de Tipo III/análisis , Nitroprusiato/farmacología , Placenta/efectos de los fármacos , Embarazo , Ratas , Ratas WistarRESUMEN
Maternal diabetes significantly increases the risk of congenital malformations, and the mechanisms involved are not yet clarified. This study was designed to address peroxisome proliferator-activated receptor delta (PPARdelta) involvement in diabetic embryopathy. We investigated the concentrations of PPARdelta and its endogenous agonist prostaglandin (PG)I(2), as well as the effect of PPARdelta activation on lipid metabolism and PGE(2) concentrations in embryos from control and streptozotocin-induced diabetic rats during early organogenesis. Embryos from diabetic rats showed decreased concentrations of PPARdelta and its endogenous agonist PGI(2) when compared with controls. In embryos from control rats, the addition of the PPARdelta activators (cPGI(2) and PGA(1)) increased embryonic phospholipid levels and de novo phospholipid synthesis studied using (14)C-acetate as a tracer. PGE(2) formed from arachidonate released from phospholipid stores was also up-regulated by PPARdelta activators. In embryos from diabetic rats, reduced phospholipid synthesis and PGE(2) content were observed, and clearly up-regulated by cPGI(2) additions to values similar to those found in control embryos. These data suggest that PPARdelta may play an important role in lipid metabolic and signalling pathways during embryo organogenesis, developmental pathways that are altered in embryos from diabetic rats, possibly as a result of a reduction in levels of PPARdelta and its endogenous activator PGI(2).
Asunto(s)
Diabetes Mellitus Experimental/embriología , Epoprostenol/metabolismo , Enfermedades Fetales/metabolismo , Metabolismo de los Lípidos , Organogénesis , PPAR delta/metabolismo , Preñez , Animales , Dinoprostona/análisis , Técnicas de Cultivo de Embriones , Embrión de Mamíferos/anatomía & histología , Embrión de Mamíferos/metabolismo , Epoprostenol/farmacología , Femenino , Desarrollo Fetal/efectos de los fármacos , Enfermedades Fetales/inducido químicamente , Metabolismo de los Lípidos/efectos de los fármacos , Masculino , PPAR delta/fisiología , Embarazo , Embarazo en Diabéticas , Ratas , Ratas Wistar , Transducción de Señal , EstreptozocinaRESUMEN
Matrix metalloproteinases (MMPs) are involved in placental remodelling throughout pregnancy. Diabetes mellitus induces alterations in tissue production of NO, a regulator of MMPs activity. The present work evaluates placental and fetal MMPs and NO levels during midpregnancy in neonatal streptozotocin-induced diabetic rats. MMP-2 and MMP-9 immunolabelling was increased both in the labyrinth zone (p<0.001) and in the giant trophoblast cells of the junctional zone (p<0.001) from diabetic placenta, when compared with controls. Also MMP-2 (p<0.01) and MMP-9 (p<0.005) activities were increased in both maternal and fetal sides of diabetic placenta when related to controls. In both sides of the diabetic placenta, nitrate/nitrite concentrations (which indicate NO production) were higher than in controls (p<0.05). An intense immunostaining for nitrotyrosine, indicating peroxynitrite-induced damage, was found in both labyrinth (p<0.001) and junctional zones (p<0.001) of diabetic placenta. Enhanced MMP-2 activity (p<0.05) and NO production were also higher in the fetuses from diabetic rats when compared to controls (p<0.005). These findings demonstrate alterations in MMPs and NO in the feto-placental unit of diabetic rats, anomalies that are likely to be involved in the developmental alterations induced by maternal diabetes.